WO2012073975A1 - Method for manufacturing catalyst for exhaust gas cleaning and exhaust gas cleaning apparatus - Google Patents
Method for manufacturing catalyst for exhaust gas cleaning and exhaust gas cleaning apparatus Download PDFInfo
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- WO2012073975A1 WO2012073975A1 PCT/JP2011/077577 JP2011077577W WO2012073975A1 WO 2012073975 A1 WO2012073975 A1 WO 2012073975A1 JP 2011077577 W JP2011077577 W JP 2011077577W WO 2012073975 A1 WO2012073975 A1 WO 2012073975A1
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- cerium
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- exhaust gas
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- 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
- B01J23/66—Silver or gold
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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
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
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- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
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- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
- B01J37/086—Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
- C01F17/241—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion containing two or more rare earth metals, e.g. NdPrO3 or LaNdPrO3
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G5/00—Compounds of silver
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- 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
- B01D2255/104—Silver
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/20—Metals or compounds thereof
- B01D2255/206—Rare earth metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/20—Metals or compounds thereof
- B01D2255/206—Rare earth metals
- B01D2255/2065—Cerium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/40—Mixed oxides
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- 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
- F01N2510/00—Surface coverings
- F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
- F01N2510/065—Surface coverings for exhaust purification, e.g. catalytic reaction for reducing soot ignition temperature
Definitions
- the present invention relates to an exhaust gas purification catalyst manufacturing method and an exhaust gas purification device for purifying suspended particulate matter contained in exhaust gas discharged from a diesel engine or the like.
- a collection device such as a ceramic filter generally called DPF (Diesel Particulate Filter) is used.
- DPF Diesel Particulate Filter
- the suspended particulate matter collected by the collection device is converted into a harmless gas and purified by being burned in the collection device.
- the DPF is formed by supporting an oxidation catalyst layer containing, for example, platinum or other noble metal inside the filter, and has a structure capable of burning suspended particulate matter at a relatively low temperature.
- an oxidation catalyst for example, it has been proposed to use a catalyst composed of ceria and silver. (See Patent Document 1 and Patent Document 2)
- An exhaust gas purifying catalyst comprising silver and ceria which is a composite oxide doped with samarium is obtained by substituting a part of cerium ions Ce 4+ in ceria with samarium ions Sm 3+ having a lower valence than cerium ions. It is. This substitution causes deficiency at the oxygen site, and therefore has higher oxygen ion conductivity than ceria. Due to this high oxygen ion conductivity, the carbon combustion start temperature of the exhaust gas purifying catalyst composed of ceria doped with samarium and silver is expected to be lowered.
- Patent Document 3 in a catalyst for purifying exhaust gas containing a composite oxide containing at least cerium and a metal or silver compound containing silver, the composite oxide contains cerium and Ln (Ln is lanthanum, praseodymium, neodymium). And at least one element selected from the group consisting of promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium.
- An exhaust gas purification catalyst characterized by being a complex oxide is described.
- the present invention has been made in view of the above circumstances, and its object is to provide a composite oxide containing cerium and a rare earth element excluding cerium having a low carbon combustion start temperature, and silver and / or silver.
- An object of the present invention is to provide a method for producing an exhaust gas purification catalyst comprising an oxide.
- the inventors of the present invention have made extensive studies in order to achieve the above-mentioned problems. As a result, a composite oxide containing cerium and a rare earth element excluding cerium, produced by a production method using lactic acid, silver and / or Alternatively, the present inventors have found that an exhaust gas purifying catalyst composed of a silver oxide exhibits a low carbon combustion start temperature and completed the present invention.
- the present invention has the following gist. 1.
- B) a silver-containing compound and a rare-earth element-containing compound excluding cerium and cerium are dissolved in an aqueous solution of lactic acid.
- the manufacturing method of the exhaust gas purification catalyst containing these. 2.
- the composite oxide is Ln x Ce 1-x O 2- ⁇ (where Ln represents at least one element selected from rare earth elements excluding cerium, and x is 0 ⁇ x ⁇ 0.5) , ⁇ represents the amount of oxygen deficiency, and 0 ⁇ ⁇ 0.25.)
- 3. The method for producing an exhaust gas purifying catalyst as described in 1 or 2 above, wherein the silver-containing compound, the cerium-containing compound, and the rare-earth element-containing compound excluding cerium are all acetates. 4).
- the production method according to the present invention can provide an exhaust gas purification catalyst having a low carbon combustion start temperature.
- this exhaust gas purification catalyst in the DPF, the suspended particulate matter can be combusted at a lower temperature.
- the present invention relates to an exhaust gas purifying catalyst manufacturing method and an exhaust gas purifying apparatus containing a composite oxide containing cerium and a rare earth element excluding cerium, and silver and / or silver oxide. Below, the manufacturing method is demonstrated.
- the powder used as the raw material of the production method according to the present invention is a silver-containing compound, a cerium-containing compound, a rare-earth element-containing compound other than cerium, or a rare-earth element-containing compound other than cerium and cerium.
- the silver-containing compound is a silver-containing oxide, nitrate, carbonate or acetate.
- the cerium-containing compound include cerium-containing oxides, hydroxides, nitrates, carbonates, acetates, and alkoxides.
- the rare earth element-containing compound excluding cerium is an oxide, hydroxide, nitrate, carbonate, acetate or alkoxide containing a rare earth element excluding cerium.
- the rare earth element-containing compound other than cerium and cerium is a compound such as oxide, nitrate, carbonate or acetate containing cerium and a rare earth element other than cerium.
- the rare earth elements excluding cerium are lanthanum (La), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb).
- the rare earth element excluding cerium samarium or gadolinium is preferable, and samarium is particularly preferable.
- the raw material of the production method according to the present invention may be a compound containing three elements of silver, cerium, and a rare earth element other than cerium separately, and further, a rare earth element excluding silver, cerium, and cerium. Of these, a compound containing two or more arbitrary elements at the same time may be used.
- any one or more compounds selected from oxides, hydroxides, nitrates, carbonates, acetates, alkoxides and the like can be selected as an element source for each element.
- Acetate is particularly preferable as a raw material because of its high solubility in water and easy removal of organic components by firing.
- the raw material powder is weighed so that silver, cerium, and rare earth elements excluding cerium have the desired composition.
- lactic acid is weighed and dissolved in water.
- the amount of lactic acid depends on the composition ratio of the rare earth elements excluding silver, cerium, and cerium, but may be an amount sufficient to completely dissolve these compounds.
- lactic acid usually has a total amount of moles of metal elements in the raw material powder, that is, a total amount of moles of silver, moles of cerium, and moles of rare earth elements excluding cerium. It is preferable to use a molar amount of 0.1 to 10 times.
- La m / ( Ag m + Ce m + Ln m ) is 10 / 1-1 is preferably from 0.1 / 1, it is preferably Among them 10/1 ⁇ 0.5 / 1, in particular 5 / 1-2 / 1 is preferred.
- the raw material powder can be completely dissolved in an aqueous solution containing lactic acid in a relatively short time.
- organic or inorganic compounds that do not adversely affect the solubility of the raw material powder and disappear upon firing such as other acids and alkalis, solubility improvers, viscosity modifiers.
- Etc. may be added to the aqueous lactic acid solution.
- the water used for the lactic acid aqueous solution may be pure water or ion-exchanged water, but ion-exchanged water is particularly preferred in order to reduce the amount of impurities in the product.
- the weighed raw material powder is added to the reaction vessel containing the lactic acid aqueous solution, and the raw material powder is stirred until the raw material powder is completely dissolved.
- a stirring device a magnetic stirrer, a stirrer using a stirring blade, or the like can be used.
- a silver-containing compound, a cerium-containing compound, and a rare earth element-containing compound other than cerium may be mixed and then added to the lactic acid aqueous solution.
- the silver-containing compound, the cerium-containing compound, and the rare-earth element-containing compound excluding cerium are separately dissolved in the lactic acid aqueous solution, and then the solutions are mixed to form a lactic acid aqueous solution in which the three components are dissolved. May be.
- the heating temperature is not particularly limited as long as the raw material is dissolved, but is preferably 100 ° C. or lower, and particularly preferably in the range of 50 ° C. to 80 ° C., because water as a solvent evaporates. It is considered that the raw material powder is completely dissolved in the lactic acid aqueous solution because the metal element in the raw material powder forms a complex with a carboxyl group or a hydroxyl group in lactic acid.
- a complex formation reaction between a metal element in the raw material powder and a carboxyl group or a hydroxyl group in lactic acid is sufficiently advanced to completely dissolve the raw material powder in the lactic acid aqueous solution and cause the reaction.
- a raw material containing silver, a raw material containing cerium, and a raw material containing a rare earth element excluding cerium can be uniformly mixed at the molecular level. Presumed.
- the drying and firing step may be a two-step process in which a separate firing step is performed after the drying step, and the drying step and the subsequent firing step are performed in a continuous manner.
- One process may be used.
- the solution in which the raw material powder is dissolved is dried.
- the drying temperature is preferably 50 ° C. to 200 ° C.
- the drying temperature is preferably 50 ° C. to 110 ° C., more preferably 80 ° C. to 100 ° C. when a re-dissolution step described later is involved. This is because the raw material powder can be dried in a shorter time than when no heating is performed, and the temperature range is such that lactic acid does not evaporate.
- the dried product obtained here is a lump of raw material powder and lactic acid in which the water in the lactic acid aqueous solution of the raw material powder has evaporated, and may contain water to the extent that it does not interfere with the subsequent re-dissolution process. .
- 80% or more of the water in the solution in which the raw material powder is dissolved may be evaporated.
- the dried product is redissolved in water as necessary.
- a raw material containing silver, a raw material containing cerium, and a raw material containing a rare earth element excluding cerium become more uniform, which is preferable.
- the solution obtained by re-dissolving the dried product is preferably dried at 120 ° C. to 200 ° C., more preferably 15 ° C. to 200 ° C. This is because the dried product can be completely re-dried, so that the re-dried powder can be easily recovered and the temperature is not so high that the oxidation reaction of the re-dried product starts.
- the drying temperature is more preferably 120 ° C.
- the dried product obtained is a lump of raw material powder and lactic acid by evaporating the water in the lactic acid aqueous solution of the raw material powder, and may contain water to the extent that it does not interfere with the subsequent firing step.
- the dried mixed raw material powder is transferred to a firing container and fired in a firing furnace.
- the material of the firing container is not particularly limited, and examples thereof include alumina, mullite, cordierite and the like.
- the firing furnace may be an electric or gas shuttle kiln, or may be a roller hearth kiln or a rotary kiln, and is not particularly limited.
- the firing temperature is preferably 335 ° C to 800 ° C, more preferably 350 ° C to 600 ° C. This is because when the temperature is 335 ° C. to 800 ° C., unreacted substances hardly remain in the reaction product, and sintering of the fired product hardly proceeds.
- the firing time is not particularly limited as long as the target catalyst compound is produced. Usually, after reaching the firing temperature range, it is preferably held for 0.5 to 72 hours, more preferably 1 to 24 hours. This is because there remains no unreacted product in the reaction product, and productivity does not decrease.
- the firing furnace atmosphere when firing is preferably an oxygen-containing atmosphere, particularly in the air (in the air).
- the temperature is lowered to room temperature.
- the temperature lowering rate is preferably 100 ° C./hour to 800 ° C./hour, more preferably 100 ° C./hour to 500 ° C./hour. This is because productivity does not decrease and the baking container is not easily broken by thermal shock.
- the oxide obtained in the firing step is crushed and pulverized (pulverized and pulverized step).
- a crushing / pulverizing machine such as a cutter mill, a jet mill, an atomizer, or a mortar is generally used.
- the pulverized powder is pulverized to a desired particle size by dry or wet as necessary.
- D 50 Disintegrated or volume average particle size after pulverization
- Is preferably 1.0 .mu.m ⁇ 50.0 micrometers, more preferably from 5.0 .mu.m ⁇ 15.0 .mu.m.
- the specific surface area is preferably 5 m 2 / g to 120 m 2 / g, more preferably 15 m 2 / g to 120 m 2 / g. It is preferable that D 50 is 1.0 ⁇ m to 50.0 ⁇ m or the specific surface area is 5 m 2 / g to 120 m 2 / g because the catalytic ability as an exhaust gas purification catalyst is high.
- the volume average particle diameter is measured by a wet particle size distribution meter, and the specific surface area is measured by a BET method using a nitrogen adsorption method.
- the drying process and the subsequent baking process which are two separate processes, can be a single continuous process. In this case, a spray pyrolysis apparatus or the like can be used.
- the exhaust gas purifying catalyst obtained by the production method according to the present invention is a compound comprising cerium and a complex oxide containing rare earth elements excluding cerium, and silver and / or an oxide of silver.
