WO2023182481A1 - Exhaust gas purification catalyst - Google Patents
Exhaust gas purification catalyst Download PDFInfo
- Publication number
- WO2023182481A1 WO2023182481A1 PCT/JP2023/011744 JP2023011744W WO2023182481A1 WO 2023182481 A1 WO2023182481 A1 WO 2023182481A1 JP 2023011744 W JP2023011744 W JP 2023011744W WO 2023182481 A1 WO2023182481 A1 WO 2023182481A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- catalyst layer
- exhaust gas
- mass
- base material
- equivalent amount
- Prior art date
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- 239000003054 catalyst Substances 0.000 title claims abstract description 598
- 238000000746 purification Methods 0.000 title claims abstract description 94
- 238000005192 partition Methods 0.000 claims abstract description 103
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
- B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
- F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
- F01N3/022—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters characterised by specially adapted filtering structure, e.g. honeycomb, mesh or fibrous
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
Definitions
- the present invention relates to an exhaust gas purifying catalyst.
- Exhaust gas emitted from internal combustion engines such as automobiles and motorcycles contains harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx).
- harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx).
- Three-way catalysts are used to purify these harmful components and render them harmless.
- a catalyst containing noble metal elements such as Pt, Pd, and Rh is used as Pt, Pd, and Rh is used as Pt, Pd, and Rh.
- the wall flow type base material has an inflow side cell with an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side, and a closed end on the exhaust gas inflow side and a closed cell on the exhaust gas outflow side. It includes an outflow side cell with an open end, and a porous partition wall that partitions the inflow side cell and the outflow side cell.
- exhaust gas flows in from the exhaust gas inflow side end (opening) of the inflow side cell, passes through the porous partition wall, and flows out from the exhaust gas outflow side end (opening) of the outflow side cell. At this time, PM in the exhaust gas is collected in the pores inside the partition wall.
- the mounting space for exhaust gas purification catalysts is limited, so a catalyst layer containing noble metal elements such as Pt, Pd, and Rh is provided on a wall flow type base material to collect PM and to collect HC, CO, NOx, etc. Purification of harmful components is being considered.
- Patent Documents 1 and 2 disclose a wall flow type base material, a first catalyst layer formed from an end on the exhaust gas inflow side in the direction in which the partition wall extends, and a wall flow type base material in which the partition wall extends from the end on the exhaust gas outflow side.
- An exhaust gas purifying catalyst is described that includes a second catalyst layer formed in the direction of the exhaust gas purifying catalyst.
- the first catalyst layer is formed inside the partition so as to be in contact with the inflow side cells, and the second catalyst layer is formed inside the partition so as to be in contact with the outflow side cells.
- the first catalyst layer contains, for example, Rh
- the second catalyst layer contains, for example, Pd.
- Patent Document 3 discloses a wall flow type base material, a first catalyst layer formed from an end on the exhaust gas inflow side in the extending direction of the partition wall, and a first catalyst layer formed in the extending direction of the partition wall from the end on the exhaust gas outflow side.
- a catalyst for exhaust gas purification is described that includes a second catalyst layer formed facing toward the patent and a third catalyst layer formed on the second catalyst layer.
- the first catalyst layer is formed on the outer surface of the partition wall on the inflow side cell side
- the second catalyst layer is formed on the outer surface of the partition wall on the outflow side cell side.
- the first catalyst layer contains, for example, Rh
- the second catalyst layer contains, for example, Rh
- the third catalyst layer contains, for example, Pd.
- Patent Documents 1 and 2 Due to the soaring price of precious metals, there is a demand for the use of Pt, which is relatively inexpensive among precious metals.
- exhaust gas purifying catalysts using Pt exhaust gas purifying catalysts described in Patent Documents 1 and 2 are known.
- the exhaust gas purification catalysts described in Patent Documents 1 and 2 do not sufficiently achieve both the purification performance of low-temperature NOx generated during low-speed operation of the internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine. could not be realized.
- the present invention provides an exhaust gas purifying catalyst comprising a wall flow type base material and a catalyst layer containing Pt, which has the ability to purify low-temperature NOx generated during low-speed operation of an internal combustion engine and ultra-high-speed operation of an internal combustion engine.
- An object of the present invention is to provide an exhaust gas purifying catalyst that can achieve both purification performance of high-temperature NOx that is sometimes generated.
- the present invention provides the following exhaust gas purifying catalyst.
- a base material extending in the exhaust gas flow direction; a first catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh; a second catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh; a third catalyst layer containing Pt and optionally containing one or more noble metal elements other than Pt;
- An exhaust gas purification catalyst comprising:
- the base material is The inflow side cell extends in the exhaust gas flow direction, and has an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side;
- the outflow side cell extends in the exhaust gas flow direction, and has a closed end on the exhaust gas inflow side and an open end on the exhaust gas outflow side; a porous partition that partitions the inflow side cell and the outflow side cell; Equipped with The first catalyst layer is formed on the inflow-side cell side of the partition wall part along the exhaust gas flow direction from the exhaust gas inflow-side end of
- the metal equivalent amount of Rh in the second catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer
- the metal equivalent amount of Pt in the third catalyst layer is larger than the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer
- the mass of the second catalyst layer per unit volume of the portion of the base material where the second catalyst layer is formed is per unit volume of the portion of the base material where the third catalyst layer is formed.
- the mass ratio of the third catalyst layer is 0.3 or more and 1.9 or less.
- the metal equivalent amount of Rh in the first catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer
- the metal equivalent amount of Rh in the second catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer
- the first catalyst layer according to any one of [1] to [3], wherein at least a portion of the first catalyst layer protrudes from the outer surface of the partition wall on the inflow side cell side toward the inflow side cell side. Catalyst for exhaust gas purification.
- an exhaust gas purification catalyst that can achieve both the purification performance of low-temperature NOx generated during low-speed operation of an internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine.
- FIG. 1 is a partial sectional view showing a state in which an exhaust gas purifying catalyst according to an embodiment of the present invention is arranged in an exhaust path of an internal combustion engine.
- FIG. 2 is an end view taken along line AA in FIG. 1.
- FIG. 3 is an end view taken along line BB in FIG. 1.
- FIG. 4 is an enlarged view of the area indicated by the symbol R1 in FIG.
- FIG. 5 is an enlarged view of the area indicated by the symbol R2 in FIG.
- FIG. 6 is an end view taken along line CC in FIG. 1.
- an exhaust gas purifying catalyst 1 is arranged in an exhaust path in an exhaust pipe P of an internal combustion engine.
- the internal combustion engine is, for example, a gasoline engine (eg, a GDI engine, etc.), a diesel engine, or the like.
- the exhaust gas purifying catalyst 1 is arranged in the exhaust path of the internal combustion engine so that the axial direction of the base material 10 substantially coincides with the exhaust gas flow direction E.
- length means the axial dimension of the base material 10, unless otherwise specified.
- the exhaust gas purifying catalyst 1 includes a base material 10, a first catalyst layer 20, a second catalyst layer 30, and a third catalyst layer 40.
- the material constituting the base material 10 can be appropriately selected from known materials.
- the material constituting the base material 10 include ceramic materials, metal materials, and the like, with ceramic materials being preferred.
- ceramic materials include carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, alumina, zirconia, cordierite, mullite, and zircon. , aluminum titanate, magnesium titanate, and other oxide ceramics.
- the metal material include alloys such as stainless steel.
- the length L 10 of the base material 10 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, etc. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the length L 10 of the base material 10 is preferably 50 mm or more and 160 mm or less, more preferably 80 mm or more and 130 mm or less.
- the volume of the base material 10 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, etc. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the volume of the base material 10 is preferably 0.5L or more and 2.5L or less, more preferably 0.5L or more and 2.0L or less, and even more preferably 0.5L or more and 2.0L or less. It is 7L or more and 1.8L or less.
- the base material 10 is a wall flow type base material. As shown in FIGS. 2 to 6, the base material 10 includes a cylindrical portion 11, cells 13 (inflow side cells 13a and outflow side cells 13b), and adjacent cells 13 (inflow side cells 13a and outflow side cells 13b). A porous partition wall portion 12 is provided. It is preferable that the base material 10 is a honeycomb structure.
- the cylindrical part 11 defines the outer shape of the base material 10, and the axial direction of the cylindrical part 11 coincides with the axial direction of the base material 10.
- the shape of the cylindrical portion 11 is cylindrical, but it may have other shapes such as an elliptical shape or a polygonal shape.
- the cells 13 each extend in the exhaust gas flow direction E, and have an end on the exhaust gas inflow side and an end on the exhaust gas outflow side. has.
- the base material 10 includes a first sealing part 14 that seals the ends of some of the cells 13 on the exhaust gas outflow side, and a first sealing part 14 that seals the ends of the remaining cells 13 on the exhaust gas inflow side.
- some of the cells 13 are open at the end on the exhaust gas inflow side, and the end on the exhaust gas outflow side is opened at the first sealing section 14.
- the remaining cells 13 have their exhaust gas inflow ends closed with the second sealing part 15 and their exhaust gas outflow ends open. This is the outflow side cell 13b.
- a partition wall 12 exists between adjacent cells 13 (inflow side cell 13a and outflow side cell 13b), and adjacent cells 13 (inflow side cell 13a and outflow side cell 13b) are partitioned by partition walls 12.
- a plurality of (four in this embodiment) outflow cells 13b are arranged around one inflow cell 13a, and an inflow cell 13a, The inflow cell 13 a is separated from the outflow cell 13 b arranged around it by a partition wall 12 .
- plan view shape of the exhaust gas inflow side end (opening) of the inflow side cell 13a and the plan view shape of the exhaust gas outflow side end (opening) of the outflow side cell 13b are shown.
- each of the shapes in plan view is a quadrilateral, other shapes such as a hexagon or an octagon may be used.
- the partition wall portion 12 is provided within the cylindrical portion 11.
- the partition wall portion 12 has a porous structure through which exhaust gas can pass.
- the partition wall portion 12 has an outer surface S1a on the inflow side cell 13a side and an outer surface S1b on the outflow side cell 13b side.
- Outer surface S1a on the inflow side cell 13a side is a region on the inflow side cell 13a side that extends in the exhaust gas flow direction E (i.e., a region in contact with the inflow side cell 13a) among the outer surfaces that define the outer shape of the partition wall portion 12. It is.
- the outer surface S1b on the outflow side cell 13b side is the area on the outflow side cell 13b side that extends in the exhaust gas flow direction E (i.e., the area in contact with the outflow side cell 13b) among the outer surfaces that define the outer shape of the partition wall 12. It is.
- the thickness of the partition wall portion 12 can be adjusted as appropriate in consideration of PM trapping performance, pressure loss, etc. From the viewpoint of improving PM trapping performance and suppressing an increase in pressure loss, the thickness of the partition wall portion 12 is preferably 110 ⁇ m or more and 380 ⁇ m or less, more preferably 150 ⁇ m or more and 330 ⁇ m or less, and even more preferably 180 ⁇ m or more and 310 ⁇ m or less.
- the cell density per square inch of the base material 10 can be adjusted as appropriate in consideration of PM trapping performance, pressure loss, etc. From the viewpoint of improving PM trapping performance and suppressing an increase in pressure loss, the cell density per square inch of the base material 10 is preferably 180 cells or more and 350 cells or less.
- the cell density per square inch of the base material 10 is the cell density per square inch of the base material 10 in a cross section obtained by cutting the base material 10 along a plane perpendicular to the axial direction of the base material 10. This is the total number of side cells 13b).
- the first catalyst layer 20 will be explained below.
- the first catalyst layer 20 contains Rh.
- Rh is present in the first catalyst layer in the form of a catalytically active component containing Rh, such as a metal Rh, an alloy containing Rh, a compound containing Rh (for example, an oxide of Rh), etc., which can function as a catalytically active component. Included in 20. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Rh is preferably in the form of particles.
- the metal equivalent amount of Rh in the first catalyst layer 20 is preferably 0.1% by mass or more and 10.0% by mass based on the mass of the first catalyst layer 20.
- the content is more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
- the first catalyst layer 20 may contain one or more noble metal elements other than Rh.
- the noble metal elements other than Rh can be selected from, for example, Pt, Pd, Ru, Ir, Os, and the like.
- the noble metal element other than Rh includes a noble metal element other than Rh in a form that can function as a catalytically active component, for example, a metal, an alloy containing a noble metal element, a compound containing a noble metal element (e.g., an oxide of a noble metal element), etc. It is contained in the first catalyst layer 20 in the form of a catalytically active component. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing a noble metal element other than Rh is preferably in the form of particles.
- the total metal equivalent amount of all noble metal elements in the first catalyst layer 20 is preferably 0.1% by mass or more based on the mass of the first catalyst layer 20.
- the content is 0% by mass or less, more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
- the metal equivalent amount of Rh in the first catalyst layer 20 should be larger than the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer 20. is preferred. Further, from the same viewpoint, the metal equivalent amount of Rh in the first catalyst layer 20 is preferably larger than the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer 20.
- the ratio of the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer 20 to the metal equivalent amount of Rh in the first catalyst layer 20 is preferably 0.9 or less, more preferably 0. .5 or less, and even more preferably 0.3 or less.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.1 or more, or 0.15 or more. Each of these lower limits may be combined with any of the above upper limits.
- the ratio of the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer 20 to the metal equivalent amount of Rh in the first catalyst layer 20 is preferably 0.9 or less, more preferably It is 0.5 or less, more preferably 0.3 or less.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more. Each of these lower limits may be combined with any of the above upper limits.
- the first catalyst layer 20 may contain Pt.
- Pt is present in the first catalyst layer in the form of a catalytically active component containing Pt, such as metal Pt, an alloy containing Pt, a compound containing Pt (for example, an oxide of Pt), etc., which can function as a catalytically active component. Included in 20. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Pt is preferably in the form of particles.
- the ratio of the metal equivalent amount of Pt in the first catalyst layer 20 to the total metal equivalent amount of all noble metal elements in the first catalyst layer 20 is preferably 0.3 or less in terms of mass ratio. If the ratio is 0.3 or less, the catalytic activity of Rh can be stabilized.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.5 or more, or 0.1 or more. Each of these lower limits can be combined with the above upper limits.
- the metal equivalent amount of each noble metal element in the first catalyst layer 20 is It can be determined from information on the raw materials used in the production of. If information on the raw materials used to manufacture the first catalyst layer 20 is not known, the metal equivalent amount of each noble metal element in the first catalyst layer 20 can be determined using an inductively coupled plasma optical emission spectrometer (ICP-OES), It can be determined using an X-ray fluorescence analyzer (XRF), a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDX), or the like. Specifically, it is as follows.
- ICP-OES inductively coupled plasma optical emission spectrometer
- XRF X-ray fluorescence analyzer
- SEM-EDX scanning electron microscope-energy dispersive X-ray analyzer
- Elemental analysis is performed on the sample obtained from the first catalyst layer 20 using a conventional method such as SEM-EDX, and the types of constituent elements of the entire sample are identified, as well as the metal equivalent amount of each identified metal element. Find (mass%). For each of the 10 fields of view of the SEM, the metal equivalent amount (mass%) of each metal element is determined, and the average value of the metal equivalent amount (mass %) of each metal element in the 10 fields of view is determined for each metal in the first catalyst layer 20. It is expressed as the metal equivalent amount (mass%) of the element.
- the mass of the first catalyst layer 20 per unit volume of the portion of the base material 10 where the first catalyst layer 20 is formed is preferably 11 g/L or more and 133 g/L. L or less, more preferably 22 g/L or more and 89 g/L or less, even more preferably 22 g/L or more and 67 g/L or less.
- the mass of the first catalyst layer 20 per unit volume of the portion of the base material 10 where the first catalyst layer 20 is formed is calculated by the formula: (mass of the first catalyst layer 20)/((volume of the base material 10) It is calculated from ⁇ (average length L 20 of first catalyst layer 20 / length L 10 of base material 10)).
- the “mass of the first catalyst layer 20” refers to the mass of noble metal elements in metal terms among all the metal elements contained in the first catalyst layer 20, and the oxidized mass of metal elements other than the noble metal elements. It means the sum of the calculated mass in physical terms. That is, “the mass of the first catalyst layer 20” is the mass of the noble metal element contained in the first catalyst layer 20 in terms of metal, and the mass of the metal element other than the noble metal element contained in the first catalyst layer 20 in terms of oxide. means the calculated mass obtained by summing the Note that the term “metal element” also includes metalloid elements such as Si and B.
- non-noble metal element includes Pt, Pd, Rh, Au, Ag, Ru, Ir, and Os.
- oxides of rare earth elements other than Ce, Pr and Tb are referred to as sesquioxides (M 2 O 3 , M represents rare earth elements other than Ce, Pr and Tb), and oxides of Ce are referred to as CeO 2 , Pr oxide is Pr 6 O 11 , Tb oxide is Tb 4 O 7 , Al oxide is Al 2 O 3 , Zr oxide is ZrO 2 , Si oxide is SiO 2 , B oxide is B 2 O 3 , Cr oxide is Cr 2 O 3 , Mg oxide is MgO, Ca oxide is CaO, Sr oxide is SrO, Ba The oxide of is BaO, the oxide of Fe is Fe 3 O 4 , the oxide of Mn is Mn 3 O 4 , the oxide of Ni is NiO, the oxide of Ti is TiO 2 , the oxide of Zn. means ZnO, and oxide of Sn means SnO2 .
- An example of a method for measuring the average length L 20 of the first catalyst layer 20 is as follows.
- a sample extending in the axial direction of the base material 10 and having the same length as the length L10 of the base material 10 is cut out from the exhaust gas purifying catalyst 1.
- the sample is, for example, cylindrical with a diameter of 25.4 mm. Note that the value of the diameter of the sample can be changed as necessary.
- the sample was cut at intervals of 5 mm along a plane perpendicular to the axial direction of the base material 10, and the first cut piece, the second cut piece, ..., the nth cut piece were cut in order from the end of the sample on the exhaust gas inflow side. obtain.
- the length of the cut piece is 5 mm.
- the composition of the cut pieces was determined using an inductively coupled plasma optical emission spectrometer (ICP-OES), an X-ray fluorescence spectrometer (XRF), a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDX), etc. Based on the composition of the cut piece, it is determined whether the cut piece includes a part of the first catalyst layer 20 or not.
- ICP-OES inductively coupled plasma optical emission spectrometer
- XRF X-ray fluorescence spectrometer
- SEM-EDX scanning electron microscope-energy dispersive X-ray spectrometer
- the cut surface can be observed using a scanning electron microscope (SEM), an electron beam microanalyzer (EPMA), etc., and it can be confirmed whether the cut piece includes a part of the first catalyst layer 20 or not.
- SEM scanning electron microscope
- EPMA electron beam microanalyzer
- elemental mapping of the cut surface may be performed. Elemental mapping can be performed using, for example, a SEM-EDX, an electron beam microanalyzer (EPMA), a transmission type X-ray inspection device, or the like.
- the first cut piece to the kth cut piece include a part of the first catalyst layer 20, but the (k+1)th to nth cut pieces do not include a part of the first catalyst layer 20, they are not included in the sample.
- the length of the first catalyst layer 20 is (5 ⁇ k) mm.
- An example of a more detailed method for measuring the length of the first catalyst layer 20 included in the sample is as follows.
- the k-th cut piece (that is, the cut piece obtained from the closest exhaust gas outflow side of the sample among the cut pieces including a part of the first catalyst layer 20) is cut in the axial direction of the base material 10, and then SEM, EPMA
- SEM, EPMA By observing a portion of the first catalyst layer 20 present on the cut surface using a tool such as a cutting tool, the length of the portion of the first catalyst layer 20 at the k-th cut section is measured.
- the length of the first catalyst layer 20 included in each sample is measured, and the average value thereof is determined as the average length of the first catalyst layer 20.
- L be 20 .
- the amount per unit volume of the portion of the base material 10 on which the first catalyst layer 20 is formed is The mass of the first catalyst layer 20 can be determined from information on the raw materials used to manufacture the first catalyst layer 20.
- the first catalyst layer 20 includes one or more types of carriers, and at least a part of the catalytically active component is supported on the one or more types of carriers.
- At least a part of the catalytically active component is supported on the carrier means that at least a part of the catalytically active component is physically and/or chemically adsorbed and/or or the state in which it is maintained. It can be confirmed that at least a portion of the catalytically active component is supported on the carrier using, for example, SEM-EDX. Specifically, in the elemental mapping obtained by analyzing the cross section of the catalyst layer with SEM-EDX, if at least part of the catalytically active component and the support are present in the same area, at least part of the catalytically active component is It can be determined that the part is supported on the carrier.
- the carrier can be selected from, for example, inorganic oxides.
- the inorganic oxide is, for example, particulate. From the viewpoint of improving the ability to support the catalytically active component, the inorganic oxide is preferably porous.
- the inorganic oxide may or may not have oxygen storage capacity (OSC).
- OSC oxygen storage capacity
- Inorganic oxides used as supports are distinguished from inorganic oxides used as binders (eg, inorganic oxide binders such as alumina binders, zirconia binders, titania binders, silica binders, etc.).
- the inorganic oxide used as the binder is derived from the sol used as a raw material (for example, an inorganic oxide sol such as alumina sol, zirconia sol, titania sol, silica sol, etc.).
- inorganic oxides include Al-based oxides, rare earth element (hereinafter sometimes referred to as "Ln") oxides, Ln-Zr-based composite oxides, zirconia (ZrO 2 ), and silica (SiO 2 ), titania (TiO 2 ), zeolite (aluminosilicate), MgO, ZnO, SnO 2 and the like-based oxides.
- Ln rare earth element
- ZrO 2 zirconia
- silica SiO 2
- TiO 2 titania
- zeolite aluminosilicate
- an Al-based oxide refers to an oxide containing Al, in which Al is the element with the highest content on a mass basis among the elements other than oxygen constituting the oxide. .
- Al-based oxides are distinguished from alumina, which is used as a binder. In this specification, alumina used as a binder may be referred to as "alumina binder”.
- Al-based oxides generally have higher heat resistance than other inorganic oxides (for example, Ln-Zr-based composite oxides). Therefore, by including the Al-based oxide in the first catalyst layer 20, the heat resistance of the first catalyst layer 20 is improved, and the exhaust gas purification performance of the first catalyst layer 20 is improved.
- Al-based oxide examples include alumina (Al 2 O 3 ), modified alumina, and the like.
- Modified alumina contains one or more elements other than Al and O.
- modified alumina examples include oxides obtained by modifying the surface of alumina with elements other than Al and O, and oxides obtained by dissolving elements other than Al and O in alumina.
- Elements other than Al and O can be selected from, for example, B, Si, Zr, Cr, rare earth elements, alkaline earth metal elements, and the like.
- the modified alumina include alumina-silica, alumina-zirconia, alumina-chromia, alumina-ceria, and alumina-lanthana.
- the Al 2 O 3 equivalent amount of Al in the Al-based oxide is preferably 50% by mass or more, more preferably 70% by mass or more, and more preferably 50% by mass or more, more preferably 70% by mass or more, based on the mass of the Al-based oxide. More preferably, it is 80% by mass or more. The upper limit is 100% by mass.
- the amount of Al in the Al-based oxide in terms of Al 2 O 3 is It can be determined from information on the raw materials used in the production of. If the information on the raw materials used for manufacturing the first catalyst layer 20 is not known, the amount of Al in the Al-based oxide in terms of Al 2 O 3 can be calculated using an energy dispersive X-ray spectrometer. (EDX) analysis and obtained elemental mapping and EDX elemental analysis of specified particles.
- EDX energy dispersive X-ray spectrometer.
- the oxide equivalent amount of a predetermined element in a specified particle can be determined.
- the amount of the Al-based oxide in the first catalyst layer 20 is preferably based on the mass of the first catalyst layer 20.
- the content is 5% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, even more preferably 7% by mass or more and 30% by mass or less. If information on the raw materials used to manufacture the first catalyst layer 20 (for example, composition, amount, etc.) is known, the amount of Al-based oxide in the first catalyst layer 20 can be determined by It can be determined from information on raw materials used in manufacturing.
- the amount of Al-based oxide in the first catalyst layer 20 can be determined using ICP-OES, XRF, SEM-EDX, etc. You can ask for it. Specifically, it is as follows.
- the Ln-Zr-based composite oxide is a composite oxide containing one or more types of Ln and Zr, and the mass of Ln in the composite oxide in terms of oxide is less than the mass of the composite oxide.
- oxidation is 3% by mass or more and 97% by mass or less
- the mass of Zr in the composite oxide in terms of ZrO 2 is 3% by mass or more and 97% by mass or less, based on the mass of the composite oxide.
- the mass of one or more types of Ln in terms of oxide means, when the Ln-Zr-based composite oxide contains one type of Ln, the amount of the one type of Ln in terms of oxide, When the Ln-Zr-based composite oxide contains two or more types of Ln, it means the total amount of the two or more types of Ln in terms of oxide.
- Ln-Zr-based composite oxides have oxygen storage ability (that is, the ability to store oxygen when the oxygen concentration in the exhaust gas is high and release oxygen when the oxygen concentration in the exhaust gas is low). Expanding the operating window of catalytically active components by mitigating concentration fluctuations. Therefore, by including the Ln-Zr-based composite oxide in the first catalyst layer 20, the exhaust gas purifying ability of the first catalyst layer 20 is improved.
- the Ln--Zr-based composite oxide (hereinafter referred to as "first Ln--Zr-based composite oxide") according to one embodiment includes Ce and Zr.
- the first Ln--Zr-based composite oxide may be referred to as a "Ce--Zr-based composite oxide.”
- Ce, Zr, and O preferably form a solid solution phase.
- Ce, Zr, and O may form a single phase (CeO 2 phase, ZrO 2 phase, etc.) that is a crystalline phase or an amorphous phase in addition to a solid solution phase. It can be confirmed using X-ray diffraction (XRD), SEM-EDX, etc. that Ce, Zr, and O form a solid solution.
- the first Ln-Zr-based composite oxide may contain one or more metal elements other than Ce and Zr.
- metal elements other than Ce and Zr include rare earth elements other than Ce.
- rare earth elements other than Ce include Y, Pr, Sc, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
- Metal elements other than Ce and Zr may form a solid solution phase together with Ce, Zr, and O, or may form a single phase that is a crystalline phase or an amorphous phase, or may form a solid solution phase or an amorphous phase. Both may form a single phase. Formation of a solid solution phase can be confirmed using XRD, SEM-EDX, etc.
- the CeO 2 equivalent amount of Ce in the first Ln-Zr composite oxide is preferably 3% by mass based on the mass of the first Ln-Zr composite oxide.
- the content is 40% by mass or less, more preferably 5% by mass or more and 30% by mass or less, even more preferably 5% by mass or more and 25% by mass or less.
- the CeO 2 equivalent amount of Ce in the first Ln-Zr based composite oxide can be determined in the same manner as the Al 2 O 3 equivalent amount of Al in the Al based oxide.
- the amount of Zr in the first Ln-Zr composite oxide converted to ZrO 2 is preferably 30% by mass or more based on the mass of the first Ln-Zr composite oxide.
- the content is 90% by mass or less, more preferably 40% by mass or more and 80% by mass or less, even more preferably 50% by mass or more and 80% by mass or less.
- the amount of Zr in the first Ln--Zr-based composite oxide in terms of ZrO 2 can be determined in the same manner as the amount of Al in the Al-based oxide in terms of Al 2 O 3 .
- the total amount of Ce in terms of CeO 2 and the amount of Zr in terms of ZrO 2 in the first Ln-Zr complex oxide is It is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, based on the mass of .
- the upper limit is 100% by mass.
- the first Ln-Zr composite oxide in the first catalyst layer 20 includes the first Ln-Zr composite oxide, from the viewpoint of improving oxygen storage capacity and heat resistance, the first Ln-Zr composite oxide in the first catalyst layer 20
- the amount is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, even more preferably 60% by mass or more and 90% by mass or less, based on the mass of the first catalyst layer 20. be.
- the amount of the first Ln--Zr-based composite oxide in the first catalyst layer 20 can be determined in the same manner as the amount of Al-based oxide in the first catalyst layer 20.
- the Ln-Zr-based composite oxide according to another embodiment contains one or more types of Ln other than Ce and Zr, Contains no Ce.
- second Ln-Zr-based composite oxide contains one or more types of Ln other than Ce and Zr, Contains no Ce.
- one or more types of Ln, Zr, and O other than Ce preferably form a solid solution phase.
- One or more types of Ln, Zr, and O other than Ce may be present in a single phase that is a crystalline phase or an amorphous phase (an oxide phase of one or more types of Ln other than Ce) in addition to a solid solution phase. , ZrO 2 phase, etc.). It can be confirmed using XRD, SEM-EDX, etc. that one or more types of Ln, Zr, and O other than Ce form a solid solution.
- the second Ln-Zr-based composite oxide may contain one or more metal elements other than Ln and Zr.
- metal elements other than Ln and Zr include alkaline earth metal elements.
- alkaline earth metal elements include Ca, Sr, and Ba.
- Metal elements other than Ln and Zr may form a solid solution phase with one or more types of Ln other than Ce, Zr, and O, or may form a single phase that is a crystalline phase or an amorphous phase. or may form both a solid solution phase and a single phase. Formation of a solid solution phase can be confirmed using XRD, SEM-EDX, etc.
- the oxide equivalent amount of one or more types of Ln other than Ce in the second Ln-Zr composite oxide is Based on the mass, the content is preferably 10% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, even more preferably 30% by mass or more and 70% by mass or less.
- the oxide equivalent amount of one or more types of Ln other than Ce in the second Ln-Zr based composite oxide means that the second Ln-Zr based composite oxide contains one type of Ln other than Ce.
- the oxide equivalent amount of one type of Ln other than Ce is Based on the mass, the content is preferably 10% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, even more preferably 30% by mass or more and 70% by mass or less.
- the oxide-equivalent amount of one or more types of Ln other than Ce in the second Ln-Zr-based composite oxide is determined in the same manner as the Al 2 O 3- equivalent amount of Al in the Al-based oxide. I can do it.
- the amount of Zr in the second Ln-Zr composite oxide converted to ZrO 2 is preferably 30% by mass or more based on the mass of the second Ln-Zr composite oxide.
- the content is 90% by mass or less, more preferably 35% by mass or more and 80% by mass or less, even more preferably 40% by mass or more and 75% by mass or less.
- the ZrO 2 equivalent amount of Zr in the second Ln-Zr based composite oxide can be determined in the same manner as the Al 2 O 3 equivalent amount of Al in the Al based oxide.
- the sum of the oxide equivalent amount of one or more types of Ln other than Ce and the ZrO 2 equivalent amount of Zr in the second Ln-Zr-based composite oxide is: It is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, based on the mass of the second Ln-Zr complex oxide.
- the upper limit is 100% by mass.
- the second Ln-Zr-based composite oxide in the first catalyst layer 20 includes the second Ln-Zr-based composite oxide, from the viewpoint of improving oxygen storage capacity and heat resistance, the second Ln-Zr-based composite oxide in the first catalyst layer 20
- the amount is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, even more preferably 60% by mass or more and 90% by mass or less, based on the mass of the first catalyst layer 20. be.
- the amount of the second Ln-Zr based composite oxide in the first catalyst layer 20 can be determined in the same manner as the amount of the Al based oxide in the first catalyst layer 20.
- the first and second Ln-Zr-based composite oxides may be used together.
- the first and second Ln-Zr-based composite oxides from the viewpoint of improving oxygen storage capacity and heat resistance, the first and second Ln- The total amount of the Zr-based composite oxide is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, even more preferably 60% by mass, based on the mass of the first catalyst layer 20. % or more and 90% by mass or less.
- the total amount of inorganic oxides other than Al-based oxides and Ln-Zr-based composite oxides in the first catalyst layer 20 is based on the mass of the first catalyst layer 20. , preferably from 0% by mass to 20% by mass, more preferably from 0.5% by mass to 15% by mass, even more preferably from 1% by mass to 15% by mass.
- the total amount of inorganic oxides other than Al-based oxides and Ln-Zr-based composite oxides in the first catalyst layer 20 can be determined in the same manner as the amount of Al-based oxides in the first catalyst layer 20. .
- the first catalyst layer 20 may contain a stabilizer, a binder, and the like.
- the binder include inorganic oxide binders such as alumina binder, zirconia binder, titania binder, and silica binder.
- the inorganic oxide binder is derived from an inorganic oxide sol such as alumina sol, zirconia sol, titania sol, and silica sol.
- the stabilizer include nitrates, carbonates, oxides, and sulfates of alkaline earth metal elements.
- the first catalyst layer 20 is formed on the inflow side cell 13a side of the partition wall portion 12.
- the first catalyst layer 20 extends along the exhaust gas flow direction E from the end of the partition wall 12 on the exhaust gas inflow side. In this embodiment, the first catalyst layer 20 does not reach the end of the partition wall 12 on the exhaust gas outflow side, but may reach the end of the partition wall 12 on the exhaust gas outflow side.
- the catalyst layer 20 has a portion that protrudes from the outer surface S1a of the partition wall portion 12 on the inflow side cell 13a side toward the inflow side cell 13a side (hereinafter referred to as “raised portion”). This improves the contact between the exhaust gas and PM, making it possible to more effectively improve the exhaust gas purification performance and the PM trapping performance.
- the first catalyst layer 20 may be composed of only a raised portion, or may include a portion existing inside the partition wall portion 12 (hereinafter referred to as “internal portion”) together with the raised portion. Since the partition wall portion 12 is porous, when forming the first catalyst layer 20, an internal portion may be formed together with a raised portion. The raised portion and the internal portion may be continuous. The first catalyst layer 20 may be composed only of an internal portion. “The first catalyst layer 20 is formed on the inflow side cell 13a side of the partition wall 12” includes an embodiment in which the first catalyst layer 20 is formed only of a raised portion, and an embodiment in which the first catalyst layer 20 is internally formed.
- first catalyst layer 20 includes only a portion and embodiments in which the first catalyst layer 20 has a raised portion and an inner portion are included.
