GB2558186A - Catalysed monolith substrate for a diesel engine - Google Patents

Catalysed monolith substrate for a diesel engine Download PDF

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GB2558186A
GB2558186A GB1614541.9A GB201614541A GB2558186A GB 2558186 A GB2558186 A GB 2558186A GB 201614541 A GB201614541 A GB 201614541A GB 2558186 A GB2558186 A GB 2558186A
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coating
longitudinal direction
face
monolith substrate
catalysed
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GB201614541D0 (en
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Frances Chiffey Andrew
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Johnson Matthey PLC
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Johnson Matthey PLC
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    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/464—Rhodium
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9022—Two layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/905—Catalysts having a gradually changing coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/915—Catalyst supported on particulate filters
    • B01D2255/9155—Wall flow filters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines
    • 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
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/42—Platinum
    • 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
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Environmental & Geological Engineering (AREA)
  • Biomedical Technology (AREA)
  • Combustion & Propulsion (AREA)
  • Catalysts (AREA)

Abstract

A catalysed monolith substrate 30 comprises: a coating 10 comprising catalytic material, wherein the catalytic material comprises a platinum group metal selected from the group consisting of platinum, palladium, rhodium and a combination of two or more thereof; and a through-flow monolith substrate having a first face and a second face defining a longitudinal direction therebetween, and a plurality of channels extending in the longitudinal direction, wherein said plurality is of channels provides a plurality of inner surfaces; wherein the amount by weight of the platinum group metal varies in the longitudinal direction of the coating. The thickness of the coating may vary along the longitudinal direction such that the amount by weight of the platinum group metal varies along the longitudinal direction of the coating. The thickness of the coating in a longitudinal direction may increase along the longitudinal direction from the first face to the second face, decrease along the longitudinal direction from the first face to the second face or decrease along the longitudinal direction from the first face to a point in the longitudinal direction between the first and second faces and increase along the longitudinal direction from or after the point to the second face.

Description

(71) Applicant(s):
Johnson Matthey Public Limited Company (Incorporated in the United Kingdom)
5th Floor, 25 Farringdon Street, LONDON, EC4A4AB, United Kingdom (56) Documents Cited:
WO 2012/146779 A2 US 20080010972 A1 JPS5712820
US 5543181 A US 20070264518 A1 (58) Field of Search:
INT CL B01D, B01J, F01N
Other: WPI, EPODOC & British Standards Online (72) Inventor(s):
Andrew Frances Chiffey (74) Agent and/or Address for Service:
Johnson Matthey PLC
Group Intellectual Property Department, Gate 20, Orchard Road, Royston, Hertfordshire, SG8 5HE, United Kingdom (54) Title of the Invention: Catalysed monolith substrate for a diesel engine Abstract Title: Catalysed monolith substrate for a diesel engine (57) A catalysed monolith substrate 30 comprises: a coating 10 comprising catalytic material, wherein the catalytic material comprises a platinum group metal selected from the group consisting of platinum, palladium, rhodium and a combination of two or more thereof; and a through-flow monolith substrate having a first face and a second face defining a longitudinal direction therebetween, and a plurality of channels extending in the longitudinal direction, wherein said plurality is of channels provides a plurality of inner surfaces; wherein the amount by weight of the platinum group metal varies in the longitudinal direction of the coating. The thickness of the coating may vary along the longitudinal direction such that the amount by weight of the platinum group metal varies along the longitudinal direction of the coating. The thickness of the coating in a longitudinal direction may increase along the longitudinal direction from the first face to the second face, decrease along the longitudinal direction from the first face to the second face or decrease along the longitudinal direction from the first face to a point in the longitudinal direction between the first and second faces and increase along the longitudinal direction from or after the point to the second face.
Figure 1
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Figure GB2558186A_D0001
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Figure GB2558186A_D0002
Figure 4
Figure GB2558186A_D0003
(10) (30)
CATALYSED MONOLITH SUBSTRATE FOR A DIESEL ENGINE
FIELD OF THE INVENTION
The present invention relates to a catalysed monolith substrate suitable for use in an emission treatment system, such as an automobile internal combustion engine exhaust system, particularly a diesel engine. The catalysed monolith substrate provides an effective method of remediating engine exhaust streams, particularly when used as a diesel oxidation catalyst.
BACKGROUND TO THE INVENTION
Emissions from internal combustion engines, particularly diesel engines, are limited by legislation put in place by governments worldwide. Manufacturers are seeking to meet these legislated requirements through a combination of engine design and exhaust gas after-treatment. The exhaust systems used to carry out exhaust gas after-treatment commonly comprise a series of emissions control devices that are designed to carry out certain reactions that reduce the proportion of exhaust gas species limited by such legislation.
A diesel engine exhaust stream is a heterogeneous mixture which contains gaseous emissions, such as carbon monoxide (CO), unburned hydrocarbons (HCs) and nitrogen oxides (NOX), and also condensed phase materials (liquids and solids), which constitute the so-called particulates or particulate matter. Often, catalyst compositions and substrates on which the compositions are disposed are provided in diesel engine exhaust systems to convert certain or all of these exhaust components to innocuous components.
Generally, each emissions control device has a specialised function and is responsible for treating one or more classes of pollutant in the exhaust gas. For example, an exhaust system for a diesel engine may include (i) a diesel oxidation catalyst (DOC) for oxidising CO and HCs and (ii) a selective catalytic reduction (SCR) catalyst or selective catalytic reduction filter (SCRF™) catalyst for reducing NOX to nitrogen (N2). The interaction between each emissions control device in the exhaust system is important to the overall efficiency of the system because the performance of an upstream emissions control device can affect the performance of a downstream emissions control device.