- the composite oxide containing cerium and a rare earth element excluding cerium is Ln x Ce 1-x O 2- ⁇ (where Ln represents at least one element selected from rare earth elements excluding cerium, and x is 0 ⁇ x ⁇ 0.5, and ⁇ represents the amount of oxygen deficiency, and 0 ⁇ ⁇ 0.25. This is because this composite oxide has a fluorite structure and has high oxygen ion conductivity.
- Sm x Ce 1-x O 2- ⁇ in which Ln is samarium is preferable because of high oxygen ion conductivity.
- the ratio of (Ag), which is the number of moles of silver contained in silver and / or silver oxide, to (Ce + Ln) is expressed as (Ag) / (Ce + Ln)
- (Ag) / ( Ce + Ln) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and particularly preferably 4/6 to 6/4. If it is 1/9 or more, the catalyst activity is higher, and if it is 9/1 or less, the catalyst cost can be further reduced.
- the content ratio of silver and / or silver oxide contained in the exhaust gas purification catalyst obtained by the production method according to the present invention can be used as an exhaust gas purification catalyst in the range of 0.1 to 90 mol%.
- the content ratio of the composite oxide contained in the exhaust gas purification catalyst obtained by the production method according to the present invention can be used as the exhaust gas purification catalyst in the range of 10 to 99.9 mol%.
- the content of metallic silver contained in silver and / or silver oxide contained in the exhaust gas purifying catalyst obtained by the production method according to the present invention is preferably 70 to 100 mol%.
- the silver oxide include Ag 2 O and AgO.
- the exhaust gas purifying catalyst manufactured by the manufacturing method of the present invention is used as an exhaust gas purifying device by supporting a suspended particulate material containing carbon contained in exhaust gas discharged from an internal combustion engine on a filter medium capable of collecting. To do.
- the exhaust gas purification device may be any device provided with the exhaust gas purification catalyst of the present invention, and the embodiment is not particularly limited, and a normal form can be applied.
- One preferred embodiment is an apparatus in which a filter capable of collecting suspended particulate matter is installed at the exhaust gas exhaust port of a diesel engine.
- the shape of the filter is not particularly limited as long as it includes the exhaust gas purifying catalyst of the present invention, but a filter having a sufficient trapping function for suspended particulate matter is preferable.
- shapes such as honeycomb, monolith, pellet, foam, fiber, foamed ceramic or wire mesh can be used. Among these, a wall-through type honeycomb-shaped filter is more preferable.
- the material of the filter medium is not particularly limited, but porous heat-resistant ceramics such as cordierite, silicon carbide, mullite, alumina, zirconia, or stainless steel containing chromium, aluminum, or the like is preferably used.
- the exhaust gas purifying catalyst according to the present invention is attached (supported) on these wall-through honeycomb-shaped filters by means such as a dipping method or a coprecipitation method, and the catalyst layer is fired by firing the catalyst. Can be formed.
- the above ceramics and metals can also be used as a carrier for an oxidation catalyst.
- a particulate carrier that is an inorganic powder such as alumina, zirconia, titania, silica, etc.
- the catalyst according to the present invention is supported by means such as a dipping method or a coprecipitation method, and the inorganic powder supporting the catalyst is used as described above It is also preferable to install and use on heat resistant ceramics or stainless steel.
- Example 1 In a 1 L (liter) beaker equipped with a stirrer, 6.70 g of cerium acetate, 1.99 g of samarium acetate, and 4.17 g of silver acetate were used so that Ce: Sm: Ag was 4: 1: 5 in molar ratio. 18.01 g of lactic acid (corresponds to a molar amount four times the total amount of cerium in cerium acetate, samarium in samarium acetate, and silver in silver acetate) 500 mL of ion-exchanged water was added to the solution, and the set temperature was 80 ° C., followed by stirring for 15 minutes. As a result, cerium acetate, samarium acetate, and silver acetate were completely dissolved into a solution state. After confirming dissolution, stirring was continued for another hour at the same set temperature.
- the obtained solution was dried with a drier set at 90 ° C., and moisture was removed until apparently no moisture as a liquid disappeared.
- 500 mL of ion-exchanged water was added to the obtained dried product, and the dried product was redissolved at room temperature, and then the solution was dried with a mantle heater set at 190 ° C. for 6 hours to obtain a dried powder. Thereafter, the dried powder was transferred to an alumina sagger, and fired in air at 400 ° C. for 6 hours.
- the rate of temperature increase from room temperature to 400 ° C. and the rate of temperature decrease from 400 ° C. to room temperature were both 120 ° C./hour.
- the gray powder is referred to as “carbon combustion catalyst A”, and the composite oxide in the powder is referred to as “composite oxide a”.
- the particle size distribution of the carbon combustion catalyst A was measured.
- a sample was prepared by dispersing a small amount of carbon combustion catalyst A in ion-exchanged water as follows. An aqueous solution having a concentration of 0.24% by weight using sodium diphosphate decahydrate manufactured by Wako Pure Chemical Industries, Ltd. was used as a dispersant.
- a dispersion was prepared from about 0.05 g of carbon combustion catalyst A, a dispersant, and ion-exchanged water so that the total volume was 10 ml, and a sample irradiated with ultrasonic waves was used as a sample.
- a laser diffraction / scattering particle size distribution apparatus LA-920 manufactured by HORIBA was used. Immediately before the measurement, ultrasonic treatment with an output of 30 W was performed for 3 minutes. As a result, D 50 was 11.0 .mu.m.
- the BET specific surface area of the carbon combustion catalyst A by the nitrogen adsorption method was measured.
- Macsorb HM-1208 manufactured by Mounttech was used.
- the BET specific surface area of the carbon combustion catalyst A was 22.8 m 2 / g.
- FIG. 1 shows a TG curve of the carbon combustion catalyst A.
- the combustion start temperature Tig determined from the TG curve by the tangential method was 219 ° C.
- the peak temperature Tm determined from the first derivative curve of the TG curve was 337 ° C.
- a gray powder containing silver and silver was obtained.
- the gray powder is referred to as “carbon combustion catalyst B”, and the composite oxide in the powder is referred to as “composite oxide b”.
- Example 1 X-ray diffraction measurement of the carbon combustion catalyst B was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide b was a fluorite structure, and the carbon combustion catalyst B was a mixture of the composite oxide b and metallic silver. Subsequently, the particle size distribution measurement and specific surface area measurement of the carbon combustion catalyst B were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst B is 11.0 .mu.m, a specific surface area of 20.1m 2 / g. Further, TG measurement of the carbon combustion catalyst B was performed in the same manner as in Example 1. The combustion start temperature Tig determined from the TG curve by the tangential method was 247 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 363 ° C.
- Example 1 X-ray diffraction measurement of the carbon combustion catalyst C was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide c was a fluorite structure, and the carbon combustion catalyst C was a mixture of the composite oxide c and metallic silver. Subsequently, the particle size distribution measurement and the specific surface area measurement of the carbon combustion catalyst C were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst C is 12.1Myuemu, a specific surface area of 18.5 m 2 / g. Further, TG measurement of the carbon combustion catalyst C was performed in the same manner as in Example 1. The combustion start temperature Tig determined from the TG curve by the tangential method was 227 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 346 ° C.
- [Comparative Example 1] Obtained by adding 56.8 g of cerium carbonate and 11.1 g of samarium carbonate to 100 mL of ion-exchanged water in a 1 L (liter) beaker equipped with a stirrer so that Ce: Sm is a molar ratio of 4: 1.
- 99.0 g of ammonium carbonate and 131.5 g of citric acid were added, the set temperature was 80 ° C., and stirring was continued for 2 hours.
- 28.6 g of silver carbonate and 29.0 g of citric acid were added to the suspension so that the Ce: Sm: Ag molar ratio was 4: 1: 5. Stirring was continued for a time to obtain a slurry containing cerium, samarium and silver.
- the obtained slurry was dried for a whole day and night in a drier set at 105 ° C., and the dried product obtained by removing moisture was transferred to an alumina mortar, and the calcining time for holding was 10 hours. It fired in the same manner.
- the gray powder is referred to as “carbon combustion catalyst D”, and the composite oxide in the powder is referred to as “composite oxide d”.
- Example 1 X-ray diffraction measurement of the carbon combustion catalyst D was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide d was a fluorite structure, and the carbon combustion catalyst D was a mixture of the composite oxide d and metallic silver. Subsequently, the particle size distribution measurement and specific surface area measurement of the carbon combustion catalyst D were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst D is 3.0 [mu] m, a specific surface area of 61.6m 2 / g. Further, TG measurement of the carbon combustion catalyst D was performed in the same manner as in Example 1. FIG. 1 shows a TG curve of the carbon combustion catalyst C. The combustion start temperature Tig determined from the TG curve by the tangential method was 257 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 379 ° C.
- the exhaust gas purifying catalyst obtained by the production method using lactic acid according to the present invention has a low carbon combustion start temperature and peak temperature, and is useful as an exhaust gas purifying catalyst for an internal combustion engine using diesel fuel.
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Abstract
Provided is a method for manufacturing a catalyst for exhaust gas cleaning with a low initiation temperature for carbon combustion.
The method is for manufacturing a catalyst for cleaning exhaust gas that contains composite oxides containing cerium and rare earth elements other than cerium, silver and/or oxides of silver from dissolution processes that manufacture solutions by dissolving compounds containing silver, compounds containing cerium, and compounds containing rare earth elements other than cerium (A) or cerium, compounds containing rare earth elements other than cerium, and compounds containing silver (B) in an aqueous solution of lactic acid and drying and sintering processes for drying and sintering those solutions.
Description
本発明は、ディーゼルエンジンなどから排出される排気ガスに含まれる浮遊粒子状物質を浄化するための排気ガス浄化用触媒の製造方法および排気ガス浄化装置に関する。
The present invention relates to an exhaust gas purification catalyst manufacturing method and an exhaust gas purification device for purifying suspended particulate matter contained in exhaust gas discharged from a diesel engine or the like.
ディーゼル燃料を用いる内燃機関は、ガソリン燃料を用いる内燃機関に比べて熱効率が高いことから省エネルギー型のエネルギー機関として注目されている。
ディーゼル機関は、熱効率が高いが、その排気ガスにカーボン、炭化水素、サルフェートなどからなる、粒径が10μm以下であるような微小な浮遊粒子状物質(Particulate Matter(PM))を多く含んでいる。浮遊粒子状物質は、大気汚染の主要因と考えられており、また発ガン性や喘息などの疾病との因果関係も指摘されている人体にとって有害物質であって、大気中に放出する前に無害化する処理が必要である。 An internal combustion engine using diesel fuel has attracted attention as an energy-saving energy engine because it has higher thermal efficiency than an internal combustion engine using gasoline fuel.
Diesel engines have high thermal efficiency, but their exhaust gas contains many fine particulate matter (Particulate Matter (PM)) made of carbon, hydrocarbons, sulfates, etc. and having a particle size of 10 μm or less. . Airborne particulate matter is considered a major cause of air pollution and is a harmful substance for the human body that has been pointed out to be causal with diseases such as carcinogenicity and asthma. A detoxifying process is required.
ディーゼル機関は、熱効率が高いが、その排気ガスにカーボン、炭化水素、サルフェートなどからなる、粒径が10μm以下であるような微小な浮遊粒子状物質(Particulate Matter(PM))を多く含んでいる。浮遊粒子状物質は、大気汚染の主要因と考えられており、また発ガン性や喘息などの疾病との因果関係も指摘されている人体にとって有害物質であって、大気中に放出する前に無害化する処理が必要である。 An internal combustion engine using diesel fuel has attracted attention as an energy-saving energy engine because it has higher thermal efficiency than an internal combustion engine using gasoline fuel.
Diesel engines have high thermal efficiency, but their exhaust gas contains many fine particulate matter (Particulate Matter (PM)) made of carbon, hydrocarbons, sulfates, etc. and having a particle size of 10 μm or less. . Airborne particulate matter is considered a major cause of air pollution and is a harmful substance for the human body that has been pointed out to be causal with diseases such as carcinogenicity and asthma. A detoxifying process is required.
浮遊粒子状物質を浄化するために、一般的にDPF(Diesel Particulate Filter)と呼ばれるセラミックス製のフィルターなどの捕集装置が用いられている。捕集装置により捕集された浮遊粒子状物質は、捕集装置内で燃焼されることにより無害の気体に変化し浄化される。
In order to purify the suspended particulate matter, a collection device such as a ceramic filter generally called DPF (Diesel Particulate Filter) is used. The suspended particulate matter collected by the collection device is converted into a harmless gas and purified by being burned in the collection device.