- the region where the raised portion of the first catalyst layer 20 exists does not overlap with the region where the partition wall portion 12 exists, but the region where the internal portion of the first catalyst layer 20 exists overlaps with the region where the partition wall portion 12 exists. Therefore, the exhaust gas purifying catalyst 1 was cut along a plane perpendicular to the axial direction of the base material 10, and the first catalyst layer 20 present on the cut surface was observed, and the morphology between the first catalyst layer 20 and the partition wall portion 12 was observed. Based on the difference, the raised portion and the inner portion of the first catalyst layer 20 can be identified.
- elemental mapping of the cut surface may be performed. Elemental mapping can be performed, for example, by using a combination of observation of the cut surface using SEM and compositional analysis of the cut surface.
- Elemental mapping can be performed using, for example, a SEM-EDX, an electron beam microanalyzer (EPMA), a transmission type X-ray inspection device, or the like.
- EMA electron beam microanalyzer
- the protruding portion and the internal portion can be identified based on the difference in morphology and composition between the first catalyst layer 20 and the partition wall portion 12.
- the average length L 20 of the first catalyst layer 20 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, and the like. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the percentage of the average length L 20 of the first catalyst layer 20 to the length L 10 of the base material 10 (L 20 /L 10 ⁇ 100) is preferably 15 % or more and 90% or less, more preferably 20% or more and 80% or less, even more preferably 30% or more and 80% or less.
- the second catalyst layer 30 contains Rh.
- Rh is present in the second catalyst layer in the form of a catalytically active component containing Rh, such as a metal Rh, an alloy containing Rh, a compound containing Rh (for example, an oxide of Rh), etc., which can function as a catalytically active component. Included in 30. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Rh is preferably in the form of particles.
- the metal equivalent amount of Rh in the second catalyst layer 30 is preferably 0.1% by mass or more and 10.0% by mass based on the mass of the second catalyst layer 30.
- the content is more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
- the second catalyst layer 30 may contain one or more noble metal elements other than Rh.
- the noble metal elements other than Rh can be selected from, for example, Pt, Pd, Ru, Ir, Os, and the like.
- the noble metal element other than Rh includes a noble metal element other than Rh in a form that can function as a catalytically active component, for example, a metal, an alloy containing a noble metal element, a compound containing a noble metal element (e.g., an oxide of a noble metal element), etc. It is contained in the second catalyst layer 30 in the form of a catalytically active component. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing a noble metal element other than Rh is preferably in the form of particles.
- the total metal equivalent amount of all noble metal elements in the second catalyst layer 30 is preferably 0.1% by mass or more based on the mass of the second catalyst layer 30.
- the content is 0% by mass or less, more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
- the metal equivalent amount of Rh in the second catalyst layer 30 should be larger than the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer 30. is preferred. Further, from the same viewpoint, the metal equivalent amount of Rh in the second catalyst layer 30 is preferably larger than the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer 30.
- the ratio of the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer 30 to the metal equivalent amount of Rh in the second catalyst layer 30 is preferably 0.9 or less, more preferably 0. .5 or less, and even more preferably 0.3 or less.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.1 or more, or 0.15 or more. Each of these lower limits may be combined with any of the above upper limits.
- the ratio of the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer 30 to the metal equivalent amount of Rh in the second catalyst layer 30 is preferably 0.9 or less, more preferably It is 0.5 or less, more preferably 0.3 or less.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more. Each of these lower limits may be combined with any of the above upper limits.
- the metal equivalent amount of each noble metal element in the second catalyst layer 30 is It can be determined from information on the raw materials used in the production of. If information on the raw materials used to manufacture the second catalyst layer 30 is not known, the amount of each noble metal element in the second catalyst layer 30 in terms of metal is the amount of each noble metal element in the first catalyst layer 20 It can be determined in the same way as the quantity.
- the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed is preferably 7 g/L or more and 86 g/L. L or less, more preferably 14 g/L or more and 57 g/L or less, even more preferably 14 g/L or more and 43 g/L or less.
- the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed is calculated by the formula: (mass of the second catalyst layer 30)/((volume of the base material 10) It is calculated from ⁇ (average length L 30 of second catalyst layer 30 / length L 10 of base material 10)).
- first catalyst layer 20 also applies to the mass of the second catalyst layer 30.
- second catalyst layer 30 is read as “second catalyst layer 30.”
- the above description regarding the method for measuring the average length L 20 of the first catalyst layer 20 also applies to the method for measuring the average length L 30 of the second catalyst layer 30 .
- the "first catalyst layer 20" is read as the "second catalyst layer 30”
- the "average length L 20 " is read as "average length L 30 ".
- the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the base material 10, and the samples are cut in order from the end of the sample on the exhaust gas outflow side.
- a first cut piece, a second cut piece, . . . , an nth cut piece are obtained.
- the amount per unit volume of the portion of the base material 10 on which the second catalyst layer 30 is formed is known.
- the mass of the second catalyst layer 30 can be determined from information on the raw materials used to manufacture the second catalyst layer 30.
- the second catalyst layer 30 includes one or more types of carriers, and at least a part of the catalytically active component is supported on the one or more types of carriers.
- the meaning and confirmation method of "at least a portion of the catalytically active component is supported on the carrier" are as described in the above description regarding the first catalyst layer 20.
- the above explanation regarding the carrier in the first catalyst layer 20 also applies to the second catalyst layer 30.
- first catalyst layer 20 is read as "second catalyst layer 30.”
- the second catalyst layer 30 may contain a stabilizer, a binder, and the like. A description of the binder and stabilizer is given above.
- the second catalyst layer 30 is formed on the outflow side cell 13b side of the partition wall portion 12.
- the second catalyst layer 30 extends from the end of the partition wall 12 on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction E.
- the second catalyst layer 30 does not reach the end of the partition wall 12 on the exhaust gas inflow side, but may reach the end of the partition wall 12 on the exhaust gas inflow side.
- the second catalyst layer 30 protrudes from the outer surface S1b of the partition wall 12 on the outflow side cell 13b side toward the outflow side cell 13b side, that is, the second It is preferable that the catalyst layer 30 has a portion that protrudes from the outer surface S1b of the partition wall portion 12 on the outflow side cell 13b side toward the outflow side cell 13b side (hereinafter referred to as “raised portion”). This improves the contact between the exhaust gas and PM, making it possible to more effectively improve the exhaust gas purification performance and the PM trapping performance.
- the second catalyst layer 30 may be composed of only a raised portion, or may include a portion existing inside the partition wall portion 12 (hereinafter referred to as “internal portion”) together with the raised portion. Since the partition wall portion 12 is porous, when forming the second catalyst layer 30, an internal portion may be formed together with a raised portion. The raised portion and the internal portion may be continuous. The second catalyst layer 30 may be composed only of an internal portion. “The second catalyst layer 30 is formed on the outflow cell 13b side of the partition wall 12” includes an embodiment in which the second catalyst layer 30 is formed only of a raised portion, and an embodiment in which the second catalyst layer 30 is internally formed.
- both embodiments in which the second catalyst layer 30 includes only a portion and embodiments in which the second catalyst layer 30 has a raised portion and an inner portion are included.
- first catalyst layer 20 is read as “second catalyst layer 30.”
- the average length L 30 of the second catalyst layer 30 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, and the like. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the percentage of the average length L 30 of the second catalyst layer 30 to the length L 10 of the base material 10 (L 30 /L 10 ⁇ 100) is preferably 15 % or more and 90% or less, more preferably 20% or more and 80% or less, even more preferably 30% or more and 80% or less.
- the percentage ((L 20 +L 30 )/L 10 ⁇ 100) is preferably 100% or more and 180% or less, more preferably 105% or more and 150% or less, even more preferably 110% or more and 130% or less.
- the third catalyst layer 40 will be explained below.
- the third catalyst layer 40 contains Pt.
- Pt is present in the third catalyst layer in the form of a catalytically active component containing Pt, such as metal Pt, an alloy containing Pt, a compound containing Pt (for example, an oxide of Pt), etc., which can function as a catalytically active component. Included in 40. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Pt is preferably in the form of particles.
- the metal equivalent amount of Pt in the third catalyst layer 40 is preferably 0.1% by mass or more and 20% by mass or less, based on the mass of the third catalyst layer 40. More preferably 0.5% by mass or more and 15% by mass or less, even more preferably 1.0% by mass or more and 10% by mass or less.
- the third catalyst layer 40 may contain one or more noble metal elements other than Pt.
- the noble metal element other than Pt can be selected from, for example, Au, Ag, Rh, Pd, Ru, Ir, Os, and the like.
- the noble metal element other than Pt includes a noble metal element other than Pt in a form that can function as a catalytically active component, for example, a metal, an alloy containing a noble metal element, a compound containing a noble metal element (e.g., an oxide of a noble metal element), etc. It is contained in the third catalyst layer 40 in the form of a catalytically active component. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing a noble metal element other than Pt is preferably in the form of particles.
- the total metal equivalent amount of all precious metal elements in the third catalyst layer 40 is preferably 0.1% by mass or more and 20% by mass based on the mass of the third catalyst layer 40. % or less, more preferably 0.5% by mass or more and 15% by mass or less, even more preferably 1.0% by mass or more and 10% by mass or less.
- the metal equivalent amount of Pt in the third catalyst layer 40 should be larger than the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer 40. is preferred. Further, from the same viewpoint, it is preferable that the metal equivalent amount of Pt in the third catalyst layer 40 is larger than the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer 40.
- the ratio of the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer 40 to the metal equivalent amount of Pt in the third catalyst layer 40 is preferably 0.9 or less, more preferably 0. .5 or less, and even more preferably 0.3 or less.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.1 or more, or 0.15 or more. Each of these lower limits may be combined with any of the above upper limits.
- the ratio of the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer 40 to the metal equivalent amount of Pt in the third catalyst layer 40 is preferably 0.9 or less, more preferably It is 0.5 or less, more preferably 0.3 or less.
- the lower limit of this ratio is zero.
- the ratio may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more. Each of these lower limits may be combined with any of the above upper limits.
- the metal equivalent amount of each noble metal element in the third catalyst layer 40 is It can be determined from information on the raw materials used in the production of. If information on the raw materials used for manufacturing the third catalyst layer 40 is not known, the amount of each noble metal element in the third catalyst layer 40 in terms of metal is It can be determined in the same way as the quantity.
- the mass of the third catalyst layer 40 per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed is preferably 7 g/L or more and 86 g/L. L or less, more preferably 14 g/L or more and 57 g/L or less, even more preferably 14 g/L or more and 43 g/L or less.
- the mass of the third catalyst layer 40 per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed is calculated by the formula: (mass of the third catalyst layer 40)/((volume of the base material 10) It is calculated from ⁇ (average length L 40 of third catalyst layer 40 / length L 10 of base material 10)).
- first catalyst layer 20 also applies to the mass of the third catalyst layer 40.
- first catalyst layer 20 is read as “third catalyst layer 40.”
- first catalyst layer 20 is read as “third catalyst layer 40.”
- the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the base material 10, and the samples are cut in order from the end of the sample on the exhaust gas outflow side.
- a first cut piece, a second cut piece, . . . , an nth cut piece are obtained.
- the amount per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed is The mass of the third catalyst layer 40 can be determined from information on the raw materials used to manufacture the third catalyst layer 40.
- the total mass of the portion where the layer 40 is formed and the mass of the third catalyst layer 40 per unit volume is preferably 14 g/L or more and 129 g/L or less, more preferably 21 g/L or more and 100 g/L or less, and even more Preferably it is 29 g/L or more and 86 g/L or less.
- the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed is The ratio of the masses of the three catalyst layers 40 is preferably 0.3 or more and 1.9 or less, more preferably 0.5 or more and 1.5 or less, and even more preferably 0.7 or more and 1.3 or less.
- the third catalyst layer 40 includes one or more types of carriers, and at least a part of the catalytically active component is supported on the one or more types of carriers.
- the meaning and confirmation method of "at least a portion of the catalytically active component is supported on the carrier" are as described in the above description regarding the first catalyst layer 20.
- the above explanation regarding the carrier in the first catalyst layer 20 also applies to the third catalyst layer 40.
- first catalyst layer 20 is read as "third catalyst layer 40.”
- the third catalyst layer 40 may contain a stabilizer, a binder, and the like. A description of the binder and stabilizer is given above.
- the third catalyst layer 40 is formed on the second catalyst layer 30.
- the expression “the third catalyst layer 40 is formed on the second catalyst layer 30” means that the main surface of the second catalyst layer 30 is opposite to the main surface on the partition wall 12 side of the base material 10. This means that at least a portion (preferably all) of the third catalyst layer 40 is present on the main surface of the side.
- the main surface of the second catalyst layer 30 means the outer surface of the second catalyst layer 30 that extends in the exhaust gas flow direction E.
- the third catalyst layer 40 may be provided directly on the main surface of the second catalyst layer 30, or may be provided via another layer.
- the third catalyst layer 40 extends from the end of the partition wall 12 on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction E.
- the third catalyst layer 40 does not reach the end of the partition wall 12 on the exhaust gas inflow side, but may reach the end of the partition wall 12 on the exhaust gas inflow side.
- the third catalyst layer 40 protrudes from the outer surface S1b of the partition wall portion 12 on the outflow side cell 13b side toward the outflow side cell 13b side. It is preferable that the catalyst layer 40 has a portion that protrudes from the outer surface S1b of the partition wall portion 12 on the outflow side cell 13b side toward the outflow side cell 13b side (hereinafter referred to as “raised portion”). This improves the contact between the exhaust gas and PM, making it possible to more effectively improve the exhaust gas purification performance and the PM trapping performance.
- the third catalyst layer 40 may be composed of only a raised portion, or may have a portion that exists inside the partition wall portion 12 (hereinafter referred to as “internal portion”) together with the raised portion. Since the partition wall portion 12 is porous, when forming the third catalyst layer 40, an internal portion may be formed together with a raised portion. The raised portion and the internal portion may be continuous.
- the third catalyst layer 40 may be composed only of an internal portion. "The third catalyst layer 40 is formed on the second catalyst layer 30" includes embodiments in which the third catalyst layer 40 is comprised only of raised parts, and embodiments in which the third catalyst layer 40 is comprised only of internal parts. Embodiments in which the third catalyst layer 40 has a raised portion and an embedded portion are both included. Among these, preferred are embodiments in which the third catalyst layer 40 includes only raised portions, and embodiments in which the third catalyst layer 40 includes raised portions and internal portions.
- the raised portion of the third catalyst layer 40 exists on the outflow side cell 13b side rather than the outer surface S1b of the partition wall section 12 on the outflow side cell 13b side. It does not need to be in contact with the surface S1b.
- the raised portion of the third catalyst layer 40 is formed on the internal portion of the second catalyst layer 30
- the raised portion of the third catalyst layer 40 is formed on the outer surface of the partition wall portion 12 on the outflow side cell 13b side. come into contact with
- the raised portion of the third catalyst layer 40 is formed on the raised portion of the second catalyst layer 30
- the raised portion of the third catalyst layer 40 is formed on the outer surface of the partition wall portion 12 on the outflow side cell 13b side. Not in contact.
- first catalyst layer 20 is read as “third catalyst layer 40.”
- the average length L 40 of the third catalyst layer 40 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, and the like. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the percentage of the average length L 40 of the third catalyst layer 40 to the length L 10 of the base material 10 (L 40 /L 10 ⁇ 100) is preferably 15 % or more and 90% or less, more preferably 20% or more and 80% or less, even more preferably 30% or more and 80% or less.
- the percentage ((L 20 +L 40 )/L 10 ⁇ 100) is preferably 100% or more and 180% or less, more preferably 105% or more and 150% or less, even more preferably 110% or more and 130% or less.
- the average length L 40 of the third catalyst layer 40 may be the same as or different from the average length L 30 of the second catalyst layer 30. Good too.
- the percentage of the average length L 40 of the third catalyst layer 40 to the average length L 30 of the second catalyst layer 30 is preferably 50% or more and 150% or less, more preferably 70%. 130% or less.
- the exhaust gas purification catalyst 1 when the exhaust gas flowing in from the end (opening) on the exhaust gas inflow side of the inflow side cell 13a passes through the porous partition wall 12, particulate matter (PM) in the exhaust gas is removed. ) is collected in the pores of the partition wall 12 , the pores of the first catalyst layer 20 , the pores of the second catalyst layer 30 , and the pores of the third catalyst layer 40 . Therefore, the exhaust gas purifying catalyst 1 is useful as a gasoline engine particulate filter or a diesel engine particulate filter.
- the exhaust gas flowing in from the end (opening) on the exhaust gas inflow side of the inflow side cell 13a comes into contact with the first catalyst layer 20, passes through the porous partition wall 12, and enters the second It contacts the catalyst layer 30 and the third catalyst layer 40 in this order.
- NOx in the exhaust gas is purified by Rh in the first catalyst layer 20.
- NOx that has passed through the first catalyst layer 20 without being purified is sequentially purified by Rh in the second catalyst layer 30 and Pt in the third catalyst layer 40.
- Per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed relative to the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed When the mass ratio of the third catalyst layer 40 is more than 1.9, Pt in the third catalyst layer 40 can sufficiently contact exhaust gas, but Rh in the second catalyst layer 30 can sufficiently contact exhaust gas. This results in a decrease in NOx purification performance.
- the third catalyst layer 40 is formed in the base material 10 relative to the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed.
- Rh in the second catalyst layer 30 can sufficiently contact the exhaust gas, and the third catalyst layer 40 The Pt inside can make sufficient contact with the exhaust gas, improving NOx purification performance.
- the exhaust gas purification catalyst 1 can achieve both the purification performance of low-temperature NOx generated during low-speed operation of the internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine. . That is, the exhaust gas purification catalyst 1 can exhibit excellent NOx purification performance in a wide temperature range from low to high temperatures.
- Purification performance of low-temperature NOx generated during low-speed operation of an internal combustion engine refers to the performance of NOx emitted from the start of operation to 589 seconds after the start of operation in WLTC mode, which is one of the internationally regulated driving modes.
- the "purification performance of high-temperature NOx generated during ultra-high-speed operation of an internal combustion engine” can be evaluated based on the amount of NOx emitted from 1477 seconds to 1800 seconds after the start of operation in the same WLTC mode. can be evaluated based on The specific evaluation method is as described in Examples.
- a base material 10 a slurry for forming the first catalyst layer 20, a slurry for forming the second catalyst layer 30, and a slurry for forming the third catalyst layer 40 are prepared.
- the composition of the slurry for forming the first catalyst layer 20, the second catalyst layer 30, and the third catalyst layer 40 depends on the composition of the first catalyst layer 20, the second catalyst layer 30, and the third catalyst layer 40, respectively. It is adjusted accordingly.
- the slurry includes, for example, a source of a noble metal element, inorganic oxide particles, a binder, a pore-forming material, a solvent, and the like.
- Examples of the source of the noble metal element include salts of the noble metal element, and examples of the salt of the noble metal element include nitrates, ammine complex salts, acetates, and chlorides.
- the explanation regarding the inorganic oxide constituting the inorganic oxide particles is as above.
- Examples of the binder include alumina sol, zirconia sol, titania sol, silica sol, and ceria sol.
- Examples of the pore-forming material include crosslinked methyl poly(meth)acrylate particles, crosslinked butyl poly(meth)acrylate particles, crosslinked polystyrene particles, crosslinked polyacrylate particles, and melamine resins.
- Examples of the solvent include water, organic solvents, and the like. Examples of the organic solvent include alcohol, acetone, dimethyl sulfoxide, and dimethyl formamide.
- the solvent may be one type of solvent or a mixture of two or more types of solvents. Examples of the mixture of two or more solvents include a mixture of water and one or more organic solvents, a mixture of two or more organic solvents, and the like.
- the end of the base material 10 on the exhaust gas inflow side is immersed in the slurry for forming the first catalyst layer 20, and after the slurry is sucked from the opposite side, it is dried. As a result, a precursor of the first catalyst layer 20 is formed.
- the length of the precursor of the first catalyst layer 20 (and thus the average length L 20 of the first catalyst layer 20) can be adjusted.
- the thickness of the precursor of the first catalyst layer 20 (and thus the thickness of the first catalyst layer 20) can be adjusted.
- the mass of the precursor of the first catalyst layer 20 per unit volume of the portion of the base material 10 on which the precursor of the first catalyst layer 20 is formed can be adjusted.
- the drying temperature is, for example, 40° C. or more and 150° C. or less, and the drying time is, for example, 5 minutes or more and 1 hour or less.
- the firing temperature is, for example, 350° C. or more and 600° C. or less
- the firing time is, for example, 20 minutes or more and 5 hours or less.
- the atmosphere during firing is usually an atmospheric atmosphere.
- the end of the base material 10 on the exhaust gas outflow side is immersed in the slurry for forming the second catalyst layer 30, and after the slurry is sucked from the opposite side, it is dried. As a result, a precursor for the second catalyst layer 30 is formed.
- the length of the precursor of the second catalyst layer 30 (and thus the average length L 30 of the second catalyst layer 30) can be adjusted.
- the thickness of the precursor of the second catalyst layer 30 (and thus the thickness of the second catalyst layer 30) can be adjusted.
- the mass of the precursor of the second catalyst layer 30 per unit volume of the portion of the base material 10 on which the precursor of the second catalyst layer 30 is formed can be adjusted.
- the drying temperature is, for example, 40° C. or more and 150° C. or less, and the drying time is, for example, 5 minutes or more and 1 hour or less.
- the end of the base material 10 on the exhaust gas outflow side is immersed in the slurry for forming the third catalyst layer 40, and after sucking the slurry from the opposite side, it is dried. let As a result, a precursor for the third catalyst layer 40 is formed on the precursor for the second catalyst layer 30.
- the length of the precursor of the third catalyst layer 40 (and thus the average length L 40 of the third catalyst layer 40) can be adjusted.
- the thickness of the precursor of the third catalyst layer 40 (and thus the thickness of the third catalyst layer 40) can be adjusted. thickness) and the mass of the precursor of the third catalyst layer 40 per unit volume of the portion of the base material 10 on which the precursor of the third catalyst layer 40 is formed (thickness of the third catalyst layer of the base material 10) The mass of the third catalyst layer 40 per unit volume of the portion where the third catalyst layer 40 is formed can be adjusted.
- the drying temperature is, for example, 40° C. or more and 150° C. or less, and the drying time is, for example, 5 minutes or more and 1 hour or less.
- the firing temperature is, for example, 350° C. or more and 600° C. or less
- the firing time is, for example, 20 minutes or more and 5 hours or less.
- the atmosphere during firing is usually an atmospheric atmosphere.
- the median D 50 of the pore-forming material is preferably 0.5 ⁇ m or more and 50 ⁇ m or less, preferably 1 ⁇ m or more and 30 ⁇ m or less, from the viewpoint of suppressing peeling, suppressing increase in pressure loss, and improving PM trapping performance.
- D50 is the particle size at which the cumulative volume is 50% in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measuring method.
- the D 90 of the inorganic oxide particles is preferably 3 ⁇ m or more and 50 ⁇ m or less, more preferably 5 ⁇ m or more and 40 ⁇ m or less, from the viewpoint of suppressing peeling, suppressing increase in pressure loss, and improving PM trapping performance.
- D90 is the particle size at which the cumulative volume is 90% in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measuring method.
- D 50 or D 90 use a laser diffraction scattering particle size distribution analyzer automatic sample feeder (Microtorac SDC manufactured by Microtrac Bell), add the sample to be measured to an aqueous dispersion medium, and add 26 mL After irradiating with 40W ultrasonic waves for 360 seconds at a flow rate of /sec, the measurement is performed using a laser diffraction scattering particle size distribution analyzer (Microtrac MT3300EXII manufactured by Microtrac Bell). The measurement was performed twice under the following conditions: particle refractive index of 1.5, particle shape of perfect sphere, solvent refractive index of 1.3, set zero for 30 seconds, and measurement time of 30 seconds. Let the average value be D50 or D90 . Pure water is used as the aqueous dispersion medium.
- Example 1 (1) Preparation of first slurry In rhodium nitrate aqueous solution, Ce-Zr composite oxide powder (Ce equivalent to CeO 2 : 15% by mass, Zr equivalent to ZrO 2 : 70% by mass, 3 types other than Ce) After adding rare earth elements (La, Nd, Y) oxide equivalent amount: 15% by mass) and alumina powder, a pore-forming material (crosslinked poly(meth)methyl acrylate particles with a median diameter D50 of 5 ⁇ m) was added. , alumina sol, zirconia sol, and water as a solvent were added to prepare a first slurry.
- the amount of each component in the first slurry is based on the mass of the catalyst layer formed by drying and firing the first slurry, rhodium is 0.5% by mass in terms of metal, and Ce-Zr composite oxide powder is 0.5% by mass.
- the content of the alumina powder was 74.6% by mass
- the alumina powder was 16.9% by mass
- the alumina sol was 3.0% by mass in terms of solid content
- the zirconia sol was 5.0% by mass in terms of solid content.
- the amount of the pore former in the first slurry was adjusted to be 30% by mass of the catalyst layer formed by drying and firing the first slurry.
- the mass of the catalyst layer formed by drying and firing the first slurry is calculated by subtracting the mass of components (e.g., solvent, pore-forming material, etc.) that disappear by drying and firing the first slurry from the mass of the first slurry. It is determined by subtracting the amount.
- D 90 of the metal oxide powder (Ce-Zr composite oxide powder and alumina powder) in the first slurry was 20 ⁇ m.
- the amount of each component in the third slurry is based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum is 7.8% by mass in terms of metal, and Ce-Zr composite oxide powder is 7.8% by mass.
- the content of the alumina powder was 15.7% by mass
- the alumina sol was 7.4% by mass in terms of solid content
- the content of zirconia sol was 1.8% by mass in terms of solid content.
- the amount of the pore former in the third slurry was adjusted to be 30% by mass of the catalyst layer formed by drying and firing the third slurry.
- the mass of the catalyst layer formed by drying and firing the third slurry is calculated by subtracting the mass of components (e.g., solvent, pore-forming material, etc.) that disappear by drying and firing the third slurry from the mass of the third slurry. It is determined by subtracting the amount.
- D 90 of the metal oxide powder (Ce-Zr composite oxide powder and alumina powder) in the third slurry was 20 ⁇ m.
- first catalyst layer Wall-flow type substrates shown in FIGS. 1 to 6 were prepared.
- the thickness of the partition wall part is 200 to 250 ⁇ m
- the total number of inflow side cells and outflow side cells in a cross section perpendicular to the axial direction of the base material is 300 cells per square inch
- the volume of the base material is 1.0L
- the base material The length was 91 mm.
- the upstream end of the base material in the exhaust gas flow direction was immersed in the first slurry, suctioned from the downstream side, and then dried at 90° C. for 10 minutes.
- a first precursor layer (a layer consisting of the solid content of the first slurry) extending from the exhaust gas inflow side end of the base material along the exhaust gas flow direction is formed on the inflow side cell side of the partition wall portion of the base material.
- the substrate was fired at 450° C. for 1 hour.
- a first catalyst layer was formed on the inflow side cell side of the partition wall portion of the base material, extending from the exhaust gas inflow side end of the base material along the exhaust gas flow direction.
- the percentage of the length of the first catalyst layer to the length of the base material was 45%.
- the mass of the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer was formed (hereinafter referred to as "WC1") was 37.8 g/L.
- the metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer was formed was 5.6 g/cft. Note that "cft" means cubic feet.
- the downstream end of the base material in the exhaust gas flow direction was immersed in the third slurry, suctioned from the upstream side, and then dried at 90° C. for 10 minutes.
- a third precursor layer (a layer consisting of the solid content of the third slurry) was formed on the second precursor layer, extending from the end of the base material on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction. .
- the base material was baked at 450° C. for 1 hour.
- a second catalyst layer extending from the exhaust gas outflow side end of the base material along a direction opposite to the exhaust gas flow direction, and a second catalyst layer on the second catalyst layer.
- a third catalyst layer was formed extending from the end of the base material on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction.
- the percentage of the length of the second catalyst layer with respect to the length of the base material was 70%.
- at least a portion of the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the mass of the second catalyst layer per unit volume (hereinafter referred to as "WC2") of the portion of the base material where the second catalyst layer was formed was 27.1 g/L.
- the metal equivalent amount of Rh in the second catalyst layer per unit volume of the portion of the base material where the second catalyst layer was formed was 3.6 g/cft.
- the percentage of the length of the third catalyst layer to the length of the base material was 70%.
- the mass of the third catalyst layer per unit volume (hereinafter referred to as "WC3") of the portion of the base material where the third catalyst layer was formed was 12.9 g/L.
- the ratio of WC3 to WC2 was 0.47.
- the metal equivalent amount of Pt in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer was formed was 28.6 g/cft.
- a vehicle equipped with an exhaust gas purification catalyst after durability treatment was operated according to the operating conditions of the internationally harmonized exhaust gas test mode (WLTC). Measures the emissions (emission values) of nitrogen oxides (NOx), non-methane hydrocarbons (HC), and carbon monoxide (CO) in the exhaust gas that has passed through the exhaust gas purification catalyst for 1800 seconds from the start of operation. Then, the emissions of NOx, HC, and CO per unit traveling distance (mg/km) were determined.
- a passenger car equipped with a 1.5L direct injection turbo engine was used as the vehicle, a certification test fuel was used as the gasoline, and an exhaust gas measuring device manufactured by Horiba, Ltd. was used as the exhaust gas measuring device.
- Table 1 shows the measurement results of NOx, HC, and CO emissions per unit traveling distance.
- the emissions of NOx, HC, and CO per unit traveling distance are shown as relative values to the emissions of NOx, HC, and CO per unit traveling distance in Comparative Example 3, which will be described later.
- low temperature NOx means the amount of NOx emitted from the start of operation to 589 seconds after the start of operation
- high temperature NOx means the amount of emissions from 1477 seconds to 1800 seconds after the start of operation. Means NOx emissions.
- Example 2 The amounts of each component in the second slurry were determined based on the mass of the catalyst layer formed by drying and firing the second slurry, rhodium was 0.6% by mass in terms of metal, and Ce-Zr composite oxide powder was The content was adjusted to 74.5% by mass, the alumina powder was 16.9% by mass, the alumina sol was 3.0% by mass in terms of solid content, and the zirconia sol was adjusted to be 5.0% by mass in terms of solid content, The amounts of each component in the third slurry were determined based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum was 5.0% by mass in metal terms, and Ce-Zr composite oxide powder was 5.0% by mass in terms of metal.
- alumina powder was adjusted to 16.1% by mass
- alumina sol was adjusted to 7.6% by mass in terms of solid content
- zirconia sol was adjusted to 1.9% by mass in terms of solid content
- WC2 was changed to 20.0g/L
- An exhaust gas purification catalyst was produced in the same manner as in Example 1, except that WC3 was changed to 20.0 g/L, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
- the ratio of WC3 to WC2 was 1.00.
- the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the third catalyst layer also protruded from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 5.6 g/cft, and the second catalyst layer is formed in the base material.
- the metal equivalent amount of Rh in the second catalyst layer per unit volume of the portion is 3.6 g/cft, and the Pt in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer is formed.
- the metal equivalent amount was 28.6 g/cft.
- the ratio of WC3 to WC2 was 2.11.
- the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the third catalyst layer also protruded from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 5.6 g/cft, and the second catalyst layer is formed in the base material.
- the metal equivalent amount of Rh in the second catalyst layer per unit volume of the portion is 3.6 g/cft, and the Pt in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer is formed.
- the metal equivalent amount was 28.6 g/cft.
- the ratio of WC3 to WC2 was 0.47.
- the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the third catalyst layer also protruded from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 5.6 g/cft, and the second catalyst layer is formed in the base material.
- the metal equivalent amount of Pt in the second catalyst layer per unit volume of the portion is 28.6 g/cft
- the amount of Rh in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer is formed is 28.6 g/cft.
- the metal equivalent amount was 3.6 g/cft.
- the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side.
- the metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 11.1 g/cft, and the second catalyst layer is formed in the base material.
- the metal equivalent amount of Pt in the second catalyst layer per unit volume of the part was 28.6 g/cft.
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Abstract
Provided is an exhaust gas purification catalyst comprising: a substrate provided with inflow-side cells, outflow-side cells, and porous partition walls; a first catalytic layer; and a second catalytic layer and a third catalytic layer in which the noble metal element that has the greatest metal-equivalent content is Rh and Pt, respectively, wherein: the first catalytic layer is formed on the inflow-side cell side of the partition walls, along an exhaust gas flow direction from an exhaust gas inflow-side end of the partition walls; the second catalytic layer is formed on the outflow-side cell side of the partition walls, along a direction opposite to the exhaust gas flow direction from an exhaust gas outflow-side end of the partition walls; the third catalytic layer is formed over the second catalytic layer such that at least part of the third catalytic layer protrudes out to the outflow-side cell side from an outflow-side cell-side outer surface of the partition walls; and the ratio of the mass of the third catalytic layer per unit volume at a portion of the substrate where the third catalytic layer is formed to the mass of the second catalytic layer per unit volume at a portion of the substrate where the second catalytic layer is formed is 0.3 to 1.9.
Description
本発明は、排ガス浄化用触媒に関する。
The present invention relates to an exhaust gas purifying catalyst.
自動車、バイク等の内燃機関から排出される排ガス中には、炭化水素（ＨＣ）、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）等の有害成分が含まれている。これらの有害成分を浄化して無害化する目的で三元触媒が使用されている。三元触媒としては、Ｐｔ、Ｐｄ、Ｒｈ等の貴金属元素を含む触媒が使用されている。
Exhaust gas emitted from internal combustion engines such as automobiles and motorcycles contains harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Three-way catalysts are used to purify these harmful components and render them harmless. As the three-way catalyst, a catalyst containing noble metal elements such as Pt, Pd, and Rh is used.
排ガス中には、ＨＣ、ＣＯ、ＮＯｘ等の有害成分とともに、粒子状物質（ＰＭ：Ｐａｒｔｉｃｕｌａｔｅ Ｍａｔｔｅｒ）が含まれており、大気汚染の原因となることが知られている。
It is known that exhaust gas contains particulate matter (PM) as well as harmful components such as HC, CO, and NOx, and causes air pollution.