Oxidation catalysts, such as DOCs, can oxidise some of the nitric oxide (NO) in an exhaust gas to nitrogen dioxide (NO2). The generated NO2 can be used to regenerate 1 particulate matter (PM) that has been trapped, for example, by a downstream diesel particulate filter (DPF) or a downstream catalysed soot filter (CSF). The NO2 generated by the oxidation catalyst can also be beneficial to the performance of selective catalytic reduction (SCR) catalyst or selective catalytic reduction filter (SCRF™) catalysts. The ratio of NO2:NO in exhaust gases directly produced by compression ignition engines is generally too low for optimum SCR catalyst or SCRF™ catalyst performance and may be too low to assist in the passive regeneration of a DPF or CSF. In particular, when an oxidation catalyst, such as a DOC, is positioned in an exhaust system upstream of an SCR or SCRF™ catalyst, the NO2 that is generated can alter the ratio of NO2:NO in the exhaust gas in favour of optimal SCR or SCRF™ catalyst performance.
SUMMARY OF THE INVENTION
Oxidation catalysts for diesel engines, such as diesel oxidation catalysts (DOCs), generally contain platinum group metals (PGMs) for the catalytic oxidation of carbon monoxide (CO) and unburned hydrocarbons (HCs). The catalyst composition of an oxidation catalyst, particularly the PGM composition, may also be formulated to oxidise nitric oxide (NO) to nitrogen dioxide (NO2). Platinum group metals are expensive constituents of oxidation catalysts and it is desirable to maximise the activity of any PGMs that are included in the catalyst composition.
The invention provides a catalysed monolith substrate for use in an emission treatment system, particularly an emissions treatment system for treating an exhaust gas produced by a diesel engine. The catalysed monolith substrate comprises:
a coating comprising catalytic material, wherein the catalytic material comprises a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh) and a combination of two or more thereof; and a through-flow monolith substrate having a first face and a second face defining a longitudinal direction therebetween, and a plurality of channels extending in the longitudinal direction, wherein said plurality of channels provide a plurality of inner surfaces;
wherein the amount by weight of the platinum group metal (PGM) varies in the longitudinal direction of the coating.
According to a further aspect there is provided an emission treatment system for treating a flow of a combustion exhaust gas, particularly a combustion exhaust gas produced by a diesel engine. The emission treatment system comprises the catalysed monolith substrate of the invention, preferably wherein the first face is upstream of the second face.
The invention also provides a vehicle. The vehicle comprises an internal combustion engine, preferably a diesel engine, and either an emission treatment system or a catalysed monolith of the invention.
According to a further aspect there is provided a method for the manufacture of a catalysed monolith substrate. The method comprises the steps of:
(i) providing a through-flow monolith substrate having a first face and a second face defining a longitudinal direction therebetween, and a plurality of channels extending in the longitudinal direction, wherein said plurality of channels provide a plurality of inner surfaces;
(ii) forming a coating comprising a catalytic material on the plurality of inner surfaces by depositing a catalytic material comprising a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and rhodium (Rh), such that the amount by weight of the platinum group metal (PGM) varies in the longitudinal direction of the coating.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1 to 5 are schematic representations of catalysed monolith substrates of the invention. In each of the Figures, the left hand side represents an inlet end of the substrate and the right hand side represents an outlet end of the substrate.
Figure 1 shows a catalysed monolith substrate with a first coating (10) and a second coating (20). The coating (10) comprises a catalytic material where the thickness of the coating uniformly increases from the inlet end of the substrate to the outlet end of the substrate. The coating (10) shown has a “wedge” or triangular shape cross-section. The first coating (10) is disposed on a second coating (20), which has the same or constant thickness along the longitudinal length of the substrate (30).
Figure 2 shows the coating of Figure 1 in further detail. The thickness of the coating uniformly varies at the inlet end and the outlet end from the mean thickness by an amount represented by x%.
Figure 3 shows a “wedge” shaped coating that varies in thickness by an amount of x% about the mean thickness.
Figure 4 shows a catalysed monolith substrate with a first coating (10) comprising a catalytic material and a second coating (20). The thickness of the first coating (10) uniformly decreases from the inlet end of the substrate (30) to a point toward the centre of the longitudinal length of the substrate (30). The thickness of the first coating (10) then uniformly increases from this point to the outlet end of the substrate (30). There are two regions of the first coating (10), which each have a “wedge” or triangular shape cross-section. The first coating (10) is disposed on a second coating (20), which has the same or constant thickness along the longitudinal length of the substrate (30).
Figure 5 shows a catalysed monolith substrate having a first coating (10) and a second coating (20), which differ in composition. The first coating (10) comprises a catalytic material and is disposed directly onto the second coating (20). The thickness of the first coating (10) uniformly increase from the inlet end of the substrate (30) to the outlet end of the substrate (30). The first coating (10) has a “wedge” or triangular shape crosssection. The second coating (20) is disposed directly onto the substrate (30). The thickness of the second coating (20) uniformly decreases from the inlet end of the substrate to the outlet end of the substrate (30). The second coating has a “wedge” or triangular shape cross-section.
DETAILED DESCRIPTION
The present invention will now be further described. In the following passages different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
The through-flow monolith substrate has a first face and a second face defining a longitudinal direction therebetween. The through-flow monolith substrate has a plurality of channels extending between the first face and the second face. The plurality of channels extend in the longitudinal direction and provide a plurality of inner surfaces (e.g. the surfaces of the walls defining each channel). Each of the plurality of channels has an opening at the first face and an opening at the second face. For the avoidance of doubt, the through-flow monolith substrate is not a wall flow filter.