浮遊粒子状物質中の主成分であるカーボンを燃焼させるには、少なくとも600℃程度の高温状態にまで加熱することが必要である。このような高温状態を実現するためには、捕集装置に断熱機構を組み込む必要が生じ、捕集装置が大型になるために、自動車などの移動体に捕集装置を実装する点では不利である。加えて、そのような高温状態を作り出すためには過剰なエネルギーを必要とするため、エネルギーの有効利用という観点からも不利である。そのため、より低い温度において、浮遊粒子状物質を燃焼することができる方法が求められている。
In order to burn carbon which is the main component in the suspended particulate matter, it is necessary to heat it to a high temperature state of at least about 600 ° C. In order to realize such a high temperature state, it is necessary to incorporate a heat insulation mechanism in the collection device, and the collection device becomes large, which is disadvantageous in that the collection device is mounted on a moving body such as an automobile. is there. In addition, in order to create such a high temperature state, excessive energy is required, which is disadvantageous from the viewpoint of effective use of energy. Therefore, there is a need for a method that can burn suspended particulate matter at lower temperatures.
通常、DPFは、フィルター内部に例えば白金その他の貴金属を含む酸化触媒層を担持することにより形成し、比較的低温で、浮遊粒子状物質を燃焼せしめることができる構造になっている。
従来、このような酸化触媒に関しては、多くの提案がされている。例えばセリアと銀からなる触媒を用いることが提案されている。(特許文献1および特許文献2参照) Usually, the DPF is formed by supporting an oxidation catalyst layer containing, for example, platinum or other noble metal inside the filter, and has a structure capable of burning suspended particulate matter at a relatively low temperature.
Conventionally, many proposals have been made regarding such an oxidation catalyst. For example, it has been proposed to use a catalyst composed of ceria and silver. (See Patent Document 1 and Patent Document 2)
従来、このような酸化触媒に関しては、多くの提案がされている。例えばセリアと銀からなる触媒を用いることが提案されている。(特許文献1および特許文献2参照) Usually, the DPF is formed by supporting an oxidation catalyst layer containing, for example, platinum or other noble metal inside the filter, and has a structure capable of burning suspended particulate matter at a relatively low temperature.
Conventionally, many proposals have been made regarding such an oxidation catalyst. For example, it has been proposed to use a catalyst composed of ceria and silver. (See Patent Document 1 and Patent Document 2)
銀と、サマリウムをドープした複合酸化物であるセリアとからなる排気ガス浄化用触媒は、セリア中のセリウムイオンCe4+の一部をセリウムイオンよりも価数の低いサマリウムイオンSm3+で置換したものである。この置換により酸素サイトに欠損が生じるために、セリアより高い酸素イオン伝導度を有する。この高い酸素イオン伝導度のために、サマリウムをドープしたセリアと銀とからなる排気ガス浄化用触媒のカーボン燃焼開始温度は低温化が期待される。
An exhaust gas purifying catalyst comprising silver and ceria which is a composite oxide doped with samarium is obtained by substituting a part of cerium ions Ce 4+ in ceria with samarium ions Sm 3+ having a lower valence than cerium ions. It is. This substitution causes deficiency at the oxygen site, and therefore has higher oxygen ion conductivity than ceria. Due to this high oxygen ion conductivity, the carbon combustion start temperature of the exhaust gas purifying catalyst composed of ceria doped with samarium and silver is expected to be lowered.
特許文献3には、少なくともセリウムを含む複合酸化物と、銀を含む金属または銀化合物とを含む排気ガスの浄化用触媒において、複合酸化物が、セリウムとLn(Lnは、ランタン、プラセオジム、ネオジム、プロメチウム、サマリウム、ユウロピウム、ガドリニウム、テルビウム、ジスプロシウム、ホロミウム、エルビウム、ツリウム、イッテルビウム、ルテチウム、イットリウムおよびスカンジウムからなる群から選ばれる少なくとも1種の元素を示す。)からなる蛍石型結晶構造を有する複合酸化物であることを特徴とする排気ガス浄化用触媒が記載されている。
In Patent Document 3, in a catalyst for purifying exhaust gas containing a composite oxide containing at least cerium and a metal or silver compound containing silver, the composite oxide contains cerium and Ln (Ln is lanthanum, praseodymium, neodymium). And at least one element selected from the group consisting of promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium. An exhaust gas purification catalyst characterized by being a complex oxide is described.
特許文献3で開示されているAg/Ce0.8Sm0.2O2-δの製造方法は、炭酸セリウムと炭酸サマリウムからなる懸濁液に、炭酸アンモニウムとクエン酸を加え、70℃~80℃の温度で反応させ、さらに炭酸銀とクエン酸を投入し、反応した後、この懸濁液を乾燥させて、乾燥物を焼成するというものである。この製造方法により得られたAg/Ce0.8Sm0.2O2-δとカーボンブラックとの混合物のDTA(示差熱分析)ピーク温度Tmは、335℃であった。このDTAピーク温度は低いものであったが、実際に触媒として使用する場合にはDTAピーク温度よりも、むしろカーボン燃焼開始温度の方が重要であり、カーボン燃焼開始温度が250℃より低いセリウムを除く希土類元素をドープしたセリアと銀および/または銀の酸化物とからなる排気ガス浄化用触媒とその製造方法の開発が望まれていた。
In the method for producing Ag / Ce 0.8 Sm 0.2 O 2-δ disclosed in Patent Document 3, ammonium carbonate and citric acid are added to a suspension composed of cerium carbonate and samarium carbonate, and 70 ° C. to The reaction is performed at a temperature of 80 ° C., and silver carbonate and citric acid are further added. After the reaction, the suspension is dried and the dried product is fired. The DTA (differential thermal analysis) peak temperature Tm of the mixture of Ag / Ce 0.8 Sm 0.2 O 2-δ and carbon black obtained by this production method was 335 ° C. Although this DTA peak temperature was low, when actually used as a catalyst, the carbon combustion start temperature is more important than the DTA peak temperature, and cerium having a carbon combustion start temperature lower than 250 ° C. is used. Development of an exhaust gas purification catalyst comprising ceria doped with rare earth elements excluding rare earth elements and silver and / or silver oxide and a method for producing the same have been desired.
本発明は、上記の事情に鑑みてなされたものであって、その目的は、カーボン燃焼開始温度の低い、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と、銀および/または銀の酸化物とからなる排気ガス浄化用触媒の製造方法を提供することである。
The present invention has been made in view of the above circumstances, and its object is to provide a composite oxide containing cerium and a rare earth element excluding cerium having a low carbon combustion start temperature, and silver and / or silver. An object of the present invention is to provide a method for producing an exhaust gas purification catalyst comprising an oxide.
本発明者らは、上記のような課題を達成するために鋭意検討したところ、乳酸を使用した製造方法で製造した、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と、銀および/または銀の酸化物とからなる排気ガス浄化用触媒が、低いカーボン燃焼開始温度を示すことを見出し、本発明を完成した。
The inventors of the present invention have made extensive studies in order to achieve the above-mentioned problems. As a result, a composite oxide containing cerium and a rare earth element excluding cerium, produced by a production method using lactic acid, silver and / or Alternatively, the present inventors have found that an exhaust gas purifying catalyst composed of a silver oxide exhibits a low carbon combustion start temperature and completed the present invention.
本発明は以下の要旨を有する。
1.(A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物とを、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物とを、乳酸の水溶液で溶解して溶液を製造する溶解工程と、前記溶液を乾燥焼成する乾燥焼成工程とを有することを特徴とする、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と銀および/または銀の酸化物とを含む排気ガス浄化用触媒の製造方法。
2.前記複合酸化物が、LnxCe1-xO2-δ(但し、Lnは、セリウムを除く希土類元素から選ばれる少なくとも1種の元素を示し、xは、0<x<0.5であり、δは、酸素欠損量を示し、0<δ<0.25である。)で表される上記1に記載の排気ガス浄化用触媒の製造方法。
3.銀含有化合物、セリウム含有化合物、およびセリウムを除く希土類元素含有化合物が、いずれも酢酸塩である上記1または2に記載の排気ガス浄化用触媒の製造方法。
4.セリウムを除く希土類元素がサマリウムである上記1~3のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
5.前記乾燥焼成工程の後、さらに解砕・粉砕工程を有する上記1~4のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
6.前記乾燥焼成工程における焼成温度が、335~800℃である上記1~5のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
7.セリウムとセリウムを除く希土類元素とを含有する複合酸化物に含まれるセリウムのモル数(Ce)とセリウムを除く希土類元素のモル数(Ln)との和である(Ce+Ln)に対する、銀および/または銀の酸化物に含まれる銀のモル数である(Ag)の比率を、(Ag)/(Ce+Ln)と表すとき、(Ag)/(Ce+Ln)が、1/9~9/1である上記1~6のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
8.A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物に含まれる、銀のモル数をAgm、セリウムのモル数をCem、及びセリウムを除く希土類元素のモル数をLnmと表し、乳酸の水溶液に含まれる乳酸のモル数をLamと表すとき、Lam/(Agm+Cem+Lnm)が、10/1~0.1/1である上記1~7のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
9.銀および/または銀の酸化物に含まれる金属銀の含有率が70~100モル%である上記1~8のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
10.上記1~9のいずれかの製造方法で製造された触媒を、フィルター媒体に担持させたことを特徴とする排気ガス浄化装置。 The present invention has the following gist.
1. (A) A silver-containing compound, a cerium-containing compound, and a rare-earth element-containing compound excluding cerium, or (B) a silver-containing compound and a rare-earth element-containing compound excluding cerium and cerium are dissolved in an aqueous solution of lactic acid. A composite oxide containing cerium and a rare earth element excluding cerium and silver and / or an oxide of silver, characterized by comprising a dissolving step for producing a solution and a drying and firing step for drying and firing the solution. The manufacturing method of the exhaust gas purification catalyst containing these.
2. The composite oxide is Ln x Ce 1-x O 2-δ (where Ln represents at least one element selected from rare earth elements excluding cerium, and x is 0 <x <0.5) , Δ represents the amount of oxygen deficiency, and 0 <δ <0.25.) The method for producing an exhaust gas purifying catalyst as described in 1 above.
3. 3. The method for producing an exhaust gas purifying catalyst as described in 1 or 2 above, wherein the silver-containing compound, the cerium-containing compound, and the rare-earth element-containing compound excluding cerium are all acetates.
4). 4. The method for producing an exhaust gas purifying catalyst as described in any one of 1 to 3 above, wherein the rare earth element excluding cerium is samarium.
5. 5. The method for producing an exhaust gas purifying catalyst according to any one of the above 1 to 4, further comprising a crushing and pulverizing step after the drying and firing step.
6). 6. The method for producing an exhaust gas purifying catalyst according to any one of 1 to 5, wherein a calcination temperature in the dry calcination step is 335 to 800 ° C.
7. Silver with respect to (Ce + Ln), which is the sum of the number of moles of cerium (Ce) contained in the composite oxide containing cerium and rare earth elements excluding cerium and the number of moles of rare earth elements excluding cerium (Ln), and When the ratio of (Ag), which is the number of moles of silver contained in the silver oxide, is expressed as (Ag) / (Ce + Ln), (Ag) / (Ce + Ln) is 1/9 to The method for producing an exhaust gas purifying catalyst according to any one of the above 1 to 6, which is 9/1.
8). A) a silver-containing compound, a cerium-containing compound, rare earth-containing compound excluding cerium, or (B) a silver-containing compound, contained in the rare earth-containing compound excluding cerium and cerium, the number of moles of silver Ag m, It represents the number of moles of cerium Ce m, and the number of moles of rare earth elements excluding cerium and Ln m, to represent the number of moles of lactic acid contained in the aqueous solution of lactic acid and La m, La m / (Ag m + Ce m + The method for producing an exhaust gas purifying catalyst according to any one of 1 to 7 above, wherein Ln m ) is 10/1 to 0.1 / 1.
9. 9. The method for producing an exhaust gas purifying catalyst as described in any one of 1 to 8 above, wherein the content of metallic silver contained in silver and / or silver oxide is 70 to 100 mol%.
10. An exhaust gas purifying apparatus characterized in that a catalyst produced by any one of the production methods 1 to 9 above is supported on a filter medium.