ＰＭに関する環境規制に対応するため、直噴エンジン（ＧＤＩ：Ｇａｓｏｌｉｎｅ Ｄｉｒｅｃｔ Ｉｎｊｅｃｔｉｏｎ ｅｎｇｉｎｅ）等のガソリンエンジン搭載車両においても、ディーゼルエンジン搭載車両と同様、ＰＭ捕集機能を有するフィルター（ＧＰＦ：Ｇａｓｏｌｉｎｅ Ｐａｒｔｉｃｕｌａｔｅ Ｆｉｌｔｅｒ）の設置が求められている。
In order to comply with environmental regulations related to PM, vehicles equipped with gasoline engines such as direct injection engines (GDI) are equipped with filters (GPF: Gasoline Particulate Filter) that have a PM collection function in the same way as vehicles equipped with diesel engines. is required to be installed.
ＧＰＦとしては、例えば、ウォールフロー型と呼ばれる構造を有する基材が使用されている。ウォールフロー型基材は、排ガス流入側の端部が開口しており、排ガス流出側の端部が閉塞している流入側セルと、排ガス流入側の端部が閉塞しており、排ガス流出側の端部が開口している流出側セルと、流入側セルと流出側セルとを仕切る多孔質の隔壁とを備える。ウォールフロー型基材では、流入側セルの排ガス流入側の端部（開口部）から流入した排ガスが多孔質の隔壁を通過して流出側セルの排ガス流出側の端部（開口部）から流出する際、排ガス中のＰＭが隔壁内部の細孔内に捕集される。
As the GPF, for example, a base material having a structure called a wall flow type is used. The wall flow type base material has an inflow side cell with an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side, and a closed end on the exhaust gas inflow side and a closed cell on the exhaust gas outflow side. It includes an outflow side cell with an open end, and a porous partition wall that partitions the inflow side cell and the outflow side cell. In a wall flow type base material, exhaust gas flows in from the exhaust gas inflow side end (opening) of the inflow side cell, passes through the porous partition wall, and flows out from the exhaust gas outflow side end (opening) of the outflow side cell. At this time, PM in the exhaust gas is collected in the pores inside the partition wall.
一般に排ガス浄化用触媒の搭載スペースは限られているため、Ｐｔ、Ｐｄ、Ｒｈ等の貴金属元素を含む触媒層をウォールフロー型基材に設けて、ＰＭの捕集とともに、ＨＣ、ＣＯ、ＮＯｘ等の有害成分の浄化を行うことが検討されている。
Generally, the mounting space for exhaust gas purification catalysts is limited, so a catalyst layer containing noble metal elements such as Pt, Pd, and Rh is provided on a wall flow type base material to collect PM and to collect HC, CO, NOx, etc. Purification of harmful components is being considered.
特許文献１及び２には、ウォールフロー型基材と、排ガス流入側の端部から隔壁の延在方向に向かって形成された第１触媒層と、排ガス流出側の端部から隔壁の延在方向に向かって形成された第２触媒層とを備える排ガス浄化用触媒が記載されている。第１触媒層は、流入側セルと接するように、隔壁の内部に形成されており、第２触媒層は、流出側セルと接するように、隔壁の内部に形成されている。第１触媒層は、例えば、Ｒｈを含み、第２触媒層は、例えば、Ｐｄを含む。
Patent Documents 1 and 2 disclose a wall flow type base material, a first catalyst layer formed from an end on the exhaust gas inflow side in the direction in which the partition wall extends, and a wall flow type base material in which the partition wall extends from the end on the exhaust gas outflow side. An exhaust gas purifying catalyst is described that includes a second catalyst layer formed in the direction of the exhaust gas purifying catalyst. The first catalyst layer is formed inside the partition so as to be in contact with the inflow side cells, and the second catalyst layer is formed inside the partition so as to be in contact with the outflow side cells. The first catalyst layer contains, for example, Rh, and the second catalyst layer contains, for example, Pd.
特許文献３には、ウォールフロー型基材と、排ガス流入側の端部から隔壁の延在方向に向かって形成された第１触媒層と、排ガス流出側の端部から隔壁の延在方向に向かって形成された第２触媒層と、第２触媒層上に形成された第３触媒層とを備える排ガス浄化用触媒が記載されている。第１触媒層は、隔壁の流入側セル側の外表面上に形成されており、第２触媒層は、隔壁の流出側セル側の外表面上に形成されている。第１触媒層は、例えば、Ｒｈを含み、第２触媒層は、例えば、Ｒｈを含み、第３触媒層は、例えば、Ｐｄを含む。
Patent Document 3 discloses a wall flow type base material, a first catalyst layer formed from an end on the exhaust gas inflow side in the extending direction of the partition wall, and a first catalyst layer formed in the extending direction of the partition wall from the end on the exhaust gas outflow side. A catalyst for exhaust gas purification is described that includes a second catalyst layer formed facing toward the patent and a third catalyst layer formed on the second catalyst layer. The first catalyst layer is formed on the outer surface of the partition wall on the inflow side cell side, and the second catalyst layer is formed on the outer surface of the partition wall on the outflow side cell side. The first catalyst layer contains, for example, Rh, the second catalyst layer contains, for example, Rh, and the third catalyst layer contains, for example, Pd.
貴金属の価格高騰により、貴金属の中では比較的価格が安いＰｔの活用が求められている。Ｐｔを使用した排ガス浄化用触媒としては、特許文献１及び２に記載の排ガス浄化用触媒が知られている。しかしながら、特許文献１及び２に記載の排ガス浄化用触媒では、内燃機関の低速運転時に発生する低温ＮＯｘの浄化性能と、内燃機関の超高速運転時に発生する高温ＮＯｘの浄化性能との両立を十分に実現することができなかった。
Due to the soaring price of precious metals, there is a demand for the use of Pt, which is relatively inexpensive among precious metals. As exhaust gas purifying catalysts using Pt, exhaust gas purifying catalysts described in Patent Documents 1 and 2 are known. However, the exhaust gas purification catalysts described in Patent Documents 1 and 2 do not sufficiently achieve both the purification performance of low-temperature NOx generated during low-speed operation of the internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine. could not be realized.
そこで、本発明は、ウォールフロー型基材と、Ｐｔを含む触媒層とを備える排ガス浄化用触媒であって、内燃機関の低速運転時に発生する低温ＮＯｘの浄化性能と、内燃機関の超高速運転時に発生する高温ＮＯｘの浄化性能との両立を実現可能な排ガス浄化用触媒を提供することを目的とする。
Accordingly, the present invention provides an exhaust gas purifying catalyst comprising a wall flow type base material and a catalyst layer containing Pt, which has the ability to purify low-temperature NOx generated during low-speed operation of an internal combustion engine and ultra-high-speed operation of an internal combustion engine. An object of the present invention is to provide an exhaust gas purifying catalyst that can achieve both purification performance of high-temperature NOx that is sometimes generated.
上記課題を解決するために、本発明は、以下の排ガス浄化用触媒を提供する。
［１］排ガス流通方向に延在する基材と、
Ｒｈを含み、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい第１触媒層と、
Ｒｈを含み、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい第２触媒層と、
Ｐｔを含み、Ｐｔ以外の１種又は２種以上の貴金属元素を含んでいてもよい第３触媒層と、
を備える、排ガス浄化用触媒であって、
前記基材は、
前記排ガス流通方向に延在する流入側セルであって、排ガス流入側の端部が開口しており、排ガス流出側の端部が閉塞している前記流入側セルと、
前記排ガス流通方向に延在する流出側セルであって、排ガス流入側の端部が閉塞しており、排ガス流出側の端部が開口している前記流出側セルと、
前記流入側セルと前記流出側セルとを仕切る多孔質の隔壁部と、
を備え、
前記第１触媒層は、前記隔壁部の前記流入側セル側に、前記隔壁部の排ガス流入側の端部から前記排ガス流通方向に沿って形成されており、
前記第２触媒層は、前記隔壁部の前記流出側セル側に、前記隔壁部の排ガス流出側の端部から前記排ガス流通方向とは反対の方向に沿って形成されており、
前記第３触媒層は、前記第３触媒層の少なくとも一部が前記隔壁部の前記流出側セル側の外表面から前記流出側セル側に***するように、前記第２触媒層上に形成されており、
前記第２触媒層中のＲｈの金属換算量は、前記第２触媒層中のＲｈ以外の各貴金属元素の金属換算量よりも大きく、
前記第３触媒層中のＰｔの金属換算量は、前記第３触媒層中のＰｔ以外の各貴金属元素の金属換算量よりも大きく、
前記基材のうち前記第２触媒層が形成されている部分の単位体積当たりの前記第２触媒層の質量に対する、前記基材のうち前記第３触媒層が形成されている部分の単位体積当たりの前記第３触媒層の質量の比は、０．３以上１．９以下である、前記排ガス浄化用触媒。
［２］前記第１触媒層中のＲｈの金属換算量が、前記第１触媒層中のＲｈ以外の各貴金属元素の金属換算量よりも大きい、［１］に記載の排ガス浄化用触媒。
［３］前記第１触媒層中のＲｈの金属換算量が、前記第１触媒層中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きく、
前記第２触媒層中のＲｈの金属換算量が、前記第２触媒層中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きく、
前記第３触媒層中のＰｔの金属換算量が、前記第３触媒層中のＰｔ以外の全貴金属元素の合計金属換算量よりも大きい、［１］又は［２］に記載の排ガス浄化用触媒。
［４］前記第１触媒層の少なくとも一部が、前記隔壁部の前記流入側セル側の外表面から前記流入側セル側に***する、［１］～［３］のいずれか一項に記載の排ガス浄化用触媒。
［５］前記第２触媒層の少なくとも一部が、前記隔壁部の前記流出側セル側の外表面から前記流出側セル側に***する、［１］～［４］のいずれか一項に記載の排ガス浄化用触媒。
［６］前記第１触媒層中の全貴金属元素の合計金属換算量に対する、前記第１触媒層中のＰｔの金属換算量の比が、質量比で、０．３以下である、［１］～［５］のいずれか一項に記載の排ガス浄化用触媒。 In order to solve the above problems, the present invention provides the following exhaust gas purifying catalyst.
[1] A base material extending in the exhaust gas flow direction;
a first catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh;
a second catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh;
a third catalyst layer containing Pt and optionally containing one or more noble metal elements other than Pt;
An exhaust gas purification catalyst comprising:
The base material is
The inflow side cell extends in the exhaust gas flow direction, and has an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side;
The outflow side cell extends in the exhaust gas flow direction, and has a closed end on the exhaust gas inflow side and an open end on the exhaust gas outflow side;
a porous partition that partitions the inflow side cell and the outflow side cell;
Equipped with
The first catalyst layer is formed on the inflow-side cell side of the partition wall part along the exhaust gas flow direction from the exhaust gas inflow-side end of the partition wall part,
The second catalyst layer is formed on the outflow-side cell side of the partition wall from the exhaust gas outflow-side end of the partition wall in a direction opposite to the exhaust gas flow direction,
The third catalyst layer is formed on the second catalyst layer such that at least a portion of the third catalyst layer protrudes from an outer surface of the partition wall portion on the outflow side cell side toward the outflow side cell side. and
The metal equivalent amount of Rh in the second catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer,
The metal equivalent amount of Pt in the third catalyst layer is larger than the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer,
The mass of the second catalyst layer per unit volume of the portion of the base material where the second catalyst layer is formed is per unit volume of the portion of the base material where the third catalyst layer is formed. In the exhaust gas purifying catalyst, the mass ratio of the third catalyst layer is 0.3 or more and 1.9 or less.
[2] The catalyst for exhaust gas purification according to [1], wherein the metal equivalent amount of Rh in the first catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer.
[3] The metal equivalent amount of Rh in the first catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer,
The metal equivalent amount of Rh in the second catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer,
The catalyst for exhaust gas purification according to [1] or [2], wherein the metal equivalent amount of Pt in the third catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer. .
[4] The first catalyst layer according to any one of [1] to [3], wherein at least a portion of the first catalyst layer protrudes from the outer surface of the partition wall on the inflow side cell side toward the inflow side cell side. Catalyst for exhaust gas purification.
[5] The second catalyst layer according to any one of [1] to [4], wherein at least a portion of the second catalyst layer protrudes from the outer surface of the partition wall on the outflow side cell side toward the outflow side cell side. Catalyst for exhaust gas purification.
[6] The ratio of the metal equivalent amount of Pt in the first catalyst layer to the total metal equivalent amount of all noble metal elements in the first catalyst layer is 0.3 or less in terms of mass ratio, [1] The catalyst for exhaust gas purification according to any one of [5] to [5].
［１］排ガス流通方向に延在する基材と、
Ｒｈを含み、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい第１触媒層と、
Ｒｈを含み、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい第２触媒層と、
Ｐｔを含み、Ｐｔ以外の１種又は２種以上の貴金属元素を含んでいてもよい第３触媒層と、
を備える、排ガス浄化用触媒であって、
前記基材は、
前記排ガス流通方向に延在する流入側セルであって、排ガス流入側の端部が開口しており、排ガス流出側の端部が閉塞している前記流入側セルと、
前記排ガス流通方向に延在する流出側セルであって、排ガス流入側の端部が閉塞しており、排ガス流出側の端部が開口している前記流出側セルと、
前記流入側セルと前記流出側セルとを仕切る多孔質の隔壁部と、
を備え、
前記第１触媒層は、前記隔壁部の前記流入側セル側に、前記隔壁部の排ガス流入側の端部から前記排ガス流通方向に沿って形成されており、
前記第２触媒層は、前記隔壁部の前記流出側セル側に、前記隔壁部の排ガス流出側の端部から前記排ガス流通方向とは反対の方向に沿って形成されており、
前記第３触媒層は、前記第３触媒層の少なくとも一部が前記隔壁部の前記流出側セル側の外表面から前記流出側セル側に***するように、前記第２触媒層上に形成されており、
前記第２触媒層中のＲｈの金属換算量は、前記第２触媒層中のＲｈ以外の各貴金属元素の金属換算量よりも大きく、
前記第３触媒層中のＰｔの金属換算量は、前記第３触媒層中のＰｔ以外の各貴金属元素の金属換算量よりも大きく、
前記基材のうち前記第２触媒層が形成されている部分の単位体積当たりの前記第２触媒層の質量に対する、前記基材のうち前記第３触媒層が形成されている部分の単位体積当たりの前記第３触媒層の質量の比は、０．３以上１．９以下である、前記排ガス浄化用触媒。
［２］前記第１触媒層中のＲｈの金属換算量が、前記第１触媒層中のＲｈ以外の各貴金属元素の金属換算量よりも大きい、［１］に記載の排ガス浄化用触媒。
［３］前記第１触媒層中のＲｈの金属換算量が、前記第１触媒層中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きく、
前記第２触媒層中のＲｈの金属換算量が、前記第２触媒層中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きく、
前記第３触媒層中のＰｔの金属換算量が、前記第３触媒層中のＰｔ以外の全貴金属元素の合計金属換算量よりも大きい、［１］又は［２］に記載の排ガス浄化用触媒。
［４］前記第１触媒層の少なくとも一部が、前記隔壁部の前記流入側セル側の外表面から前記流入側セル側に***する、［１］～［３］のいずれか一項に記載の排ガス浄化用触媒。
［５］前記第２触媒層の少なくとも一部が、前記隔壁部の前記流出側セル側の外表面から前記流出側セル側に***する、［１］～［４］のいずれか一項に記載の排ガス浄化用触媒。
［６］前記第１触媒層中の全貴金属元素の合計金属換算量に対する、前記第１触媒層中のＰｔの金属換算量の比が、質量比で、０．３以下である、［１］～［５］のいずれか一項に記載の排ガス浄化用触媒。 In order to solve the above problems, the present invention provides the following exhaust gas purifying catalyst.
[1] A base material extending in the exhaust gas flow direction;
a first catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh;
a second catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh;
a third catalyst layer containing Pt and optionally containing one or more noble metal elements other than Pt;
An exhaust gas purification catalyst comprising:
The base material is
The inflow side cell extends in the exhaust gas flow direction, and has an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side;
The outflow side cell extends in the exhaust gas flow direction, and has a closed end on the exhaust gas inflow side and an open end on the exhaust gas outflow side;
a porous partition that partitions the inflow side cell and the outflow side cell;
Equipped with
The first catalyst layer is formed on the inflow-side cell side of the partition wall part along the exhaust gas flow direction from the exhaust gas inflow-side end of the partition wall part,
The second catalyst layer is formed on the outflow-side cell side of the partition wall from the exhaust gas outflow-side end of the partition wall in a direction opposite to the exhaust gas flow direction,
The third catalyst layer is formed on the second catalyst layer such that at least a portion of the third catalyst layer protrudes from an outer surface of the partition wall portion on the outflow side cell side toward the outflow side cell side. and
The metal equivalent amount of Rh in the second catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer,
The metal equivalent amount of Pt in the third catalyst layer is larger than the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer,
The mass of the second catalyst layer per unit volume of the portion of the base material where the second catalyst layer is formed is per unit volume of the portion of the base material where the third catalyst layer is formed. In the exhaust gas purifying catalyst, the mass ratio of the third catalyst layer is 0.3 or more and 1.9 or less.
[2] The catalyst for exhaust gas purification according to [1], wherein the metal equivalent amount of Rh in the first catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer.
[3] The metal equivalent amount of Rh in the first catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer,
The metal equivalent amount of Rh in the second catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer,
The catalyst for exhaust gas purification according to [1] or [2], wherein the metal equivalent amount of Pt in the third catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer. .
[4] The first catalyst layer according to any one of [1] to [3], wherein at least a portion of the first catalyst layer protrudes from the outer surface of the partition wall on the inflow side cell side toward the inflow side cell side. Catalyst for exhaust gas purification.
[5] The second catalyst layer according to any one of [1] to [4], wherein at least a portion of the second catalyst layer protrudes from the outer surface of the partition wall on the outflow side cell side toward the outflow side cell side. Catalyst for exhaust gas purification.
[6] The ratio of the metal equivalent amount of Pt in the first catalyst layer to the total metal equivalent amount of all noble metal elements in the first catalyst layer is 0.3 or less in terms of mass ratio, [1] The catalyst for exhaust gas purification according to any one of [5] to [5].
本発明によれば、内燃機関の低速運転時時に発生する低温ＮＯｘの浄化性能と、内燃機関の超高速運転時に発生する高温ＮＯｘの浄化性能との両立を実現可能な排ガス浄化用触媒が提供される。
According to the present invention, there is provided an exhaust gas purification catalyst that can achieve both the purification performance of low-temperature NOx generated during low-speed operation of an internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine. Ru.
≪排ガス浄化用触媒≫
以下、図面に基づいて、本発明の排ガス浄化用触媒の実施形態を説明する。 <<Catalyst for exhaust gas purification>>
Hereinafter, embodiments of the exhaust gas purifying catalyst of the present invention will be described based on the drawings.
以下、図面に基づいて、本発明の排ガス浄化用触媒の実施形態を説明する。 <<Catalyst for exhaust gas purification>>
Hereinafter, embodiments of the exhaust gas purifying catalyst of the present invention will be described based on the drawings.
図１に示すように、本発明の一実施形態に係る排ガス浄化用触媒１は、内燃機関の排気管Ｐ内の排気経路に配置されている。内燃機関は、例えば、ガソリンエンジン（例えば、ＧＤＩエンジン等）、ディーゼルエンジン等である。
As shown in FIG. 1, an exhaust gas purifying catalyst 1 according to an embodiment of the present invention is arranged in an exhaust path in an exhaust pipe P of an internal combustion engine. The internal combustion engine is, for example, a gasoline engine (eg, a GDI engine, etc.), a diesel engine, or the like.
図１において、内燃機関の排気経路の排ガス流通方向は、符号Ｅで示されている。他の図においても同様である。本明細書において、排ガス流通方向Ｅの上流側（例えば、図１の左側）を「排ガス流入側」又は「上流側」、排ガス流通方向Ｅの下流側（例えば、図１の右側）を「排ガス流出側」又は「下流側」という。
In FIG. 1, the direction of exhaust gas flow in the exhaust path of the internal combustion engine is indicated by the symbol E. The same applies to other figures. In this specification, the upstream side in the exhaust gas flow direction E (for example, the left side in FIG. 1) is referred to as the "exhaust gas inflow side" or "upstream side," and the downstream side in the exhaust gas flow direction E (for example, the right side in FIG. 1) is referred to as the "exhaust gas inflow side" or "upstream side." "outflow side" or "downstream side".
図１に示すように、排ガス浄化用触媒１は、基材１０の軸方向が排ガス流通方向Ｅと略一致するように、内燃機関の排気経路に配置されている。本明細書において、「長さ」は、別段規定される場合を除き、基材１０の軸方向の寸法を意味する。
As shown in FIG. 1, the exhaust gas purifying catalyst 1 is arranged in the exhaust path of the internal combustion engine so that the axial direction of the base material 10 substantially coincides with the exhaust gas flow direction E. In this specification, "length" means the axial dimension of the base material 10, unless otherwise specified.
図１～図６に示すように、排ガス浄化用触媒１は、基材１０と、第１触媒層２０と、第２触媒層３０と、第３触媒層４０とを備える。
As shown in FIGS. 1 to 6, the exhaust gas purifying catalyst 1 includes a base material 10, a first catalyst layer 20, a second catalyst layer 30, and a third catalyst layer 40.
＜基材＞
以下、基材１０について説明する。 <Base material>
The base material 10 will be explained below.
以下、基材１０について説明する。 <Base material>
The base material 10 will be explained below.
基材１０を構成する材料は、公知の材料から適宜選択することができる。基材１０を構成する材料としては、例えば、セラミックス材料、金属材料等が挙げられるが、セラミックス材料が好ましい。セラミックス材料としては、例えば、炭化ケイ素、炭化チタン、炭化タンタル、炭化タングステン等の炭化物セラミックス、窒化アルミニウム、窒化ケイ素、窒化ホウ素、窒化チタン等の窒化物セラミックス、アルミナ、ジルコニア、コージェライト、ムライト、ジルコン、チタン酸アルミニウム、チタン酸マグネシウム等の酸化物セラミックス等が挙げられる。金属材料としては、例えば、ステンレス鋼等の合金等が挙げられる。
The material constituting the base material 10 can be appropriately selected from known materials. Examples of the material constituting the base material 10 include ceramic materials, metal materials, and the like, with ceramic materials being preferred. Examples of ceramic materials include carbide ceramics such as silicon carbide, titanium carbide, tantalum carbide, and tungsten carbide, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, alumina, zirconia, cordierite, mullite, and zircon. , aluminum titanate, magnesium titanate, and other oxide ceramics. Examples of the metal material include alloys such as stainless steel.
基材１０の長さＬ１０は、排ガス浄化性能、ＰＭ捕集性能等を考慮して適宜調整することができる。排ガス浄化性能及びＰＭ捕集性を向上させる観点から、基材１０の長さＬ１０は、好ましくは５０ｍｍ以上１６０ｍｍ以下、より好ましくは８０ｍｍ以上１３０ｍｍ以下である。
The length L 10 of the base material 10 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, etc. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the length L 10 of the base material 10 is preferably 50 mm or more and 160 mm or less, more preferably 80 mm or more and 130 mm or less.
基材１０の体積は、排ガス浄化性能、ＰＭ捕集性能等を考慮して適宜調整することができる。排ガス浄化性能及びＰＭ捕集性を向上させる観点から、基材１０の体積は、好ましくは０．５Ｌ以上２．５Ｌ以下、より好ましくは０．５Ｌ以上２．０Ｌ以下、より一層好ましくは０．７Ｌ以上１．８Ｌ以下である。基材１０の体積は、基材１０の見かけの体積である。基材１０が円柱状である場合、基材１０の外径を２ｒとし、基材１０の長さをＬ１０とすると、基材１０の体積は、式：基材１０の体積＝π×ｒ２×Ｌ１０から算出される。
The volume of the base material 10 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, etc. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the volume of the base material 10 is preferably 0.5L or more and 2.5L or less, more preferably 0.5L or more and 2.0L or less, and even more preferably 0.5L or more and 2.0L or less. It is 7L or more and 1.8L or less. The volume of the base material 10 is the apparent volume of the base material 10. When the base material 10 is cylindrical, when the outer diameter of the base material 10 is 2r and the length of the base material 10 is L10 , the volume of the base material 10 is calculated by the formula: Volume of base material 10 = π x r Calculated from 2 ×L 10 .
基材１０は、ウォールフロー型基材である。図２～６に示すように、基材１０は、筒状部１１と、セル１３（流入側セル１３ａ及び流出側セル１３ｂ）と、隣接するセル１３（流入側セル１３ａ及び流出側セル１３ｂ）を仕切る多孔質の隔壁部１２とを備える。基材１０は、ハニカム構造体であることが好ましい。
The base material 10 is a wall flow type base material. As shown in FIGS. 2 to 6, the base material 10 includes a cylindrical portion 11, cells 13 (inflow side cells 13a and outflow side cells 13b), and adjacent cells 13 (inflow side cells 13a and outflow side cells 13b). A porous partition wall portion 12 is provided. It is preferable that the base material 10 is a honeycomb structure.
図２及び３に示すように、筒状部１１は、基材１０の外形を規定し、筒状部１１の軸方向は、基材１０の軸方向と一致する。本実施形態において、筒状部１１の形状は、円筒状であるが、楕円筒状、多角筒状等のその他の形状であってもよい。
As shown in FIGS. 2 and 3, the cylindrical part 11 defines the outer shape of the base material 10, and the axial direction of the cylindrical part 11 coincides with the axial direction of the base material 10. In this embodiment, the shape of the cylindrical portion 11 is cylindrical, but it may have other shapes such as an elliptical shape or a polygonal shape.
図２～６に示すように、セル１３（流入側セル１３ａ及び流出側セル１３ｂ）は、それぞれ、排ガス流通方向Ｅに延在しており、排ガス流入側の端部及び排ガス流出側の端部を有する。
As shown in FIGS. 2 to 6, the cells 13 (inflow side cells 13a and outflow side cells 13b) each extend in the exhaust gas flow direction E, and have an end on the exhaust gas inflow side and an end on the exhaust gas outflow side. has.
図６に示すように、基材１０には、一部のセル１３の排ガス流出側の端部を封止する第１封止部１４と、残りのセル１３の排ガス流入側の端部を封止する第２封止部１５とが設けられており、これにより、一部のセル１３は、排ガス流入側の端部が開口しており、排ガス流出側の端部が第１封止部１４で閉塞している流入側セル１３ａとなっており、残りのセル１３は、排ガス流入側の端部が第２封止部１５で閉塞しており、排ガス流出側の端部が開口している流出側セル１３ｂとなっている。
As shown in FIG. 6, the base material 10 includes a first sealing part 14 that seals the ends of some of the cells 13 on the exhaust gas outflow side, and a first sealing part 14 that seals the ends of the remaining cells 13 on the exhaust gas inflow side. As a result, some of the cells 13 are open at the end on the exhaust gas inflow side, and the end on the exhaust gas outflow side is opened at the first sealing section 14. The remaining cells 13 have their exhaust gas inflow ends closed with the second sealing part 15 and their exhaust gas outflow ends open. This is the outflow side cell 13b.
図２～６に示すように、隣接するセル１３（流入側セル１３ａ及び流出側セル１３ｂ）の間には隔壁部１２が存在し、隣接するセル１３（流入側セル１３ａ及び流出側セル１３ｂ）は、隔壁部１２によって仕切られている。本実施形態では、図４～６に示すように、１個の流入側セル１３ａの周りに複数（本実施形態では４個）の流出側セル１３ｂが配置されており、流入側セル１３ａと、当該流入側セル１３ａに周りに配置された流出側セル１３ｂとは、隔壁部１２によって仕切られている。
As shown in FIGS. 2 to 6, a partition wall 12 exists between adjacent cells 13 (inflow side cell 13a and outflow side cell 13b), and adjacent cells 13 (inflow side cell 13a and outflow side cell 13b) are partitioned by partition walls 12. In this embodiment, as shown in FIGS. 4 to 6, a plurality of (four in this embodiment) outflow cells 13b are arranged around one inflow cell 13a, and an inflow cell 13a, The inflow cell 13 a is separated from the outflow cell 13 b arranged around it by a partition wall 12 .
本実施形態では、図４～６に示すように、流入側セル１３ａの排ガス流入側の端部（開口部）の平面視形状及び流出側セル１３ｂの排ガス流出側の端部（開口部）の平面視形状がそれぞれ、四角形であるが、六角形、八角形等のその他の形状であってもよい。
In this embodiment, as shown in FIGS. 4 to 6, the plan view shape of the exhaust gas inflow side end (opening) of the inflow side cell 13a and the plan view shape of the exhaust gas outflow side end (opening) of the outflow side cell 13b are shown. Although each of the shapes in plan view is a quadrilateral, other shapes such as a hexagon or an octagon may be used.
図２及び３に示すように、隔壁部１２は、筒状部１１内に設けられている。隔壁部１２は、排ガスが通過可能な多孔質構造を有する。
As shown in FIGS. 2 and 3, the partition wall portion 12 is provided within the cylindrical portion 11. The partition wall portion 12 has a porous structure through which exhaust gas can pass.
図４～６に示すように、隔壁部１２は、流入側セル１３ａ側の外表面Ｓ１ａと、流出側セル１３ｂ側の外表面Ｓ１ｂとを有する。流入側セル１３ａ側の外表面Ｓ１ａは、隔壁部１２の外形を規定する外表面のうち、排ガス流通方向Ｅに延在する流入側セル１３ａ側の領域（すなわち、流入側セル１３ａと接する領域）である。流出側セル１３ｂ側の外表面Ｓ１ｂは、隔壁部１２の外形を規定する外表面のうち、排ガス流通方向Ｅに延在する流出側セル１３ｂ側の領域（すなわち、流出側セル１３ｂと接する領域）である。
As shown in FIGS. 4 to 6, the partition wall portion 12 has an outer surface S1a on the inflow side cell 13a side and an outer surface S1b on the outflow side cell 13b side. Outer surface S1a on the inflow side cell 13a side is a region on the inflow side cell 13a side that extends in the exhaust gas flow direction E (i.e., a region in contact with the inflow side cell 13a) among the outer surfaces that define the outer shape of the partition wall portion 12. It is. The outer surface S1b on the outflow side cell 13b side is the area on the outflow side cell 13b side that extends in the exhaust gas flow direction E (i.e., the area in contact with the outflow side cell 13b) among the outer surfaces that define the outer shape of the partition wall 12. It is.
隔壁部１２の厚みは、ＰＭ捕集性能、圧損等を考慮して適宜調整することができる。ＰＭ捕集性能を向上させるとともに圧損上昇を抑制する観点から、隔壁部１２の厚みは、好ましくは１１０μｍ以上３８０μｍ以下、より好ましくは１５０μｍ以上３３０μｍ以下、より一層好ましくは１８０μｍ以上３１０μｍ以下である。
The thickness of the partition wall portion 12 can be adjusted as appropriate in consideration of PM trapping performance, pressure loss, etc. From the viewpoint of improving PM trapping performance and suppressing an increase in pressure loss, the thickness of the partition wall portion 12 is preferably 110 μm or more and 380 μm or less, more preferably 150 μm or more and 330 μm or less, and even more preferably 180 μm or more and 310 μm or less.
基材１０の１平方インチあたりのセル密度は、ＰＭ捕集性能、圧損等を考慮して適宜調整することができる。ＰＭ捕集性能を向上させるとともに圧損上昇を抑制する観点から、基材１０の１平方インチあたりのセル密度は、好ましくは１８０セル以上３５０セル以下である。基材１０の１平方インチあたりのセル密度は、基材１０を基材１０の軸方向と垂直な平面で切断して得られた断面における１平方インチあたりのセル１３（流入側セル１３ａ及び流出側セル１３ｂ）の合計個数である。
The cell density per square inch of the base material 10 can be adjusted as appropriate in consideration of PM trapping performance, pressure loss, etc. From the viewpoint of improving PM trapping performance and suppressing an increase in pressure loss, the cell density per square inch of the base material 10 is preferably 180 cells or more and 350 cells or less. The cell density per square inch of the base material 10 is the cell density per square inch of the base material 10 in a cross section obtained by cutting the base material 10 along a plane perpendicular to the axial direction of the base material 10. This is the total number of side cells 13b).
＜第１触媒層＞
以下、第１触媒層２０について説明する。 <First catalyst layer>
The first catalyst layer 20 will be explained below.
以下、第１触媒層２０について説明する。 <First catalyst layer>
The first catalyst layer 20 will be explained below.
第１触媒層２０は、Ｒｈを含む。
The first catalyst layer 20 contains Rh.
Ｒｈは、触媒活性成分として機能し得る形態、例えば、金属Ｒｈ、Ｒｈを含む合金、Ｒｈを含む化合物（例えば、Ｒｈの酸化物）等の、Ｒｈを含む触媒活性成分の形態で第１触媒層２０に含まれる。排ガス浄化性能を高める観点から、Ｒｈを含む触媒活性成分は、粒子状であることが好ましい。
Rh is present in the first catalyst layer in the form of a catalytically active component containing Rh, such as a metal Rh, an alloy containing Rh, a compound containing Rh (for example, an oxide of Rh), etc., which can function as a catalytically active component. Included in 20. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Rh is preferably in the form of particles.