The first face is typically at an inlet end of the substrate and the second face is at an outlet end of the substrate.
The channels may be of a constant width and each plurality of channels may have a uniform channel width.
Preferably within a plane orthogonal to the longitudinal direction, the monolith substrate has from 100 to 500 channels per square inch, preferably from 200 to 400. For example, on the first face, the density of open first channels and closed second channels is from 200 to 400 channels per square inch. The channels can have cross sections that are rectangular, square, circular, oval, triangular, hexagonal, or other polygonal shapes.
The monolith substrate acts as a support for holding catalytic material. Suitable materials for forming the monolith substrate include ceramic-like materials such as cordierite, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silicamagnesia or zirconium silicate, or of porous, refractory metal. Such materials and their use in the manufacture of porous monolith substrates is well known in the art.
It should be noted that the through-flow monolith substrate described herein is a single component (i.e. a single brick). Nonetheless, when forming an emission treatment system, the monolith used may be formed by adhering together a plurality of channels or by adhering together a plurality of smaller monoliths as described herein. Such techniques are well known in the art, as well as suitable casings and configurations of the emission treatment system.
The catalysed monolith substrate is suitable for use as a diesel oxidation catalyst (DOC), a lean NOX trap (LNT) [also referred to as a NOX storage catalyst (NSC) or a NOX absorber catalyst (NAC)], a cold start concept catalyst (CSC catalyst) or a passive NOX absorber catalyst (PNA). When the catalysed monolith substrate is suitable for one of these uses, then the catalyst material may contain suitable catalysts for this function and/or the catalysed monolith substrate may further comprise one or more additional coatings that contain suitable catalysts for this function.
The amount by weight of the platinum group metal (PGM) (e.g. per unit volume in a longitudinal direction) varies along the longitudinal direction of the coating. Thus, in each of the plurality of channels the amount by weight of the platinum group metal (PGM) varies along the longitudinal direction. As described below, the absolute weight of the platinum group metal (PGM) may vary in a longitudinal direction of the coating by virtue of a variation in the thickness of the coating in a longitudinal direction. Alternatively, the concentration or loading of the platinum group metal (PGM) may vary in a longitudinal direction of the coating.
In general, the amount by weight of the platinum group metal (PGM) (e.g. per unit volume) may vary continuously along the longitudinal direction (e.g. the total length) of the coating. The amount by weight of the PGM (e.g. per unit volume) may vary continuously and uniformly (e.g. linearly) along the longitudinal direction of the coating. For the avoidance of doubt, the amount by weight of the PGM (per unit volume) does not vary continuously when there is a stepwise variation in the thickness of the coating.
The coating or the catalytic material thereof has a mean weight of the platinum group metal (PGM). Typically, the maximal (i.e. the maximum) and minimal (i.e. the minimum) variation of the weight of the PGM along the longitudinal direction of the coating is at least ± 5 % of the mean weight of the PGM, preferably at least ± 10 % of the mean weight of the PGM, more preferably at least ± 25 % of the mean weight of the PGM, and even more preferably at least ± 40 % of the mean weight of the PGM.
The amount by weight of the platinum group metal (PGM) (i.e. per unit volume) in a longitudinal direction of the coating may increase, preferably only increase, along the longitudinal direction from the first face to the second face. See, for example, Figures 1 to 3.
The amount by weight of the platinum group metal (PGM) (e.g. per unit volume) in a longitudinal direction of the coating may decrease, preferably only decrease, along the longitudinal direction of the coating from the first face to the second face.
The amount by weight of the platinum group metal (PGM) (e.g. per unit volume in a longitudinal direction of the coating) may (i) decrease along the longitudinal direction from the first face to a point in the longitudinal direction between the first face and the second face, and (ii) increase along the longitudinal direction from the point (e.g. between the first face and the second face) to the second face.
The variation in the amount by weight of the platinum group metal (PGM) (e.g. per unit volume) in the longitudinal direction of the coating can be achieved by varying the density of the coating or by varying the thickness of the coating. Methods for varying the density of the coating or the thickness of the coating are known in the art. See, for example, WO 2014/132034 and US 5,543,181. A variation in the thickness of the coating can be obtained using the device in US 5,543,181 by varying the amount of time that the injector needles spend over the inner surface of the channels or the amount of material that is deposit onto each part of the channels. Suitable coating methods are also described in WO2011/080525, WO1999/047260 and WO2014/195685. All of these documents are incorporated herein by reference.
When the amount by weight of the platinum group metal (PGM) (e.g. per unit volume) in the longitudinal direction of the coating is achieved by varying the density of the coating, then typically the coating has a uniform thickness in the longitudinal direction.
When the amount by weight of the platinum group metal (PGM) (e.g. per unit volume) in the longitudinal direction of the coating is achieved by varying the thickness of the coating, then preferably the coating has a uniform density in the longitudinal direction.
It is preferred that the amount by weight of the platinum group metal (PGM) (e.g. per unit volume) varies along the longitudinal direction of the coating is provided by a variation in the thickness along the longitudinal direction of the coating.
In general, the coating is a layer.
In general, the thickness of the coating may vary continuously along the longitudinal direction. The thickness of the coating may vary continuously and uniformly (e.g. linearly) along the longitudinal direction. For the avoidance of doubt, the thickness of the coating does not vary continuously when there is a stepwise variation in the thickness of the coating.