1.(A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物とを、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物とを、乳酸の水溶液で溶解して溶液を製造する溶解工程と、前記溶液を乾燥焼成する乾燥焼成工程とを有することを特徴とする、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と銀および/または銀の酸化物とを含む排気ガス浄化用触媒の製造方法。
2.前記複合酸化物が、LnxCe1-xO2-δ(但し、Lnは、セリウムを除く希土類元素から選ばれる少なくとも1種の元素を示し、xは、0<x<0.5であり、δは、酸素欠損量を示し、0<δ<0.25である。)で表される上記1に記載の排気ガス浄化用触媒の製造方法。
3.銀含有化合物、セリウム含有化合物、およびセリウムを除く希土類元素含有化合物が、いずれも酢酸塩である上記1または2に記載の排気ガス浄化用触媒の製造方法。
4.セリウムを除く希土類元素がサマリウムである上記1~3のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
5.前記乾燥焼成工程の後、さらに解砕・粉砕工程を有する上記1~4のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
6.前記乾燥焼成工程における焼成温度が、335~800℃である上記1~5のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
7.セリウムとセリウムを除く希土類元素とを含有する複合酸化物に含まれるセリウムのモル数(Ce)とセリウムを除く希土類元素のモル数(Ln)との和である(Ce+Ln)に対する、銀および/または銀の酸化物に含まれる銀のモル数である(Ag)の比率を、(Ag)/(Ce+Ln)と表すとき、(Ag)/(Ce+Ln)が、1/9~9/1である上記1~6のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
8.A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物に含まれる、銀のモル数をAgm、セリウムのモル数をCem、及びセリウムを除く希土類元素のモル数をLnmと表し、乳酸の水溶液に含まれる乳酸のモル数をLamと表すとき、Lam/(Agm+Cem+Lnm)が、10/1~0.1/1である上記1~7のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
9.銀および/または銀の酸化物に含まれる金属銀の含有率が70~100モル%である上記1~8のいずれか1つに記載の排気ガス浄化用触媒の製造方法。
10.上記1~9のいずれかの製造方法で製造された触媒を、フィルター媒体に担持させたことを特徴とする排気ガス浄化装置。 The present invention has the following gist.
1. (A) A silver-containing compound, a cerium-containing compound, and a rare-earth element-containing compound excluding cerium, or (B) a silver-containing compound and a rare-earth element-containing compound excluding cerium and cerium are dissolved in an aqueous solution of lactic acid. A composite oxide containing cerium and a rare earth element excluding cerium and silver and / or an oxide of silver, characterized by comprising a dissolving step for producing a solution and a drying and firing step for drying and firing the solution. The manufacturing method of the exhaust gas purification catalyst containing these.
2. The composite oxide is Ln x Ce 1-x O 2-δ (where Ln represents at least one element selected from rare earth elements excluding cerium, and x is 0 <x <0.5) , Δ represents the amount of oxygen deficiency, and 0 <δ <0.25.) The method for producing an exhaust gas purifying catalyst as described in 1 above.
3. 3. The method for producing an exhaust gas purifying catalyst as described in 1 or 2 above, wherein the silver-containing compound, the cerium-containing compound, and the rare-earth element-containing compound excluding cerium are all acetates.
4). 4. The method for producing an exhaust gas purifying catalyst as described in any one of 1 to 3 above, wherein the rare earth element excluding cerium is samarium.
5. 5. The method for producing an exhaust gas purifying catalyst according to any one of the above 1 to 4, further comprising a crushing and pulverizing step after the drying and firing step.
6). 6. The method for producing an exhaust gas purifying catalyst according to any one of 1 to 5, wherein a calcination temperature in the dry calcination step is 335 to 800 ° C.
7. Silver with respect to (Ce + Ln), which is the sum of the number of moles of cerium (Ce) contained in the composite oxide containing cerium and rare earth elements excluding cerium and the number of moles of rare earth elements excluding cerium (Ln), and When the ratio of (Ag), which is the number of moles of silver contained in the silver oxide, is expressed as (Ag) / (Ce + Ln), (Ag) / (Ce + Ln) is 1/9 to The method for producing an exhaust gas purifying catalyst according to any one of the above 1 to 6, which is 9/1.
8). A) a silver-containing compound, a cerium-containing compound, rare earth-containing compound excluding cerium, or (B) a silver-containing compound, contained in the rare earth-containing compound excluding cerium and cerium, the number of moles of silver Ag m, It represents the number of moles of cerium Ce m, and the number of moles of rare earth elements excluding cerium and Ln m, to represent the number of moles of lactic acid contained in the aqueous solution of lactic acid and La m, La m / (Ag m + Ce m + The method for producing an exhaust gas purifying catalyst according to any one of 1 to 7 above, wherein Ln m ) is 10/1 to 0.1 / 1.
9. 9. The method for producing an exhaust gas purifying catalyst as described in any one of 1 to 8 above, wherein the content of metallic silver contained in silver and / or silver oxide is 70 to 100 mol%.
10. An exhaust gas purifying apparatus characterized in that a catalyst produced by any one of the production methods 1 to 9 above is supported on a filter medium.
本発明に係る製造方法によれば、カーボン燃焼開始温度の低い排気ガス浄化用触媒を提供することができる。この排気ガス浄化用触媒をDPFに使用することにより、より低い温度において、浮遊粒子状物質を燃焼することができる。
The production method according to the present invention can provide an exhaust gas purification catalyst having a low carbon combustion start temperature. By using this exhaust gas purification catalyst in the DPF, the suspended particulate matter can be combusted at a lower temperature.
本発明は、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と、銀および/または銀の酸化物とを含有する排気ガス浄化用触媒の製造方法および排気ガス浄化装置に関するものである。以下に、その製造方法について説明する。
The present invention relates to an exhaust gas purifying catalyst manufacturing method and an exhaust gas purifying apparatus containing a composite oxide containing cerium and a rare earth element excluding cerium, and silver and / or silver oxide. Below, the manufacturing method is demonstrated.
本発明に係る製造方法の原料となる粉末は、以下のような銀含有化合物、セリウム含有化合物、セリウムを除く希土類元素含有化合物、セリウムおよびセリウム以外の希土類元素含有化合物である。
銀含有化合物は、銀を含む酸化物、硝酸塩、炭酸塩または酢酸塩などである。
セリウム含有化合物は、セリウムを含む酸化物、水酸化物、硝酸塩、炭酸塩、酢酸塩またはアルコキシドなどである。
セリウムを除く希土類元素含有化合物は、セリウムを除く希土類元素を含む酸化物、水酸化物、硝酸塩、炭酸塩、酢酸塩またはアルコキシドなどである。
セリウムおよびセリウム以外の希土類元素含有化合物は、セリウムと、セリウム以外の希土類元素とを含有する、酸化物、硝酸塩、炭酸塩または酢酸塩などの化合物である。
ここで、セリウムを除く希土類元素とは、ランタン(La)、プラセオジム(Pr)、ネオジム(Nd)、プロメチウム(Pm)、サマリウム(Sm)、ユウロピウム(Eu)、ガドリニウム(Gd)、テルビウム(Tb)、ジスプロシウム(Dy)、ホロミウム(Ho)、エルビウム(Er)、ツリウム(Tm)、イッテルビウム(Yb)、ルテチウム(Lu)、イットリウム(Y)およびスカンジウム(Sc)のことをいう。
セリウムを除く希土類元素としては、サマリウムまたはガドリニウムが好ましく、サマリウムが特に好ましい。 The powder used as the raw material of the production method according to the present invention is a silver-containing compound, a cerium-containing compound, a rare-earth element-containing compound other than cerium, or a rare-earth element-containing compound other than cerium and cerium.
The silver-containing compound is a silver-containing oxide, nitrate, carbonate or acetate.
Examples of the cerium-containing compound include cerium-containing oxides, hydroxides, nitrates, carbonates, acetates, and alkoxides.
The rare earth element-containing compound excluding cerium is an oxide, hydroxide, nitrate, carbonate, acetate or alkoxide containing a rare earth element excluding cerium.
The rare earth element-containing compound other than cerium and cerium is a compound such as oxide, nitrate, carbonate or acetate containing cerium and a rare earth element other than cerium.
Here, the rare earth elements excluding cerium are lanthanum (La), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb). Dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), yttrium (Y) and scandium (Sc).
As the rare earth element excluding cerium, samarium or gadolinium is preferable, and samarium is particularly preferable.
銀含有化合物は、銀を含む酸化物、硝酸塩、炭酸塩または酢酸塩などである。
セリウム含有化合物は、セリウムを含む酸化物、水酸化物、硝酸塩、炭酸塩、酢酸塩またはアルコキシドなどである。
セリウムを除く希土類元素含有化合物は、セリウムを除く希土類元素を含む酸化物、水酸化物、硝酸塩、炭酸塩、酢酸塩またはアルコキシドなどである。
セリウムおよびセリウム以外の希土類元素含有化合物は、セリウムと、セリウム以外の希土類元素とを含有する、酸化物、硝酸塩、炭酸塩または酢酸塩などの化合物である。
ここで、セリウムを除く希土類元素とは、ランタン(La)、プラセオジム(Pr)、ネオジム(Nd)、プロメチウム(Pm)、サマリウム(Sm)、ユウロピウム(Eu)、ガドリニウム(Gd)、テルビウム(Tb)、ジスプロシウム(Dy)、ホロミウム(Ho)、エルビウム(Er)、ツリウム(Tm)、イッテルビウム(Yb)、ルテチウム(Lu)、イットリウム(Y)およびスカンジウム(Sc)のことをいう。
セリウムを除く希土類元素としては、サマリウムまたはガドリニウムが好ましく、サマリウムが特に好ましい。 The powder used as the raw material of the production method according to the present invention is a silver-containing compound, a cerium-containing compound, a rare-earth element-containing compound other than cerium, or a rare-earth element-containing compound other than cerium and cerium.
The silver-containing compound is a silver-containing oxide, nitrate, carbonate or acetate.
Examples of the cerium-containing compound include cerium-containing oxides, hydroxides, nitrates, carbonates, acetates, and alkoxides.
The rare earth element-containing compound excluding cerium is an oxide, hydroxide, nitrate, carbonate, acetate or alkoxide containing a rare earth element excluding cerium.
The rare earth element-containing compound other than cerium and cerium is a compound such as oxide, nitrate, carbonate or acetate containing cerium and a rare earth element other than cerium.
Here, the rare earth elements excluding cerium are lanthanum (La), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb). Dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), yttrium (Y) and scandium (Sc).
As the rare earth element excluding cerium, samarium or gadolinium is preferable, and samarium is particularly preferable.
また、本発明に係る製造方法の原料は、銀と、セリウムと、セリウムを除く希土類元素の3元素をそれぞれ別々に含有する化合物でもよく、さらには銀と、セリウムと、セリウムを除く希土類元素のうち、任意の2種類以上の元素を同時に含有する化合物であってもよい。
In addition, the raw material of the production method according to the present invention may be a compound containing three elements of silver, cerium, and a rare earth element other than cerium separately, and further, a rare earth element excluding silver, cerium, and cerium. Of these, a compound containing two or more arbitrary elements at the same time may be used.
原料は1つの元素につき酸化物、水酸化物、硝酸塩、炭酸塩、酢酸塩およびアルコキシドなどから選ばれた任意の1種以上の化合物を元素源として選択することができる。水に対する溶解性が高いこと、焼成による有機成分の除去が容易であることから、原料としては酢酸塩が特に好ましい。
As the raw material, any one or more compounds selected from oxides, hydroxides, nitrates, carbonates, acetates, alkoxides and the like can be selected as an element source for each element. Acetate is particularly preferable as a raw material because of its high solubility in water and easy removal of organic components by firing.
まず、銀とセリウムとセリウムを除く希土類元素とが目的の組成になるように原料粉末を秤量する。
一方、乳酸を量り採り、水に溶解させる。乳酸の量は、銀とセリウムとセリウムを除く希土類元素の組成比にもよるが、これらの化合物が完全に溶解するのに足りる量であればよい。具体的には、通常、乳酸は、原料粉末中の金属元素のモル数の合計量、すなわち、銀のモル数と、セリウムのモル数と、セリウムを除く希土類元素のモル数との合計量に対して0.1~10倍のモル量を使用するのが好ましい。
具体的には、(A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物に含まれる、銀のモル数をAgm、セリウムのモル数をCem、及びセリウムを除く希土類元素のモル数をLnmと表し、乳酸の水溶液に含まれる乳酸のモル数をLamと表すとき、Lam/(Agm+Cem+Lnm)が、10/1~0.1/1であるのが好ましく、なかでも10/1~0.5/1であるのが好ましく、特に5/1~2/1であるのが好ましい。 First, the raw material powder is weighed so that silver, cerium, and rare earth elements excluding cerium have the desired composition.
On the other hand, lactic acid is weighed and dissolved in water. The amount of lactic acid depends on the composition ratio of the rare earth elements excluding silver, cerium, and cerium, but may be an amount sufficient to completely dissolve these compounds. Specifically, lactic acid usually has a total amount of moles of metal elements in the raw material powder, that is, a total amount of moles of silver, moles of cerium, and moles of rare earth elements excluding cerium. It is preferable to use a molar amount of 0.1 to 10 times.