排ガス浄化性能とコストとのバランスの観点から、第１触媒層２０中のＲｈの金属換算量は、第１触媒層２０の質量を基準として、好ましくは０．１質量％以上１０．０質量％以下、より好ましくは０．２質量％以上５．０質量％以下、より一層好ましくは０．３質量％以上３．０質量％以下である。
From the viewpoint of balance between exhaust gas purification performance and cost, the metal equivalent amount of Rh in the first catalyst layer 20 is preferably 0.1% by mass or more and 10.0% by mass based on the mass of the first catalyst layer 20. The content is more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
第１触媒層２０は、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい。Ｒｈ以外の貴金属元素は、例えば、Ｐｔ、Ｐｄ、Ｒｕ、Ｉｒ、Ｏｓ等から選択することができる。Ｒｈ以外の貴金属元素は、触媒活性成分として機能し得る形態、例えば、金属、貴金属元素を含む合金、貴金属元素を含む化合物（例えば、貴金属元素の酸化物）等の、Ｒｈ以外の貴金属元素を含む触媒活性成分の形態で第１触媒層２０に含まれる。排ガス浄化性能を高める観点から、Ｒｈ以外の貴金属元素を含む触媒活性成分は、粒子状であることが好ましい。
The first catalyst layer 20 may contain one or more noble metal elements other than Rh. The noble metal elements other than Rh can be selected from, for example, Pt, Pd, Ru, Ir, Os, and the like. The noble metal element other than Rh includes a noble metal element other than Rh in a form that can function as a catalytically active component, for example, a metal, an alloy containing a noble metal element, a compound containing a noble metal element (e.g., an oxide of a noble metal element), etc. It is contained in the first catalyst layer 20 in the form of a catalytically active component. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing a noble metal element other than Rh is preferably in the form of particles.
排ガス浄化性能とコストとのバランスの観点から、第１触媒層２０中の全貴金属元素の合計金属換算量は、第１触媒層２０の質量を基準として、好ましくは０．１質量％以上１０．０質量％以下、より好ましくは０．２質量％以上５．０質量％以下、より一層好ましくは０．３質量％以上３．０質量％以下である。
From the viewpoint of the balance between exhaust gas purification performance and cost, the total metal equivalent amount of all noble metal elements in the first catalyst layer 20 is preferably 0.1% by mass or more based on the mass of the first catalyst layer 20. The content is 0% by mass or less, more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
第１触媒層２０がＲｈとＲｈ以外の１種又は２種以上の貴金属元素とを含む場合、ＲｈとＲｈ以外の１種又は２種以上の貴金属元素とが触媒活性の低い合金を形成し、排ガス浄化性能に関与するＲｈの活性点が減少するおそれがある。したがって、Ｒｈの排ガス浄化性能の低下を抑制する観点から、第１触媒層２０中のＲｈの金属換算量は、第１触媒層２０中のＲｈ以外の各貴金属元素の金属換算量よりも大きいことが好ましい。また、同様の観点から、第１触媒層２０中のＲｈの金属換算量は、第１触媒層２０中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きいことが好ましい。
When the first catalyst layer 20 contains Rh and one or more noble metal elements other than Rh, Rh and the one or more noble metal elements other than Rh form an alloy with low catalytic activity, There is a possibility that the active sites of Rh, which are involved in exhaust gas purification performance, will decrease. Therefore, from the viewpoint of suppressing the deterioration of the exhaust gas purification performance of Rh, the metal equivalent amount of Rh in the first catalyst layer 20 should be larger than the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer 20. is preferred. Further, from the same viewpoint, the metal equivalent amount of Rh in the first catalyst layer 20 is preferably larger than the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer 20.
第１触媒層２０中のＲｈの金属換算量に対する、第１触媒層２０中のＲｈ以外の各貴金属元素の金属換算量の比は、質量比で、好ましくは０．９以下、より好ましくは０．５以下、より一層好ましくは０．３以下である。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．１以上又は０．１５以上であってもよい。これらの下限値はそれぞれ、上記の上限値のいずれと組み合わせてもよい。
The ratio of the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer 20 to the metal equivalent amount of Rh in the first catalyst layer 20 is preferably 0.9 or less, more preferably 0. .5 or less, and even more preferably 0.3 or less. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.1 or more, or 0.15 or more. Each of these lower limits may be combined with any of the above upper limits.
第１触媒層２０中のＲｈの金属換算量に対する、第１触媒層２０中のＲｈ以外の全貴金属元素の合計金属換算量の比は、質量比で、好ましくは０．９以下、より好ましくは０．５以下、より一層好ましくは０．３以下である。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．１以上又は０．２以上であってもよい。これらの下限値はそれぞれ、上記の上限値のいずれと組み合わせてもよい。
The ratio of the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer 20 to the metal equivalent amount of Rh in the first catalyst layer 20 is preferably 0.9 or less, more preferably It is 0.5 or less, more preferably 0.3 or less. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more. Each of these lower limits may be combined with any of the above upper limits.
第１触媒層２０は、Ｐｔを含んでいてもよい。Ｐｔは、触媒活性成分として機能し得る形態、例えば、金属Ｐｔ、Ｐｔを含む合金、Ｐｔを含む化合物（例えば、Ｐｔの酸化物）等の、Ｐｔを含む触媒活性成分の形態で第１触媒層２０に含まれる。排ガス浄化性能を高める観点から、Ｐｔを含む触媒活性成分は、粒子状であることが好ましい。
The first catalyst layer 20 may contain Pt. Pt is present in the first catalyst layer in the form of a catalytically active component containing Pt, such as metal Pt, an alloy containing Pt, a compound containing Pt (for example, an oxide of Pt), etc., which can function as a catalytically active component. Included in 20. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Pt is preferably in the form of particles.
第１触媒層２０中の全貴金属元素の合計金属換算量に対する、第１触媒層２０中のＰｔの金属換算量の比は、質量比で、好ましくは０．３以下である。当該比が０．３以下であれば、Ｒｈの触媒活性の安定化を図ることができる。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．５以上又は０．１以上であってもよい。これらの下限値はそれぞれ、上記の上限値と組み合わせることができる。
The ratio of the metal equivalent amount of Pt in the first catalyst layer 20 to the total metal equivalent amount of all noble metal elements in the first catalyst layer 20 is preferably 0.3 or less in terms of mass ratio. If the ratio is 0.3 or less, the catalytic activity of Rh can be stabilized. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.5 or more, or 0.1 or more. Each of these lower limits can be combined with the above upper limits.
第１触媒層２０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、第１触媒層２０中の各貴金属元素の金属換算量は、第１触媒層２０の製造に使用される原料の情報から求めることができる。第１触媒層２０の製造に使用される原料の情報が判明していない場合、第１触媒層２０中の各貴金属元素の金属換算量は、誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＯＥＳ）、蛍光Ｘ線分析装置（ＸＲＦ）、走査型電子顕微鏡－エネルギー分散型Ｘ線分析装置（ＳＥＭ－ＥＤＸ）等を使用して求めることができる。具体的には、下記の通りである。
When information on the raw materials (for example, composition, amount, etc.) used to manufacture the first catalyst layer 20 is known, the metal equivalent amount of each noble metal element in the first catalyst layer 20 is It can be determined from information on the raw materials used in the production of. If information on the raw materials used to manufacture the first catalyst layer 20 is not known, the metal equivalent amount of each noble metal element in the first catalyst layer 20 can be determined using an inductively coupled plasma optical emission spectrometer (ICP-OES), It can be determined using an X-ray fluorescence analyzer (XRF), a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDX), or the like. Specifically, it is as follows.
第１触媒層２０から得られた試料について、ＳＥＭ－ＥＤＸ等の常法を使用して元素分析を行い、試料全体の構成元素の種類を特定するとともに、特定された各金属元素の金属換算量（質量％）を求める。ＳＥＭの１０視野の各々について、各金属元素の金属換算量（質量％）を求め、１０視野における各金属元素の金属換算量（質量％）の平均値を、第１触媒層２０中の各金属元素の金属換算量（質量％）とする。
Elemental analysis is performed on the sample obtained from the first catalyst layer 20 using a conventional method such as SEM-EDX, and the types of constituent elements of the entire sample are identified, as well as the metal equivalent amount of each identified metal element. Find (mass%). For each of the 10 fields of view of the SEM, the metal equivalent amount (mass%) of each metal element is determined, and the average value of the metal equivalent amount (mass %) of each metal element in the 10 fields of view is determined for each metal in the first catalyst layer 20. It is expressed as the metal equivalent amount (mass%) of the element.
排ガス浄化性能とコストとのバランスの観点から、基材１０のうち第１触媒層２０が形成されている部分の単位体積当たりの第１触媒層２０の質量は、好ましくは１１ｇ／Ｌ以上１３３ｇ／Ｌ以下、より好ましくは２２ｇ／Ｌ以上８９ｇ／Ｌ以下、より一層好ましくは２２ｇ／Ｌ以上６７ｇ／Ｌ以下である。基材１０のうち第１触媒層２０が形成されている部分の単位体積当たりの第１触媒層２０の質量は、式：（第１触媒層２０の質量）／（（基材１０の体積）×（第１触媒層２０の平均長さＬ２０／基材１０の長さＬ１０））から算出される。
From the viewpoint of balance between exhaust gas purification performance and cost, the mass of the first catalyst layer 20 per unit volume of the portion of the base material 10 where the first catalyst layer 20 is formed is preferably 11 g/L or more and 133 g/L. L or less, more preferably 22 g/L or more and 89 g/L or less, even more preferably 22 g/L or more and 67 g/L or less. The mass of the first catalyst layer 20 per unit volume of the portion of the base material 10 where the first catalyst layer 20 is formed is calculated by the formula: (mass of the first catalyst layer 20)/((volume of the base material 10) It is calculated from ×(average length L 20 of first catalyst layer 20 / length L 10 of base material 10)).
本明細書において、「第１触媒層２０の質量」は、第１触媒層２０に含まれる全ての金属元素のうち、貴金属元素については金属換算の質量を、貴金属元素以外の金属元素については酸化物換算の質量を求め、これらを合計したものを意味する。すなわち、「第１触媒層２０の質量」は、第１触媒層２０に含まれる貴金属元素の金属換算の質量と、第１触媒層２０に含まれる貴金属元素以外の金属元素の酸化物換算の質量とを合計することにより求められた計算質量を意味する。なお、「金属元素」には、Ｓｉ、Ｂ等の半金属元素も包含される。
In this specification, the "mass of the first catalyst layer 20" refers to the mass of noble metal elements in metal terms among all the metal elements contained in the first catalyst layer 20, and the oxidized mass of metal elements other than the noble metal elements. It means the sum of the calculated mass in physical terms. That is, "the mass of the first catalyst layer 20" is the mass of the noble metal element contained in the first catalyst layer 20 in terms of metal, and the mass of the metal element other than the noble metal element contained in the first catalyst layer 20 in terms of oxide. means the calculated mass obtained by summing the Note that the term "metal element" also includes metalloid elements such as Si and B.
本明細書において、「貴金属元素」には、Ｐｔ、Ｐｄ、Ｒｈ、Ａｕ、Ａｇ、Ｒｕ、Ｉｒ及びＯｓが包含される。
In this specification, "noble metal element" includes Pt, Pd, Rh, Au, Ag, Ru, Ir, and Os.
本明細書において、Ｃｅ、Ｐｒ及びＴｂを除く希土類元素の酸化物はセスキ酸化物（Ｍ２Ｏ３，ＭはＣｅ、Ｐｒ及びＴｂ以外の希土類元素を表す）を、Ｃｅの酸化物はＣｅＯ２を、Ｐｒの酸化物はＰｒ６Ｏ１１を、Ｔｂの酸化物はＴｂ４Ｏ７を、Ａｌの酸化物はＡｌ２Ｏ３を、Ｚｒの酸化物はＺｒＯ２を、Ｓｉの酸化物はＳｉＯ２を、Ｂの酸化物はＢ２Ｏ３を、Ｃｒの酸化物はＣｒ２Ｏ３を、Ｍｇの酸化物はＭｇＯを、Ｃａの酸化物はＣａＯを、Ｓｒの酸化物はＳｒＯを、Ｂａの酸化物はＢａＯを、Ｆｅの酸化物はＦｅ３Ｏ４を、Ｍｎの酸化物はＭｎ３Ｏ４を、Ｎｉの酸化物はＮｉＯを、Ｔｉの酸化物はＴｉＯ２を、Ｚｎの酸化物はＺｎＯを、Ｓｎの酸化物はＳｎＯ２を意味する。
In this specification, oxides of rare earth elements other than Ce, Pr and Tb are referred to as sesquioxides (M 2 O 3 , M represents rare earth elements other than Ce, Pr and Tb), and oxides of Ce are referred to as CeO 2 , Pr oxide is Pr 6 O 11 , Tb oxide is Tb 4 O 7 , Al oxide is Al 2 O 3 , Zr oxide is ZrO 2 , Si oxide is SiO 2 , B oxide is B 2 O 3 , Cr oxide is Cr 2 O 3 , Mg oxide is MgO, Ca oxide is CaO, Sr oxide is SrO, Ba The oxide of is BaO, the oxide of Fe is Fe 3 O 4 , the oxide of Mn is Mn 3 O 4 , the oxide of Ni is NiO, the oxide of Ti is TiO 2 , the oxide of Zn. means ZnO, and oxide of Sn means SnO2 .
第１触媒層２０の平均長さＬ２０の測定方法の一例は、以下の通りである。
An example of a method for measuring the average length L 20 of the first catalyst layer 20 is as follows.
排ガス浄化用触媒１から、基材１０の軸方向に延在し、基材１０の長さＬ１０と同一の長さを有するサンプルを切り出す。サンプルは、例えば、直径２５．４ｍｍの円柱状である。なお、サンプルの直径の値は必要に応じて変更することができる。サンプルを基材１０の軸方向と垂直な平面によって５ｍｍ間隔で切断し、サンプルの排ガス流入側の端部側から順に、第１切断片、第２切断片、・・・、第ｎ切断片を得る。切断片の長さは５ｍｍである。切断片の組成を、誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＯＥＳ）、蛍光Ｘ線分析装置（ＸＲＦ）、走査型電子顕微鏡－エネルギー分散型Ｘ線分析法（ＳＥＭ－ＥＤＸ）等を使用して分析し、切断片の組成に基づいて、切断片が第１触媒層２０の一部を含むか否かを確認する。
A sample extending in the axial direction of the base material 10 and having the same length as the length L10 of the base material 10 is cut out from the exhaust gas purifying catalyst 1. The sample is, for example, cylindrical with a diameter of 25.4 mm. Note that the value of the diameter of the sample can be changed as necessary. The sample was cut at intervals of 5 mm along a plane perpendicular to the axial direction of the base material 10, and the first cut piece, the second cut piece, ..., the nth cut piece were cut in order from the end of the sample on the exhaust gas inflow side. obtain. The length of the cut piece is 5 mm. The composition of the cut pieces was determined using an inductively coupled plasma optical emission spectrometer (ICP-OES), an X-ray fluorescence spectrometer (XRF), a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDX), etc. Based on the composition of the cut piece, it is determined whether the cut piece includes a part of the first catalyst layer 20 or not.
第１触媒層２０の一部を含むことが明らかである切断片に関しては、必ずしも組成分析を行う必要はない。例えば、走査型電子顕微鏡（ＳＥＭ）、電子線マイクロアナライザー（ＥＰＭＡ）等を使用して切断面を観察し、切断片が第１触媒層２０の一部を含むか否かを確認することができる。切断面の観察を行う際、切断面の元素マッピングを行ってもよい。元素マッピングは、例えば、ＳＥＭ－ＥＤＸ、電子線マイクロアナライザー（ＥＰＭＡ）、透過型Ｘ線検査装置等を使用して行うことができる。
It is not necessarily necessary to perform a composition analysis on a cut piece that clearly includes a part of the first catalyst layer 20. For example, the cut surface can be observed using a scanning electron microscope (SEM), an electron beam microanalyzer (EPMA), etc., and it can be confirmed whether the cut piece includes a part of the first catalyst layer 20 or not. . When observing the cut surface, elemental mapping of the cut surface may be performed. Elemental mapping can be performed using, for example, a SEM-EDX, an electron beam microanalyzer (EPMA), a transmission type X-ray inspection device, or the like.
切断片が第１触媒層２０の一部を含むか否かを確認した後、下記式に基づいて、サンプルに含まれる第１触媒層２０の長さを算出する。
サンプルに含まれる第１触媒層２０の長さ＝５ｍｍ×（第１触媒層２０の一部を含む切断片の数） After confirming whether the cut piece includes a part of the first catalyst layer 20, the length of the first catalyst layer 20 included in the sample is calculated based on the following formula.
Length of the first catalyst layer 20 included in the sample = 5 mm x (number of cut pieces including a part of the first catalyst layer 20)
サンプルに含まれる第１触媒層２０の長さ＝５ｍｍ×（第１触媒層２０の一部を含む切断片の数） After confirming whether the cut piece includes a part of the first catalyst layer 20, the length of the first catalyst layer 20 included in the sample is calculated based on the following formula.
Length of the first catalyst layer 20 included in the sample = 5 mm x (number of cut pieces including a part of the first catalyst layer 20)
例えば、第１切断片～第ｋ切断片は第１触媒層２０の一部を含むが、第（ｋ＋１）～第ｎ切断片は第１触媒層２０の一部を含まない場合、サンプルに含まれる第１触媒層２０の長さは、（５×ｋ）ｍｍである。
For example, if the first cut piece to the kth cut piece include a part of the first catalyst layer 20, but the (k+1)th to nth cut pieces do not include a part of the first catalyst layer 20, they are not included in the sample. The length of the first catalyst layer 20 is (5×k) mm.
サンプルに含まれる第１触媒層２０の長さのより詳細な測定方法の一例は、以下の通りである。
第ｋ切断片（すなわち、第１触媒層２０の一部を含む切断片のうち、サンプルの最も排ガス流出側から得られた切断片）を基材１０の軸方向で切断して、ＳＥＭ、ＥＰＭＡ等を使用して切断面に存在する第１触媒層２０の一部を観察することにより、第ｋ切断片における第１触媒層２０の一部の長さを測定する。そして、下記式に基づいて、サンプルに含まれる第１触媒層２０の長さを算出する。
サンプルに含まれる第１触媒層２０の長さ＝（５ｍｍ×（ｋ－１））＋（第ｋ切断片に含まれる第１触媒層２０の一部の長さ） An example of a more detailed method for measuring the length of the first catalyst layer 20 included in the sample is as follows.
The k-th cut piece (that is, the cut piece obtained from the closest exhaust gas outflow side of the sample among the cut pieces including a part of the first catalyst layer 20) is cut in the axial direction of the base material 10, and then SEM, EPMA By observing a portion of the first catalyst layer 20 present on the cut surface using a tool such as a cutting tool, the length of the portion of the first catalyst layer 20 at the k-th cut section is measured. Then, the length of the first catalyst layer 20 included in the sample is calculated based on the following formula.
Length of the first catalyst layer 20 included in the sample = (5 mm x (k-1)) + (length of part of the first catalyst layer 20 included in the k-th cut piece)
第ｋ切断片（すなわち、第１触媒層２０の一部を含む切断片のうち、サンプルの最も排ガス流出側から得られた切断片）を基材１０の軸方向で切断して、ＳＥＭ、ＥＰＭＡ等を使用して切断面に存在する第１触媒層２０の一部を観察することにより、第ｋ切断片における第１触媒層２０の一部の長さを測定する。そして、下記式に基づいて、サンプルに含まれる第１触媒層２０の長さを算出する。
サンプルに含まれる第１触媒層２０の長さ＝（５ｍｍ×（ｋ－１））＋（第ｋ切断片に含まれる第１触媒層２０の一部の長さ） An example of a more detailed method for measuring the length of the first catalyst layer 20 included in the sample is as follows.
The k-th cut piece (that is, the cut piece obtained from the closest exhaust gas outflow side of the sample among the cut pieces including a part of the first catalyst layer 20) is cut in the axial direction of the base material 10, and then SEM, EPMA By observing a portion of the first catalyst layer 20 present on the cut surface using a tool such as a cutting tool, the length of the portion of the first catalyst layer 20 at the k-th cut section is measured. Then, the length of the first catalyst layer 20 included in the sample is calculated based on the following formula.
Length of the first catalyst layer 20 included in the sample = (5 mm x (k-1)) + (length of part of the first catalyst layer 20 included in the k-th cut piece)
排ガス浄化用触媒１から任意に切り出された８～１６個のサンプルに関して、各サンプルに含まれる第１触媒層２０の長さを測定し、それらの平均値を第１触媒層２０の平均長さＬ２０とする。
Regarding 8 to 16 samples arbitrarily cut out from the exhaust gas purification catalyst 1, the length of the first catalyst layer 20 included in each sample is measured, and the average value thereof is determined as the average length of the first catalyst layer 20. Let L be 20 .
第１触媒層２０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、基材１０のうち第１触媒層２０が形成されている部分の単位体積当たりの第１触媒層２０の質量は、第１触媒層２０の製造に使用される原料の情報から求めることができる。
If information on the raw materials used to manufacture the first catalyst layer 20 (for example, composition, amount, etc.) is known, the amount per unit volume of the portion of the base material 10 on which the first catalyst layer 20 is formed is The mass of the first catalyst layer 20 can be determined from information on the raw materials used to manufacture the first catalyst layer 20.
第１触媒層２０は、１種又は２種以上の担体を含み、触媒活性成分の少なくとも一部は１種又は２種以上の担体に担持されていることが好ましい。
It is preferable that the first catalyst layer 20 includes one or more types of carriers, and at least a part of the catalytically active component is supported on the one or more types of carriers.
「触媒活性成分の少なくとも一部が担体に担持されている」とは、担体の外表面又は細孔内表面に、触媒活性成分の少なくとも一部が、物理的及び／又は化学的に吸着及び／又は保持されている状態を意味する。触媒活性成分の少なくとも一部が担体に担持されていることは、例えば、ＳＥＭ－ＥＤＸ等を使用して確認することができる。具体的には、触媒層の断面をＳＥＭ－ＥＤＸで分析して得られた元素マッピングにおいて、触媒活性成分の少なくとも一部と担体とが同じ領域に存在している場合、触媒活性成分の少なくとも一部が担体に担持されていると判断することができる。
"At least a part of the catalytically active component is supported on the carrier" means that at least a part of the catalytically active component is physically and/or chemically adsorbed and/or or the state in which it is maintained. It can be confirmed that at least a portion of the catalytically active component is supported on the carrier using, for example, SEM-EDX. Specifically, in the elemental mapping obtained by analyzing the cross section of the catalyst layer with SEM-EDX, if at least part of the catalytically active component and the support are present in the same area, at least part of the catalytically active component is It can be determined that the part is supported on the carrier.
担体は、例えば、無機酸化物から選択することができる。無機酸化物は、例えば、粒子状である。触媒活性成分の担持性を向上させる観点から、無機酸化物は、多孔質であることが好ましい。無機酸化物は、酸素貯蔵能（ＯＳＣ：Ｏｘｙｇｅｎ Ｓｔｏｒａｇｅ Ｃａｐａｃｉｔｙ）を有していてもよいし、有していなくてもよい。担体として使用される無機酸化物は、バインダとして使用される無機酸化物（例えば、アルミナバインダ、ジルコニアバインダ、チタニアバインダ、シリカバインダ等の無機酸化物系バインダ）とは区別される。バインダとして使用される無機酸化物は、原料として使用されるゾル（例えば、アルミナバゾル、ジルコニアゾル、チタニアゾル、シリカゾル等の無機酸化物系ゾル）に由来する。
The carrier can be selected from, for example, inorganic oxides. The inorganic oxide is, for example, particulate. From the viewpoint of improving the ability to support the catalytically active component, the inorganic oxide is preferably porous. The inorganic oxide may or may not have oxygen storage capacity (OSC). Inorganic oxides used as supports are distinguished from inorganic oxides used as binders (eg, inorganic oxide binders such as alumina binders, zirconia binders, titania binders, silica binders, etc.). The inorganic oxide used as the binder is derived from the sol used as a raw material (for example, an inorganic oxide sol such as alumina sol, zirconia sol, titania sol, silica sol, etc.).
無機酸化物としては、例えば、Ａｌ系酸化物、希土類元素（以下「Ｌｎ」と表記する場合がある。）の酸化物、Ｌｎ－Ｚｒ系複合酸化物、ジルコニア（ＺｒＯ２）、シリカ（ＳｉＯ２）、チタニア（ＴｉＯ２）、ゼオライト（アルミノケイ酸塩）、ＭｇＯ、ＺｎＯ、ＳｎＯ２等をベースとした酸化物等が挙げられる。
Examples of inorganic oxides include Al-based oxides, rare earth element (hereinafter sometimes referred to as "Ln") oxides, Ln-Zr-based composite oxides, zirconia (ZrO 2 ), and silica (SiO 2 ), titania (TiO 2 ), zeolite (aluminosilicate), MgO, ZnO, SnO 2 and the like-based oxides.
本明細書において、Ａｌ系酸化物は、Ａｌを含む酸化物であって、酸化物を構成する酸素以外の元素のうち、質量基準で最も含有率が大きい元素がＡｌである酸化物を意味する。但し、Ｌｎ－Ｚｒ系複合酸化物に該当するものは、Ａｌ系酸化物に該当しないものとする。Ｌｎ－Ｚｒ系複合酸化物については後述する。Ａｌ系酸化物は、バインダとして使用されるアルミナとは区別される。本明細書において、バインダとして使用されるアルミナを「アルミナバインダ」という場合がある。
As used herein, an Al-based oxide refers to an oxide containing Al, in which Al is the element with the highest content on a mass basis among the elements other than oxygen constituting the oxide. . However, what falls under the Ln-Zr-based composite oxide does not fall under the Al-based oxide. The Ln-Zr based composite oxide will be described later. Al-based oxides are distinguished from alumina, which is used as a binder. In this specification, alumina used as a binder may be referred to as "alumina binder".
Ａｌ系酸化物は、一般的に、その他の無機酸化物（例えば、Ｌｎ－Ｚｒ系複合酸化物）よりも、耐熱性が高い。したがって、第１触媒層２０がＡｌ系酸化物を含むことにより、第１触媒層２０の耐熱性が向上し、第１触媒層２０の排ガス浄化性能が向上する。
Al-based oxides generally have higher heat resistance than other inorganic oxides (for example, Ln-Zr-based composite oxides). Therefore, by including the Al-based oxide in the first catalyst layer 20, the heat resistance of the first catalyst layer 20 is improved, and the exhaust gas purification performance of the first catalyst layer 20 is improved.
Ａｌ系酸化物としては、例えば、アルミナ（Ａｌ２Ｏ３）、修飾アルミナ等が挙げられる。修飾アルミナは、Ａｌ及びＯ以外の１種又は２種以上の元素を含む。修飾アルミナとしては、例えば、アルミナの表面をＡｌ及びＯ以外の元素で修飾して得られる酸化物、アルミナ中にＡｌ及びＯ以外の元素を固溶して得られる酸化物等が挙げられる。Ａｌ及びＯ以外の元素は、例えば、Ｂ、Ｓｉ、Ｚｒ、Ｃｒ、希土類元素、アルカリ土類金属元素等から選択することができる。修飾アルミナとしては、例えば、アルミナ－シリカ、アルミナ－ジルコニア、アルミナ－クロミア、アルミナ－セリア、アルミナ－ランタナ等が挙げられる。
Examples of the Al-based oxide include alumina (Al 2 O 3 ), modified alumina, and the like. Modified alumina contains one or more elements other than Al and O. Examples of modified alumina include oxides obtained by modifying the surface of alumina with elements other than Al and O, and oxides obtained by dissolving elements other than Al and O in alumina. Elements other than Al and O can be selected from, for example, B, Si, Zr, Cr, rare earth elements, alkaline earth metal elements, and the like. Examples of the modified alumina include alumina-silica, alumina-zirconia, alumina-chromia, alumina-ceria, and alumina-lanthana.
耐熱性を向上させる観点から、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量は、Ａｌ系酸化物の質量を基準として、好ましくは５０質量％以上、より好ましくは７０質量％以上、より一層好ましくは８０質量％以上である。上限は１００質量％である。
From the viewpoint of improving heat resistance, the Al 2 O 3 equivalent amount of Al in the Al-based oxide is preferably 50% by mass or more, more preferably 70% by mass or more, and more preferably 50% by mass or more, more preferably 70% by mass or more, based on the mass of the Al-based oxide. More preferably, it is 80% by mass or more. The upper limit is 100% by mass.
第１触媒層２０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量は、第１触媒層２０の製造に使用される原料の情報から求めることができる。第１触媒層２０の製造に使用される原料の情報が判明していない場合、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量は、第１触媒層２０をエネルギー分散型Ｘ線分光装置（ＥＤＸ）で分析し、得られた元素マッピングと、指定した粒子のＥＤＸ元素分析とから求めることができる。具体的には、元素マッピングにより定性的にＡｌ系酸化物粒子及びその他の粒子（例えば、Ｌｎ－Ｚｒ系複合酸化物粒子）を識別（色分け）し、指定した粒子に対して組成分析（元素分析）することにより、指定した粒子中の所定元素の酸化物換算量を求めることができる。
If information on the raw materials (e.g., composition, amount, etc.) used to manufacture the first catalyst layer 20 is known, the amount of Al in the Al-based oxide in terms of Al 2 O 3 is It can be determined from information on the raw materials used in the production of. If the information on the raw materials used for manufacturing the first catalyst layer 20 is not known, the amount of Al in the Al-based oxide in terms of Al 2 O 3 can be calculated using an energy dispersive X-ray spectrometer. (EDX) analysis and obtained elemental mapping and EDX elemental analysis of specified particles. Specifically, we qualitatively identify (color-code) Al-based oxide particles and other particles (for example, Ln-Zr-based composite oxide particles) through elemental mapping, and perform compositional analysis (elemental analysis) on the specified particles. ), the oxide equivalent amount of a predetermined element in a specified particle can be determined.
第１触媒層２０がＡｌ系酸化物を含む場合、耐熱性を向上させる観点から、第１触媒層２０中のＡｌ系酸化物の量は、第１触媒層２０の質量を基準として、好ましくは５質量％以上５０質量％以下、より好ましくは５質量％以上４０質量％以下、より一層好ましくは７質量％以上３０質量％以下である。第１触媒層２０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、第１触媒層２０中のＡｌ系酸化物の量は、第１触媒層２０の製造に使用される原料の情報から求めることができる。第１触媒層２０の製造に使用される原料の情報が判明していない場合、第１触媒層２０中のＡｌ系酸化物の量は、ＩＣＰ－ＯＥＳ、ＸＲＦ、ＳＥＭ－ＥＤＸ等を使用して求めることができる。具体的には、下記の通りである。
When the first catalyst layer 20 contains an Al-based oxide, from the viewpoint of improving heat resistance, the amount of the Al-based oxide in the first catalyst layer 20 is preferably based on the mass of the first catalyst layer 20. The content is 5% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, even more preferably 7% by mass or more and 30% by mass or less. If information on the raw materials used to manufacture the first catalyst layer 20 (for example, composition, amount, etc.) is known, the amount of Al-based oxide in the first catalyst layer 20 can be determined by It can be determined from information on raw materials used in manufacturing. If information on the raw materials used to manufacture the first catalyst layer 20 is not known, the amount of Al-based oxide in the first catalyst layer 20 can be determined using ICP-OES, XRF, SEM-EDX, etc. You can ask for it. Specifically, it is as follows.
（１）第１触媒層２０から得られた試料について、ＳＥＭ－ＥＤＸ等の常法を用いて元素分析を行い、試料全体の構成元素の種類を特定するとともに、特定された各元素の含有量（質量％）を求める。
（２）第１触媒層２０から得られた試料について、ＳＥＭ－ＥＤＸ等の常法を用いて元素マッピングを行い、試料に含まれる粒子の種類（例えば、Ａｌ系酸化物粒子及び場合によりその他の粒子）を特定する。
（３）各種類の粒子について、任意に選択された複数個（例えば５０個）の粒子をＳＥＭ－ＥＤＸにて元素分析し、粒子の構成元素の種類を特定するとともに、特定された各元素の含有量（質量％）を求める。各種類の粒子について、各元素の含有量（質量％）の平均値を求める。
（４）試料における各元素の含有量（質量％）と、各種類の粒子における各元素の含有量（質量％）と、試料における各種類の粒子の含有量（質量％）との関係を表す方程式を作成して解くことにより、試料における各種類の粒子の含有量（質量％）を算出し、これを、第１触媒層２０中の各種類の粒子の含有量（質量％）とする。 (1) Perform elemental analysis on the sample obtained from the first catalyst layer 20 using a conventional method such as SEM-EDX, identify the types of constituent elements of the entire sample, and determine the content of each identified element. Find (mass%).
(2) Elemental mapping is performed on the sample obtained from the first catalyst layer 20 using a conventional method such as SEM-EDX, and the types of particles contained in the sample (for example, Al-based oxide particles and other particles).
(3) For each type of particle, a plurality of arbitrarily selected particles (for example, 50 particles) are subjected to elemental analysis using SEM-EDX, the types of constituent elements of the particles are identified, and each of the identified elements Find the content (mass%). For each type of particle, the average content (mass %) of each element is determined.
(4) Represents the relationship between the content (mass%) of each element in the sample, the content (mass%) of each element in each type of particle, and the content (mass%) of each type of particle in the sample By creating and solving equations, the content (mass%) of each type of particle in the sample is calculated, and this is taken as the content (mass%) of each type of particle in the first catalyst layer 20.
（２）第１触媒層２０から得られた試料について、ＳＥＭ－ＥＤＸ等の常法を用いて元素マッピングを行い、試料に含まれる粒子の種類（例えば、Ａｌ系酸化物粒子及び場合によりその他の粒子）を特定する。
（３）各種類の粒子について、任意に選択された複数個（例えば５０個）の粒子をＳＥＭ－ＥＤＸにて元素分析し、粒子の構成元素の種類を特定するとともに、特定された各元素の含有量（質量％）を求める。各種類の粒子について、各元素の含有量（質量％）の平均値を求める。
（４）試料における各元素の含有量（質量％）と、各種類の粒子における各元素の含有量（質量％）と、試料における各種類の粒子の含有量（質量％）との関係を表す方程式を作成して解くことにより、試料における各種類の粒子の含有量（質量％）を算出し、これを、第１触媒層２０中の各種類の粒子の含有量（質量％）とする。 (1) Perform elemental analysis on the sample obtained from the first catalyst layer 20 using a conventional method such as SEM-EDX, identify the types of constituent elements of the entire sample, and determine the content of each identified element. Find (mass%).
(2) Elemental mapping is performed on the sample obtained from the first catalyst layer 20 using a conventional method such as SEM-EDX, and the types of particles contained in the sample (for example, Al-based oxide particles and other particles).