The thickness of the coating in a longitudinal direction may increase, preferably only increase, along the longitudinal direction from the first face to the second face. See, for example, Figures 1 to 3.
The thickness of the coating in a longitudinal direction may decrease, preferably only decrease, along the longitudinal direction from the first face to the second face.
The thickness of the coating may (i) decrease along the longitudinal direction from the first face to a point in the longitudinal direction between the first face and the second face, and (ii) increase along the longitudinal direction from or after the point (e.g. between the first face and the second face) to the second face.
Preferably the coating has a mean thickness of from 10 to 150 microns, more preferably from 50 to 100 microns.
The coating has a mean thickness. Typically, the maximal (i.e. the maximum) and minimal (i.e. the minimum) variation of the thickness of the coating along the longitudinal direction is at least ± 5 % of the mean thickness, preferably at least ± 10 % of the mean thickness, more preferably at least ± 25 % of the mean thickness, and even more preferably at least ± 40 % of the mean thickness.
Typically, the coating comprises or consists essentially of a catalytic composition. The catalytic composition comprises, or consists essentially of, the catalytic material. It is preferred that the coating comprises, or consists essentially of, a single catalytic composition.
In general, the catalytic composition is homogeneous (i.e. the catalytic composition has a single fixed composition, which is homogeneous throughout the coating or layer).
The catalytic material comprises a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh) and a combination or mixture of two or more thereof. It is generally preferred that the catalytic material comprises the platinum group metal (PGM) as the only platinum group metal (i.e. there are no other PGM components present in the catalytic material, except for those specified).
In general, the catalytic material comprises a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd), and a combination or mixture of platinum (Pt) and palladium (Pd). When the catalysed monolith substrate is for use as a DOC, then it is preferred that the PGM is platinum, palladium or platinum and palladium.
It is preferred that the catalytic material comprises a platinum group metal (PGM) selected from the group consisting of platinum (Pt), and a combination or mixture of platinum (Pt) and palladium (Pd). More preferably, the platinum group metal (PGM) is platinum (Pt).
Advantageous activity can be obtained when the coating or the catalytic material thereof is formulated for NO oxidation (i.e. to generate NO2). Such activity can be obtained when the coating or the catalytic material contains platinum as the only PGM or is platinum rich (e.g. when it additionally contains palladium).
Preferably, the coating or the catalytic material thereof comprises platinum (Pt) and optionally palladium (Pd) in a ratio by weight of 4:1 to 1:0 (e.g. Pt only). When the platinum group metal is a combination or mixture of platinum and palladium, then the coating or the catalytic material thereof comprises platinum (Pt) and palladium (Pd) in a ratio by weight of > 4:1 (e.g. 4:1 to 25:1), preferably > 5:1, more preferably > 10:1 (e.g. 10:1 to 20:1).
When the platinum group metal (PGM) is selected from the group consisting of platinum (Pt), and a combination or mixture of platinum (Pt) and palladium (Pd), it is preferred that the thickness of the coating in a longitudinal direction increases, preferably only increases, along the longitudinal direction from the first face to the second face. This arrangement maximises the NO2 generating capacity of the coating because the coating is able to oxidise NO to NO2 as the exhaust emission flows toward the outlet of the catalysed monolith substrate.
The catalytic material may further comprise a support material. The platinum group metal (PGM) is generally disposed or supported on the support material.
Typically, the support material is a refractory oxide. The refractory oxide may be selected from the group consisting of alumina, silica, ceria, silica-alumina, ceria-alumina, ceria-zirconia and alumina-magnesium oxide. It is preferred that the refractory oxide is selected from the group consisting of alumina, ceria, silica-alumina and ceria-zirconia. More preferably, the refractory oxide is alumina or silica-alumina, particularly silicaalumina.
The catalysed monolith substrate may further comprise a second coating (the coating described hereinabove is referred to herein below as the “first coating”). For the avoidance of doubt, the second coating has a different composition to the first coating.
Typically, the second coating comprises a platinum group metal (PGM) (referred to below as the “second platinum group metal”). It is generally preferred that the second coating comprises the second platinum group metal (PGM) as the only platinum group metal (i.e. there are no other PGM components present in the catalytic material, except for those specified).
The second PGM may be selected from the group consisting of platinum, palladium, and a combination or mixture of platinum (Pt) and palladium (Pd). Preferably, the platinum group metal is selected from the group consisting of palladium (Pd) and a combination or a mixture of platinum (Pt) and palladium (Pd). More preferably, the platinum group metal is selected from the group consisting of a combination or a mixture of platinum (Pt) and palladium (Pd).
It is generally preferred that the second coating is (i.e. is formulated) for the oxidation of carbon monoxide (CO) and/or hydrocarbons (HCs).
The ratio by weight of platinum (Pt) to palladium (Pd) in the second coating is typically lower than the ratio by weight of platinum (Pt) to palladium (Pd) in the first coating.
Preferably, the second coating comprises palladium (Pd) and optionally platinum (Pt) in a ratio by weight of 1:0 (e.g. Pd only) to 1:4 (this is equivalent to a ratio by weight of Pt:Pd of 4:1 to 0:1). More preferably, the second coating comprises platinum (Pt) and palladium (Pd) in a ratio by weight of < 4:1, such as < 3.5:1.
When the platinum group metal is a combination or mixture of platinum and palladium, then the second coating comprises platinum (Pt) and palladium (Pd) in a ratio by weight of 5:1 to 3.5:1, preferably 2.5:1 to 1:2.5, more preferably 1:1 to 2:1.