Specifically, silver contained in (A) a silver-containing compound, a cerium-containing compound, and a rare-earth element-containing compound excluding cerium, or (B) a silver-containing compound and a rare-earth element-containing compound excluding cerium and cerium. represents the number of moles Ag m, the number of moles of cerium Ce m, and the number of moles of rare earth elements excluding cerium and Ln m, to represent the number of moles of lactic acid contained in the aqueous solution of lactic acid and La m, La m / ( Ag m + Ce m + Ln m ) is 10 / 1-1 is preferably from 0.1 / 1, it is preferably Among them 10/1 ~ 0.5 / 1, in particular 5 / 1-2 / 1 is preferred.
一方、乳酸を量り採り、水に溶解させる。乳酸の量は、銀とセリウムとセリウムを除く希土類元素の組成比にもよるが、これらの化合物が完全に溶解するのに足りる量であればよい。具体的には、通常、乳酸は、原料粉末中の金属元素のモル数の合計量、すなわち、銀のモル数と、セリウムのモル数と、セリウムを除く希土類元素のモル数との合計量に対して0.1~10倍のモル量を使用するのが好ましい。
具体的には、(A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物に含まれる、銀のモル数をAgm、セリウムのモル数をCem、及びセリウムを除く希土類元素のモル数をLnmと表し、乳酸の水溶液に含まれる乳酸のモル数をLamと表すとき、Lam/(Agm+Cem+Lnm)が、10/1~0.1/1であるのが好ましく、なかでも10/1~0.5/1であるのが好ましく、特に5/1~2/1であるのが好ましい。 First, the raw material powder is weighed so that silver, cerium, and rare earth elements excluding cerium have the desired composition.
On the other hand, lactic acid is weighed and dissolved in water. The amount of lactic acid depends on the composition ratio of the rare earth elements excluding silver, cerium, and cerium, but may be an amount sufficient to completely dissolve these compounds. Specifically, lactic acid usually has a total amount of moles of metal elements in the raw material powder, that is, a total amount of moles of silver, moles of cerium, and moles of rare earth elements excluding cerium. It is preferable to use a molar amount of 0.1 to 10 times.
Specifically, silver contained in (A) a silver-containing compound, a cerium-containing compound, and a rare-earth element-containing compound excluding cerium, or (B) a silver-containing compound and a rare-earth element-containing compound excluding cerium and cerium. represents the number of moles Ag m, the number of moles of cerium Ce m, and the number of moles of rare earth elements excluding cerium and Ln m, to represent the number of moles of lactic acid contained in the aqueous solution of lactic acid and La m, La m / ( Ag m + Ce m + Ln m ) is 10 / 1-1 is preferably from 0.1 / 1, it is preferably Among them 10/1 ~ 0.5 / 1, in particular 5 / 1-2 / 1 is preferred.
0.1~10倍のモル量であると、比較的短時間で原料粉末を完全に乳酸を含む水溶液に溶解することができる。なお、本発明では必要に応じて、原料粉末の溶解性に悪影響を与えることがなく、かつ、焼成により消失する有機または無機の化合物、例えば他の酸やアルカリ、溶解性改善剤、粘性調整剤などを乳酸水溶液に加えてもよい。乳酸水溶液に使用する水は、純水でも、イオン交換水でもよいが、生成物中の不純物量を低減させるために、イオン交換水が特に好ましい。
When the molar amount is 0.1 to 10 times, the raw material powder can be completely dissolved in an aqueous solution containing lactic acid in a relatively short time. In the present invention, if necessary, organic or inorganic compounds that do not adversely affect the solubility of the raw material powder and disappear upon firing, such as other acids and alkalis, solubility improvers, viscosity modifiers. Etc. may be added to the aqueous lactic acid solution. The water used for the lactic acid aqueous solution may be pure water or ion-exchanged water, but ion-exchanged water is particularly preferred in order to reduce the amount of impurities in the product.
次に、乳酸水溶液の入った反応容器に秤量した原料粉末を加え、攪拌装置を用いて原料粉末が完全に溶解するまで攪拌する。攪拌装置には、マグネチックスターラー、攪拌翼による攪拌機などが使用できる。銀含有化合物、セリウム含有化合物およびセリウムを除く希土類元素含有化合物を混合してから、乳酸水溶液に加えてもよい。場合によっては、原料である銀含有化合物、セリウム含有化合物およびセリウムを除く希土類元素含有化合物のそれぞれを別々に乳酸水溶液に溶解させた後、その溶液を混ぜ合わせて、3成分が溶解した乳酸水溶液にしてもよい。
Next, the weighed raw material powder is added to the reaction vessel containing the lactic acid aqueous solution, and the raw material powder is stirred until the raw material powder is completely dissolved. As the stirring device, a magnetic stirrer, a stirrer using a stirring blade, or the like can be used. A silver-containing compound, a cerium-containing compound, and a rare earth element-containing compound other than cerium may be mixed and then added to the lactic acid aqueous solution. In some cases, the silver-containing compound, the cerium-containing compound, and the rare-earth element-containing compound excluding cerium are separately dissolved in the lactic acid aqueous solution, and then the solutions are mixed to form a lactic acid aqueous solution in which the three components are dissolved. May be.
短時間で原料を完全に溶解させるためには、原料を溶解する際に、反応容器を加熱することが好ましい。加熱温度は、原料が溶解する温度ならば特に限定されないが、溶媒である水が蒸発することから、100℃以下が好ましく、通常50℃から80℃の範囲が特に好ましい。原料粉末が乳酸水溶液に完全に溶解するのは、原料粉末中の金属元素が、乳酸中のカルボキシル基や水酸基と錯体を形成するためであると考えられる。
In order to completely dissolve the raw material in a short time, it is preferable to heat the reaction vessel when dissolving the raw material. The heating temperature is not particularly limited as long as the raw material is dissolved, but is preferably 100 ° C. or lower, and particularly preferably in the range of 50 ° C. to 80 ° C., because water as a solvent evaporates. It is considered that the raw material powder is completely dissolved in the lactic acid aqueous solution because the metal element in the raw material powder forms a complex with a carboxyl group or a hydroxyl group in lactic acid.
原料が溶解した後、反応容器を加熱した状態で、30分から2時間撹拌することが好ましい。原料粉末中の金属元素と乳酸中のカルボキシル基や水酸基との錯体形成反応を十分に進行させることにより、完全に原料粉末を乳酸水溶液に溶解させ、反応させるためである。原料粉末を完全に乳酸水溶液に溶解することにより、銀を含有する原料と、セリウムを含有する原料と、セリウムを除く希土類元素を含有する原料とを、分子レベルで均一に混合することができると推定される。
It is preferable to stir for 30 minutes to 2 hours in a state where the reaction vessel is heated after the raw materials are dissolved. This is because a complex formation reaction between a metal element in the raw material powder and a carboxyl group or a hydroxyl group in lactic acid is sufficiently advanced to completely dissolve the raw material powder in the lactic acid aqueous solution and cause the reaction. By completely dissolving the raw material powder in an aqueous lactic acid solution, a raw material containing silver, a raw material containing cerium, and a raw material containing a rare earth element excluding cerium can be uniformly mixed at the molecular level. Presumed.
本発明において、乾燥焼成工程は、以下に述べるように、乾燥工程の後に、さらに別途焼成工程を行う2工程からなる工程であってもよく、乾燥工程とその後の焼成工程を、連続的な一つの工程とする工程であってもよい。
具体的には、上記の原料粉末が溶解した溶液を乾燥する。乾燥温度は、50℃~200℃とすることが好ましい。
乾燥温度は、後述する再溶解工程を伴う場合には、50℃~110℃が好ましく、80℃~100℃がより好ましい。加熱がない場合と比較して短時間で原料粉末を乾燥することができ、かつ乳酸が蒸発しない温度範囲であるからである。ここで得られる乾燥物は、原料粉末の乳酸水溶液中の水分が蒸発した原料粉末と乳酸とからなる塊状物であり、またその後の再溶解工程の妨げにならない程度に水分を含んでいてもよい。例えば、原料粉末が溶解した溶液中の水分の80%以上が蒸発していればよい。 In the present invention, as described below, the drying and firing step may be a two-step process in which a separate firing step is performed after the drying step, and the drying step and the subsequent firing step are performed in a continuous manner. One process may be used.
Specifically, the solution in which the raw material powder is dissolved is dried. The drying temperature is preferably 50 ° C. to 200 ° C.
The drying temperature is preferably 50 ° C. to 110 ° C., more preferably 80 ° C. to 100 ° C. when a re-dissolution step described later is involved. This is because the raw material powder can be dried in a shorter time than when no heating is performed, and the temperature range is such that lactic acid does not evaporate. The dried product obtained here is a lump of raw material powder and lactic acid in which the water in the lactic acid aqueous solution of the raw material powder has evaporated, and may contain water to the extent that it does not interfere with the subsequent re-dissolution process. . For example, 80% or more of the water in the solution in which the raw material powder is dissolved may be evaporated.
具体的には、上記の原料粉末が溶解した溶液を乾燥する。乾燥温度は、50℃~200℃とすることが好ましい。
乾燥温度は、後述する再溶解工程を伴う場合には、50℃~110℃が好ましく、80℃~100℃がより好ましい。加熱がない場合と比較して短時間で原料粉末を乾燥することができ、かつ乳酸が蒸発しない温度範囲であるからである。ここで得られる乾燥物は、原料粉末の乳酸水溶液中の水分が蒸発した原料粉末と乳酸とからなる塊状物であり、またその後の再溶解工程の妨げにならない程度に水分を含んでいてもよい。例えば、原料粉末が溶解した溶液中の水分の80%以上が蒸発していればよい。 In the present invention, as described below, the drying and firing step may be a two-step process in which a separate firing step is performed after the drying step, and the drying step and the subsequent firing step are performed in a continuous manner. One process may be used.
Specifically, the solution in which the raw material powder is dissolved is dried. The drying temperature is preferably 50 ° C. to 200 ° C.
The drying temperature is preferably 50 ° C. to 110 ° C., more preferably 80 ° C. to 100 ° C. when a re-dissolution step described later is involved. This is because the raw material powder can be dried in a shorter time than when no heating is performed, and the temperature range is such that lactic acid does not evaporate. The dried product obtained here is a lump of raw material powder and lactic acid in which the water in the lactic acid aqueous solution of the raw material powder has evaporated, and may contain water to the extent that it does not interfere with the subsequent re-dissolution process. . For example, 80% or more of the water in the solution in which the raw material powder is dissolved may be evaporated.
その後、必要に応じて、その乾燥物を水に再溶解する。再溶解することにより、銀を含有する原料とセリウムを含有する原料とセリウムを除く希土類元素を含有する原料とがより均一になるので好ましい。乾燥物を再溶解した溶液は、120℃~200℃で乾燥することが好ましく、15℃~200℃で乾燥することがより好ましい。上記乾燥物を完全に再乾燥することができるため、再乾燥粉の回収が容易となり、かつ再乾燥物の酸化反応が始まる程、温度が高くないからである。
一方、再溶解工程を伴わない場合には、乾燥温度を120℃~200℃とすることがより好ましく、150℃~200℃が特に好ましい。同様に、得られる乾燥物は原料粉末の乳酸水溶液の水分が蒸発し、原料粉末と乳酸との塊状物であり、後の焼成工程の妨げにならない程度に水分を含んでいてもよい。 Thereafter, the dried product is redissolved in water as necessary. By re-dissolving, a raw material containing silver, a raw material containing cerium, and a raw material containing a rare earth element excluding cerium become more uniform, which is preferable. The solution obtained by re-dissolving the dried product is preferably dried at 120 ° C. to 200 ° C., more preferably 15 ° C. to 200 ° C. This is because the dried product can be completely re-dried, so that the re-dried powder can be easily recovered and the temperature is not so high that the oxidation reaction of the re-dried product starts.
On the other hand, when no re-dissolution step is involved, the drying temperature is more preferably 120 ° C. to 200 ° C., and particularly preferably 150 ° C. to 200 ° C. Similarly, the dried product obtained is a lump of raw material powder and lactic acid by evaporating the water in the lactic acid aqueous solution of the raw material powder, and may contain water to the extent that it does not interfere with the subsequent firing step.