(3) For each type of particle, a plurality of arbitrarily selected particles (for example, 50 particles) are subjected to elemental analysis using SEM-EDX, the types of constituent elements of the particles are identified, and each of the identified elements Find the content (mass%). For each type of particle, the average content (mass %) of each element is determined.
(4) Represents the relationship between the content (mass%) of each element in the sample, the content (mass%) of each element in each type of particle, and the content (mass%) of each type of particle in the sample By creating and solving equations, the content (mass%) of each type of particle in the sample is calculated, and this is taken as the content (mass%) of each type of particle in the first catalyst layer 20.
Ｌｎ－Ｚｒ系複合酸化物は、１種又は２種以上のＬｎと、Ｚｒとを含む複合酸化物であって、複合酸化物中のＬｎの酸化物換算の質量が、複合酸化物の質量を基準として、３質量％以上９７質量％以下であり、且つ、複合酸化物中のＺｒのＺｒＯ２換算の質量が、複合酸化物の質量を基準として、３質量％以上９７質量％以下である酸化物を意味する。「１種又は２種以上のＬｎの酸化物換算の質量」は、Ｌｎ－Ｚｒ系複合酸化物が１種のＬｎを含む場合には、当該１種のＬｎの酸化物換算量を意味し、Ｌｎ－Ｚｒ系複合酸化物が２種以上のＬｎを含む場合には、当該２種以上のＬｎの酸化物換算量の合計を意味する。
The Ln-Zr-based composite oxide is a composite oxide containing one or more types of Ln and Zr, and the mass of Ln in the composite oxide in terms of oxide is less than the mass of the composite oxide. As a standard, oxidation is 3% by mass or more and 97% by mass or less, and the mass of Zr in the composite oxide in terms of ZrO 2 is 3% by mass or more and 97% by mass or less, based on the mass of the composite oxide. means something "The mass of one or more types of Ln in terms of oxide" means, when the Ln-Zr-based composite oxide contains one type of Ln, the amount of the one type of Ln in terms of oxide, When the Ln-Zr-based composite oxide contains two or more types of Ln, it means the total amount of the two or more types of Ln in terms of oxide.
Ｌｎ－Ｚｒ系複合酸化物は、酸素貯蔵能（すなわち、排ガス中の酸素濃度が高い時には酸素を吸蔵し、排ガス中の酸素濃度が低い時には酸素を放出する能力）を有し、排ガス中の酸素濃度の変動を緩和して触媒活性成分の作動ウインドウを拡大する。したがって、第１触媒層２０がＬｎ－Ｚｒ系複合酸化物を含むことにより、第１触媒層２０の排ガス浄化能が向上する。
Ln-Zr-based composite oxides have oxygen storage ability (that is, the ability to store oxygen when the oxygen concentration in the exhaust gas is high and release oxygen when the oxygen concentration in the exhaust gas is low). Expanding the operating window of catalytically active components by mitigating concentration fluctuations. Therefore, by including the Ln-Zr-based composite oxide in the first catalyst layer 20, the exhaust gas purifying ability of the first catalyst layer 20 is improved.
一実施形態に係るＬｎ－Ｚｒ系複合酸化物（以下「第１のＬｎ－Ｚｒ系複合酸化物」という。）は、Ｃｅと、Ｚｒとを含む。第１のＬｎ－Ｚｒ系複合酸化物を「Ｃｅ－Ｚｒ系複合酸化物」という場合がある。第１のＬｎ－Ｚｒ系複合酸化物において、Ｃｅ、Ｚｒ及びＯは固溶体相を形成していることが好ましい。Ｃｅ、Ｚｒ及びＯは、固溶体相に加えて、結晶相又は非晶質相である単独相（ＣｅＯ２相、ＺｒＯ２相等）を形成していてもよい。Ｃｅ、Ｚｒ及びＯが固溶体を形成していることは、Ｘ線回折法（ＸＲＤ）、ＳＥＭ－ＥＤＸ等を使用して確認することができる。
The Ln--Zr-based composite oxide (hereinafter referred to as "first Ln--Zr-based composite oxide") according to one embodiment includes Ce and Zr. The first Ln--Zr-based composite oxide may be referred to as a "Ce--Zr-based composite oxide." In the first Ln--Zr-based composite oxide, Ce, Zr, and O preferably form a solid solution phase. Ce, Zr, and O may form a single phase (CeO 2 phase, ZrO 2 phase, etc.) that is a crystalline phase or an amorphous phase in addition to a solid solution phase. It can be confirmed using X-ray diffraction (XRD), SEM-EDX, etc. that Ce, Zr, and O form a solid solution.
第１のＬｎ－Ｚｒ系複合酸化物は、Ｃｅ及びＺｒ以外の１種又は２種以上の金属元素を含んでいてもよい。Ｃｅ及びＺｒ以外の金属元素としては、例えば、Ｃｅ以外の希土類元素等が挙げられる。Ｃｅ以外の希土類元素としては、例えば、Ｙ、Ｐｒ、Ｓｃ、Ｌａ、Ｎｄ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ等が挙げられる。Ｃｅ及びＺｒ以外の金属元素は、Ｃｅ、Ｚｒ及びＯとともに、固溶体相を形成していてもよいし、結晶相又は非晶質相である単独相を形成していてもよいし、固溶体相及び単独相の両方を形成していてもよい。固溶体相の形成は、ＸＲＤ、ＳＥＭ－ＥＤＸ等を使用して確認することができる。
The first Ln-Zr-based composite oxide may contain one or more metal elements other than Ce and Zr. Examples of metal elements other than Ce and Zr include rare earth elements other than Ce. Examples of rare earth elements other than Ce include Y, Pr, Sc, La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Metal elements other than Ce and Zr may form a solid solution phase together with Ce, Zr, and O, or may form a single phase that is a crystalline phase or an amorphous phase, or may form a solid solution phase or an amorphous phase. Both may form a single phase. Formation of a solid solution phase can be confirmed using XRD, SEM-EDX, etc.
酸素貯蔵能を向上させる観点から、第１のＬｎ－Ｚｒ系複合酸化物中のＣｅのＣｅＯ２換算量は、第１のＬｎ－Ｚｒ系複合酸化物の質量を基準として、好ましくは３質量％以上４０質量％以下、より好ましくは５質量％以上３０質量％以下、より一層好ましくは５質量％以上２５質量％以下である。第１のＬｎ－Ｚｒ系複合酸化物中のＣｅのＣｅＯ２換算量は、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量と同様にして求めることができる。
From the viewpoint of improving oxygen storage capacity, the CeO 2 equivalent amount of Ce in the first Ln-Zr composite oxide is preferably 3% by mass based on the mass of the first Ln-Zr composite oxide. The content is 40% by mass or less, more preferably 5% by mass or more and 30% by mass or less, even more preferably 5% by mass or more and 25% by mass or less. The CeO 2 equivalent amount of Ce in the first Ln-Zr based composite oxide can be determined in the same manner as the Al 2 O 3 equivalent amount of Al in the Al based oxide.
耐熱性を向上させる観点から、第１のＬｎ－Ｚｒ系複合酸化物中のＺｒのＺｒＯ２換算量は、第１のＬｎ－Ｚｒ系複合酸化物の質量を基準として、好ましくは３０質量％以上９０質量％以下、より好ましくは４０質量％以上８０質量％以下、より一層好ましくは５０質量％以上８０質量％以下である。第１のＬｎ－Ｚｒ系複合酸化物中のＺｒのＺｒＯ２換算量は、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量と同様にして求めることができる。
From the viewpoint of improving heat resistance, the amount of Zr in the first Ln-Zr composite oxide converted to ZrO 2 is preferably 30% by mass or more based on the mass of the first Ln-Zr composite oxide. The content is 90% by mass or less, more preferably 40% by mass or more and 80% by mass or less, even more preferably 50% by mass or more and 80% by mass or less. The amount of Zr in the first Ln--Zr-based composite oxide in terms of ZrO 2 can be determined in the same manner as the amount of Al in the Al-based oxide in terms of Al 2 O 3 .
酸素貯蔵能及び耐熱性を向上させる観点から、第１のＬｎ－Ｚｒ系複合酸化物におけるＣｅのＣｅＯ２換算量及びＺｒのＺｒＯ２換算量の合計は、第１のＬｎ－Ｚｒ系複合酸化物の質量を基準として、好ましくは５０質量％以上、より好ましくは６０質量％以上、より一層好ましくは７０質量％以上である。上限は、１００質量％である。
From the viewpoint of improving oxygen storage capacity and heat resistance, the total amount of Ce in terms of CeO 2 and the amount of Zr in terms of ZrO 2 in the first Ln-Zr complex oxide is It is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, based on the mass of . The upper limit is 100% by mass.
第１触媒層２０が第１のＬｎ－Ｚｒ系複合酸化物を含む場合、酸素貯蔵能及び耐熱性を向上させる観点から、第１触媒層２０中の第１のＬｎ－Ｚｒ系複合酸化物の量は、第１触媒層２０の質量を基準として、好ましくは４０質量％以上９５質量％以下、より好ましくは５０質量％以上９３質量％以下、より一層好ましくは６０質量％以上９０質量％以下である。第１触媒層２０中の第１のＬｎ－Ｚｒ系複合酸化物の量は、第１触媒層２０中のＡｌ系酸化物の量と同様にして求めることができる。
When the first catalyst layer 20 includes the first Ln-Zr composite oxide, from the viewpoint of improving oxygen storage capacity and heat resistance, the first Ln-Zr composite oxide in the first catalyst layer 20 The amount is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, even more preferably 60% by mass or more and 90% by mass or less, based on the mass of the first catalyst layer 20. be. The amount of the first Ln--Zr-based composite oxide in the first catalyst layer 20 can be determined in the same manner as the amount of Al-based oxide in the first catalyst layer 20.
別の実施形態に係るＬｎ－Ｚｒ系複合酸化物（以下「第２のＬｎ－Ｚｒ系複合酸化物」という。）は、Ｃｅ以外の１種又は２種以上のＬｎと、Ｚｒとを含み、Ｃｅを含まない。第２のＬｎ－Ｚｒ系複合酸化物において、Ｃｅ以外の１種又は２種以上のＬｎ、Ｚｒ及びＯは固溶体相を形成していることが好ましい。Ｃｅ以外の１種又は２種以上のＬｎ、Ｚｒ及びＯは、固溶体相に加えて、結晶相又は非晶質相である単独相（Ｃｅ以外の１種又は２種以上のＬｎの酸化物相、ＺｒＯ２相等）を形成していてもよい。Ｃｅ以外の１種又は２種以上のＬｎ、Ｚｒ及びＯが固溶体を形成していることは、ＸＲＤ、ＳＥＭ－ＥＤＸ等を使用して確認することができる。
The Ln-Zr-based composite oxide according to another embodiment (hereinafter referred to as "second Ln-Zr-based composite oxide") contains one or more types of Ln other than Ce and Zr, Contains no Ce. In the second Ln--Zr-based composite oxide, one or more types of Ln, Zr, and O other than Ce preferably form a solid solution phase. One or more types of Ln, Zr, and O other than Ce may be present in a single phase that is a crystalline phase or an amorphous phase (an oxide phase of one or more types of Ln other than Ce) in addition to a solid solution phase. , ZrO 2 phase, etc.). It can be confirmed using XRD, SEM-EDX, etc. that one or more types of Ln, Zr, and O other than Ce form a solid solution.
第２のＬｎ－Ｚｒ系複合酸化物は、Ｌｎ及びＺｒ以外の１種又は２種以上の金属元素を含んでいてもよい。Ｌｎ及びＺｒ以外の金属元素としては、例えば、アルカリ土類金属元素等が挙げられる。アルカリ土類金属元素としては、例えば、Ｃａ、Ｓｒ、Ｂａ等が挙げられる。Ｌｎ及びＺｒ以外の金属元素は、Ｃｅ以外の１種又は２種以上のＬｎ、Ｚｒ及びＯとともに、固溶体相を形成していてもよいし、結晶相又は非晶質相である単独相を形成していてもよいし、固溶体相及び単独相の両方を形成していてもよい。固溶体相の形成は、ＸＲＤ、ＳＥＭ－ＥＤＸ等を使用して確認することができる。
The second Ln-Zr-based composite oxide may contain one or more metal elements other than Ln and Zr. Examples of metal elements other than Ln and Zr include alkaline earth metal elements. Examples of the alkaline earth metal elements include Ca, Sr, and Ba. Metal elements other than Ln and Zr may form a solid solution phase with one or more types of Ln other than Ce, Zr, and O, or may form a single phase that is a crystalline phase or an amorphous phase. or may form both a solid solution phase and a single phase. Formation of a solid solution phase can be confirmed using XRD, SEM-EDX, etc.
酸素貯蔵能を向上させる観点から、第２のＬｎ－Ｚｒ系複合酸化物中のＣｅ以外の１種又は２種以上のＬｎの酸化物換算量は、第２のＬｎ－Ｚｒ系複合酸化物の質量を基準として、好ましくは１０質量％以上８０質量％以下、より好ましくは２０質量％以上７０質量％以下、より一層好ましくは３０質量％以上７０質量％以下である。「第２のＬｎ－Ｚｒ系複合酸化物中のＣｅ以外の１種又は２種以上のＬｎの酸化物換算量」は、第２のＬｎ－Ｚｒ系複合酸化物がＣｅ以外の１種のＬｎを含む場合には、当該Ｃｅ以外の１種のＬｎの酸化物換算量を意味し、第２のＬｎ－Ｚｒ系複合酸化物がＣｅ以外の２種以上のＬｎを含む場合には、当該Ｃｅ以外の２種以上のＬｎの酸化物換算量の合計を意味する。第２のＬｎ－Ｚｒ系複合酸化物中のＣｅ以外の１種又は２種以上のＬｎの酸化物換算量は、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量と同様にして求めることができる。
From the viewpoint of improving oxygen storage capacity, the oxide equivalent amount of one or more types of Ln other than Ce in the second Ln-Zr composite oxide is Based on the mass, the content is preferably 10% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, even more preferably 30% by mass or more and 70% by mass or less. "The oxide equivalent amount of one or more types of Ln other than Ce in the second Ln-Zr based composite oxide" means that the second Ln-Zr based composite oxide contains one type of Ln other than Ce. When the second Ln-Zr-based composite oxide contains two or more types of Ln other than Ce, it means the oxide equivalent amount of one type of Ln other than Ce. It means the total amount of two or more types of Ln in terms of oxide. The oxide-equivalent amount of one or more types of Ln other than Ce in the second Ln-Zr-based composite oxide is determined in the same manner as the Al 2 O 3- equivalent amount of Al in the Al-based oxide. I can do it.
耐熱性を向上させる観点から、第２のＬｎ－Ｚｒ系複合酸化物中のＺｒのＺｒＯ２換算量は、第２のＬｎ－Ｚｒ系複合酸化物の質量を基準として、好ましくは３０質量％以上９０質量％以下、より好ましくは３５質量％以上８０質量％以下、より一層好ましくは４０質量％以上７５質量％以下である。第２のＬｎ－Ｚｒ系複合酸化物中のＺｒのＺｒＯ２換算量は、Ａｌ系酸化物中のＡｌのＡｌ２Ｏ３換算量と同様にして求めることができる。
From the viewpoint of improving heat resistance, the amount of Zr in the second Ln-Zr composite oxide converted to ZrO 2 is preferably 30% by mass or more based on the mass of the second Ln-Zr composite oxide. The content is 90% by mass or less, more preferably 35% by mass or more and 80% by mass or less, even more preferably 40% by mass or more and 75% by mass or less. The ZrO 2 equivalent amount of Zr in the second Ln-Zr based composite oxide can be determined in the same manner as the Al 2 O 3 equivalent amount of Al in the Al based oxide.
酸素貯蔵能及び耐熱性を向上させる観点から、第２のＬｎ－Ｚｒ系複合酸化物におけるＣｅ以外の１種又は２種以上のＬｎの酸化物換算量及びＺｒのＺｒＯ２換算量の合計は、第２のＬｎ－Ｚｒ系複合酸化物の質量を基準として、好ましくは５０質量％以上、より好ましくは６０質量％以上、より一層好ましくは７０質量％以上である。上限は、１００質量％である。
From the viewpoint of improving oxygen storage capacity and heat resistance, the sum of the oxide equivalent amount of one or more types of Ln other than Ce and the ZrO 2 equivalent amount of Zr in the second Ln-Zr-based composite oxide is: It is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, based on the mass of the second Ln-Zr complex oxide. The upper limit is 100% by mass.
第１触媒層２０が第２のＬｎ－Ｚｒ系複合酸化物を含む場合、酸素貯蔵能及び耐熱性を向上させる観点から、第１触媒層２０中の第２のＬｎ－Ｚｒ系複合酸化物の量は、第１触媒層２０の質量を基準として、好ましくは４０質量％以上９５質量％以下、より好ましくは５０質量％以上９３質量％以下、より一層好ましくは６０質量％以上９０質量％以下である。第１触媒層２０中の第２のＬｎ－Ｚｒ系複合酸化物の量は、第１触媒層２０中のＡｌ系酸化物の量と同様にして求めることができる。
When the first catalyst layer 20 includes the second Ln-Zr-based composite oxide, from the viewpoint of improving oxygen storage capacity and heat resistance, the second Ln-Zr-based composite oxide in the first catalyst layer 20 The amount is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, even more preferably 60% by mass or more and 90% by mass or less, based on the mass of the first catalyst layer 20. be. The amount of the second Ln-Zr based composite oxide in the first catalyst layer 20 can be determined in the same manner as the amount of the Al based oxide in the first catalyst layer 20.
第１及び第２のＬｎ－Ｚｒ系複合酸化物を併用してもよい。第１触媒層２０が第１及び第２のＬｎ－Ｚｒ系複合酸化物を含む場合、酸素貯蔵能及び耐熱性を向上させる観点から、第１触媒層２０中の第１及び第２のＬｎ－Ｚｒ系複合酸化物の合計量は、第１触媒層２０の質量を基準として、好ましくは４０質量％以上９５質量％以下、より好ましくは５０質量％以上９３質量％以下、より一層好ましくは６０質量％以上９０質量％以下である。
The first and second Ln-Zr-based composite oxides may be used together. When the first catalyst layer 20 contains the first and second Ln-Zr-based composite oxides, from the viewpoint of improving oxygen storage capacity and heat resistance, the first and second Ln- The total amount of the Zr-based composite oxide is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, even more preferably 60% by mass, based on the mass of the first catalyst layer 20. % or more and 90% by mass or less.
排ガス浄化性能を維持又は向上させる観点から、第１触媒層２０中のＡｌ系酸化物及びＬｎ－Ｚｒ系複合酸化物以外の無機酸化物の合計量は、第１触媒層２０の質量を基準として、好ましくは０質量％以上２０質量％以下、より好ましくは０．５質量％以上１５質量％以下、より一層好ましくは１質量％以上１５質量％以下である。第１触媒層２０中のＡｌ系酸化物及びＬｎ－Ｚｒ系複合酸化物以外の無機酸化物の合計量は、第１触媒層２０中のＡｌ系酸化物の量と同様にして求めることができる。
From the perspective of maintaining or improving exhaust gas purification performance, the total amount of inorganic oxides other than Al-based oxides and Ln-Zr-based composite oxides in the first catalyst layer 20 is based on the mass of the first catalyst layer 20. , preferably from 0% by mass to 20% by mass, more preferably from 0.5% by mass to 15% by mass, even more preferably from 1% by mass to 15% by mass. The total amount of inorganic oxides other than Al-based oxides and Ln-Zr-based composite oxides in the first catalyst layer 20 can be determined in the same manner as the amount of Al-based oxides in the first catalyst layer 20. .
第１触媒層２０は、安定剤、バインダ等を含んでいてもよい。バインダとしては、アルミナバインダ、ジルコニアバインダ、チタニアバインダ、シリカバインダ等の無機酸化物系バインダが挙げられる。無機酸化物系バインダは、アルミナゾル、ジルコニアゾル、チタニアゾル、シリカゾル等の無機酸化物系ゾルに由来する。安定剤としては、例えば、アルカリ土類金属元素の硝酸塩、炭酸塩、酸化物、硫酸塩等が挙げられる。
The first catalyst layer 20 may contain a stabilizer, a binder, and the like. Examples of the binder include inorganic oxide binders such as alumina binder, zirconia binder, titania binder, and silica binder. The inorganic oxide binder is derived from an inorganic oxide sol such as alumina sol, zirconia sol, titania sol, and silica sol. Examples of the stabilizer include nitrates, carbonates, oxides, and sulfates of alkaline earth metal elements.
図４及び６に示すように、第１触媒層２０は、隔壁部１２の流入側セル１３ａ側に形成されている。
As shown in FIGS. 4 and 6, the first catalyst layer 20 is formed on the inflow side cell 13a side of the partition wall portion 12.
図６に示すように、第１触媒層２０は、隔壁部１２の排ガス流入側の端部から排ガス流通方向Ｅに沿って延在している。本実施形態において、第１触媒層２０は、隔壁部１２の排ガス流出側の端部に至っていないが、隔壁部１２の排ガス流出側の端部に至っていてもよい。
As shown in FIG. 6, the first catalyst layer 20 extends along the exhaust gas flow direction E from the end of the partition wall 12 on the exhaust gas inflow side. In this embodiment, the first catalyst layer 20 does not reach the end of the partition wall 12 on the exhaust gas outflow side, but may reach the end of the partition wall 12 on the exhaust gas outflow side.
図４及び６に示すように、第１触媒層２０の少なくとも一部は、隔壁部１２の流入側セル１３ａ側の外表面Ｓ１ａから流入側セル１３ａ側に***していること、すなわち、第１触媒層２０は、隔壁部１２の流入側セル１３ａ側の外表面Ｓ１ａから流入側セル１３ａ側に***する部分（以下「***部分」という。）を有することが好ましい。これにより、排ガス及びＰＭの接触性が向上し、排ガス浄化性能の向上及びＰＭ捕集性能の向上をより効果的に実現することができる。
As shown in FIGS. 4 and 6, at least a portion of the first catalyst layer 20 protrudes from the outer surface S1a of the partition wall 12 on the inflow side cell 13a side toward the inflow side cell 13a, that is, the first It is preferable that the catalyst layer 20 has a portion that protrudes from the outer surface S1a of the partition wall portion 12 on the inflow side cell 13a side toward the inflow side cell 13a side (hereinafter referred to as “raised portion”). This improves the contact between the exhaust gas and PM, making it possible to more effectively improve the exhaust gas purification performance and the PM trapping performance.
第１触媒層２０は、***部分のみで構成されていてもよいし、***部分とともに、隔壁部１２の内部に存在する部分（以下「内在部分」という。）を有していてもよい。隔壁部１２は多孔質であるため、第１触媒層２０を形成する際、***部分とともに内在部分が形成される場合がある。***部分と内在部分とは、連続していてもよい。第１触媒層２０は内在部分のみで構成されていてもよい。「第１触媒層２０が、隔壁部１２の流入側セル１３ａ側に形成されている」には、第１触媒層２０が***部分のみで構成されている実施形態、第１触媒層２０が内在部分のみで構成されている実施形態、並びに、第１触媒層２０が***部分及び内在部分を有する実施形態のいずれもが包含される。これらのうち、第１触媒層２０が***部分のみで構成されている実施形態、並びに、第１触媒層２０が***部分及び内在部分を有する実施形態が好ましい。
The first catalyst layer 20 may be composed of only a raised portion, or may include a portion existing inside the partition wall portion 12 (hereinafter referred to as “internal portion”) together with the raised portion. Since the partition wall portion 12 is porous, when forming the first catalyst layer 20, an internal portion may be formed together with a raised portion. The raised portion and the internal portion may be continuous. The first catalyst layer 20 may be composed only of an internal portion. “The first catalyst layer 20 is formed on the inflow side cell 13a side of the partition wall 12” includes an embodiment in which the first catalyst layer 20 is formed only of a raised portion, and an embodiment in which the first catalyst layer 20 is internally formed. Both embodiments in which the first catalyst layer 20 includes only a portion and embodiments in which the first catalyst layer 20 has a raised portion and an inner portion are included. Among these, preferred are embodiments in which the first catalyst layer 20 includes only raised portions, and embodiments in which the first catalyst layer 20 includes raised portions and internal portions.
第１触媒層２０の***部分が存在する領域は、隔壁部１２が存在する領域と重ならないが、第１触媒層２０の内在部分が存在する領域は、隔壁部１２が存在する領域と重なる。したがって、排ガス浄化用触媒１を基材１０の軸方向と垂直な平面で切断し、切断面に存在する第１触媒層２０を観察し、第１触媒層２０と隔壁部１２との間の形態の相違に基づいて、第１触媒層２０の***部分及び内在部分を特定することができる。切断面の観察を行う際、切断面の元素マッピングを行ってもよい。元素マッピングは、例えば、ＳＥＭによる切断面の観察と、切断面の組成分析とを併用することにより行うことができる。元素マッピングは、例えば、ＳＥＭ－ＥＤＸ、電子線マイクロアナライザー（ＥＰＭＡ）、透過型Ｘ線検査装置等を使用して行うことができる。切断面の元素マッピングにより、第１触媒層２０と隔壁部１２との間の形態及び組成の相違に基づいて、***部分及び内在部分を特定することができる。
The region where the raised portion of the first catalyst layer 20 exists does not overlap with the region where the partition wall portion 12 exists, but the region where the internal portion of the first catalyst layer 20 exists overlaps with the region where the partition wall portion 12 exists. Therefore, the exhaust gas purifying catalyst 1 was cut along a plane perpendicular to the axial direction of the base material 10, and the first catalyst layer 20 present on the cut surface was observed, and the morphology between the first catalyst layer 20 and the partition wall portion 12 was observed. Based on the difference, the raised portion and the inner portion of the first catalyst layer 20 can be identified. When observing the cut surface, elemental mapping of the cut surface may be performed. Elemental mapping can be performed, for example, by using a combination of observation of the cut surface using SEM and compositional analysis of the cut surface. Elemental mapping can be performed using, for example, a SEM-EDX, an electron beam microanalyzer (EPMA), a transmission type X-ray inspection device, or the like. By elemental mapping of the cut surface, the protruding portion and the internal portion can be identified based on the difference in morphology and composition between the first catalyst layer 20 and the partition wall portion 12.
第１触媒層２０の平均長さＬ２０は、排ガス浄化性能、ＰＭ捕集性能等を考慮して適宜調整することができる。排ガス浄化性能及びＰＭ捕集性能を向上させる観点から、基材１０の長さＬ１０に対する第１触媒層２０の平均長さＬ２０の百分率（Ｌ２０／Ｌ１０×１００）は、好ましくは１５％以上９０％以下、より好ましくは２０％以上８０％以下、より一層好ましくは３０％以上８０％以下である。
The average length L 20 of the first catalyst layer 20 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, and the like. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the percentage of the average length L 20 of the first catalyst layer 20 to the length L 10 of the base material 10 (L 20 /L 10 ×100) is preferably 15 % or more and 90% or less, more preferably 20% or more and 80% or less, even more preferably 30% or more and 80% or less.
＜第２触媒層＞
以下、第２触媒層３０について説明する。 <Second catalyst layer>
The second catalyst layer 30 will be explained below.
以下、第２触媒層３０について説明する。 <Second catalyst layer>
The second catalyst layer 30 will be explained below.
第２触媒層３０は、Ｒｈを含む。
The second catalyst layer 30 contains Rh.
Ｒｈは、触媒活性成分として機能し得る形態、例えば、金属Ｒｈ、Ｒｈを含む合金、Ｒｈを含む化合物（例えば、Ｒｈの酸化物）等の、Ｒｈを含む触媒活性成分の形態で第２触媒層３０に含まれる。排ガス浄化性能を高める観点から、Ｒｈを含む触媒活性成分は、粒子状であることが好ましい。
Rh is present in the second catalyst layer in the form of a catalytically active component containing Rh, such as a metal Rh, an alloy containing Rh, a compound containing Rh (for example, an oxide of Rh), etc., which can function as a catalytically active component. Included in 30. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Rh is preferably in the form of particles.
排ガス浄化性能とコストとのバランスの観点から、第２触媒層３０中のＲｈの金属換算量は、第２触媒層３０の質量を基準として、好ましくは０．１質量％以上１０．０質量％以下、より好ましくは０．２質量％以上５．０質量％以下、より一層好ましくは０．３質量％以上３．０質量％以下である。
From the viewpoint of balance between exhaust gas purification performance and cost, the metal equivalent amount of Rh in the second catalyst layer 30 is preferably 0.1% by mass or more and 10.0% by mass based on the mass of the second catalyst layer 30. The content is more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
第２触媒層３０は、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい。Ｒｈ以外の貴金属元素は、例えば、Ｐｔ、Ｐｄ、Ｒｕ、Ｉｒ、Ｏｓ等から選択することができる。Ｒｈ以外の貴金属元素は、触媒活性成分として機能し得る形態、例えば、金属、貴金属元素を含む合金、貴金属元素を含む化合物（例えば、貴金属元素の酸化物）等の、Ｒｈ以外の貴金属元素を含む触媒活性成分の形態で第２触媒層３０に含まれる。排ガス浄化性能を高める観点から、Ｒｈ以外の貴金属元素を含む触媒活性成分は、粒子状であることが好ましい。
The second catalyst layer 30 may contain one or more noble metal elements other than Rh. The noble metal elements other than Rh can be selected from, for example, Pt, Pd, Ru, Ir, Os, and the like. The noble metal element other than Rh includes a noble metal element other than Rh in a form that can function as a catalytically active component, for example, a metal, an alloy containing a noble metal element, a compound containing a noble metal element (e.g., an oxide of a noble metal element), etc. It is contained in the second catalyst layer 30 in the form of a catalytically active component. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing a noble metal element other than Rh is preferably in the form of particles.
排ガス浄化性能とコストとのバランスの観点から、第２触媒層３０中の全貴金属元素の合計金属換算量は、第２触媒層３０の質量を基準として、好ましくは０．１質量％以上１０．０質量％以下、より好ましくは０．２質量％以上５．０質量％以下、より一層好ましくは０．３質量％以上３．０質量％以下である。
From the viewpoint of the balance between exhaust gas purification performance and cost, the total metal equivalent amount of all noble metal elements in the second catalyst layer 30 is preferably 0.1% by mass or more based on the mass of the second catalyst layer 30. The content is 0% by mass or less, more preferably 0.2% by mass or more and 5.0% by mass or less, even more preferably 0.3% by mass or more and 3.0% by mass or less.
第２触媒層３０がＲｈとＲｈ以外の１種又は２種以上の貴金属元素とを含む場合、ＲｈとＲｈ以外の１種又は２種以上の貴金属元素とが触媒活性の低い合金を形成し、排ガス浄化性能に関与するＲｈの活性点が減少するおそれがある。したがって、Ｒｈの排ガス浄化性能の低下を抑制する観点から、第２触媒層３０中のＲｈの金属換算量は、第２触媒層３０中のＲｈ以外の各貴金属元素の金属換算量よりも大きいことが好ましい。また、同様の観点から、第２触媒層３０中のＲｈの金属換算量は、第２触媒層３０中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きいことが好ましい。
When the second catalyst layer 30 contains Rh and one or more noble metal elements other than Rh, Rh and the one or more noble metal elements other than Rh form an alloy with low catalytic activity; There is a possibility that the active sites of Rh, which are involved in exhaust gas purification performance, will decrease. Therefore, from the viewpoint of suppressing the deterioration of the exhaust gas purification performance of Rh, the metal equivalent amount of Rh in the second catalyst layer 30 should be larger than the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer 30. is preferred. Further, from the same viewpoint, the metal equivalent amount of Rh in the second catalyst layer 30 is preferably larger than the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer 30.
第２触媒層３０中のＲｈの金属換算量に対する、第２触媒層３０中のＲｈ以外の各貴金属元素の金属換算量の比は、質量比で、好ましくは０．９以下、より好ましくは０．５以下、より一層好ましくは０．３以下である。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．１以上又は０．１５以上であってもよい。これらの下限値はそれぞれ、上記の上限値のいずれと組み合わせてもよい。
The ratio of the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer 30 to the metal equivalent amount of Rh in the second catalyst layer 30 is preferably 0.9 or less, more preferably 0. .5 or less, and even more preferably 0.3 or less. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.1 or more, or 0.15 or more. Each of these lower limits may be combined with any of the above upper limits.
第２触媒層３０中のＲｈの金属換算量に対する、第２触媒層３０中のＲｈ以外の全貴金属元素の合計金属換算量の比は、質量比で、好ましくは０．９以下、より好ましくは０．５以下、より一層好ましくは０．３以下である。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．１以上又は０．２以上であってもよい。これらの下限値はそれぞれ、上記の上限値のいずれと組み合わせてもよい。
The ratio of the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer 30 to the metal equivalent amount of Rh in the second catalyst layer 30 is preferably 0.9 or less, more preferably It is 0.5 or less, more preferably 0.3 or less. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more. Each of these lower limits may be combined with any of the above upper limits.
第２触媒層３０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、第２触媒層３０中の各貴金属元素の金属換算量は、第２触媒層３０の製造に使用される原料の情報から求めることができる。第２触媒層３０の製造に使用される原料の情報が判明していない場合、第２触媒層３０中の各貴金属元素の金属換算量は、第１触媒層２０中の各貴金属元素の金属換算量と同様にして求めることができる。
When information on the raw materials used to manufacture the second catalyst layer 30 (for example, composition, amount, etc.) is known, the metal equivalent amount of each noble metal element in the second catalyst layer 30 is It can be determined from information on the raw materials used in the production of. If information on the raw materials used to manufacture the second catalyst layer 30 is not known, the amount of each noble metal element in the second catalyst layer 30 in terms of metal is the amount of each noble metal element in the first catalyst layer 20 It can be determined in the same way as the quantity.