The second coating typically further comprises a support material (referred to herein below as the “second support material”). The second PGM is generally disposed or supported on the second support material.
The second support material is preferably a refractory oxide. It is preferred that the refractory oxide is selected from the group consisting of alumina, silica, ceria, silicaalumina, ceria-alumina, ceria-zirconia and alumina-magnesium oxide. More preferably, the refractory oxide is selected from the group consisting of alumina, ceria, silica-alumina and ceria-zirconia. Even more preferably, the refractory oxide is alumina or silicaalumina, particularly silica-alumina.
Typically, the second coating has an amount by weight of the second platinum group metal (PGM) in the second coating (e.g. per unit volume of the second coating) that is constant in the longitudinal direction.
It may be preferable that the thickness of the second coating (e.g. along the longitudinal direction) is the same from the first face to the second face.
The second coating is typically a layer.
The first coating may be disposed or supported on the second coating or the substrate (e.g. the plurality of inner surfaces of the through-flow monolith substrate), preferably the first coating is disposed or supported on the second coating.
The second coating may be disposed or supported on the substrate (e.g. the plurality of inner surfaces of the through-flow monolith substrate).
Alternatively, the amount by weight of the second PGM (e.g. per unit volume) varies in the longitudinal direction of the second coating. The amount by weight of the second PGM (e.g. per unit volume) may vary continuously along the longitudinal direction of the second coating. The amount by weight of the second PGM (e.g. per unit volume) may vary continuously and uniformly (e.g. linearly) along the longitudinal direction of the second coating. For the avoidance of doubt, the amount by weight of the second PGM (e.g. per unit volume) does not vary continuously when there is a stepwise variation in the thickness of the second coating.
The amount by weight of the second PGM (e.g. per unit volume) in a longitudinal direction of the second coating may increase, preferably only increase, along the longitudinal direction of the second coating from the first face to the second face.
The amount by weight of the second PGM (e.g. per unit volume) in the second coating in a longitudinal direction, may decrease, preferably only decrease, along the longitudinal direction from the first face to the second face.
The amount by weight of the second PGM (e.g. per unit volume) may (i) decrease along the longitudinal direction of the second coating from the first face to a point in the longitudinal direction of the second coating between the first face and the second face, and (ii) increase along the longitudinal direction of the second coating from the point (e.g. between the first face and the second face) to the second face.
The amount by weight of the first platinum group metal (PGM) in the first coating and the amount by weight of second platinum group metal in the second coating may vary independently along the longitudinal direction. That is, the amount of the first PGM can increase or decrease, or remain the same, and the amount of the second PGM can increase or decrease, or remain the same, provided that both do not simply remain the same along the longitudinal length.
It is preferred that when the amount by weight of the second PGM (i.e. per unit volume) varies along the longitudinal direction of the second coating, then there is (e.g. this feature is provided by) a variation in the thickness along the longitudinal direction of the second coating.
In general, it is preferred that the thickness of the first coating increases from the first face to the second face and the thickness of the second coating decreases from the first face to the second face.
The second coating may be disposed or supported on the first coating. The first coating may be disposed or supported on the substrate (e.g. the inner surfaces of the plurality of channels of the substrate).
Alternatively, the first coating may be disposed or supported on the second coating. The second coating may be disposed or supported on the substrate (e.g. the inner surfaces of the plurality of channels of the substrate).
When the catalysed monolith substrate is used as a diesel oxidation catalyst (DOC), a high palladium to platinum ratio favours hydrocarbon (HC) and carbon monoxide (CO) oxidation, while a lower palladium to platinum ratio is able to increase the NO2/NOX ratio of the exhaust emission. By using a high palladium to platinum ratio coating that tapers from the inlet face, and a low palladium to platinum ratio coating that tapers inwardly from the outlet face, it is possible to achieve a substantial amount of carbon monoxide and hydrocarbon oxidation in the first inlet portion of the monolith, while achieving the attainment of a suitable NO2/NOX ratio in the outlet portion of the monolith. It is advantageous to have the low ratio palladium to platinum coating at the outlet end of the monolith, since if the nitric oxide is transformed to NO2 in earlier portion of the monolith, there is a risk that it will reconvert back to the nitric oxide in the later portion of the monolith.
The invention also provides an emission treatment system for treating a flow of a combustion exhaust gas, particularly a combustion exhaust gas produced by a diesel engine. The emission treatment system comprises the catalysed monolith substrate of the invention, preferably wherein the first face is upstream of the second face.
The emission treatment system typically further comprises an emissions control device. The emissions control devices is preferably downstream of the catalysed monolith substrate.
Examples of an emissions control device include a diesel particulate filter (DPF), a lean NOxtrap (LNT), a lean NOxcatalyst (LNC), a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), a catalysed soot filter (CSF), a selective catalytic reduction filter (SCRF™) catalyst, an ammonia slip catalyst (ASC) and combinations of two or more thereof. Such emissions control devices are all well known in the art.
Some of the aforementioned emissions control devices have filtering substrates. An emissions control device having a filtering substrate may be selected from the group consisting of a diesel particulate filter (DPF), a catalysed soot filter (CSF), and a selective catalytic reduction filter (SCRF™) catalyst.