一方、再溶解工程を伴わない場合には、乾燥温度を120℃~200℃とすることがより好ましく、150℃~200℃が特に好ましい。同様に、得られる乾燥物は原料粉末の乳酸水溶液の水分が蒸発し、原料粉末と乳酸との塊状物であり、後の焼成工程の妨げにならない程度に水分を含んでいてもよい。 Thereafter, the dried product is redissolved in water as necessary. By re-dissolving, a raw material containing silver, a raw material containing cerium, and a raw material containing a rare earth element excluding cerium become more uniform, which is preferable. The solution obtained by re-dissolving the dried product is preferably dried at 120 ° C. to 200 ° C., more preferably 15 ° C. to 200 ° C. This is because the dried product can be completely re-dried, so that the re-dried powder can be easily recovered and the temperature is not so high that the oxidation reaction of the re-dried product starts.
On the other hand, when no re-dissolution step is involved, the drying temperature is more preferably 120 ° C. to 200 ° C., and particularly preferably 150 ° C. to 200 ° C. Similarly, the dried product obtained is a lump of raw material powder and lactic acid by evaporating the water in the lactic acid aqueous solution of the raw material powder, and may contain water to the extent that it does not interfere with the subsequent firing step.
次に、乾燥させた混合原料粉末を焼成容器に移し、焼成炉にて焼成する。焼成容器の材質は、特に限定されず、例えばアルミナ、ムライト、コージェライトなどが挙げられる。焼成炉は電気式またはガス式のシャトルキルンでも、場合によってはローラーハースキルンでもロータリーキルンでもよく、特に限定されない。
焼成工程においては、焼成炉の温度を20℃/時~500℃/時の昇温速度で目的の焼成温度まで上げることが好ましい。昇温速度がこの範囲であれば、比較的短時間で、目的の焼成温度まで到達することができ、かつ昇温過程の各温度で反応物質の化学反応を十分に進行させることができるからである。 Next, the dried mixed raw material powder is transferred to a firing container and fired in a firing furnace. The material of the firing container is not particularly limited, and examples thereof include alumina, mullite, cordierite and the like. The firing furnace may be an electric or gas shuttle kiln, or may be a roller hearth kiln or a rotary kiln, and is not particularly limited.
In the firing step, it is preferable to raise the temperature of the firing furnace to the desired firing temperature at a temperature increase rate of 20 ° C./hour to 500 ° C./hour. If the rate of temperature increase is within this range, the target firing temperature can be reached in a relatively short time, and the chemical reaction of the reactants can proceed sufficiently at each temperature in the temperature increase process. is there.
焼成工程においては、焼成炉の温度を20℃/時~500℃/時の昇温速度で目的の焼成温度まで上げることが好ましい。昇温速度がこの範囲であれば、比較的短時間で、目的の焼成温度まで到達することができ、かつ昇温過程の各温度で反応物質の化学反応を十分に進行させることができるからである。 Next, the dried mixed raw material powder is transferred to a firing container and fired in a firing furnace. The material of the firing container is not particularly limited, and examples thereof include alumina, mullite, cordierite and the like. The firing furnace may be an electric or gas shuttle kiln, or may be a roller hearth kiln or a rotary kiln, and is not particularly limited.
In the firing step, it is preferable to raise the temperature of the firing furnace to the desired firing temperature at a temperature increase rate of 20 ° C./hour to 500 ° C./hour. If the rate of temperature increase is within this range, the target firing temperature can be reached in a relatively short time, and the chemical reaction of the reactants can proceed sufficiently at each temperature in the temperature increase process. is there.
焼成温度は、335℃~800℃が好ましく、350℃~600℃がより好ましい。335℃~800℃であると反応生成物中に未反応物が残留しにくく、焼成物の焼結が進行しにくいためである。
The firing temperature is preferably 335 ° C to 800 ° C, more preferably 350 ° C to 600 ° C. This is because when the temperature is 335 ° C. to 800 ° C., unreacted substances hardly remain in the reaction product, and sintering of the fired product hardly proceeds.
焼成時間は目的の触媒化合物が生成すればよく、特に限定されない。通常は焼成温度範囲に到達した後に0.5時間~72時間保持することが好ましく、1時間~24時間保持することがより好ましい。反応生成物中の未反応物の残留がなく、生産性が低下することもないためである。焼成を行う際の焼成炉の雰囲気は、酸素含有雰囲気、特に空気中(大気中)であることが好ましい。
The firing time is not particularly limited as long as the target catalyst compound is produced. Usually, after reaching the firing temperature range, it is preferably held for 0.5 to 72 hours, more preferably 1 to 24 hours. This is because there remains no unreacted product in the reaction product, and productivity does not decrease. The firing furnace atmosphere when firing is preferably an oxygen-containing atmosphere, particularly in the air (in the air).
焼成を所定時間行った後、室温まで降温する。降温速度は、100℃/時~800℃/時が好ましく、100℃/時~500℃/時がより好ましい。生産性が落ちることなく、かつ焼成容器が熱衝撃により割れにくくなるためである。
次いで、焼成工程で得られた酸化物を解砕・粉砕(解砕・粉砕工程)する。解砕にはカッターミル、ジェットミル、アトマイザー、乳鉢などの解砕・粉砕機を用い、一般に乾式で行う。解砕粉は、必要に応じて乾式または湿式で目的の粒度まで粉砕する。解砕後または粉砕後の体積平均粒径(以下、D50とする。)は、好ましくは1.0μm~50.0μm、より好ましくは5.0μm~15.0μmである。また、比表面積は、好ましくは5m2/g~120m2/g、より好ましくは15m2/g~120m2/gである。D50が1.0μm~50.0μm、または比表面積が5m2/g~120m2/gであると好ましいのは、排気ガス浄化用触媒としての触媒能が高いからである。体積平均粒径は湿式の粒度分布計で測定し、比表面積は窒素吸着法によるBET法により測定する。
また、上記のように個別の2工程とする、乾燥工程とその後の焼成工程とは、連続的な一つの工程とすることもできる。この場合には、噴霧熱分解装置等を用いることができる。 After firing for a predetermined time, the temperature is lowered to room temperature. The temperature lowering rate is preferably 100 ° C./hour to 800 ° C./hour, more preferably 100 ° C./hour to 500 ° C./hour. This is because productivity does not decrease and the baking container is not easily broken by thermal shock.
Next, the oxide obtained in the firing step is crushed and pulverized (pulverized and pulverized step). For crushing, a crushing / pulverizing machine such as a cutter mill, a jet mill, an atomizer, or a mortar is generally used. The pulverized powder is pulverized to a desired particle size by dry or wet as necessary. Disintegrated or volume average particle size after pulverization (hereinafter referred to as D 50.) Is preferably 1.0 .mu.m ~ 50.0 micrometers, more preferably from 5.0 .mu.m ~ 15.0 .mu.m. The specific surface area is preferably 5 m 2 / g to 120 m 2 / g, more preferably 15 m 2 / g to 120 m 2 / g. It is preferable that D 50 is 1.0 μm to 50.0 μm or the specific surface area is 5 m 2 / g to 120 m 2 / g because the catalytic ability as an exhaust gas purification catalyst is high. The volume average particle diameter is measured by a wet particle size distribution meter, and the specific surface area is measured by a BET method using a nitrogen adsorption method.
In addition, as described above, the drying process and the subsequent baking process, which are two separate processes, can be a single continuous process. In this case, a spray pyrolysis apparatus or the like can be used.
次いで、焼成工程で得られた酸化物を解砕・粉砕(解砕・粉砕工程)する。解砕にはカッターミル、ジェットミル、アトマイザー、乳鉢などの解砕・粉砕機を用い、一般に乾式で行う。解砕粉は、必要に応じて乾式または湿式で目的の粒度まで粉砕する。解砕後または粉砕後の体積平均粒径(以下、D50とする。)は、好ましくは1.0μm~50.0μm、より好ましくは5.0μm~15.0μmである。また、比表面積は、好ましくは5m2/g~120m2/g、より好ましくは15m2/g~120m2/gである。D50が1.0μm~50.0μm、または比表面積が5m2/g~120m2/gであると好ましいのは、排気ガス浄化用触媒としての触媒能が高いからである。体積平均粒径は湿式の粒度分布計で測定し、比表面積は窒素吸着法によるBET法により測定する。
また、上記のように個別の2工程とする、乾燥工程とその後の焼成工程とは、連続的な一つの工程とすることもできる。この場合には、噴霧熱分解装置等を用いることができる。 After firing for a predetermined time, the temperature is lowered to room temperature. The temperature lowering rate is preferably 100 ° C./hour to 800 ° C./hour, more preferably 100 ° C./hour to 500 ° C./hour. This is because productivity does not decrease and the baking container is not easily broken by thermal shock.
Next, the oxide obtained in the firing step is crushed and pulverized (pulverized and pulverized step). For crushing, a crushing / pulverizing machine such as a cutter mill, a jet mill, an atomizer, or a mortar is generally used. The pulverized powder is pulverized to a desired particle size by dry or wet as necessary. Disintegrated or volume average particle size after pulverization (hereinafter referred to as D 50.) Is preferably 1.0 .mu.m ~ 50.0 micrometers, more preferably from 5.0 .mu.m ~ 15.0 .mu.m. The specific surface area is preferably 5 m 2 / g to 120 m 2 / g, more preferably 15 m 2 / g to 120 m 2 / g. It is preferable that D 50 is 1.0 μm to 50.0 μm or the specific surface area is 5 m 2 / g to 120 m 2 / g because the catalytic ability as an exhaust gas purification catalyst is high. The volume average particle diameter is measured by a wet particle size distribution meter, and the specific surface area is measured by a BET method using a nitrogen adsorption method.
In addition, as described above, the drying process and the subsequent baking process, which are two separate processes, can be a single continuous process. In this case, a spray pyrolysis apparatus or the like can be used.
本発明に係る製造方法により得られる排気ガス浄化用触媒は、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と、銀および/または銀の酸化物とからなる化合物である。セリウムとセリウムを除く希土類元素とを含有する複合酸化物は、LnxCe1-xO2-δ(但し、Lnは、セリウムを除く希土類元素から選ばれる少なくとも1種の元素を示し、xは、0<x<0.5であり、δは、酸素欠損量を示し、0<δ<0.25である。)の組成式で表されることが好ましい。この複合酸化物は、蛍石型構造をとっており、高い酸素イオン伝導度を有するからである。なかでも、LnがサマリウムであるSmxCe1-xO2-δは、酸素イオン伝導度が高いので好ましい。
The exhaust gas purifying catalyst obtained by the production method according to the present invention is a compound comprising cerium and a complex oxide containing rare earth elements excluding cerium, and silver and / or an oxide of silver. The composite oxide containing cerium and a rare earth element excluding cerium is Ln x Ce 1-x O 2-δ (where Ln represents at least one element selected from rare earth elements excluding cerium, and x is 0 <x <0.5, and δ represents the amount of oxygen deficiency, and 0 <δ <0.25. This is because this composite oxide has a fluorite structure and has high oxygen ion conductivity. Among these, Sm x Ce 1-x O 2-δ in which Ln is samarium is preferable because of high oxygen ion conductivity.
本発明の排気ガス浄化用触媒において、セリウムとセリウムを除く希土類元素とを含有する複合酸化物に含まれるセリウムのモル数(Ce)とセリウムを除く希土類元素のモル数(Ln)との和である(Ce+Ln)に対する、銀および/または銀の酸化物に含まれる銀のモル数である(Ag)の比率を、(Ag)/(Ce+Ln)と表すとき、(Ag)/(Ce+Ln)が、1/9~9/1であるのが好ましく、3/7~7/3であるのがさらに好ましく、4/6~6/4であるのが特に好ましい。1/9以上であると触媒活性をより高く、9/1以下であると触媒コストをより低くできるので好ましい。
本発明に係る製造方法により得られる排気ガス浄化用触媒に含まれる銀および/または銀の酸化物の含有比率は、0.1~90モル%の範囲で排気ガス浄化用触媒として使用可能である。一方、本発明に係る製造方法により得られる排気ガス浄化用触媒に含まれる上記複合酸化物の含有比率は、10~99.9モル%の範囲で排気ガス浄化用触媒として使用可能である。
本発明に係る製造方法により得られる排気ガス浄化用触媒に含まれる、銀および/または銀の酸化物に含まれる金属銀の含有率は、70~100モル%であるのが好ましい。銀の酸化物としては、Ag2O又はAgOが挙げられる。 In the exhaust gas purifying catalyst of the present invention, the sum of the number of moles of cerium (Ce) contained in the composite oxide containing cerium and rare earth elements excluding cerium and the number of moles of rare earth elements excluding cerium (Ln). When the ratio of (Ag), which is the number of moles of silver contained in silver and / or silver oxide, to (Ce + Ln) is expressed as (Ag) / (Ce + Ln), (Ag) / ( Ce + Ln) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and particularly preferably 4/6 to 6/4. If it is 1/9 or more, the catalyst activity is higher, and if it is 9/1 or less, the catalyst cost can be further reduced.