排ガス浄化性能とコストとのバランスの観点から、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量は、好ましくは７ｇ／Ｌ以上８６ｇ／Ｌ以下、より好ましくは１４ｇ／Ｌ以上５７ｇ／Ｌ以下、より一層好ましくは１４ｇ／Ｌ以上４３ｇ／Ｌ以下である。基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量は、式：（第２触媒層３０の質量）／（（基材１０の体積）×（第２触媒層３０の平均長さＬ３０／基材１０の長さＬ１０））から算出される。
From the viewpoint of balance between exhaust gas purification performance and cost, the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed is preferably 7 g/L or more and 86 g/L. L or less, more preferably 14 g/L or more and 57 g/L or less, even more preferably 14 g/L or more and 43 g/L or less. The mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed is calculated by the formula: (mass of the second catalyst layer 30)/((volume of the base material 10) It is calculated from ×(average length L 30 of second catalyst layer 30 / length L 10 of base material 10)).
第１触媒層２０の質量に関する上記説明は、第２触媒層３０の質量にも適用される。適用の際、「第１触媒層２０」は「第２触媒層３０」に読み替えられる。
The above description regarding the mass of the first catalyst layer 20 also applies to the mass of the second catalyst layer 30. In application, "first catalyst layer 20" is read as "second catalyst layer 30."
第１触媒層２０の平均長さＬ２０の測定方法に関する上記説明は、第２触媒層３０の平均長さＬ３０の測定方法にも適用される。適用の際、「第１触媒層２０」は「第２触媒層３０」に、「平均長さＬ２０」は「平均長さＬ３０」に読み替えられる。但し、第２触媒層３０の平均長さＬ３０の測定方法では、サンプルを基材１０の軸方向と垂直な平面によって５ｍｍ間隔で切断し、サンプルの排ガス流出側の端部側から順に、第１切断片、第２切断片、・・・、第ｎ切断片を得る。
The above description regarding the method for measuring the average length L 20 of the first catalyst layer 20 also applies to the method for measuring the average length L 30 of the second catalyst layer 30 . In application, the "first catalyst layer 20" is read as the "second catalyst layer 30", and the "average length L 20 " is read as "average length L 30 ". However, in the method of measuring the average length L 30 of the second catalyst layer 30, the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the base material 10, and the samples are cut in order from the end of the sample on the exhaust gas outflow side. A first cut piece, a second cut piece, . . . , an nth cut piece are obtained.
第２触媒層３０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量は、第２触媒層３０の製造に使用される原料の情報から求めることができる。
If information on the raw materials used to manufacture the second catalyst layer 30 (for example, composition, amount, etc.) is known, the amount per unit volume of the portion of the base material 10 on which the second catalyst layer 30 is formed is known. The mass of the second catalyst layer 30 can be determined from information on the raw materials used to manufacture the second catalyst layer 30.
第２触媒層３０は、１種又は２種以上の担体を含み、触媒活性成分の少なくとも一部は１種又は２種以上の担体に担持されていることが好ましい。「触媒活性成分の少なくとも一部が担体に担持されている」の意義及び確認方法は、第１触媒層２０に関する上記説明中に記載した通りである。第１触媒層２０における担体に関する上記説明（無機酸化物の種類、組成、量等に関する上記説明を含む）は、第２触媒層３０にも適用される。適用の際、「第１触媒層２０」は「第２触媒層３０」に読み替えられる。
It is preferable that the second catalyst layer 30 includes one or more types of carriers, and at least a part of the catalytically active component is supported on the one or more types of carriers. The meaning and confirmation method of "at least a portion of the catalytically active component is supported on the carrier" are as described in the above description regarding the first catalyst layer 20. The above explanation regarding the carrier in the first catalyst layer 20 (including the above explanation regarding the type, composition, amount, etc. of the inorganic oxide) also applies to the second catalyst layer 30. In application, "first catalyst layer 20" is read as "second catalyst layer 30."
第２触媒層３０は、安定剤、バインダ等を含んでいてもよい。バインダ及び安定剤に関する説明は、上記の通りである。
The second catalyst layer 30 may contain a stabilizer, a binder, and the like. A description of the binder and stabilizer is given above.
図５及び６に示すように、第２触媒層３０は、隔壁部１２の流出側セル１３ｂ側に形成されている。
As shown in FIGS. 5 and 6, the second catalyst layer 30 is formed on the outflow side cell 13b side of the partition wall portion 12.
図６に示すように、第２触媒層３０は、隔壁部１２の排ガス流出側の端部から排ガス流通方向Ｅとは反対の方向に沿って延在している。本実施形態において、第２触媒層３０は、隔壁部１２の排ガス流入側の端部に至っていないが、隔壁部１２の排ガス流入側の端部に至っていてもよい。
As shown in FIG. 6, the second catalyst layer 30 extends from the end of the partition wall 12 on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction E. In this embodiment, the second catalyst layer 30 does not reach the end of the partition wall 12 on the exhaust gas inflow side, but may reach the end of the partition wall 12 on the exhaust gas inflow side.
図５及び６に示すように、第２触媒層３０の少なくとも一部は、隔壁部１２の流出側セル１３ｂ側の外表面Ｓ１ｂから流出側セル１３ｂ側に***していること、すなわち、第２触媒層３０は、隔壁部１２の流出側セル１３ｂ側の外表面Ｓ１ｂから流出側セル１３ｂ側に***する部分（以下「***部分」という。）を有することが好ましい。これにより、排ガス及びＰＭの接触性が向上し、排ガス浄化性能の向上及びＰＭ捕集性能の向上をより効果的に実現することができる。
As shown in FIGS. 5 and 6, at least a portion of the second catalyst layer 30 protrudes from the outer surface S1b of the partition wall 12 on the outflow side cell 13b side toward the outflow side cell 13b side, that is, the second It is preferable that the catalyst layer 30 has a portion that protrudes from the outer surface S1b of the partition wall portion 12 on the outflow side cell 13b side toward the outflow side cell 13b side (hereinafter referred to as “raised portion”). This improves the contact between the exhaust gas and PM, making it possible to more effectively improve the exhaust gas purification performance and the PM trapping performance.
第２触媒層３０は、***部分のみで構成されていてもよいし、***部分とともに、隔壁部１２の内部に存在する部分（以下「内在部分」という。）を有していてもよい。隔壁部１２は多孔質であるため、第２触媒層３０を形成する際、***部分とともに内在部分が形成される場合がある。***部分と内在部分とは、連続していてもよい。第２触媒層３０は内在部分のみで構成されていてもよい。「第２触媒層３０が、隔壁部１２の流出側セル１３ｂ側に形成されている」には、第２触媒層３０が***部分のみで構成されている実施形態、第２触媒層３０が内在部分のみで構成されている実施形態、並びに、第２触媒層３０が***部分及び内在部分を有する実施形態のいずれもが包含される。これらのうち、第２触媒層３０が***部分のみで構成されている実施形態、並びに、第２触媒層３０が***部分及び内在部分を有する実施形態が好ましい。
The second catalyst layer 30 may be composed of only a raised portion, or may include a portion existing inside the partition wall portion 12 (hereinafter referred to as “internal portion”) together with the raised portion. Since the partition wall portion 12 is porous, when forming the second catalyst layer 30, an internal portion may be formed together with a raised portion. The raised portion and the internal portion may be continuous. The second catalyst layer 30 may be composed only of an internal portion. “The second catalyst layer 30 is formed on the outflow cell 13b side of the partition wall 12” includes an embodiment in which the second catalyst layer 30 is formed only of a raised portion, and an embodiment in which the second catalyst layer 30 is internally formed. Both embodiments in which the second catalyst layer 30 includes only a portion and embodiments in which the second catalyst layer 30 has a raised portion and an inner portion are included. Among these, preferred are embodiments in which the second catalyst layer 30 includes only raised portions, and embodiments in which the second catalyst layer 30 includes raised portions and internal portions.
第１触媒層２０の***部分及び内在部分の特定方法に関する上記説明は、第２触媒層３０にも適用される。適用の際、「第１触媒層２０」は「第２触媒層３０」に読み替えられる。
The above description regarding the method for identifying the raised portion and the internal portion of the first catalyst layer 20 also applies to the second catalyst layer 30. In application, "first catalyst layer 20" is read as "second catalyst layer 30."
第２触媒層３０の平均長さＬ３０は、排ガス浄化性能、ＰＭ捕集性能等を考慮して適宜調整することができる。排ガス浄化性能及びＰＭ捕集性能を向上させる観点から、基材１０の長さＬ１０に対する第２触媒層３０の平均長さＬ３０の百分率（Ｌ３０／Ｌ１０×１００）は、好ましくは１５％以上９０％以下、より好ましくは２０％以上８０％以下、より一層好ましくは３０％以上８０％以下である。
The average length L 30 of the second catalyst layer 30 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, and the like. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the percentage of the average length L 30 of the second catalyst layer 30 to the length L 10 of the base material 10 (L 30 /L 10 ×100) is preferably 15 % or more and 90% or less, more preferably 20% or more and 80% or less, even more preferably 30% or more and 80% or less.
排ガス浄化性能及びＰＭ捕集性能を向上させる観点から、基材１０の長さＬ１０に対する、第１触媒層２０の平均長さＬ２０と第２触媒層３０の平均長さＬ３０との合計の百分率（（Ｌ２０＋Ｌ３０）／Ｌ１０×１００）は、好ましくは１００％以上１８０％以下、より好ましくは１０５％以上１５０％以下、より一層好ましくは１１０％以上１３０％以下である。
From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the sum of the average length L 20 of the first catalyst layer 20 and the average length L 30 of the second catalyst layer 30 with respect to the length L 10 of the base material 10. The percentage ((L 20 +L 30 )/L 10 ×100) is preferably 100% or more and 180% or less, more preferably 105% or more and 150% or less, even more preferably 110% or more and 130% or less.
＜第３触媒層＞
以下、第３触媒層４０について説明する。 <Third catalyst layer>
The third catalyst layer 40 will be explained below.
以下、第３触媒層４０について説明する。 <Third catalyst layer>
The third catalyst layer 40 will be explained below.
第３触媒層４０は、Ｐｔを含む。
The third catalyst layer 40 contains Pt.
Ｐｔは、触媒活性成分として機能し得る形態、例えば、金属Ｐｔ、Ｐｔを含む合金、Ｐｔを含む化合物（例えば、Ｐｔの酸化物）等の、Ｐｔを含む触媒活性成分の形態で第３触媒層４０に含まれる。排ガス浄化性能を高める観点から、Ｐｔを含む触媒活性成分は、粒子状であることが好ましい。
Pt is present in the third catalyst layer in the form of a catalytically active component containing Pt, such as metal Pt, an alloy containing Pt, a compound containing Pt (for example, an oxide of Pt), etc., which can function as a catalytically active component. Included in 40. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing Pt is preferably in the form of particles.
排ガス浄化性能とコストとのバランスの観点から、第３触媒層４０中のＰｔの金属換算量は、第３触媒層４０の質量を基準として、好ましくは０．１質量％以上２０質量％以下、より好ましくは０．５質量％以上１５質量％以下、より一層好ましくは１．０質量％以上１０質量％以下である。
From the viewpoint of the balance between exhaust gas purification performance and cost, the metal equivalent amount of Pt in the third catalyst layer 40 is preferably 0.1% by mass or more and 20% by mass or less, based on the mass of the third catalyst layer 40. More preferably 0.5% by mass or more and 15% by mass or less, even more preferably 1.0% by mass or more and 10% by mass or less.
第３触媒層４０は、Ｐｔ以外の１種又は２種以上の貴金属元素を含んでいてもよい。Ｐｔ以外の貴金属元素は、例えば、Ａｕ、Ａｇ、Ｒｈ、Ｐｄ、Ｒｕ、Ｉｒ、Ｏｓ等から選択することができる。Ｐｔ以外の貴金属元素は、触媒活性成分として機能し得る形態、例えば、金属、貴金属元素を含む合金、貴金属元素を含む化合物（例えば、貴金属元素の酸化物）等の、Ｐｔ以外の貴金属元素を含む触媒活性成分の形態で第３触媒層４０に含まれる。排ガス浄化性能を向上させる観点から、Ｐｔ以外の貴金属元素を含む触媒活性成分は、粒子状であることが好ましい。
The third catalyst layer 40 may contain one or more noble metal elements other than Pt. The noble metal element other than Pt can be selected from, for example, Au, Ag, Rh, Pd, Ru, Ir, Os, and the like. The noble metal element other than Pt includes a noble metal element other than Pt in a form that can function as a catalytically active component, for example, a metal, an alloy containing a noble metal element, a compound containing a noble metal element (e.g., an oxide of a noble metal element), etc. It is contained in the third catalyst layer 40 in the form of a catalytically active component. From the viewpoint of improving exhaust gas purification performance, the catalytically active component containing a noble metal element other than Pt is preferably in the form of particles.
排ガス浄化性能とコストとのバランスの観点から、第３触媒層４０中の全貴金属元素の合計金属換算量は、第３触媒層４０の質量を基準として、好ましくは０．１質量％以上２０質量％以下、より好ましくは０．５質量％以上１５質量％以下、より一層好ましくは１．０質量％以上１０質量％以下である。
From the viewpoint of balance between exhaust gas purification performance and cost, the total metal equivalent amount of all precious metal elements in the third catalyst layer 40 is preferably 0.1% by mass or more and 20% by mass based on the mass of the third catalyst layer 40. % or less, more preferably 0.5% by mass or more and 15% by mass or less, even more preferably 1.0% by mass or more and 10% by mass or less.
第３触媒層４０がＰｔとＰｔ以外の１種又は２種以上の貴金属元素とを含む場合、ＰｔとＰｔ以外の１種又は２種以上の貴金属元素とが触媒活性の低い合金を形成し、排ガス浄化性能に関与するＰｔの活性点が減少するおそれがある。したがって、Ｐｔの排ガス浄化性能の低下を抑制する観点から、第３触媒層４０中のＰｔの金属換算量は、第３触媒層４０中のＰｔ以外の各貴金属元素の金属換算量よりも大きいことが好ましい。また、同様の観点から、第３触媒層４０中のＰｔの金属換算量は、第３触媒層４０中のＰｔ以外の全貴金属元素の合計金属換算量よりも大きいことが好ましい。
When the third catalyst layer 40 contains Pt and one or more noble metal elements other than Pt, Pt and one or more noble metal elements other than Pt form an alloy with low catalytic activity, There is a possibility that active sites of Pt, which are involved in exhaust gas purification performance, may decrease. Therefore, from the viewpoint of suppressing the deterioration of the exhaust gas purification performance of Pt, the metal equivalent amount of Pt in the third catalyst layer 40 should be larger than the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer 40. is preferred. Further, from the same viewpoint, it is preferable that the metal equivalent amount of Pt in the third catalyst layer 40 is larger than the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer 40.
第３触媒層４０中のＰｔの金属換算量に対する、第３触媒層４０中のＰｔ以外の各貴金属元素の金属換算量の比は、質量比で、好ましくは０．９以下、より好ましくは０．５以下、より一層好ましくは０．３以下である。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．１以上又は０．１５以上であってもよい。これらの下限値はそれぞれ、上記の上限値のいずれと組み合わせてもよい。
The ratio of the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer 40 to the metal equivalent amount of Pt in the third catalyst layer 40 is preferably 0.9 or less, more preferably 0. .5 or less, and even more preferably 0.3 or less. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.1 or more, or 0.15 or more. Each of these lower limits may be combined with any of the above upper limits.
第３触媒層４０中のＰｔの金属換算量に対する、第３触媒層４０中のＰｔ以外の全貴金属元素の合計金属換算量の比は、質量比で、好ましくは０．９以下、より好ましくは０．５以下、より一層好ましくは０．３以下である。当該比の下限値はゼロである。当該比は、例えば、０．０１以上、０．１以上又は０．２以上であってもよい。これらの下限値はそれぞれ、上記の上限値のいずれと組み合わせてもよい。
The ratio of the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer 40 to the metal equivalent amount of Pt in the third catalyst layer 40 is preferably 0.9 or less, more preferably It is 0.5 or less, more preferably 0.3 or less. The lower limit of this ratio is zero. The ratio may be, for example, 0.01 or more, 0.1 or more, or 0.2 or more. Each of these lower limits may be combined with any of the above upper limits.
第３触媒層４０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、第３触媒層４０中の各貴金属元素の金属換算量は、第３触媒層４０の製造に使用される原料の情報から求めることができる。第３触媒層４０の製造に使用される原料の情報が判明していない場合、第３触媒層４０中の各貴金属元素の金属換算量は、第１触媒層２０中の各貴金属元素の金属換算量と同様にして求めることができる。
When information on the raw materials (for example, composition, amount, etc.) used to manufacture the third catalyst layer 40 is known, the metal equivalent amount of each noble metal element in the third catalyst layer 40 is It can be determined from information on the raw materials used in the production of. If information on the raw materials used for manufacturing the third catalyst layer 40 is not known, the amount of each noble metal element in the third catalyst layer 40 in terms of metal is It can be determined in the same way as the quantity.
排ガス浄化性能とコストとのバランスの観点から、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量は、好ましくは７ｇ／Ｌ以上８６ｇ／Ｌ以下、より好ましくは１４ｇ／Ｌ以上５７ｇ／Ｌ以下、より一層好ましくは１４ｇ／Ｌ以上４３ｇ／Ｌ以下である。基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量は、式：（第３触媒層４０の質量）／（（基材１０の体積）×（第３触媒層４０の平均長さＬ４０／基材１０の長さＬ１０））から算出される。
From the viewpoint of balance between exhaust gas purification performance and cost, the mass of the third catalyst layer 40 per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed is preferably 7 g/L or more and 86 g/L. L or less, more preferably 14 g/L or more and 57 g/L or less, even more preferably 14 g/L or more and 43 g/L or less. The mass of the third catalyst layer 40 per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed is calculated by the formula: (mass of the third catalyst layer 40)/((volume of the base material 10) It is calculated from ×(average length L 40 of third catalyst layer 40 / length L 10 of base material 10)).
第１触媒層２０の質量に関する上記説明は、第３触媒層４０の質量にも適用される。適用の際、「第１触媒層２０」は「第３触媒層４０」に読み替えられる。
The above description regarding the mass of the first catalyst layer 20 also applies to the mass of the third catalyst layer 40. In application, "first catalyst layer 20" is read as "third catalyst layer 40."
第１触媒層２０の平均長さＬ２０の測定方法に関する上記説明は、第３触媒層４０の平均長さＬ４０の測定方法にも適用される。適用の際、「第１触媒層２０」は「第３触媒層４０」に読み替えられる。但し、第３触媒層４０の平均長さＬ４０の測定方法では、サンプルを基材１０の軸方向と垂直な平面によって５ｍｍ間隔で切断し、サンプルの排ガス流出側の端部側から順に、第１切断片、第２切断片、・・・、第ｎ切断片を得る。
The above description regarding the method for measuring the average length L 20 of the first catalyst layer 20 also applies to the method for measuring the average length L 40 of the third catalyst layer 40 . In application, "first catalyst layer 20" is read as "third catalyst layer 40." However, in the method of measuring the average length L 40 of the third catalyst layer 40, the sample is cut at 5 mm intervals along a plane perpendicular to the axial direction of the base material 10, and the samples are cut in order from the end of the sample on the exhaust gas outflow side. A first cut piece, a second cut piece, . . . , an nth cut piece are obtained.
第３触媒層４０の製造に使用される原料の情報（例えば、組成、量等）が判明している場合、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量は、第３触媒層４０の製造に使用される原料の情報から求めることができる。
If information on the raw materials used to manufacture the third catalyst layer 40 (for example, composition, amount, etc.) is known, the amount per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed is The mass of the third catalyst layer 40 can be determined from information on the raw materials used to manufacture the third catalyst layer 40.
排ガス浄化性能とコストとのバランスの観点から、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量と、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量との合計は、好ましくは１４ｇ／Ｌ以上１２９ｇ／Ｌ以下、より好ましくは２１ｇ／Ｌ以上１００ｇ／Ｌ以下、より一層好ましくは２９ｇ／Ｌ以上８６ｇ／Ｌ以下である。
From the perspective of the balance between exhaust gas purification performance and cost, the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed, and the mass of the third catalyst of the base material 10. The total mass of the portion where the layer 40 is formed and the mass of the third catalyst layer 40 per unit volume is preferably 14 g/L or more and 129 g/L or less, more preferably 21 g/L or more and 100 g/L or less, and even more Preferably it is 29 g/L or more and 86 g/L or less.
排ガス浄化性能を向上させる（特に、内燃機関の低速運転時に発生する低温ＮＯｘの浄化性能と、内燃機関の超高速運転時に発生する高温ＮＯｘの浄化性能との両立を実現する）観点から、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量に対する、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量の比は、好ましくは０．３以上１．９以下、より好ましくは０．５以上１．５以下、より一層好ましくは０．７以上１．３以下である。
From the perspective of improving exhaust gas purification performance (particularly achieving both the purification performance of low-temperature NOx generated during low-speed operation of the internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine), we have developed base materials. The mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed is The ratio of the masses of the three catalyst layers 40 is preferably 0.3 or more and 1.9 or less, more preferably 0.5 or more and 1.5 or less, and even more preferably 0.7 or more and 1.3 or less.
第３触媒層４０は、１種又は２種以上の担体を含み、触媒活性成分の少なくとも一部は１種又は２種以上の担体に担持されていることが好ましい。「触媒活性成分の少なくとも一部が担体に担持されている」の意義及び確認方法は、第１触媒層２０に関する上記説明中に記載した通りである。第１触媒層２０における担体に関する上記説明（無機酸化物の種類、組成、量等に関する上記説明を含む）は、第３触媒層４０にも適用される。適用の際、「第１触媒層２０」は「第３触媒層４０」に読み替えられる。
It is preferable that the third catalyst layer 40 includes one or more types of carriers, and at least a part of the catalytically active component is supported on the one or more types of carriers. The meaning and confirmation method of "at least a portion of the catalytically active component is supported on the carrier" are as described in the above description regarding the first catalyst layer 20. The above explanation regarding the carrier in the first catalyst layer 20 (including the above explanation regarding the type, composition, amount, etc. of the inorganic oxide) also applies to the third catalyst layer 40. In application, "first catalyst layer 20" is read as "third catalyst layer 40."
第３触媒層４０は、安定剤、バインダ等を含んでいてもよい。バインダ及び安定剤に関する説明は、上記の通りである。
The third catalyst layer 40 may contain a stabilizer, a binder, and the like. A description of the binder and stabilizer is given above.
図５及び６に示すように、第３触媒層４０は、第２触媒層３０上に形成されている。「第３触媒層４０が第２触媒層３０上に形成されている」という表現は、第２触媒層３０の２つの主面のうち、基材１０の隔壁部１２側の主面とは反対側の主面上に、第３触媒層４０の少なくとも一部（好ましくは全部）が存在することを意味する。「第２触媒層３０の主面」は、排ガス流通方向Ｅに延在する、第２触媒層３０の外表面を意味する。第３触媒層４０は、第２触媒層３０の主面上に、直接設けられていてもよいし、別の層を介して設けられていてもよい。
As shown in FIGS. 5 and 6, the third catalyst layer 40 is formed on the second catalyst layer 30. The expression "the third catalyst layer 40 is formed on the second catalyst layer 30" means that the main surface of the second catalyst layer 30 is opposite to the main surface on the partition wall 12 side of the base material 10. This means that at least a portion (preferably all) of the third catalyst layer 40 is present on the main surface of the side. "The main surface of the second catalyst layer 30" means the outer surface of the second catalyst layer 30 that extends in the exhaust gas flow direction E. The third catalyst layer 40 may be provided directly on the main surface of the second catalyst layer 30, or may be provided via another layer.
図６に示すように、第３触媒層４０は、隔壁部１２の排ガス流出側の端部から排ガス流通方向Ｅとは反対の方向に沿って延在している。本実施形態において、第３触媒層４０は、隔壁部１２の排ガス流入側の端部に至っていないが、隔壁部１２の排ガス流入側の端部に至っていてもよい。
As shown in FIG. 6, the third catalyst layer 40 extends from the end of the partition wall 12 on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction E. In the present embodiment, the third catalyst layer 40 does not reach the end of the partition wall 12 on the exhaust gas inflow side, but may reach the end of the partition wall 12 on the exhaust gas inflow side.
図５及び６に示すように、第３触媒層４０の少なくとも一部は、隔壁部１２の流出側セル１３ｂ側の外表面Ｓ１ｂから流出側セル１３ｂ側に***していること、すなわち、第３触媒層４０は、隔壁部１２の流出側セル１３ｂ側の外表面Ｓ１ｂから流出側セル１３ｂ側に***する部分（以下「***部分」という。）を有することが好ましい。これにより、排ガス及びＰＭの接触性が向上し、排ガス浄化性能の向上及びＰＭ捕集性能の向上をより効果的に実現することができる。
As shown in FIGS. 5 and 6, at least a portion of the third catalyst layer 40 protrudes from the outer surface S1b of the partition wall portion 12 on the outflow side cell 13b side toward the outflow side cell 13b side. It is preferable that the catalyst layer 40 has a portion that protrudes from the outer surface S1b of the partition wall portion 12 on the outflow side cell 13b side toward the outflow side cell 13b side (hereinafter referred to as “raised portion”). This improves the contact between the exhaust gas and PM, making it possible to more effectively improve the exhaust gas purification performance and the PM trapping performance.
第３触媒層４０は、***部分のみで構成されていてもよいし、***部分とともに、隔壁部１２の内部に存在する部分（以下「内在部分」という。）を有していてもよい。隔壁部１２は多孔質であるため、第３触媒層４０を形成する際、***部分とともに内在部分が形成される場合がある。***部分と内在部分とは、連続していてもよい。第３触媒層４０は内在部分のみで構成されていてもよい。「第３触媒層４０が、第２触媒層３０上に形成されている」には、第３触媒層４０が***部分のみで構成されている実施形態、第３触媒層４０が内在部分のみで構成されている実施形態、並びに、第３触媒層４０が***部分及び内在部分を有する実施形態のいずれもが包含される。これらのうち、第３触媒層４０が***部分のみで構成されている実施形態、並びに、第３触媒層４０が***部分及び内在部分を有する実施形態が好ましい。
The third catalyst layer 40 may be composed of only a raised portion, or may have a portion that exists inside the partition wall portion 12 (hereinafter referred to as “internal portion”) together with the raised portion. Since the partition wall portion 12 is porous, when forming the third catalyst layer 40, an internal portion may be formed together with a raised portion. The raised portion and the internal portion may be continuous. The third catalyst layer 40 may be composed only of an internal portion. "The third catalyst layer 40 is formed on the second catalyst layer 30" includes embodiments in which the third catalyst layer 40 is comprised only of raised parts, and embodiments in which the third catalyst layer 40 is comprised only of internal parts. Embodiments in which the third catalyst layer 40 has a raised portion and an embedded portion are both included. Among these, preferred are embodiments in which the third catalyst layer 40 includes only raised portions, and embodiments in which the third catalyst layer 40 includes raised portions and internal portions.
第３触媒層４０の***部分は、隔壁部１２の流出側セル１３ｂ側の外表面Ｓ１ｂよりも、流出側セル１３ｂ側に存在していればよく、隔壁部１２の流出側セル１３ｂ側の外表面Ｓ１ｂと接している必要はない。例えば、第３触媒層４０の***部分が第２触媒層３０の内在部分上に形成されている場合、第３触媒層４０の***部分は、隔壁部１２の流出側セル１３ｂ側の外表面と接する。一方、第３触媒層４０の***部分が第２触媒層３０の***部分上に形成されている場合、第３触媒層４０の***部分は、隔壁部１２の流出側セル１３ｂ側の外表面と接していない。
It is sufficient that the raised portion of the third catalyst layer 40 exists on the outflow side cell 13b side rather than the outer surface S1b of the partition wall section 12 on the outflow side cell 13b side. It does not need to be in contact with the surface S1b. For example, when the raised portion of the third catalyst layer 40 is formed on the internal portion of the second catalyst layer 30, the raised portion of the third catalyst layer 40 is formed on the outer surface of the partition wall portion 12 on the outflow side cell 13b side. come into contact with On the other hand, when the raised portion of the third catalyst layer 40 is formed on the raised portion of the second catalyst layer 30, the raised portion of the third catalyst layer 40 is formed on the outer surface of the partition wall portion 12 on the outflow side cell 13b side. Not in contact.
第１触媒層２０の***部分及び内在部分の特定方法に関する上記説明は、第３触媒層４０にも適用される。適用の際、「第１触媒層２０」は「第３触媒層４０」に読み替えられる。
The above description regarding the method for identifying the raised portion and the internal portion of the first catalyst layer 20 also applies to the third catalyst layer 40. In application, "first catalyst layer 20" is read as "third catalyst layer 40."
第３触媒層４０の平均長さＬ４０は、排ガス浄化性能、ＰＭ捕集性能等を考慮して適宜調整することができる。排ガス浄化性能及びＰＭ捕集性能を向上させる観点から、基材１０の長さＬ１０に対する第３触媒層４０の平均長さＬ４０の百分率（Ｌ４０／Ｌ１０×１００）は、好ましくは１５％以上９０％以下、より好ましくは２０％以上８０％以下、より一層好ましくは３０％以上８０％以下である。
The average length L 40 of the third catalyst layer 40 can be adjusted as appropriate in consideration of exhaust gas purification performance, PM trapping performance, and the like. From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the percentage of the average length L 40 of the third catalyst layer 40 to the length L 10 of the base material 10 (L 40 /L 10 × 100) is preferably 15 % or more and 90% or less, more preferably 20% or more and 80% or less, even more preferably 30% or more and 80% or less.
排ガス浄化性能及びＰＭ捕集性能を向上させる観点から、基材１０の長さＬ１０に対する、第１触媒層２０の平均長さＬ２０と第３触媒層４０の平均長さＬ４０との合計の百分率（（Ｌ２０＋Ｌ４０）／Ｌ１０×１００）は、好ましくは１００％以上１８０％以下、より好ましくは１０５％以上１５０％以下、より一層好ましくは１１０％以上１３０％以下である。
From the viewpoint of improving exhaust gas purification performance and PM trapping performance, the sum of the average length L 20 of the first catalyst layer 20 and the average length L 40 of the third catalyst layer 40 with respect to the length L 10 of the base material 10. The percentage ((L 20 +L 40 )/L 10 ×100) is preferably 100% or more and 180% or less, more preferably 105% or more and 150% or less, even more preferably 110% or more and 130% or less.
排ガス浄化性能及びＰＭ捕集性能を向上させる観点から、第３触媒層４０の平均長さＬ４０は、第２触媒層３０の平均長さＬ３０と同一であってもよいし、異なっていてもよい。第２触媒層３０の平均長さＬ３０に対する第３触媒層４０の平均長さＬ４０の百分率（Ｌ４０／Ｌ３０×１００）は、好ましくは５０％以上１５０％以下、より好ましくは７０％以上１３０％以下である。
From the perspective of improving exhaust gas purification performance and PM trapping performance, the average length L 40 of the third catalyst layer 40 may be the same as or different from the average length L 30 of the second catalyst layer 30. Good too. The percentage of the average length L 40 of the third catalyst layer 40 to the average length L 30 of the second catalyst layer 30 (L 40 /L 30 ×100) is preferably 50% or more and 150% or less, more preferably 70%. 130% or less.
＜排ガス浄化用触媒の作用効果＞
内燃機関から排出された排ガスは、排気管Ｐの一端から他端に向けて排気管Ｐ内の排気経路を流通し、排気管Ｐ内に配置された排ガス浄化用触媒１で浄化される。この際、流入側セル１３ａの排ガス流入側の端部（開口部）から流入した排ガスは、多孔質の隔壁部１２を通過して流出側セル１３ｂの排ガス流出側の端部（開口部）から流出する。このような様式は、ウォールフロー型と呼ばれる。 <Effects of exhaust gas purification catalyst>
Exhaust gas discharged from the internal combustion engine flows through an exhaust path within the exhaust pipe P from one end of the exhaust pipe P to the other end, and is purified by the exhaust gas purification catalyst 1 disposed within the exhaust pipe P. At this time, the exhaust gas flowing in from the exhaust gas inflow side end (opening) of the inflow side cell 13a passes through the porous partition wall 12 and flows from the exhaust gas outflow side end (opening) of the outflow side cell 13b. leak. Such a style is called a wall flow type.
内燃機関から排出された排ガスは、排気管Ｐの一端から他端に向けて排気管Ｐ内の排気経路を流通し、排気管Ｐ内に配置された排ガス浄化用触媒１で浄化される。この際、流入側セル１３ａの排ガス流入側の端部（開口部）から流入した排ガスは、多孔質の隔壁部１２を通過して流出側セル１３ｂの排ガス流出側の端部（開口部）から流出する。このような様式は、ウォールフロー型と呼ばれる。 <Effects of exhaust gas purification catalyst>
Exhaust gas discharged from the internal combustion engine flows through an exhaust path within the exhaust pipe P from one end of the exhaust pipe P to the other end, and is purified by the exhaust gas purification catalyst 1 disposed within the exhaust pipe P. At this time, the exhaust gas flowing in from the exhaust gas inflow side end (opening) of the inflow side cell 13a passes through the porous partition wall 12 and flows from the exhaust gas outflow side end (opening) of the outflow side cell 13b. leak. Such a style is called a wall flow type.
排ガス浄化用触媒１において、流入側セル１３ａの排ガス流入側の端部（開口部）から流入した排ガスが、多孔質の隔壁部１２を通過する際、排ガス中の粒子状物質（ＰＭ：Ｐａｒｔｉｃｕｌａｔｅ Ｍａｔｔｅｒ）は、隔壁部１２の細孔、第１触媒層２０の細孔、第２触媒層３０の細孔及び第３触媒層４０の細孔に捕集される。したがって、排ガス浄化用触媒１は、ガソリンエンジン用のパティキュレートフィルタ（Ｇａｓｏｌｉｎｅ Ｐａｒｔｉｃｕｌａｔｅ Ｆｉｌｔｅｒ）又はディーゼルエンジン用のパティキュレートフィルタ（Ｄｉｅｓｅｌ Ｐａｒｔｉｃｕｌａｔｅ Ｆｉｌｔｅｒ）として有用である。
In the exhaust gas purification catalyst 1, when the exhaust gas flowing in from the end (opening) on the exhaust gas inflow side of the inflow side cell 13a passes through the porous partition wall 12, particulate matter (PM) in the exhaust gas is removed. ) is collected in the pores of the partition wall 12 , the pores of the first catalyst layer 20 , the pores of the second catalyst layer 30 , and the pores of the third catalyst layer 40 . Therefore, the exhaust gas purifying catalyst 1 is useful as a gasoline engine particulate filter or a diesel engine particulate filter.