It is preferred that the emission treatment system comprises an emissions control device selected from the group consisting of a lean NOxtrap (LNT), an ammonia slip catalyst (ASC), diesel particulate filter (DPF), a selective catalytic reduction (SCR) catalyst, a catalysed soot filter (CSF), a selective catalytic reduction filter (SCRF™) catalyst, and combinations of two or more thereof. More preferably, the emissions control device is selected from the group consisting of a diesel particulate filter (DPF), a selective catalytic reduction (SCR) catalyst, a catalysed soot filter (CSF), a selective catalytic reduction filter (SCRF™) catalyst, and combinations of two or more thereof. Even more preferably, the emissions control device is a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction filter (SCRF™) catalyst.
When the emission treatment system of the invention comprises an SCR catalyst or an SCRF™ catalyst, then the emission treatment system may further comprise an injector for injecting a nitrogenous reductant, such as ammonia, or an ammonia precursor, such as urea or ammonium formate, preferably urea, into exhaust gas downstream of the catalysed monolith substrate and upstream of the SCR catalyst or the SCRF™ catalyst. Such an injector may be fluidly linked to a source (e.g. a tank) of a nitrogenous reductant precursor. Valve-controlled dosing of the precursor into the exhaust gas may be regulated by suitably programmed engine management means and closed loop or open loop feedback provided by sensors monitoring the composition of the exhaust gas. Ammonia can also be generated by heating ammonium carbamate (a solid) and the ammonia generated can be injected into the exhaust gas.
Alternatively or in addition to the injector, ammonia can be generated in situ (e.g. during rich regeneration of a LNT disposed upstream of the SCR catalyst or the SCRF™ catalyst). Thus, the emission treatment system may further comprise an engine management means for enriching the exhaust gas with hydrocarbons.
The SCR catalyst or the SCRF™ catalyst may comprise a metal selected from the group consisting of at least one of Cu, Hf, La, Au, In, V, lanthanides and Group VIII transition metals (e.g. Fe), wherein the metal is supported on a refractory oxide or molecular sieve. The metal is preferably selected from Ce, Fe, Cu and combinations of any two or more thereof, more preferably the metal is Fe or Cu.
The refractory oxide for the SCR catalyst or the SCRF™ catalyst may be selected from the group consisting of AI2O3, TiO2, CeO2, SiO2, ZrO2 and mixed oxides containing two or more thereof. The non-zeolite catalyst can also include tungsten oxide (e.g. V2O5/WO3/TiO2, WOx/CeZrO2, WO></ZrO2 or Fe/WO></ZrO2).
It is particularly preferred when an SCR catalyst, an SCRF™ catalyst or a washcoat thereof comprises at least one molecular sieve, such as an aluminosilicate zeolite or a SAPO. The at least one molecular sieve can be a small, a medium or a large pore molecular sieve. By “small pore molecular sieve” herein we mean molecular sieves containing a maximum ring size of 8, such as CHA; by “medium pore molecular sieve” herein we mean a molecular sieve containing a maximum ring size of 10, such as ZSM5; and by “large pore molecular sieve” herein we mean a molecular sieve having a maximum ring size of 12, such as beta. Small pore molecular sieves are potentially advantageous for use in SCR catalysts.
In the emission treatment system of the invention, preferred molecular sieves for an SCR catalyst or an SCRF™ catalyst are synthetic aluminosilicate zeolite molecular sieves selected from the group consisting of AEI, ZSM-5, ZSM-20, ERI including ZSM-34, mordenite, ferrierite, BEA including Beta, Y, CHA, LEV including Nu-3, MCM-22 and EU1, preferably AEI or CHA, and having a silica-to-alumina ratio of about 10 to about 50, such as about 15 to about 40.
In a first emission treatment system embodiment, the emission treatment system comprises the catalysed monolith substrate of the invention and a catalysed soot filter (CSF). The catalysed monolith substrate is typically followed by (e.g. is upstream of) the catalysed soot filter (CSF). Thus, for example, an outlet of the catalysed monolith substrate is connected to an inlet of the catalysed soot filter.
A second emission treatment system embodiment relates to an emission treatment system comprising the catalysed monolith substrate of the invention, a catalysed soot filter (CSF) and a selective catalytic reduction (SCR) catalyst.
The catalysed monolith substrate is typically followed by (e.g. is upstream of) the catalysed soot filter (CSF). The catalysed soot filter is typically followed by (e.g. is upstream of) the selective catalytic reduction (SCR) catalyst. A nitrogenous reductant injector may be arranged between the catalysed soot filter (CSF) and the selective catalytic reduction (SCR) catalyst. Thus, the catalysed soot filter (CSF) may be followed by (e.g. is upstream of) a nitrogenous reductant injector, and the nitrogenous reductant injector may be followed by (e.g. is upstream of) the selective catalytic reduction (SCR) catalyst.
In a third emission treatment system embodiment, the emission treatment system comprises the catalysed monolith substrate of the invention, a selective catalytic reduction (SCR) catalyst and either a catalysed soot filter (CSF) or a diesel particulate filter (DPF).
In the third emission treatment system embodiment, the catalysed monolith substrate of the invention is typically followed by (e.g. is upstream of) the selective catalytic reduction (SCR) catalyst. A nitrogenous reductant injector may be arranged between the oxidation catalyst and the selective catalytic reduction (SCR) catalyst. Thus, the catalysed monolith substrate may be followed by (e.g. is upstream of) a nitrogenous reductant injector, and the nitrogenous reductant injector may be followed by (e.g. is upstream of) the selective catalytic reduction (SCR) catalyst. The selective catalytic reduction (SCR) catalyst are followed by (e.g. are upstream of) the catalysed soot filter (CSF) or the diesel particulate filter (DPF).