The content ratio of silver and / or silver oxide contained in the exhaust gas purification catalyst obtained by the production method according to the present invention can be used as an exhaust gas purification catalyst in the range of 0.1 to 90 mol%. . On the other hand, the content ratio of the composite oxide contained in the exhaust gas purification catalyst obtained by the production method according to the present invention can be used as the exhaust gas purification catalyst in the range of 10 to 99.9 mol%.
The content of metallic silver contained in silver and / or silver oxide contained in the exhaust gas purifying catalyst obtained by the production method according to the present invention is preferably 70 to 100 mol%. Examples of the silver oxide include Ag 2 O and AgO.
本発明に係る製造方法により得られる排気ガス浄化用触媒に含まれる銀および/または銀の酸化物の含有比率は、0.1~90モル%の範囲で排気ガス浄化用触媒として使用可能である。一方、本発明に係る製造方法により得られる排気ガス浄化用触媒に含まれる上記複合酸化物の含有比率は、10~99.9モル%の範囲で排気ガス浄化用触媒として使用可能である。
本発明に係る製造方法により得られる排気ガス浄化用触媒に含まれる、銀および/または銀の酸化物に含まれる金属銀の含有率は、70~100モル%であるのが好ましい。銀の酸化物としては、Ag2O又はAgOが挙げられる。 In the exhaust gas purifying catalyst of the present invention, the sum of the number of moles of cerium (Ce) contained in the composite oxide containing cerium and rare earth elements excluding cerium and the number of moles of rare earth elements excluding cerium (Ln). When the ratio of (Ag), which is the number of moles of silver contained in silver and / or silver oxide, to (Ce + Ln) is expressed as (Ag) / (Ce + Ln), (Ag) / ( Ce + Ln) is preferably 1/9 to 9/1, more preferably 3/7 to 7/3, and particularly preferably 4/6 to 6/4. If it is 1/9 or more, the catalyst activity is higher, and if it is 9/1 or less, the catalyst cost can be further reduced.
The content ratio of silver and / or silver oxide contained in the exhaust gas purification catalyst obtained by the production method according to the present invention can be used as an exhaust gas purification catalyst in the range of 0.1 to 90 mol%. . On the other hand, the content ratio of the composite oxide contained in the exhaust gas purification catalyst obtained by the production method according to the present invention can be used as the exhaust gas purification catalyst in the range of 10 to 99.9 mol%.
The content of metallic silver contained in silver and / or silver oxide contained in the exhaust gas purifying catalyst obtained by the production method according to the present invention is preferably 70 to 100 mol%. Examples of the silver oxide include Ag 2 O and AgO.
本発明の製造方法で製造した排気ガス浄化用触媒は、内燃機関から排出される排気ガスに含まれるカーボンを含む浮遊粒子状物質を捕集可能なフィルター媒体に担持させ、排気ガス浄化装置として使用するものである。
The exhaust gas purifying catalyst manufactured by the manufacturing method of the present invention is used as an exhaust gas purifying device by supporting a suspended particulate material containing carbon contained in exhaust gas discharged from an internal combustion engine on a filter medium capable of collecting. To do.
ここで、排気ガス浄化装置は、本発明の排気ガス浄化用触媒を備えるものであればよく、実施形態は特に限定されず、通常の形態を適用することができる。好適な実施形態の1つとしては、ディーゼル機関の排出ガスの排出口に浮遊粒子状物質を捕集できるフィルターを設置した装置が例示される。このフィルターの形状は特に限定されず、本発明の排気ガス浄化用触媒を備えるものであればよいが、十分な浮遊粒子状物質捕集機能を有するものが好ましい。例えば、ハニカム状、モノリス状、ペレット状、フォーム状、ファイバー状、発泡状のセラミックスまたはワイヤメッシュ等の形状が使用できる。これらの中でも、ウォールスルー型ハニカム形状のフィルターがより好ましい。
Here, the exhaust gas purification device may be any device provided with the exhaust gas purification catalyst of the present invention, and the embodiment is not particularly limited, and a normal form can be applied. One preferred embodiment is an apparatus in which a filter capable of collecting suspended particulate matter is installed at the exhaust gas exhaust port of a diesel engine. The shape of the filter is not particularly limited as long as it includes the exhaust gas purifying catalyst of the present invention, but a filter having a sufficient trapping function for suspended particulate matter is preferable. For example, shapes such as honeycomb, monolith, pellet, foam, fiber, foamed ceramic or wire mesh can be used. Among these, a wall-through type honeycomb-shaped filter is more preferable.
フィルター媒体の材質は特に限定されないが、コージェライト、炭化ケイ素、ムライト、アルミナ、ジルコニアなどの多孔質状耐熱セラミックス、またはクロム、アルミニウムなどを含むステンレス鋼が好適に使用される。
例えば、これらのウォールスルー型ハニカム形状のフィルター上に、浸漬法や共沈法などの手段で本発明に係る排気ガス浄化用触媒を付着(担持)させ、これを焼成することにより、触媒層を形成することができる。 The material of the filter medium is not particularly limited, but porous heat-resistant ceramics such as cordierite, silicon carbide, mullite, alumina, zirconia, or stainless steel containing chromium, aluminum, or the like is preferably used.
For example, the exhaust gas purifying catalyst according to the present invention is attached (supported) on these wall-through honeycomb-shaped filters by means such as a dipping method or a coprecipitation method, and the catalyst layer is fired by firing the catalyst. Can be formed.
例えば、これらのウォールスルー型ハニカム形状のフィルター上に、浸漬法や共沈法などの手段で本発明に係る排気ガス浄化用触媒を付着(担持)させ、これを焼成することにより、触媒層を形成することができる。 The material of the filter medium is not particularly limited, but porous heat-resistant ceramics such as cordierite, silicon carbide, mullite, alumina, zirconia, or stainless steel containing chromium, aluminum, or the like is preferably used.
For example, the exhaust gas purifying catalyst according to the present invention is attached (supported) on these wall-through honeycomb-shaped filters by means such as a dipping method or a coprecipitation method, and the catalyst layer is fired by firing the catalyst. Can be formed.
なお、上記のセラミックスや金属は、酸化触媒の担体としても使用することができる。例えば、アルミナ、ジルコニア、チタニア、シリカなどの無機粉末である粒子状担体上に、浸漬法や共沈法などの手段により、本発明に係る触媒を担持させ、触媒を担持させた無機粉末を上記の耐熱性セラミックス、またはステンレス鋼上に設置し使用することも好ましい。
The above ceramics and metals can also be used as a carrier for an oxidation catalyst. For example, on a particulate carrier that is an inorganic powder such as alumina, zirconia, titania, silica, etc., the catalyst according to the present invention is supported by means such as a dipping method or a coprecipitation method, and the inorganic powder supporting the catalyst is used as described above It is also preferable to install and use on heat resistant ceramics or stainless steel.
以下、実施例により本発明を説明する。ただし、これらは単なる実施の態様の一例であり、本発明の技術的範囲がこれら実施例に限定されたり、また、これにより限定的に解釈されたりするものではない。
Hereinafter, the present invention will be described with reference to examples. However, these are merely examples of embodiments, and the technical scope of the present invention is not limited to these examples, and is not construed as being limited thereto.
[実施例1]
撹拌機を備えた1L(リットル)ビーカー中で、Ce:Sm:Agがモル比で4:1:5となるように、酢酸セリウム6.70g、酢酸サマリウム1.99g、酢酸銀4.17gと乳酸18.01g(酢酸セリウム中のセリウムのモル数と、酢酸サマリウム中のサマリウムのモル数と、酢酸銀中の銀のモル数との合計量に対して4倍のモル量に相当する。)に500mLのイオン交換水を加え、設定温度を80℃とし、15分間撹拌した。その結果、酢酸セリウムと酢酸サマリウムおよび酢酸銀は、完全に溶解し、溶液状態になった。溶解を確認した後、同様の設定温度でさらに1時間撹拌を継続した。 [Example 1]
In a 1 L (liter) beaker equipped with a stirrer, 6.70 g of cerium acetate, 1.99 g of samarium acetate, and 4.17 g of silver acetate were used so that Ce: Sm: Ag was 4: 1: 5 in molar ratio. 18.01 g of lactic acid (corresponds to a molar amount four times the total amount of cerium in cerium acetate, samarium in samarium acetate, and silver in silver acetate) 500 mL of ion-exchanged water was added to the solution, and the set temperature was 80 ° C., followed by stirring for 15 minutes. As a result, cerium acetate, samarium acetate, and silver acetate were completely dissolved into a solution state. After confirming dissolution, stirring was continued for another hour at the same set temperature.
撹拌機を備えた1L(リットル)ビーカー中で、Ce:Sm:Agがモル比で4:1:5となるように、酢酸セリウム6.70g、酢酸サマリウム1.99g、酢酸銀4.17gと乳酸18.01g(酢酸セリウム中のセリウムのモル数と、酢酸サマリウム中のサマリウムのモル数と、酢酸銀中の銀のモル数との合計量に対して4倍のモル量に相当する。)に500mLのイオン交換水を加え、設定温度を80℃とし、15分間撹拌した。その結果、酢酸セリウムと酢酸サマリウムおよび酢酸銀は、完全に溶解し、溶液状態になった。溶解を確認した後、同様の設定温度でさらに1時間撹拌を継続した。 [Example 1]
In a 1 L (liter) beaker equipped with a stirrer, 6.70 g of cerium acetate, 1.99 g of samarium acetate, and 4.17 g of silver acetate were used so that Ce: Sm: Ag was 4: 1: 5 in molar ratio. 18.01 g of lactic acid (corresponds to a molar amount four times the total amount of cerium in cerium acetate, samarium in samarium acetate, and silver in silver acetate) 500 mL of ion-exchanged water was added to the solution, and the set temperature was 80 ° C., followed by stirring for 15 minutes. As a result, cerium acetate, samarium acetate, and silver acetate were completely dissolved into a solution state. After confirming dissolution, stirring was continued for another hour at the same set temperature.
得られた溶液を90℃に設定した乾燥機で乾燥し、見かけ上液体としての水分がなくなるまで水分を除去した。得られた乾燥物に500mLのイオン交換水を加え、常温で乾燥物を再溶解した後、その溶液を190℃に設定したマントルヒーターで6時間乾燥し、乾燥粉末を得た。その後、乾燥粉末をアルミナ製の匣鉢に移し、空気中にて400℃で6時間保持して焼成した。なお、室温から400℃までの昇温速度、および400℃から室温までの降温速度は、共に120℃/時とした。得られた焼成物を乳鉢で解砕し、Ce0.8Sm0.2O2-δ(δ=0.1)の組成を有する複合酸化物と銀とを含む灰色の粉末を得た。当該灰色の粉末を「カーボン燃焼触媒A」とし、粉末中の複合酸化物を「複合酸化物a」とする。
The obtained solution was dried with a drier set at 90 ° C., and moisture was removed until apparently no moisture as a liquid disappeared. 500 mL of ion-exchanged water was added to the obtained dried product, and the dried product was redissolved at room temperature, and then the solution was dried with a mantle heater set at 190 ° C. for 6 hours to obtain a dried powder. Thereafter, the dried powder was transferred to an alumina sagger, and fired in air at 400 ° C. for 6 hours. The rate of temperature increase from room temperature to 400 ° C. and the rate of temperature decrease from 400 ° C. to room temperature were both 120 ° C./hour. The obtained fired product was pulverized in a mortar to obtain a gray powder containing silver and a composite oxide having a composition of Ce 0.8 Sm 0.2 O 2-δ (δ = 0.1). The gray powder is referred to as “carbon combustion catalyst A”, and the composite oxide in the powder is referred to as “composite oxide a”.
(X線回折測定)
カーボン燃焼触媒AのX線回折測定を行った。X線回折測定には、Rigaku社製のXRD測定装置(RINT2000)を使用した。40kV×40mAの出力のCuKα線をX線源とし、2°/分のスキャン速度で測定した。その結果、X線回折により、カーボン燃焼触媒Aは、複合酸化物aの結晶構造が蛍石型構造であり、酸化銀を含まず、銀は金属銀として存在していることが確認された。よって、カーボン燃焼触媒Aは、複合酸化物aと金属銀との混合物であることが確認された。 (X-ray diffraction measurement)
X-ray diffraction measurement of the carbon combustion catalyst A was performed. For X-ray diffraction measurement, an XRD measurement apparatus (RINT2000) manufactured by Rigaku was used. Measurement was performed at a scan rate of 2 ° / min using CuKα rays with an output of 40 kV × 40 mA as an X-ray source. As a result, it was confirmed by X-ray diffraction that the carbon combustion catalyst A had a fluorite-type structure in the composite oxide a, did not contain silver oxide, and silver was present as metallic silver. Therefore, it was confirmed that the carbon combustion catalyst A is a mixture of the composite oxide a and metallic silver.