排ガス浄化用触媒１において、流入側セル１３ａの排ガス流入側の端部（開口部）から流入した排ガスは、第１触媒層２０と接触した後、多孔質の隔壁部１２を通過し、第２触媒層３０及び第３触媒層４０と順次接触する。排ガス中のＮＯｘは、第１触媒層２０中のＲｈにより浄化される。浄化されずに第１触媒層２０を通過したＮＯｘは、第２触媒層３０中のＲｈ及び第３触媒層４０中のＰｔにより順次浄化される。基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量に対する、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量の比が１．９超であると、第３触媒層４０中のＰｔは排ガスと十分に接触できるが、第２触媒層３０中のＲｈは排ガスと十分に接触できず、ＮＯｘ浄化性能が低下する。一方、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量に対する、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量の比が０．３未満であると、第２触媒層３０中のＲｈは排ガスと十分に接触できるが、第３触媒層４０中のＰｔは排ガスと十分に接触できず、ＮＯｘ浄化性能が低下する。これに対して、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量に対する、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量の比が０．３以上１．９以下であると、第２触媒層３０中のＲｈが排ガスと十分に接触できるとともに、第３触媒層４０中のＰｔが排ガスと十分に接触でき、ＮＯｘ浄化性能が向上する。また、排ガスは、第１触媒層２０、隔壁部１２、第２触媒層３０及び第３触媒層４０と順次接触するため、第３触媒層４０と接触する排ガスの温度は最も低くなる。Ｐｔは熱耐久性が低く、劣化しやすいが、第３触媒層４０と接触する排ガスの温度が最も低くなるため、第３触媒層４０中のＰｔの劣化を防止することができる。以上のことから、排ガス浄化用触媒１は、内燃機関の低速運転時に発生する低温ＮＯｘの浄化性能と、内燃機関の超高速運転時に発生する高温ＮＯｘの浄化性能との両立を実現することができる。すなわち、排ガス浄化用触媒１は、低温～高温の広い温度範囲において、優れたＮＯｘ浄化性能を発揮することができる。「内燃機関の低速運転時に発生する低温ＮＯｘの浄化性能」は、国際的に規定された走行モードの１つであるＷＬＴＣモードにおいて運転開始から運転開始後５８９秒までの間に排出されるＮＯｘの量に基づいて評価することができ、「内燃機関の超高速運転時に発生する高温ＮＯｘの浄化性能」は、同ＷＬＴＣモードにおいて運転開始後１４７７秒から１８００秒までの間に排出されるＮＯｘの量に基づいて評価することができる。具体的な評価方法は、実施例に記載の通りである。
In the exhaust gas purification catalyst 1, the exhaust gas flowing in from the end (opening) on the exhaust gas inflow side of the inflow side cell 13a comes into contact with the first catalyst layer 20, passes through the porous partition wall 12, and enters the second It contacts the catalyst layer 30 and the third catalyst layer 40 in this order. NOx in the exhaust gas is purified by Rh in the first catalyst layer 20. NOx that has passed through the first catalyst layer 20 without being purified is sequentially purified by Rh in the second catalyst layer 30 and Pt in the third catalyst layer 40. Per unit volume of the portion of the base material 10 where the third catalyst layer 40 is formed relative to the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed When the mass ratio of the third catalyst layer 40 is more than 1.9, Pt in the third catalyst layer 40 can sufficiently contact exhaust gas, but Rh in the second catalyst layer 30 can sufficiently contact exhaust gas. This results in a decrease in NOx purification performance. On the other hand, the unit of the portion of the base material 10 where the third catalyst layer 40 is formed relative to the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed. When the ratio of the mass of the third catalyst layer 40 per volume is less than 0.3, Rh in the second catalyst layer 30 can sufficiently contact the exhaust gas, but Pt in the third catalyst layer 40 can sufficiently contact the exhaust gas. NOx purification performance deteriorates. On the other hand, the third catalyst layer 40 is formed in the base material 10 relative to the mass of the second catalyst layer 30 per unit volume of the portion of the base material 10 where the second catalyst layer 30 is formed. When the ratio of the mass of the third catalyst layer 40 per unit volume of the portion is 0.3 or more and 1.9 or less, Rh in the second catalyst layer 30 can sufficiently contact the exhaust gas, and the third catalyst layer 40 The Pt inside can make sufficient contact with the exhaust gas, improving NOx purification performance. Further, since the exhaust gas sequentially contacts the first catalyst layer 20, the partition wall portion 12, the second catalyst layer 30, and the third catalyst layer 40, the temperature of the exhaust gas that contacts the third catalyst layer 40 is the lowest. Although Pt has low thermal durability and is easily deteriorated, since the temperature of the exhaust gas that contacts the third catalyst layer 40 is the lowest, deterioration of Pt in the third catalyst layer 40 can be prevented. From the above, the exhaust gas purification catalyst 1 can achieve both the purification performance of low-temperature NOx generated during low-speed operation of the internal combustion engine and the purification performance of high-temperature NOx generated during ultra-high-speed operation of the internal combustion engine. . That is, the exhaust gas purification catalyst 1 can exhibit excellent NOx purification performance in a wide temperature range from low to high temperatures. "Purification performance of low-temperature NOx generated during low-speed operation of an internal combustion engine" refers to the performance of NOx emitted from the start of operation to 589 seconds after the start of operation in WLTC mode, which is one of the internationally regulated driving modes. The "purification performance of high-temperature NOx generated during ultra-high-speed operation of an internal combustion engine" can be evaluated based on the amount of NOx emitted from 1477 seconds to 1800 seconds after the start of operation in the same WLTC mode. can be evaluated based on The specific evaluation method is as described in Examples.
≪排ガス浄化用触媒の製造方法≫
以下、排ガス浄化用触媒１の製造方法について説明する。 ≪Method for producing exhaust gas purification catalyst≫
The method for manufacturing the exhaust gas purifying catalyst 1 will be described below.
以下、排ガス浄化用触媒１の製造方法について説明する。 ≪Method for producing exhaust gas purification catalyst≫
The method for manufacturing the exhaust gas purifying catalyst 1 will be described below.
基材１０と、第１触媒層２０を形成するためのスラリー、第２触媒層３０を形成するためのスラリー及び第３触媒層４０を形成するためのスラリーを準備する。
A base material 10, a slurry for forming the first catalyst layer 20, a slurry for forming the second catalyst layer 30, and a slurry for forming the third catalyst layer 40 are prepared.
第１触媒層２０、第２触媒層３０及び第３触媒層４０を形成するためのスラリーの組成は、それぞれ、第１触媒層２０、第２触媒層３０及び第３触媒層４０の組成に応じて調整される。スラリーは、例えば、貴金属元素の供給源、無機酸化物粒子、バインダ、造孔材、溶媒等を含む。貴金属元素の供給源としては、例えば、貴金属元素の塩が挙げられ、貴金属元素の塩としては、例えば、硝酸塩、アンミン錯体塩、酢酸塩、塩化物等が挙げられる。無機酸化物粒子を構成する無機酸化物に関する説明は、上記の通りである。バインダとしては、例えば、アルミナゾル、ジルコニアゾル、チタニアゾル、シリカゾル、セリアゾル等が挙げられる。造孔材としては、例えば、架橋ポリ（メタ）アクリル酸メチル粒子、架橋ポリ（メタ）アクリル酸ブチル粒子、架橋ポリスチレン粒子、架橋ポリアクリル酸エステル粒子、メラミン系樹脂等が挙げられる。溶媒としては、例えば、水、有機溶媒等が挙げられる。有機溶媒としては、例えば、アルコール、アセトン、ジメチルスルホキシド、ジメチルホルムアミド等が挙げられる。溶媒は、１種の溶媒であってもよいし、２種以上の溶媒の混合物であってもよい。２種以上の溶媒の混合物としては、例えば、水と１種又は２種以上の有機溶媒との混合物、２種以上の有機溶媒の混合物等が挙げられる。
The composition of the slurry for forming the first catalyst layer 20, the second catalyst layer 30, and the third catalyst layer 40 depends on the composition of the first catalyst layer 20, the second catalyst layer 30, and the third catalyst layer 40, respectively. It is adjusted accordingly. The slurry includes, for example, a source of a noble metal element, inorganic oxide particles, a binder, a pore-forming material, a solvent, and the like. Examples of the source of the noble metal element include salts of the noble metal element, and examples of the salt of the noble metal element include nitrates, ammine complex salts, acetates, and chlorides. The explanation regarding the inorganic oxide constituting the inorganic oxide particles is as above. Examples of the binder include alumina sol, zirconia sol, titania sol, silica sol, and ceria sol. Examples of the pore-forming material include crosslinked methyl poly(meth)acrylate particles, crosslinked butyl poly(meth)acrylate particles, crosslinked polystyrene particles, crosslinked polyacrylate particles, and melamine resins. Examples of the solvent include water, organic solvents, and the like. Examples of the organic solvent include alcohol, acetone, dimethyl sulfoxide, and dimethyl formamide. The solvent may be one type of solvent or a mixture of two or more types of solvents. Examples of the mixture of two or more solvents include a mixture of water and one or more organic solvents, a mixture of two or more organic solvents, and the like.
基材１０の排ガス流入側の端部を、第１触媒層２０を形成するためのスラリー中に浸漬し、反対側からスラリーを吸引した後、乾燥させる。これにより、第１触媒層２０の前駆体が形成される。スラリーの固形分濃度、粘度等を調整することにより、第１触媒層２０の前駆体の長さ（ひいては、第１触媒層２０の平均長さＬ２０）を調整することができる。また、スラリーのコート量、スラリーを構成する材料の種類、スラリーに含まれる造孔材の粒径等を調整することにより、第１触媒層２０の前駆体の厚み（ひいては、第１触媒層２０の厚み）及び基材１０のうち第１触媒層２０の前駆体が形成されている部分の単位体積当たりの第１触媒層２０の前駆体の質量（ひいては、基材１０のうち第１触媒層２０が形成されている部分の単位体積当たりの第１触媒層２０の質量）を調整することができる。乾燥温度は、例えば４０℃以上１５０℃以下、乾燥時間は、例えば５分以上１時間以下である。
The end of the base material 10 on the exhaust gas inflow side is immersed in the slurry for forming the first catalyst layer 20, and after the slurry is sucked from the opposite side, it is dried. As a result, a precursor of the first catalyst layer 20 is formed. By adjusting the solid content concentration, viscosity, etc. of the slurry, the length of the precursor of the first catalyst layer 20 (and thus the average length L 20 of the first catalyst layer 20) can be adjusted. In addition, by adjusting the coating amount of the slurry, the type of material constituting the slurry, the particle size of the pore-forming material contained in the slurry, etc., the thickness of the precursor of the first catalyst layer 20 (and thus the thickness of the first catalyst layer 20) can be adjusted. thickness) and the mass of the precursor of the first catalyst layer 20 per unit volume of the portion of the base material 10 on which the precursor of the first catalyst layer 20 is formed (thickness of the first catalyst layer of the base material 10) The mass of the first catalyst layer 20 per unit volume of the portion in which the first catalyst layer 20 is formed can be adjusted. The drying temperature is, for example, 40° C. or more and 150° C. or less, and the drying time is, for example, 5 minutes or more and 1 hour or less.
第１触媒層２０の前駆体の形成後、焼成を行う。これにより、第１触媒層２０が形成される。焼成温度は、例えば３５０℃以上６００℃以下、焼成時間は、例えば２０分以上５時間以下である。焼成時の雰囲気は、通常、大気雰囲気である。
After forming the precursor of the first catalyst layer 20, firing is performed. As a result, the first catalyst layer 20 is formed. The firing temperature is, for example, 350° C. or more and 600° C. or less, and the firing time is, for example, 20 minutes or more and 5 hours or less. The atmosphere during firing is usually an atmospheric atmosphere.
基材１０の排ガス流出側の端部を、第２触媒層３０を形成するためのスラリー中に浸漬し、反対側からスラリーを吸引した後、乾燥させる。これにより、第２触媒層３０の前駆体が形成される。スラリーの固形分濃度、粘度等を調整することにより、第２触媒層３０の前駆体の長さ（ひいては、第２触媒層３０の平均長さＬ３０）を調整することができる。また、スラリーのコート量、スラリーを構成する材料の種類、スラリーに含まれる造孔材の粒径等を調整することにより、第２触媒層３０の前駆体の厚み（ひいては、第２触媒層３０の厚み）及び基材１０のうち第２触媒層３０の前駆体が形成されている部分の単位体積当たりの第２触媒層３０の前駆体の質量（ひいては、基材１０のうち第２触媒層３０が形成されている部分の単位体積当たりの第２触媒層３０の質量）を調整することができる。乾燥温度は、例えば４０℃以上１５０℃以下、乾燥時間は、例えば５分以上１時間以下である。
The end of the base material 10 on the exhaust gas outflow side is immersed in the slurry for forming the second catalyst layer 30, and after the slurry is sucked from the opposite side, it is dried. As a result, a precursor for the second catalyst layer 30 is formed. By adjusting the solid content concentration, viscosity, etc. of the slurry, the length of the precursor of the second catalyst layer 30 (and thus the average length L 30 of the second catalyst layer 30) can be adjusted. In addition, by adjusting the coating amount of the slurry, the type of material constituting the slurry, the particle size of the pore-forming material contained in the slurry, etc., the thickness of the precursor of the second catalyst layer 30 (and thus the thickness of the second catalyst layer 30) can be adjusted. thickness) and the mass of the precursor of the second catalyst layer 30 per unit volume of the portion of the base material 10 on which the precursor of the second catalyst layer 30 is formed (thickness of the second catalyst layer of the base material 10) The mass of the second catalyst layer 30 per unit volume of the portion where the second catalyst layer 30 is formed can be adjusted. The drying temperature is, for example, 40° C. or more and 150° C. or less, and the drying time is, for example, 5 minutes or more and 1 hour or less.
第２触媒層３０の前駆体の形成後、基材１０の排ガス流出側の端部を、第３触媒層４０を形成するためのスラリー中に浸漬し、反対側からスラリーを吸引した後、乾燥させる。これにより、第２触媒層３０の前駆体上に第３触媒層４０の前駆体が形成される。スラリーの固形分濃度、粘度等を調整することにより、第３触媒層４０の前駆体の長さ（ひいては、第３触媒層４０の平均長さＬ４０）を調整することができる。また、スラリーのコート量、スラリーを構成する材料の種類、スラリーに含まれる造孔材の粒径等を調整することにより、第３触媒層４０の前駆体の厚み（ひいては、第３触媒層４０の厚み）及び基材１０のうち第３触媒層４０の前駆体が形成されている部分の単位体積当たりの第３触媒層４０の前駆体の質量（ひいては、基材１０のうち第３触媒層４０が形成されている部分の単位体積当たりの第３触媒層４０の質量）を調整することができる。乾燥温度は、例えば４０℃以上１５０℃以下、乾燥時間は、例えば５分以上１時間以下である。
After forming the precursor of the second catalyst layer 30, the end of the base material 10 on the exhaust gas outflow side is immersed in the slurry for forming the third catalyst layer 40, and after sucking the slurry from the opposite side, it is dried. let As a result, a precursor for the third catalyst layer 40 is formed on the precursor for the second catalyst layer 30. By adjusting the solid content concentration, viscosity, etc. of the slurry, the length of the precursor of the third catalyst layer 40 (and thus the average length L 40 of the third catalyst layer 40) can be adjusted. In addition, by adjusting the coating amount of the slurry, the type of material constituting the slurry, the particle size of the pore-forming material contained in the slurry, etc., the thickness of the precursor of the third catalyst layer 40 (and thus the thickness of the third catalyst layer 40) can be adjusted. thickness) and the mass of the precursor of the third catalyst layer 40 per unit volume of the portion of the base material 10 on which the precursor of the third catalyst layer 40 is formed (thickness of the third catalyst layer of the base material 10) The mass of the third catalyst layer 40 per unit volume of the portion where the third catalyst layer 40 is formed can be adjusted. The drying temperature is, for example, 40° C. or more and 150° C. or less, and the drying time is, for example, 5 minutes or more and 1 hour or less.
第２触媒層３０の前駆体及び第３触媒層４０の前駆体の形成後、焼成を行う。これにより、第２触媒層３０及び第３触媒層４０が形成される。焼成温度は、例えば３５０℃以上６００℃以下、焼成時間は、例えば２０分以上５時間以下である。焼成時の雰囲気は、通常、大気雰囲気である。
After forming the precursor of the second catalyst layer 30 and the precursor of the third catalyst layer 40, firing is performed. As a result, the second catalyst layer 30 and the third catalyst layer 40 are formed. The firing temperature is, for example, 350° C. or more and 600° C. or less, and the firing time is, for example, 20 minutes or more and 5 hours or less. The atmosphere during firing is usually an atmospheric atmosphere.
造孔材のメジアンＤ５０は、剥離抑制、圧損上昇抑制、ＰＭ捕集性能向上等の観点から、好ましくは０．５μｍ以上５０μｍ以下、好ましくは１μｍ以上３０μｍ以下である。造孔材の粒径が大きいほど、第１触媒層２０、第２触媒層３０及び第３触媒層４０の圧損が低くなる。Ｄ５０は、レーザー回折散乱式粒度分布測定法によって測定される体積基準の粒度分布において、累積体積が５０％となる粒径である。
The median D 50 of the pore-forming material is preferably 0.5 μm or more and 50 μm or less, preferably 1 μm or more and 30 μm or less, from the viewpoint of suppressing peeling, suppressing increase in pressure loss, and improving PM trapping performance. The larger the particle size of the pore-forming material, the lower the pressure loss of the first catalyst layer 20, second catalyst layer 30, and third catalyst layer 40. D50 is the particle size at which the cumulative volume is 50% in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measuring method.
無機酸化物粒子のＤ９０は、剥離抑制、圧損上昇抑制、ＰＭ捕集性能向上等の観点から、好ましくは３μｍ以上５０μｍ以下、より好ましくは５μｍ以上４０μｍ以下である。Ｄ９０は、レーザー回折散乱式粒度分布測定法によって測定される体積基準の粒度分布において、累積体積が９０％となる粒径である。
The D 90 of the inorganic oxide particles is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, from the viewpoint of suppressing peeling, suppressing increase in pressure loss, and improving PM trapping performance. D90 is the particle size at which the cumulative volume is 90% in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measuring method.
Ｄ５０又はＤ９０の測定は、レーザー回折散乱式粒度分布測定装置自動試料供給機（マイクロトラック・ベル社製「Ｍｉｃｒｏｔｏｒａｃ ＳＤＣ」）を使用して、測定対象試料を水性分散媒に投入し、２６ｍＬ／ｓｅｃの流速中、４０Ｗの超音波を３６０秒間照射した後、レーザー回折散乱式粒度分布測定装置（マイクロトラック・ベル社製「マイクロトラックＭＴ３３００ＥＸＩＩ」）を使用して行う。測定は、粒子屈折率を１．５、粒子形状を真球形、溶媒屈折率を１．３、セットゼロを３０秒、測定時間を３０秒の条件で、２回行い、得られた測定値の平均値をＤ５０又はＤ９０とする。水性分散媒としては純水を使用する。
To measure D 50 or D 90 , use a laser diffraction scattering particle size distribution analyzer automatic sample feeder (Microtorac SDC manufactured by Microtrac Bell), add the sample to be measured to an aqueous dispersion medium, and add 26 mL After irradiating with 40W ultrasonic waves for 360 seconds at a flow rate of /sec, the measurement is performed using a laser diffraction scattering particle size distribution analyzer (Microtrac MT3300EXII manufactured by Microtrac Bell). The measurement was performed twice under the following conditions: particle refractive index of 1.5, particle shape of perfect sphere, solvent refractive index of 1.3, set zero for 30 seconds, and measurement time of 30 seconds. Let the average value be D50 or D90 . Pure water is used as the aqueous dispersion medium.
〔実施例１〕
（１）第１スラリーの調製
硝酸ロジウム水溶液中に、Ｃｅ－Ｚｒ系複合酸化物粉末（ＣｅのＣｅＯ２換算量：１５質量％，ＺｒのＺｒＯ２換算量：７０質量％，Ｃｅ以外の３種の希土類元素（Ｌａ，Ｎｄ，Ｙ）の酸化物換算量：１５質量％）及びアルミナ粉末を添加した後、造孔材（メジアン径Ｄ５０が５μｍである架橋ポリ（メタ）アクリル酸メチル粒子）、アルミナゾル、ジルコニアゾル及び溶媒としての水を添加し、第１スラリーを調製した。第１スラリー中の各成分の量は、第１スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で０．５質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．６質量％、アルミナ粉末が１６．９質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した。また、第１スラリー中の造孔材の量は、第１スラリーの乾燥及び焼成によって形成される触媒層の質量の３０質量％となるように調整した。なお、第１スラリーの乾燥及び焼成によって形成される触媒層の質量は、第１スラリーの質量から、第１スラリーの乾燥及び焼成によって消失する成分（例えば、溶媒、造孔材等）の質量を差し引くことにより求められる。第１スラリー中の金属酸化物粉末（Ｃｅ－Ｚｒ系複合酸化物粉末及びアルミナ粉末）のＤ９０は、２０μｍであった。 [Example 1]
(1) Preparation of first slurry In rhodium nitrate aqueous solution, Ce-Zr composite oxide powder (Ce equivalent to CeO 2 : 15% by mass, Zr equivalent to ZrO 2 : 70% by mass, 3 types other than Ce) After adding rare earth elements (La, Nd, Y) oxide equivalent amount: 15% by mass) and alumina powder, a pore-forming material (crosslinked poly(meth)methyl acrylate particles with a median diameter D50 of 5 μm) was added. , alumina sol, zirconia sol, and water as a solvent were added to prepare a first slurry. The amount of each component in the first slurry is based on the mass of the catalyst layer formed by drying and firing the first slurry, rhodium is 0.5% by mass in terms of metal, and Ce-Zr composite oxide powder is 0.5% by mass. The content of the alumina powder was 74.6% by mass, the alumina powder was 16.9% by mass, the alumina sol was 3.0% by mass in terms of solid content, and the zirconia sol was 5.0% by mass in terms of solid content. Further, the amount of the pore former in the first slurry was adjusted to be 30% by mass of the catalyst layer formed by drying and firing the first slurry. Note that the mass of the catalyst layer formed by drying and firing the first slurry is calculated by subtracting the mass of components (e.g., solvent, pore-forming material, etc.) that disappear by drying and firing the first slurry from the mass of the first slurry. It is determined by subtracting the amount. D 90 of the metal oxide powder (Ce-Zr composite oxide powder and alumina powder) in the first slurry was 20 μm.
（１）第１スラリーの調製
硝酸ロジウム水溶液中に、Ｃｅ－Ｚｒ系複合酸化物粉末（ＣｅのＣｅＯ２換算量：１５質量％，ＺｒのＺｒＯ２換算量：７０質量％，Ｃｅ以外の３種の希土類元素（Ｌａ，Ｎｄ，Ｙ）の酸化物換算量：１５質量％）及びアルミナ粉末を添加した後、造孔材（メジアン径Ｄ５０が５μｍである架橋ポリ（メタ）アクリル酸メチル粒子）、アルミナゾル、ジルコニアゾル及び溶媒としての水を添加し、第１スラリーを調製した。第１スラリー中の各成分の量は、第１スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で０．５質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．６質量％、アルミナ粉末が１６．９質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した。また、第１スラリー中の造孔材の量は、第１スラリーの乾燥及び焼成によって形成される触媒層の質量の３０質量％となるように調整した。なお、第１スラリーの乾燥及び焼成によって形成される触媒層の質量は、第１スラリーの質量から、第１スラリーの乾燥及び焼成によって消失する成分（例えば、溶媒、造孔材等）の質量を差し引くことにより求められる。第１スラリー中の金属酸化物粉末（Ｃｅ－Ｚｒ系複合酸化物粉末及びアルミナ粉末）のＤ９０は、２０μｍであった。 [Example 1]
(1) Preparation of first slurry In rhodium nitrate aqueous solution, Ce-Zr composite oxide powder (Ce equivalent to CeO 2 : 15% by mass, Zr equivalent to ZrO 2 : 70% by mass, 3 types other than Ce) After adding rare earth elements (La, Nd, Y) oxide equivalent amount: 15% by mass) and alumina powder, a pore-forming material (crosslinked poly(meth)methyl acrylate particles with a median diameter D50 of 5 μm) was added. , alumina sol, zirconia sol, and water as a solvent were added to prepare a first slurry. The amount of each component in the first slurry is based on the mass of the catalyst layer formed by drying and firing the first slurry, rhodium is 0.5% by mass in terms of metal, and Ce-Zr composite oxide powder is 0.5% by mass. The content of the alumina powder was 74.6% by mass, the alumina powder was 16.9% by mass, the alumina sol was 3.0% by mass in terms of solid content, and the zirconia sol was 5.0% by mass in terms of solid content. Further, the amount of the pore former in the first slurry was adjusted to be 30% by mass of the catalyst layer formed by drying and firing the first slurry. Note that the mass of the catalyst layer formed by drying and firing the first slurry is calculated by subtracting the mass of components (e.g., solvent, pore-forming material, etc.) that disappear by drying and firing the first slurry from the mass of the first slurry. It is determined by subtracting the amount. D 90 of the metal oxide powder (Ce-Zr composite oxide powder and alumina powder) in the first slurry was 20 μm.
（２）第２スラリーの調製
第１スラリーと同様にして、第２スラリーを調製した。第２スラリーの組成は、第１スラリーの組成と同一である。 (2) Preparation of second slurry A second slurry was prepared in the same manner as the first slurry. The composition of the second slurry is the same as the composition of the first slurry.
第１スラリーと同様にして、第２スラリーを調製した。第２スラリーの組成は、第１スラリーの組成と同一である。 (2) Preparation of second slurry A second slurry was prepared in the same manner as the first slurry. The composition of the second slurry is the same as the composition of the first slurry.
（３）第３スラリーの調製
ジニトロジアンミン白金硝酸水溶液に、Ｃｅ－Ｚｒ系複合酸化物粉末（ＣｅのＣｅＯ２換算量：４８質量％，ＺｒのＺｒＯ２換算量：４２質量％，Ｃｅ以外の３種の希土類元素（Ｌａ，Ｎｄ，Ｐｒ）の酸化物換算量：１０質量％）及びアルミナ粉末を添加した後、造孔材（メジアン径Ｄ５０が５μｍである架橋ポリ（メタ）アクリル酸メチル粒子）、アルミナゾル、ジルコニアゾル及び溶媒としての水を添加し、第３スラリーを調製した。第３スラリー中の各成分の量は、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で７．８質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が６７．３質量％、アルミナ粉末が１５．７質量％、アルミナゾルが固形分換算で７．４質量％、ジルコニアゾルが固形分換算で１．８質量％となるように調整した。また、第３スラリー中の造孔材の量は、第３スラリーの乾燥及び焼成によって形成される触媒層の質量の３０質量％となるように調整した。なお、第３スラリーの乾燥及び焼成によって形成される触媒層の質量は、第３スラリーの質量から、第３スラリーの乾燥及び焼成によって消失する成分（例えば、溶媒、造孔材等）の質量を差し引くことにより求められる。第３スラリー中の金属酸化物粉末（Ｃｅ－Ｚｒ系複合酸化物粉末及びアルミナ粉末）のＤ９０は、２０μｍであった。 (3) Preparation of third slurry Ce-Zr based composite oxide powder (amount of Ce in terms of CeO2 : 48% by mass, amount of Zr in terms of ZrO2: 42% by mass, 3% by mass of ZrO2 in terms of ZrO2, 3% by mass in terms of ZrO2, After adding rare earth elements (La, Nd, Pr) oxide equivalent amount: 10% by mass) and alumina powder, a pore-forming material (crosslinked poly(meth)methyl acrylate particles having a median diameter D50 of 5 μm) was added. ), alumina sol, zirconia sol, and water as a solvent were added to prepare a third slurry. The amount of each component in the third slurry is based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum is 7.8% by mass in terms of metal, and Ce-Zr composite oxide powder is 7.8% by mass. The content of the alumina powder was 15.7% by mass, the alumina sol was 7.4% by mass in terms of solid content, and the content of zirconia sol was 1.8% by mass in terms of solid content. Further, the amount of the pore former in the third slurry was adjusted to be 30% by mass of the catalyst layer formed by drying and firing the third slurry. The mass of the catalyst layer formed by drying and firing the third slurry is calculated by subtracting the mass of components (e.g., solvent, pore-forming material, etc.) that disappear by drying and firing the third slurry from the mass of the third slurry. It is determined by subtracting the amount. D 90 of the metal oxide powder (Ce-Zr composite oxide powder and alumina powder) in the third slurry was 20 μm.
ジニトロジアンミン白金硝酸水溶液に、Ｃｅ－Ｚｒ系複合酸化物粉末（ＣｅのＣｅＯ２換算量：４８質量％，ＺｒのＺｒＯ２換算量：４２質量％，Ｃｅ以外の３種の希土類元素（Ｌａ，Ｎｄ，Ｐｒ）の酸化物換算量：１０質量％）及びアルミナ粉末を添加した後、造孔材（メジアン径Ｄ５０が５μｍである架橋ポリ（メタ）アクリル酸メチル粒子）、アルミナゾル、ジルコニアゾル及び溶媒としての水を添加し、第３スラリーを調製した。第３スラリー中の各成分の量は、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で７．８質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が６７．３質量％、アルミナ粉末が１５．７質量％、アルミナゾルが固形分換算で７．４質量％、ジルコニアゾルが固形分換算で１．８質量％となるように調整した。また、第３スラリー中の造孔材の量は、第３スラリーの乾燥及び焼成によって形成される触媒層の質量の３０質量％となるように調整した。なお、第３スラリーの乾燥及び焼成によって形成される触媒層の質量は、第３スラリーの質量から、第３スラリーの乾燥及び焼成によって消失する成分（例えば、溶媒、造孔材等）の質量を差し引くことにより求められる。第３スラリー中の金属酸化物粉末（Ｃｅ－Ｚｒ系複合酸化物粉末及びアルミナ粉末）のＤ９０は、２０μｍであった。 (3) Preparation of third slurry Ce-Zr based composite oxide powder (amount of Ce in terms of CeO2 : 48% by mass, amount of Zr in terms of ZrO2: 42% by mass, 3% by mass of ZrO2 in terms of ZrO2, 3% by mass in terms of ZrO2, After adding rare earth elements (La, Nd, Pr) oxide equivalent amount: 10% by mass) and alumina powder, a pore-forming material (crosslinked poly(meth)methyl acrylate particles having a median diameter D50 of 5 μm) was added. ), alumina sol, zirconia sol, and water as a solvent were added to prepare a third slurry. The amount of each component in the third slurry is based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum is 7.8% by mass in terms of metal, and Ce-Zr composite oxide powder is 7.8% by mass. The content of the alumina powder was 15.7% by mass, the alumina sol was 7.4% by mass in terms of solid content, and the content of zirconia sol was 1.8% by mass in terms of solid content. Further, the amount of the pore former in the third slurry was adjusted to be 30% by mass of the catalyst layer formed by drying and firing the third slurry. The mass of the catalyst layer formed by drying and firing the third slurry is calculated by subtracting the mass of components (e.g., solvent, pore-forming material, etc.) that disappear by drying and firing the third slurry from the mass of the third slurry. It is determined by subtracting the amount. D 90 of the metal oxide powder (Ce-Zr composite oxide powder and alumina powder) in the third slurry was 20 μm.
（４）第１触媒層の形成
図１～６に示すウォールフロー型基材を準備した。隔壁部の厚みは２００～２５０μｍ、基材の軸方向に対して垂直な断面における流入側セル及び流出側セルの合計数は１平方インチあたり３００セル、基材の体積は１．０Ｌ、基材の長さは９１ｍｍであった。 (4) Formation of first catalyst layer Wall-flow type substrates shown in FIGS. 1 to 6 were prepared. The thickness of the partition wall part is 200 to 250 μm, the total number of inflow side cells and outflow side cells in a cross section perpendicular to the axial direction of the base material is 300 cells per square inch, the volume of the base material is 1.0L, the base material The length was 91 mm.
図１～６に示すウォールフロー型基材を準備した。隔壁部の厚みは２００～２５０μｍ、基材の軸方向に対して垂直な断面における流入側セル及び流出側セルの合計数は１平方インチあたり３００セル、基材の体積は１．０Ｌ、基材の長さは９１ｍｍであった。 (4) Formation of first catalyst layer Wall-flow type substrates shown in FIGS. 1 to 6 were prepared. The thickness of the partition wall part is 200 to 250 μm, the total number of inflow side cells and outflow side cells in a cross section perpendicular to the axial direction of the base material is 300 cells per square inch, the volume of the base material is 1.0L, the base material The length was 91 mm.
基材の排ガス流通方向の上流側の端部を第１スラリー中に浸漬し、下流側から吸引した後、９０℃で１０分間、乾燥させた。これにより、基材の隔壁部の流入側セル側に、基材の排ガス流入側の端部から排ガス流通方向に沿って延在する第１前駆層（第１スラリーの固形分からなる層）を形成した。その後、基材を、４５０℃で１時間、焼成した。これにより、基材の隔壁部の流入側セル側に、基材の排ガス流入側の端部から排ガス流通方向に沿って延在する第１触媒層を形成した。
The upstream end of the base material in the exhaust gas flow direction was immersed in the first slurry, suctioned from the downstream side, and then dried at 90° C. for 10 minutes. As a result, a first precursor layer (a layer consisting of the solid content of the first slurry) extending from the exhaust gas inflow side end of the base material along the exhaust gas flow direction is formed on the inflow side cell side of the partition wall portion of the base material. did. Thereafter, the substrate was fired at 450° C. for 1 hour. Thereby, a first catalyst layer was formed on the inflow side cell side of the partition wall portion of the base material, extending from the exhaust gas inflow side end of the base material along the exhaust gas flow direction.