A fourth emission treatment system embodiment comprises the catalysed monolith substrate of the invention and a selective catalytic reduction filter (SCRF™) catalyst. The catalysed monolith substrate of the invention is typically followed by (e.g. is upstream of) the selective catalytic reduction filter (SCRF™) catalyst.
A nitrogenous reductant injector may be arranged between the catalysed monolith substrate and the selective catalytic reduction filter (SCRF™) catalyst. Thus, the catalysed monolith substrate may be followed by (e.g. is upstream of) a nitrogenous reductant injector, and the nitrogenous reductant injector may be followed by (e.g. is upstream of) the selective catalytic reduction filter (SCRF™) catalyst.
When the emission treatment system comprises a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction filter (SCRF™) catalyst, such as in the second to fourth exhaust system embodiments described hereinabove, an ASC can be disposed downstream from the SCR catalyst or the SCRF™ catalyst (i.e. as a separate monolith substrate), or more preferably a zone on a downstream or trailing end of the monolith substrate comprising the SCR catalyst can be used as a support for the ASC.
Another aspect of the invention relates to a vehicle. The vehicle comprises an internal combustion engine, preferably a diesel engine. The internal combustion engine, preferably the diesel engine, is coupled to an emission treatment system of the invention.
It is preferred that the diesel engine is configured or adapted to run on fuel, preferably diesel fuel, comprises < 50 ppm of sulfur, more preferably <15 ppm of sulfur, such as <10 ppm of sulfur, and even more preferably < 5 ppm of sulfur.
The vehicle may be a light-duty diesel vehicle (LDV), such as defined in US or European legislation. A light-duty diesel vehicle typically has a weight of < 2840 kg, more preferably a weight of < 2610 kg. In the US, a light-duty diesel vehicle (LDV) refers to a diesel vehicle having a gross weight of < 8,500 pounds (US lbs). In Europe, the term light-duty diesel vehicle (LDV) refers to (i) passenger vehicles comprising no more than eight seats in addition to the driver’s seat and having a maximum mass not exceeding 5 tonnes, and (ii) vehicles for the carriage of goods having a maximum mass not exceeding 12 tonnes.
Alternatively, the vehicle may be a heavy-duty diesel vehicle (HDV), such as a diesel vehicle having a gross weight of > 8,500 pounds (US lbs), as defined in US legislation.
The invention also relates to a method for the manufacture of a catalysed monolith substrate.
It is preferred step (ii) comprises (ii) forming a coating comprising a catalytic material on the plurality of inner surfaces by depositing the catalytic material in a thickness that varies in the longitudinal direction such that the amount by weight of the platinum group metal (PGM) in the coating varies in the longitudinal direction.
As mentioned above, various methods are known for applying coatings onto a monolith substrate. A variation in the thickness of the coating can be obtained using the device in US 5,543,181 by varying the amount of time that the injector needles spend over the inner surface of the channels or the amount of material that is deposit onto each part of the channels. Alternatively, when a vacuum is applied to one end of the substrate to draw a washcoat into the monolith substrate (see, for example, WO 2011/080525,
WO 1999/047260 and WO 2014/195685), then strength of the vacuum can be varied during this step to vary the amount of washcoat that is deposited along the longitudinal length of the substrate.
EXAMPLE
The invention will now be illustrated by the following non-limiting example.
A through-flow monolith substrate having dimensions of 4.66 (diameter) x 4.5 (length), a cell density/wall thickness 300/8, a washcoat loading of 2.4 g/in3. The loading was applied in a wedge form using a method as described above. Measurements were taken at regular intervals along the length of the substrate (in a longitudinal direction) and the measurements are denoted below as A-E. The catalysed monolith substrate obtained had a coating arrangement as shown in Figure 4.
Section Wall washcoat thickness (pm)
A 82.3
B 49
C 9
D 22.5
E 63.3
The amount of Pt can be increased towards the back of the substrate to encourage NO2 formation.
For the avoidance of any doubt, the entire content of any and all documents cited herein is incorporated by reference into the present application.

Claims (25)

1. A catalysed monolith substrate for use in an emission treatment system comprising:
a coating comprising catalytic material, wherein the catalytic material comprises a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh) and a combination of two or more thereof; and a through-flow monolith substrate having a first face and a second face defining a longitudinal direction therebetween, and a plurality of channels extending in the longitudinal direction, wherein said plurality of channels provide a plurality of inner surfaces;
wherein the amount by weight of the platinum group metal (PGM) varies in the longitudinal direction of the coating.
2. A catalysed monolith substrate according to claim 1, wherein the amount by weight of the platinum group metal (PGM) varies continuously along the longitudinal direction of the coating.
3. A catalysed monolith substrate according to claim 1 or claim 2, wherein the coating has a thickness, and the thickness of the coating varies along the longitudinal direction such that the amount by weight of the platinum group metal (PGM) varies along the longitudinal direction of the coating.
4. A catalysed monolith substrate according to claim 3, wherein the thickness of the coating in a longitudinal direction increases along the longitudinal direction from the first face to the second face.
5. A catalysed monolith substrate according to claim 3, wherein the thickness of the coating in a longitudinal direction decreases along the longitudinal direction from the first face to the second face.
6. A catalysed monolith substrate according to claim 3, wherein the thickness of the coating (i) decreases along the longitudinal direction from the first face to a point in the longitudinal direction between the first face and the second face, and (ii) increases along the longitudinal direction from or after the point to the second face.
7. A catalysed monolith substrate according to any one of the preceding claims, wherein the platinum group metal (PGM) is selected from the group consisting of 18 platinum (Pt), palladium (Pd), and a combination or mixture of platinum (Pt) and palladium (Pd).
8. A catalysed monolith substrate according to claim 7, wherein the platinum group metal (PGM) is selected from the group consisting of platinum (Pt), and a combination or mixture of platinum (Pt) and palladium (Pd).
9. A catalysed monolith substrate according to claim 7 or claim 8, wherein the coating comprises platinum (Pt) and optionally palladium (Pd) in a ratio by weight of 4:1 to 1:0.
10. A catalysed monolith substrate according to any one of the preceding claims, wherein the catalytic material further comprises a support material, and the platinum group metal (PGM) is supported on the support material.
11. A catalysed monolith substrate according to claim 10, wherein the support material is a refractory oxide selected from the group consisting of alumina, silica, ceria, silica-alumina, ceria-alumina, ceria-zirconia and alumina-magnesium oxide.
12. A catalysed monolith substrate according to any one of the preceding claims, wherein the coating is a first coating and the catalysed monolith substrate further comprises a second coating, wherein the second coating comprises a platinum group metal (PGM).
13. A catalysed monolith substrate according to claim 12, wherein the platinum group metal is selected from the group consisting of palladium (Pd) and a combination or a mixture of platinum (Pt) and palladium (Pd).
14. A catalysed monolith substrate according to claim 13, wherein the second coating comprises palladium (Pd) and optionally platinum (Pt) in a ratio by weight of 1:0 to 1:4.
15. A catalysed monolith substrate according to any one of claims 12 to 14, wherein the second coating further comprises a support material, and wherein the platinum group metal (PGM) is supported on the support material.
16. A catalysed monolith substrate according to any one of claims 12 to 15, wherein the first coating is disposed on the second coating.
17. A catalysed monolith substrate according to any one of claims 12 to 16, wherein the second coating is disposed on the plurality of inner surfaces of the through-flow monolith substrate.
18. A catalysed monolith substrate according to any one of claims 12 to 17, wherein the second coating has a thickness, and wherein the thickness of the second coating along the longitudinal direction is the same from the first face to the second face.
19. A catalysed monolith substrate according to any one of claims 12 to 17, wherein the second coating has a thickness, and the thickness varies along the longitudinal direction of the second coating such that the amount by weight of the platinum group metal (PGM) varies along the longitudinal direction of the second coating.
20. A catalysed monolith substrate according to claim 19, wherein the thickness of the second coating in a longitudinal direction of the second coating increases along the longitudinal direction from the first face to the second face.
21. A catalysed monolith substrate according to claim 19, wherein the thickness of the second coating in a longitudinal direction of the second coating decreases along the longitudinal direction from the first face to the second face.
22. A catalysed monolith substrate according to claim 19, wherein the thickness of the second coating (i) decreases along the longitudinal direction from the first face to a point in the longitudinal direction between the first face and the second face, and (ii) increases along the longitudinal direction from or after the point to the second face.
23. An emission treatment system for treating a flow of a combustion exhaust gas, wherein the system comprises the catalysed monolith substrate according to any one of claims 1 to 22 and an emissions control device.
24. An emission treatment system according to claim 23, wherein the emissions control device is a selective catalytic reduction (SCR) catalyst or a selective catalytic reduction filter catalyst.
25. A vehicle comprising an internal combustion engine, which is a diesel engine, and either a catalysed monolith according to any one of claims 1 to 22 or an emission treatment system according to claims 23 or 24.
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Application No: GB1614541.9 Examiner: Dr Matthew Hall
GB1614541.9A 2015-10-23 2016-08-26 Catalysed monolith substrate for a diesel engine Withdrawn GB2558186A (en)

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CN110732320A (en) * 2019-10-13 2020-01-31 苏州倍友环保科技有限公司 diesel engine tail gas oxidation catalyst and preparation method and application thereof
EP3689458A4 (en) * 2017-09-27 2021-06-09 Ibiden Co., Ltd. Honeycomb catalyst
US11298686B2 (en) 2017-09-27 2022-04-12 Ibiden Co., Ltd. Honeycomb catalytic converter
US11298685B2 (en) 2017-09-27 2022-04-12 Ibiden Co., Ltd. Honeycomb catalytic converter
US11618009B2 (en) 2017-09-27 2023-04-04 Ibiden Co., Ltd. Honeycomb catalytic converter

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WO2012146779A2 (en) * 2011-04-29 2012-11-01 Süd-Chemie AG Method for the production of multi-zoned catalysts

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US5543181A (en) * 1993-12-16 1996-08-06 Degussa Aktiengesellschaft Process and device for defined impregnation of honeycomb structures with parallel flow channels
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Publication number Priority date Publication date Assignee Title
EP3689458A4 (en) * 2017-09-27 2021-06-09 Ibiden Co., Ltd. Honeycomb catalyst
US11298686B2 (en) 2017-09-27 2022-04-12 Ibiden Co., Ltd. Honeycomb catalytic converter
US11298687B2 (en) 2017-09-27 2022-04-12 Ibiden Co., Ltd. Honeycomb catalytic converter
US11298685B2 (en) 2017-09-27 2022-04-12 Ibiden Co., Ltd. Honeycomb catalytic converter
US11618009B2 (en) 2017-09-27 2023-04-04 Ibiden Co., Ltd. Honeycomb catalytic converter
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CN110732320B (en) * 2019-10-13 2022-04-08 苏州倍友环保科技有限公司 Diesel engine tail gas oxidation catalyst and preparation method and application thereof

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