基材の長さに対する第１触媒層の長さの百分率は４５％であった。ＳＥＭ観察したところ、第１触媒層の少なくとも一部は、基材の隔壁の流入側セル側の外表面から流入側セル側に***していた。基材のうち第１触媒層が形成されている部分の単位体積当たりの第１触媒層の質量（以下「ＷＣ１」という。）は３７．８ｇ／Ｌであった。基材のうち第１触媒層が形成されている部分の単位体積当たりの第１触媒層中のＲｈの金属換算量は５．６ｇ／ｃｆｔであった。なお、「ｃｆｔ」は、立方フィート（ｃｕｂｉｃ ｆｅｅｆ）を意味する。
The percentage of the length of the first catalyst layer to the length of the base material was 45%. As a result of SEM observation, at least a portion of the first catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the inflow side cell side toward the inflow side cell side. The mass of the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer was formed (hereinafter referred to as "WC1") was 37.8 g/L. The metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer was formed was 5.6 g/cft. Note that "cft" means cubic feet.
（５）第２触媒層及び第３触媒層の形成
第１触媒層の形成後、基材の排ガス流通方向の下流側の端部を第２スラリー中に浸漬し、上流側から吸引した後、９０℃で１０分間、乾燥させた。これにより、基材の隔壁部の流出側セル側に、基材の排ガス流出側の端部から排ガス流通方向とは反対方向に沿って延在する第２前駆層（第２スラリーの固形分からなる層）を形成した。 (5) Formation of the second catalyst layer and the third catalyst layer After forming the first catalyst layer, the downstream end of the base material in the exhaust gas flow direction is immersed in the second slurry, and the slurry is sucked from the upstream side. It was dried at 90°C for 10 minutes. As a result, a second precursor layer (consisting of solid components of the second slurry) extending from the end of the base material on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction is formed on the outflow side cell side of the partition wall portion of the base material. layer) was formed.
第１触媒層の形成後、基材の排ガス流通方向の下流側の端部を第２スラリー中に浸漬し、上流側から吸引した後、９０℃で１０分間、乾燥させた。これにより、基材の隔壁部の流出側セル側に、基材の排ガス流出側の端部から排ガス流通方向とは反対方向に沿って延在する第２前駆層（第２スラリーの固形分からなる層）を形成した。 (5) Formation of the second catalyst layer and the third catalyst layer After forming the first catalyst layer, the downstream end of the base material in the exhaust gas flow direction is immersed in the second slurry, and the slurry is sucked from the upstream side. It was dried at 90°C for 10 minutes. As a result, a second precursor layer (consisting of solid components of the second slurry) extending from the end of the base material on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction is formed on the outflow side cell side of the partition wall portion of the base material. layer) was formed.
第２前駆層の形成後、基材の排ガス流通方向の下流側の端部を第３スラリー中に浸漬し、上流側から吸引した後、９０℃で１０分間、乾燥させた。これにより、第２前駆層上に、基材の排ガス流出側の端部から排ガス流通方向とは反対方向に沿って延在する第３前駆層（第３スラリーの固形分からなる層）を形成した。
After forming the second precursor layer, the downstream end of the base material in the exhaust gas flow direction was immersed in the third slurry, suctioned from the upstream side, and then dried at 90° C. for 10 minutes. As a result, a third precursor layer (a layer consisting of the solid content of the third slurry) was formed on the second precursor layer, extending from the end of the base material on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction. .
第２前駆層及び第３前駆層の形成後、基材を、４５０℃で１時間、焼成した。これにより、基材の隔壁部の流出側セル側に、基材の排ガス流出側の端部から排ガス流通方向とは反対方向に沿って延在する第２触媒層と、第２触媒層上に、基材の排ガス流出側の端部から排ガス流通方向とは反対方向に沿って延在する第３触媒層とを形成した。以上のようにして、排ガス浄化用触媒を作製した。
After forming the second precursor layer and the third precursor layer, the base material was baked at 450° C. for 1 hour. As a result, on the outflow side cell side of the partition part of the base material, there is provided a second catalyst layer extending from the exhaust gas outflow side end of the base material along a direction opposite to the exhaust gas flow direction, and a second catalyst layer on the second catalyst layer. A third catalyst layer was formed extending from the end of the base material on the exhaust gas outflow side in a direction opposite to the exhaust gas flow direction. In the manner described above, an exhaust gas purifying catalyst was produced.
基材の長さに対する第２触媒層の長さの百分率は７０％であった。ＳＥＭ観察したところ、第２触媒層の少なくとも一部は、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。基材のうち第２触媒層が形成されている部分の単位体積当たりの第２触媒層の質量（以下「ＷＣ２」という）は２７．１ｇ／Ｌであった。基材のうち第２触媒層が形成されている部分の単位体積当たりの第２触媒層中のＲｈの金属換算量は３．６ｇ／ｃｆｔであった。
The percentage of the length of the second catalyst layer with respect to the length of the base material was 70%. As a result of SEM observation, at least a portion of the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. The mass of the second catalyst layer per unit volume (hereinafter referred to as "WC2") of the portion of the base material where the second catalyst layer was formed was 27.1 g/L. The metal equivalent amount of Rh in the second catalyst layer per unit volume of the portion of the base material where the second catalyst layer was formed was 3.6 g/cft.
基材の長さに対する第３触媒層の長さの百分率は７０％であった。ＳＥＭ観察したところ、第３触媒層の少なくとも一部は、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。基材のうち第３触媒層が形成されている部分の単位体積当たりの第３触媒層の質量（以下「ＷＣ３」という）は１２．９ｇ／Ｌであった。ＷＣ２に対するＷＣ３の比は０．４７であった。基材のうち第３触媒層が形成されている部分の単位体積当たりの第３触媒層中のＰｔの金属換算量は２８．６ｇ／ｃｆｔであった。
The percentage of the length of the third catalyst layer to the length of the base material was 70%. As a result of SEM observation, at least a portion of the third catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. The mass of the third catalyst layer per unit volume (hereinafter referred to as "WC3") of the portion of the base material where the third catalyst layer was formed was 12.9 g/L. The ratio of WC3 to WC2 was 0.47. The metal equivalent amount of Pt in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer was formed was 28.6 g/cft.
（６）排ガス浄化性能の評価
得られた排ガス浄化用触媒を、エンジンの排気経路に配置し、以下の耐久条件にて耐久処理を行った。
（耐久条件）
・耐久用エンジン：乗用ＮＡ ２Ｌ ガソリンエンジン
・使用ガソリン：市販レギュラーガソリン
・耐久温度及び時間：９５０℃で１０時間 (6) Evaluation of exhaust gas purification performance The obtained exhaust gas purification catalyst was placed in the exhaust path of the engine, and subjected to durability treatment under the following durability conditions.
(Durability conditions)
・Durability engine: Passenger NA 2L gasoline engine ・Gasoline used: Commercially available regular gasoline ・Durability temperature and time: 10 hours at 950℃
得られた排ガス浄化用触媒を、エンジンの排気経路に配置し、以下の耐久条件にて耐久処理を行った。
（耐久条件）
・耐久用エンジン：乗用ＮＡ ２Ｌ ガソリンエンジン
・使用ガソリン：市販レギュラーガソリン
・耐久温度及び時間：９５０℃で１０時間 (6) Evaluation of exhaust gas purification performance The obtained exhaust gas purification catalyst was placed in the exhaust path of the engine, and subjected to durability treatment under the following durability conditions.
(Durability conditions)
・Durability engine: Passenger NA 2L gasoline engine ・Gasoline used: Commercially available regular gasoline ・Durability temperature and time: 10 hours at 950℃
耐久処理後の排ガス浄化用触媒を設置した車両を、国際調和排ガス試験モード（ＷＬＴＣ）の運転条件に従って運転した。運転開始から１８００秒までの間に排ガス浄化用触媒を通過した排ガス中の窒素酸化物（ＮＯｘ）、非メタン系炭化水素（ＨＣ）及び一酸化炭素（ＣＯ）の排出量（エミッション値）を測定し、単位走行距離当たりのＮＯｘ、ＨＣ及びＣＯの排出量（ｍｇ／ｋｍ）を求めた。車両としては、１．５Ｌ直噴ターボエンジン搭載乗用車を使用し、ガソリンとしては、認証試験用燃料を使用し、排ガス測定装置としては、堀場製作所社製の排ガス測定装置を使用した。ＮＯｘ、ＨＣ及びＣＯに関する単位走行距離当たりの排出量の測定結果を表１に示す。表１中、単位走行距離当たりのＮＯｘ、ＨＣ及びＣＯの排出量は、それぞれ、後述する比較例３における単位走行距離当たりのＮＯｘ、ＨＣ及びＣＯの排出量に対する相対値として示す。また、表１中、「低温ＮＯｘ」は、運転開始から運転開始後５８９秒までの間のＮＯｘの排出量を意味し、「高温ＮＯｘ」は、運転開始後１４７７秒から１８００秒までの間のＮＯｘ排出量を意味する。
A vehicle equipped with an exhaust gas purification catalyst after durability treatment was operated according to the operating conditions of the internationally harmonized exhaust gas test mode (WLTC). Measures the emissions (emission values) of nitrogen oxides (NOx), non-methane hydrocarbons (HC), and carbon monoxide (CO) in the exhaust gas that has passed through the exhaust gas purification catalyst for 1800 seconds from the start of operation. Then, the emissions of NOx, HC, and CO per unit traveling distance (mg/km) were determined. A passenger car equipped with a 1.5L direct injection turbo engine was used as the vehicle, a certification test fuel was used as the gasoline, and an exhaust gas measuring device manufactured by Horiba, Ltd. was used as the exhaust gas measuring device. Table 1 shows the measurement results of NOx, HC, and CO emissions per unit traveling distance. In Table 1, the emissions of NOx, HC, and CO per unit traveling distance are shown as relative values to the emissions of NOx, HC, and CO per unit traveling distance in Comparative Example 3, which will be described later. In addition, in Table 1, "low temperature NOx" means the amount of NOx emitted from the start of operation to 589 seconds after the start of operation, and "high temperature NOx" means the amount of emissions from 1477 seconds to 1800 seconds after the start of operation. Means NOx emissions.
〔実施例２〕
第２スラリー中の各成分の量を、第２スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で０．６質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．５質量％、アルミナ粉末が１６．９質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した点、
第３スラリー中の各成分の量を、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で５．０質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が６９．４質量％、アルミナ粉末が１６．１質量％、アルミナゾルが固形分換算で７．６質量％、ジルコニアゾルが固形分換算で１．９質量％となるように調整した点、
ＷＣ２を２０．０ｇ／Ｌに変更した点、及び、
ＷＣ３を２０．０ｇ／Ｌに変更した点を除き、実施例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Example 2]
The amounts of each component in the second slurry were determined based on the mass of the catalyst layer formed by drying and firing the second slurry, rhodium was 0.6% by mass in terms of metal, and Ce-Zr composite oxide powder was The content was adjusted to 74.5% by mass, the alumina powder was 16.9% by mass, the alumina sol was 3.0% by mass in terms of solid content, and the zirconia sol was adjusted to be 5.0% by mass in terms of solid content,
The amounts of each component in the third slurry were determined based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum was 5.0% by mass in metal terms, and Ce-Zr composite oxide powder was 5.0% by mass in terms of metal. 69.4% by mass, alumina powder was adjusted to 16.1% by mass, alumina sol was adjusted to 7.6% by mass in terms of solid content, and zirconia sol was adjusted to 1.9% by mass in terms of solid content,
WC2 was changed to 20.0g/L, and
An exhaust gas purification catalyst was produced in the same manner as in Example 1, except that WC3 was changed to 20.0 g/L, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
第２スラリー中の各成分の量を、第２スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で０．６質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．５質量％、アルミナ粉末が１６．９質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した点、
第３スラリー中の各成分の量を、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で５．０質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が６９．４質量％、アルミナ粉末が１６．１質量％、アルミナゾルが固形分換算で７．６質量％、ジルコニアゾルが固形分換算で１．９質量％となるように調整した点、
ＷＣ２を２０．０ｇ／Ｌに変更した点、及び、
ＷＣ３を２０．０ｇ／Ｌに変更した点を除き、実施例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Example 2]
The amounts of each component in the second slurry were determined based on the mass of the catalyst layer formed by drying and firing the second slurry, rhodium was 0.6% by mass in terms of metal, and Ce-Zr composite oxide powder was The content was adjusted to 74.5% by mass, the alumina powder was 16.9% by mass, the alumina sol was 3.0% by mass in terms of solid content, and the zirconia sol was adjusted to be 5.0% by mass in terms of solid content,
The amounts of each component in the third slurry were determined based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum was 5.0% by mass in metal terms, and Ce-Zr composite oxide powder was 5.0% by mass in terms of metal. 69.4% by mass, alumina powder was adjusted to 16.1% by mass, alumina sol was adjusted to 7.6% by mass in terms of solid content, and zirconia sol was adjusted to 1.9% by mass in terms of solid content,
WC2 was changed to 20.0g/L, and
An exhaust gas purification catalyst was produced in the same manner as in Example 1, except that WC3 was changed to 20.0 g/L, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
ＷＣ２に対するＷＣ３の比は１．００であった。ＳＥＭ観察したところ、第２触媒層の少なくとも一部は、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。同様に、第３触媒層の少なくとも一部も、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。基材のうち第１触媒層が形成されている部分の単位体積当たりの第１触媒層中のＲｈの金属換算量は５．６ｇ／ｃｆｔ、基材のうち第２触媒層が形成されている部分の単位体積当たりの第２触媒層中のＲｈの金属換算量は３．６ｇ／ｃｆｔ、基材のうち第３触媒層が形成されている部分の単位体積当たりの第３触媒層中のＰｔの金属換算量は２８．６ｇ／ｃｆｔであった。
The ratio of WC3 to WC2 was 1.00. As a result of SEM observation, at least a portion of the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. Similarly, at least a portion of the third catalyst layer also protruded from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. The metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 5.6 g/cft, and the second catalyst layer is formed in the base material. The metal equivalent amount of Rh in the second catalyst layer per unit volume of the portion is 3.6 g/cft, and the Pt in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer is formed. The metal equivalent amount was 28.6 g/cft.
〔比較例１〕
第２スラリー中の各成分の量を、第２スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で１．０質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．２質量％、アルミナ粉末が１６．８質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した点、
第３スラリー中の各成分の量を、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で３．７質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７０．３質量％、アルミナ粉末が１６．４質量％、アルミナゾルが固形分換算で７．７質量％、ジルコニアゾルが固形分換算で１．９質量％となるように調整した点、
ＷＣ２を１２．９ｇ／Ｌに変更した点、及び、
ＷＣ３を２７．１ｇ／Ｌに変更した点を除き、実施例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Comparative example 1]
The amounts of each component in the second slurry were determined based on the mass of the catalyst layer formed by drying and firing the second slurry, rhodium was 1.0% by mass in metal terms, and Ce-Zr composite oxide powder was 1.0% by mass in terms of metal. 74.2% by mass, alumina powder 16.8% by mass, alumina sol 3.0% by mass in terms of solid content, and zirconia sol 5.0% by mass in terms of solid content,
Based on the mass of the catalyst layer formed by drying and firing the third slurry, the amounts of each component in the third slurry were as follows: platinum was 3.7% by mass in metal terms, and Ce-Zr composite oxide powder was 3.7% by mass in terms of metal. 70.3% by mass, alumina powder was adjusted to 16.4% by mass, alumina sol was adjusted to 7.7% by mass in terms of solid content, and zirconia sol was adjusted to 1.9% by mass in terms of solid content,
WC2 was changed to 12.9g/L, and
An exhaust gas purification catalyst was produced in the same manner as in Example 1 except that WC3 was changed to 27.1 g/L, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
第２スラリー中の各成分の量を、第２スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で１．０質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．２質量％、アルミナ粉末が１６．８質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した点、
第３スラリー中の各成分の量を、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で３．７質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７０．３質量％、アルミナ粉末が１６．４質量％、アルミナゾルが固形分換算で７．７質量％、ジルコニアゾルが固形分換算で１．９質量％となるように調整した点、
ＷＣ２を１２．９ｇ／Ｌに変更した点、及び、
ＷＣ３を２７．１ｇ／Ｌに変更した点を除き、実施例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Comparative example 1]
The amounts of each component in the second slurry were determined based on the mass of the catalyst layer formed by drying and firing the second slurry, rhodium was 1.0% by mass in metal terms, and Ce-Zr composite oxide powder was 1.0% by mass in terms of metal. 74.2% by mass, alumina powder 16.8% by mass, alumina sol 3.0% by mass in terms of solid content, and zirconia sol 5.0% by mass in terms of solid content,
Based on the mass of the catalyst layer formed by drying and firing the third slurry, the amounts of each component in the third slurry were as follows: platinum was 3.7% by mass in metal terms, and Ce-Zr composite oxide powder was 3.7% by mass in terms of metal. 70.3% by mass, alumina powder was adjusted to 16.4% by mass, alumina sol was adjusted to 7.7% by mass in terms of solid content, and zirconia sol was adjusted to 1.9% by mass in terms of solid content,
WC2 was changed to 12.9g/L, and
An exhaust gas purification catalyst was produced in the same manner as in Example 1 except that WC3 was changed to 27.1 g/L, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
ＷＣ２に対するＷＣ３の比は２．１１であった。ＳＥＭ観察したところ、第２触媒層の少なくとも一部は、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。同様に、第３触媒層の少なくとも一部も、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。基材のうち第１触媒層が形成されている部分の単位体積当たりの第１触媒層中のＲｈの金属換算量は５．６ｇ／ｃｆｔ、基材のうち第２触媒層が形成されている部分の単位体積当たりの第２触媒層中のＲｈの金属換算量は３．６ｇ／ｃｆｔ、基材のうち第３触媒層が形成されている部分の単位体積当たりの第３触媒層中のＰｔの金属換算量は２８．６ｇ／ｃｆｔであった。
The ratio of WC3 to WC2 was 2.11. As a result of SEM observation, at least a portion of the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. Similarly, at least a portion of the third catalyst layer also protruded from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. The metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 5.6 g/cft, and the second catalyst layer is formed in the base material. The metal equivalent amount of Rh in the second catalyst layer per unit volume of the portion is 3.6 g/cft, and the Pt in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer is formed. The metal equivalent amount was 28.6 g/cft.
〔比較例２〕
第２触媒層及び第３触媒層を入れ替えた点（第２触媒層を比較例１の第３触媒層と同様に形成し、第３触媒層を比較例１の第２触媒層と同様に形成した点）を除き、比較例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Comparative example 2]
The second catalyst layer and the third catalyst layer were exchanged (the second catalyst layer was formed in the same manner as the third catalyst layer in Comparative Example 1, and the third catalyst layer was formed in the same manner as the second catalyst layer in Comparative Example 1). An exhaust gas purification catalyst was produced in the same manner as in Comparative Example 1 except for the following points), and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
第２触媒層及び第３触媒層を入れ替えた点（第２触媒層を比較例１の第３触媒層と同様に形成し、第３触媒層を比較例１の第２触媒層と同様に形成した点）を除き、比較例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Comparative example 2]
The second catalyst layer and the third catalyst layer were exchanged (the second catalyst layer was formed in the same manner as the third catalyst layer in Comparative Example 1, and the third catalyst layer was formed in the same manner as the second catalyst layer in Comparative Example 1). An exhaust gas purification catalyst was produced in the same manner as in Comparative Example 1 except for the following points), and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
ＷＣ２に対するＷＣ３の比は０．４７であった。ＳＥＭ観察したところ、第２触媒層の少なくとも一部は、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。同様に、第３触媒層の少なくとも一部も、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。基材のうち第１触媒層が形成されている部分の単位体積当たりの第１触媒層中のＲｈの金属換算量は５．６ｇ／ｃｆｔ、基材のうち第２触媒層が形成されている部分の単位体積当たりの第２触媒層中のＰｔの金属換算量は２８．６ｇ／ｃｆｔ、基材のうち第３触媒層が形成されている部分の単位体積当たりの第３触媒層中のＲｈの金属換算量は３．６ｇ／ｃｆｔであった。
The ratio of WC3 to WC2 was 0.47. As a result of SEM observation, at least a portion of the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. Similarly, at least a portion of the third catalyst layer also protruded from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. The metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 5.6 g/cft, and the second catalyst layer is formed in the base material. The metal equivalent amount of Pt in the second catalyst layer per unit volume of the portion is 28.6 g/cft, and the amount of Rh in the third catalyst layer per unit volume of the portion of the base material where the third catalyst layer is formed is 28.6 g/cft. The metal equivalent amount was 3.6 g/cft.
〔比較例３〕
第１スラリー中の各成分の量を、第１スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で１．０質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．２質量％、アルミナ粉末が１６．８質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した点、
第３スラリー中の各成分の量を、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で２．５質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７３．１質量％、アルミナ粉末が１６．６質量％、アルミナゾルが固形分換算で２．９質量％、ジルコニアゾルが固形分換算で４．９質量％となるように調整した点、
第２スラリーに代えて第３スラリーを使用して第２触媒層を形成した点、
ＷＣ２を４０．０ｇ／Ｌに変更した点、及び、
第３触媒層を形成しなかった点を除き、実施例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Comparative example 3]
The amounts of each component in the first slurry were determined based on the mass of the catalyst layer formed by drying and firing the first slurry, rhodium was 1.0% by mass in metal terms, and Ce-Zr composite oxide powder was 1.0% by mass in terms of metal. 74.2% by mass, alumina powder 16.8% by mass, alumina sol 3.0% by mass in terms of solid content, and zirconia sol 5.0% by mass in terms of solid content,
The amounts of each component in the third slurry were determined based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum was 2.5% by mass in metal terms, and Ce-Zr composite oxide powder was 2.5% by mass in terms of metal. 73.1% by mass, alumina powder was adjusted to 16.6% by mass, alumina sol was adjusted to 2.9% by mass in terms of solid content, and zirconia sol was adjusted to 4.9% by mass in terms of solid content,
The point that the second catalyst layer was formed using the third slurry instead of the second slurry,
WC2 was changed to 40.0g/L, and
An exhaust gas purification catalyst was produced in the same manner as in Example 1, except that the third catalyst layer was not formed, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
第１スラリー中の各成分の量を、第１スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、ロジウムが金属換算で１．０質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７４．２質量％、アルミナ粉末が１６．８質量％、アルミナゾルが固形分換算で３．０質量％、ジルコニアゾルが固形分換算で５．０質量％となるように調整した点、
第３スラリー中の各成分の量を、第３スラリーの乾燥及び焼成によって形成される触媒層の質量を基準として、白金が金属換算で２．５質量％、Ｃｅ－Ｚｒ系複合酸化物粉末が７３．１質量％、アルミナ粉末が１６．６質量％、アルミナゾルが固形分換算で２．９質量％、ジルコニアゾルが固形分換算で４．９質量％となるように調整した点、
第２スラリーに代えて第３スラリーを使用して第２触媒層を形成した点、
ＷＣ２を４０．０ｇ／Ｌに変更した点、及び、
第３触媒層を形成しなかった点を除き、実施例１と同様にして排ガス浄化用触媒を作製し、排ガス浄化性能を評価した。結果を表１に示す。 [Comparative example 3]
The amounts of each component in the first slurry were determined based on the mass of the catalyst layer formed by drying and firing the first slurry, rhodium was 1.0% by mass in metal terms, and Ce-Zr composite oxide powder was 1.0% by mass in terms of metal. 74.2% by mass, alumina powder 16.8% by mass, alumina sol 3.0% by mass in terms of solid content, and zirconia sol 5.0% by mass in terms of solid content,
The amounts of each component in the third slurry were determined based on the mass of the catalyst layer formed by drying and firing the third slurry, platinum was 2.5% by mass in metal terms, and Ce-Zr composite oxide powder was 2.5% by mass in terms of metal. 73.1% by mass, alumina powder was adjusted to 16.6% by mass, alumina sol was adjusted to 2.9% by mass in terms of solid content, and zirconia sol was adjusted to 4.9% by mass in terms of solid content,
The point that the second catalyst layer was formed using the third slurry instead of the second slurry,
WC2 was changed to 40.0g/L, and
An exhaust gas purification catalyst was produced in the same manner as in Example 1, except that the third catalyst layer was not formed, and the exhaust gas purification performance was evaluated. The results are shown in Table 1.
ＳＥＭ観察したところ、第２触媒層の少なくとも一部は、基材の隔壁の流出側セル側の外表面から流出側セル側に***していた。基材のうち第１触媒層が形成されている部分の単位体積当たりの第１触媒層中のＲｈの金属換算量は１１．１ｇ／ｃｆｔ、基材のうち第２触媒層が形成されている部分の単位体積当たりの第２触媒層中のＰｔの金属換算量は２８．６ｇ／ｃｆｔであった。
As a result of SEM observation, at least a portion of the second catalyst layer was found to be protruding from the outer surface of the partition wall of the base material on the outflow side cell side toward the outflow side cell side. The metal equivalent amount of Rh in the first catalyst layer per unit volume of the portion of the base material where the first catalyst layer is formed is 11.1 g/cft, and the second catalyst layer is formed in the base material. The metal equivalent amount of Pt in the second catalyst layer per unit volume of the part was 28.6 g/cft.
１・・・排ガス浄化用触媒
１０・・・基材
１１・・・筒状部
１２・・・隔壁部
１３・・・セル
１３ａ・・・流入側セル
１３ｂ・・・流出側セル
１４・・・第１封止部
１５・・・第２封止部
２０・・・第１触媒層
３０・・・第２触媒層
４０・・・第３触媒層
Ｓ１ａ・・・隔壁部の流入側セル側の外表面
Ｓ１ｂ・・・隔壁部の流出側セル側の外表面 1... Exhaust gas purification catalyst 10... Base material 11... Cylindrical part 12... Partition wall part 13... Cell 13a... Inflow side cell 13b... Outflow side cell 14... First sealing part 15...Second sealing part 20...First catalyst layer 30...Second catalyst layer 40...Third catalyst layer S1a...On the inflow side cell side of the partition wall part Outer surface S1b: outer surface of the partition wall on the outflow side cell side
１０・・・基材
１１・・・筒状部
１２・・・隔壁部
１３・・・セル
１３ａ・・・流入側セル
１３ｂ・・・流出側セル
１４・・・第１封止部
１５・・・第２封止部
２０・・・第１触媒層
３０・・・第２触媒層
４０・・・第３触媒層
Ｓ１ａ・・・隔壁部の流入側セル側の外表面
Ｓ１ｂ・・・隔壁部の流出側セル側の外表面 1... Exhaust gas purification catalyst 10... Base material 11... Cylindrical part 12... Partition wall part 13... Cell 13a... Inflow side cell 13b... Outflow side cell 14... First sealing part 15...Second sealing part 20...First catalyst layer 30...Second catalyst layer 40...Third catalyst layer S1a...On the inflow side cell side of the partition wall part Outer surface S1b: outer surface of the partition wall on the outflow side cell side
Claims (6)
- 排ガス流通方向に延在する基材と、
Ｒｈを含み、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい第１触媒層と、
Ｒｈを含み、Ｒｈ以外の１種又は２種以上の貴金属元素を含んでいてもよい第２触媒層と、
Ｐｔを含み、Ｐｔ以外の１種又は２種以上の貴金属元素を含んでいてもよい第３触媒層と、
を備える、排ガス浄化用触媒であって、
前記基材は、
前記排ガス流通方向に延在する流入側セルであって、排ガス流入側の端部が開口しており、排ガス流出側の端部が閉塞している前記流入側セルと、
前記排ガス流通方向に延在する流出側セルであって、排ガス流入側の端部が閉塞しており、排ガス流出側の端部が開口している前記流出側セルと、
前記流入側セルと前記流出側セルとを仕切る多孔質の隔壁部と、
を備え、
前記第１触媒層は、前記隔壁部の前記流入側セル側に、前記隔壁部の排ガス流入側の端部から前記排ガス流通方向に沿って形成されており、
前記第２触媒層は、前記隔壁部の前記流出側セル側に、前記隔壁部の排ガス流出側の端部から前記排ガス流通方向とは反対の方向に沿って形成されており、
前記第３触媒層は、前記第３触媒層の少なくとも一部が前記隔壁部の前記流出側セル側の外表面から前記流出側セル側に***するように、前記第２触媒層上に形成されており、
前記第２触媒層中のＲｈの金属換算量は、前記第２触媒層中のＲｈ以外の各貴金属元素の金属換算量よりも大きく、
前記第３触媒層中のＰｔの金属換算量は、前記第３触媒層中のＰｔ以外の各貴金属元素の金属換算量よりも大きく、
前記基材のうち前記第２触媒層が形成されている部分の単位体積当たりの前記第２触媒層の質量に対する、前記基材のうち前記第３触媒層が形成されている部分の単位体積当たりの前記第３触媒層の質量の比は、０．３以上１．９以下である、前記排ガス浄化用触媒。 a base material extending in the exhaust gas flow direction;
a first catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh;
a second catalyst layer containing Rh and optionally containing one or more noble metal elements other than Rh;
a third catalyst layer containing Pt and optionally containing one or more noble metal elements other than Pt;
An exhaust gas purification catalyst comprising:
The base material is
The inflow side cell extends in the exhaust gas flow direction, and has an open end on the exhaust gas inflow side and a closed end on the exhaust gas outflow side;
The outflow side cell extends in the exhaust gas flow direction, and has a closed end on the exhaust gas inflow side and an open end on the exhaust gas outflow side;
a porous partition that partitions the inflow side cell and the outflow side cell;
Equipped with
The first catalyst layer is formed on the inflow-side cell side of the partition wall part along the exhaust gas flow direction from the exhaust gas inflow-side end of the partition wall part,
The second catalyst layer is formed on the outflow-side cell side of the partition wall from the exhaust gas outflow-side end of the partition wall in a direction opposite to the exhaust gas flow direction,
The third catalyst layer is formed on the second catalyst layer such that at least a portion of the third catalyst layer protrudes from an outer surface of the partition wall portion on the outflow side cell side toward the outflow side cell side. and
The metal equivalent amount of Rh in the second catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the second catalyst layer,
The metal equivalent amount of Pt in the third catalyst layer is larger than the metal equivalent amount of each noble metal element other than Pt in the third catalyst layer,
The mass of the second catalyst layer per unit volume of the portion of the base material where the second catalyst layer is formed is per unit volume of the portion of the base material where the third catalyst layer is formed. In the exhaust gas purifying catalyst, the mass ratio of the third catalyst layer is 0.3 or more and 1.9 or less. - 前記第１触媒層中のＲｈの金属換算量が、前記第１触媒層中のＲｈ以外の各貴金属元素の金属換算量よりも大きい、請求項１に記載の排ガス浄化用触媒。 The exhaust gas purifying catalyst according to claim 1, wherein the metal equivalent amount of Rh in the first catalyst layer is larger than the metal equivalent amount of each noble metal element other than Rh in the first catalyst layer.
- 前記第１触媒層中のＲｈの金属換算量が、前記第１触媒層中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きく、
前記第２触媒層中のＲｈの金属換算量が、前記第２触媒層中のＲｈ以外の全貴金属元素の合計金属換算量よりも大きく、
前記第３触媒層中のＰｔの金属換算量が、前記第３触媒層中のＰｔ以外の全貴金属元素の合計金属換算量よりも大きい、請求項１又は２に記載の排ガス浄化用触媒。 The metal equivalent amount of Rh in the first catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the first catalyst layer,
The metal equivalent amount of Rh in the second catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Rh in the second catalyst layer,
The exhaust gas purifying catalyst according to claim 1 or 2, wherein the metal equivalent amount of Pt in the third catalyst layer is larger than the total metal equivalent amount of all noble metal elements other than Pt in the third catalyst layer. - 前記第１触媒層の少なくとも一部が、前記隔壁部の前記流入側セル側の外表面から前記流入側セル側に***する、請求項１又は２に記載の排ガス浄化用触媒。 The exhaust gas purifying catalyst according to claim 1 or 2, wherein at least a portion of the first catalyst layer protrudes from an outer surface of the partition wall portion on the inflow side cell side toward the inflow side cell side.
- 前記第２触媒層の少なくとも一部が、前記隔壁部の前記流出側セル側の外表面から前記流出側セル側に***する、請求項１又は２に記載の排ガス浄化用触媒。 The exhaust gas purifying catalyst according to claim 1 or 2, wherein at least a portion of the second catalyst layer protrudes from an outer surface of the partition wall portion on the outflow side cell side toward the outflow side cell side.
- 前記第１触媒層中の全貴金属元素の合計金属換算量に対する、前記第１触媒層中のＰｔの金属換算量の比が、質量比で、０．３以下である、請求項１又は２に記載の排ガス浄化用触媒。 3. The method according to claim 1 or 2, wherein the ratio of the metal equivalent amount of Pt in the first catalyst layer to the total metal equivalent amount of all noble metal elements in the first catalyst layer is 0.3 or less in terms of mass ratio. The exhaust gas purification catalyst described above.
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| WO2016060049A1 (en) * | 2014-10-16 | 2016-04-21 | 株式会社キャタラー | Exhaust gas purification catalyst |
| WO2020039650A1 (en) * | 2018-08-22 | 2020-02-27 | 三井金属鉱業株式会社 | Exhaust gas purification catalyst |
| JP2020193568A (en) * | 2019-05-24 | 2020-12-03 | トヨタ自動車株式会社 | Exhaust emission control device |
| WO2021029098A1 (en) * | 2019-08-09 | 2021-02-18 | 三井金属鉱業株式会社 | Exhaust gas purification catalyst and production method therefor |
| WO2021125256A1 (en) * | 2019-12-18 | 2021-06-24 | 三井金属鉱業株式会社 | Exhaust gas purification catalyst |
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| WO2016060049A1 (en) * | 2014-10-16 | 2016-04-21 | 株式会社キャタラー | Exhaust gas purification catalyst |
| WO2020039650A1 (en) * | 2018-08-22 | 2020-02-27 | 三井金属鉱業株式会社 | Exhaust gas purification catalyst |
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