カーボン燃焼触媒AのX線回折測定を行った。X線回折測定には、Rigaku社製のXRD測定装置(RINT2000)を使用した。40kV×40mAの出力のCuKα線をX線源とし、2°/分のスキャン速度で測定した。その結果、X線回折により、カーボン燃焼触媒Aは、複合酸化物aの結晶構造が蛍石型構造であり、酸化銀を含まず、銀は金属銀として存在していることが確認された。よって、カーボン燃焼触媒Aは、複合酸化物aと金属銀との混合物であることが確認された。 (X-ray diffraction measurement)
X-ray diffraction measurement of the carbon combustion catalyst A was performed. For X-ray diffraction measurement, an XRD measurement apparatus (RINT2000) manufactured by Rigaku was used. Measurement was performed at a scan rate of 2 ° / min using CuKα rays with an output of 40 kV × 40 mA as an X-ray source. As a result, it was confirmed by X-ray diffraction that the carbon combustion catalyst A had a fluorite-type structure in the composite oxide a, did not contain silver oxide, and silver was present as metallic silver. Therefore, it was confirmed that the carbon combustion catalyst A is a mixture of the composite oxide a and metallic silver.
(粒度分布測定)
カーボン燃焼触媒Aの粒度分布を測定した。少量のカーボン燃焼触媒Aを以下のようにイオン交換水に分散させて試料を調製した。分散剤として和光純薬社製の二リン酸ナトリウム十水和物を使用した濃度0.24重量%の水溶液を用いた。約0.05gのカーボン燃焼触媒Aと分散剤とイオン交換水とから全体が10mlとなるように分散液を調製し、超音波を照射したものを試料とした。測定には、HORIBA社製のレーザー回折/散乱式粒度分布装置(LA-920)を用いた。測定の直前に3分間出力30Wの超音波処理を施した。その結果、D50は11.0μmであった。 (Particle size distribution measurement)
The particle size distribution of the carbon combustion catalyst A was measured. A sample was prepared by dispersing a small amount of carbon combustion catalyst A in ion-exchanged water as follows. An aqueous solution having a concentration of 0.24% by weight using sodium diphosphate decahydrate manufactured by Wako Pure Chemical Industries, Ltd. was used as a dispersant. A dispersion was prepared from about 0.05 g of carbon combustion catalyst A, a dispersant, and ion-exchanged water so that the total volume was 10 ml, and a sample irradiated with ultrasonic waves was used as a sample. For the measurement, a laser diffraction / scattering particle size distribution apparatus (LA-920) manufactured by HORIBA was used. Immediately before the measurement, ultrasonic treatment with an output of 30 W was performed for 3 minutes. As a result, D 50 was 11.0 .mu.m.
カーボン燃焼触媒Aの粒度分布を測定した。少量のカーボン燃焼触媒Aを以下のようにイオン交換水に分散させて試料を調製した。分散剤として和光純薬社製の二リン酸ナトリウム十水和物を使用した濃度0.24重量%の水溶液を用いた。約0.05gのカーボン燃焼触媒Aと分散剤とイオン交換水とから全体が10mlとなるように分散液を調製し、超音波を照射したものを試料とした。測定には、HORIBA社製のレーザー回折/散乱式粒度分布装置(LA-920)を用いた。測定の直前に3分間出力30Wの超音波処理を施した。その結果、D50は11.0μmであった。 (Particle size distribution measurement)
The particle size distribution of the carbon combustion catalyst A was measured. A sample was prepared by dispersing a small amount of carbon combustion catalyst A in ion-exchanged water as follows. An aqueous solution having a concentration of 0.24% by weight using sodium diphosphate decahydrate manufactured by Wako Pure Chemical Industries, Ltd. was used as a dispersant. A dispersion was prepared from about 0.05 g of carbon combustion catalyst A, a dispersant, and ion-exchanged water so that the total volume was 10 ml, and a sample irradiated with ultrasonic waves was used as a sample. For the measurement, a laser diffraction / scattering particle size distribution apparatus (LA-920) manufactured by HORIBA was used. Immediately before the measurement, ultrasonic treatment with an output of 30 W was performed for 3 minutes. As a result, D 50 was 11.0 .mu.m.
(比表面積測定)
カーボン燃焼触媒Aの窒素吸着法によるBET比表面積を測定した。測定には、マウンテック(Mountech)社製のMacsorb HM-1208を使用した。その結果、カーボン燃焼触媒AのBET比表面積は、22.8m2/gであった。 (Specific surface area measurement)
The BET specific surface area of the carbon combustion catalyst A by the nitrogen adsorption method was measured. For measurement, Macsorb HM-1208 manufactured by Mounttech was used. As a result, the BET specific surface area of the carbon combustion catalyst A was 22.8 m 2 / g.
カーボン燃焼触媒Aの窒素吸着法によるBET比表面積を測定した。測定には、マウンテック(Mountech)社製のMacsorb HM-1208を使用した。その結果、カーボン燃焼触媒AのBET比表面積は、22.8m2/gであった。 (Specific surface area measurement)
The BET specific surface area of the carbon combustion catalyst A by the nitrogen adsorption method was measured. For measurement, Macsorb HM-1208 manufactured by Mounttech was used. As a result, the BET specific surface area of the carbon combustion catalyst A was 22.8 m 2 / g.
東海カーボン社製のカーボンブラック(商品名:シーストFM)の5.0mgとカーボン燃焼触媒Aの100mgを秤量し、乳鉢で5分間混合し測定試料とした。
測定には、パーキンエルマー社製の熱重量分析計(PYRIS 1 TGA)を使用し、SHEATHガス側流量20ml/分、PURGEガス側流量40ml/分の乾燥空気雰囲気中で測定した。測定は、10℃/分の昇温速度で、30℃~700℃まで昇温する過程で行った。図1にカーボン燃焼触媒AのTG曲線を示す。TG曲線から接線法で求めた燃焼開始温度 Tigは219℃であり、TG曲線の一次微分曲線から求めたピーク温度 Tmは337℃であった。 5.0 mg of carbon black (trade name: Seast FM) manufactured by Tokai Carbon Co., Ltd. and 100 mg of carbon combustion catalyst A were weighed and mixed for 5 minutes in a mortar to obtain a measurement sample.
For the measurement, a thermogravimetric analyzer (PYRIS 1 TGA) manufactured by Perkin Elmer was used, and measurement was performed in a dry air atmosphere with a SHEATH gas side flow rate of 20 ml / min and a PURGE gas side flow rate of 40 ml / min. The measurement was performed in the process of increasing the temperature from 30 ° C. to 700 ° C. at a temperature increase rate of 10 ° C./min. FIG. 1 shows a TG curve of the carbon combustion catalyst A. The combustion start temperature Tig determined from the TG curve by the tangential method was 219 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 337 ° C.
測定には、パーキンエルマー社製の熱重量分析計(PYRIS 1 TGA)を使用し、SHEATHガス側流量20ml/分、PURGEガス側流量40ml/分の乾燥空気雰囲気中で測定した。測定は、10℃/分の昇温速度で、30℃~700℃まで昇温する過程で行った。図1にカーボン燃焼触媒AのTG曲線を示す。TG曲線から接線法で求めた燃焼開始温度 Tigは219℃であり、TG曲線の一次微分曲線から求めたピーク温度 Tmは337℃であった。 5.0 mg of carbon black (trade name: Seast FM) manufactured by Tokai Carbon Co., Ltd. and 100 mg of carbon combustion catalyst A were weighed and mixed for 5 minutes in a mortar to obtain a measurement sample.
For the measurement, a thermogravimetric analyzer (PYRIS 1 TGA) manufactured by Perkin Elmer was used, and measurement was performed in a dry air atmosphere with a SHEATH gas side flow rate of 20 ml / min and a PURGE gas side flow rate of 40 ml / min. The measurement was performed in the process of increasing the temperature from 30 ° C. to 700 ° C. at a temperature increase rate of 10 ° C./min. FIG. 1 shows a TG curve of the carbon combustion catalyst A. The combustion start temperature Tig determined from the TG curve by the tangential method was 219 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 337 ° C.
[実施例2]
実施例1の酢酸サマリウム1.99gの代わりに、酢酸ガドリニウム2.03gを使用した以外は、実施例1と同様にしてCe0.8Gd0.2O2-δ(δ=0.1)と銀とを含む灰色の粉末を得た。当該灰色の粉末を「カーボン燃焼触媒B」とし、粉末中の複合酸化物を「複合酸化物b」とする。 [Example 2]
Ce 0.8 Gd 0.2 O 2-δ (δ = 0.1) in the same manner as in Example 1 except that 2.03 g of gadolinium acetate was used instead of 1.99 g of samarium acetate of Example 1. A gray powder containing silver and silver was obtained. The gray powder is referred to as “carbon combustion catalyst B”, and the composite oxide in the powder is referred to as “composite oxide b”.
実施例1の酢酸サマリウム1.99gの代わりに、酢酸ガドリニウム2.03gを使用した以外は、実施例1と同様にしてCe0.8Gd0.2O2-δ(δ=0.1)と銀とを含む灰色の粉末を得た。当該灰色の粉末を「カーボン燃焼触媒B」とし、粉末中の複合酸化物を「複合酸化物b」とする。 [Example 2]
Ce 0.8 Gd 0.2 O 2-δ (δ = 0.1) in the same manner as in Example 1 except that 2.03 g of gadolinium acetate was used instead of 1.99 g of samarium acetate of Example 1. A gray powder containing silver and silver was obtained. The gray powder is referred to as “carbon combustion catalyst B”, and the composite oxide in the powder is referred to as “composite oxide b”.
カーボン燃焼触媒BのX線回折測定を実施例1と同様にして行った。その結果、複合酸化物bの結晶構造は蛍石型構造であり、カーボン燃焼触媒Bは、複合酸化物bと金属銀の混合物であることが確認された。
次いで、カーボン燃焼触媒Bの粒度分布測定、および比表面積測定を実施例1と同様にして行った。その結果、カーボン燃焼触媒BのD50は11.0μmであり、比表面積は20.1m2/gであった。
また、カーボン燃焼触媒BのTG測定を実施例1と同様にして行った。TG曲線から接線法で求めた燃焼開始温度 Tigは247℃であり、TG曲線の一次微分曲線から求めたピーク温度 Tmは363℃であった。 X-ray diffraction measurement of the carbon combustion catalyst B was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide b was a fluorite structure, and the carbon combustion catalyst B was a mixture of the composite oxide b and metallic silver.
Subsequently, the particle size distribution measurement and specific surface area measurement of the carbon combustion catalyst B were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst B is 11.0 .mu.m, a specific surface area of 20.1m 2 / g.
Further, TG measurement of the carbon combustion catalyst B was performed in the same manner as in Example 1. The combustion start temperature Tig determined from the TG curve by the tangential method was 247 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 363 ° C.
次いで、カーボン燃焼触媒Bの粒度分布測定、および比表面積測定を実施例1と同様にして行った。その結果、カーボン燃焼触媒BのD50は11.0μmであり、比表面積は20.1m2/gであった。
また、カーボン燃焼触媒BのTG測定を実施例1と同様にして行った。TG曲線から接線法で求めた燃焼開始温度 Tigは247℃であり、TG曲線の一次微分曲線から求めたピーク温度 Tmは363℃であった。 X-ray diffraction measurement of the carbon combustion catalyst B was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide b was a fluorite structure, and the carbon combustion catalyst B was a mixture of the composite oxide b and metallic silver.
Subsequently, the particle size distribution measurement and specific surface area measurement of the carbon combustion catalyst B were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst B is 11.0 .mu.m, a specific surface area of 20.1m 2 / g.
Further, TG measurement of the carbon combustion catalyst B was performed in the same manner as in Example 1. The combustion start temperature Tig determined from the TG curve by the tangential method was 247 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 363 ° C.
[実施例3]
Ce:Sm:Agがモル比で4:1:3となるように、酢酸銀2.50gを使用し、乳酸28.82g(酢酸セリウム中のセリウムモル数と、酢酸サマリウム中のサマリウムのモル数と、酢酸銀中の銀のモル数との合計に対して8倍のモル量に相当する。)を使用し、焼成温度を600℃とした以外は、実施例1と同様にしてCe0.8Sm0.2O2-δ(δ=0.1)と銀とを含む灰色の粉末を得た。当該灰色の粉末を「カーボン燃焼触媒C」とし、粉末中の複合酸化物を「複合酸化物c」とする。 [Example 3]
Silver acetate 2.50g was used so that Ce: Sm: Ag might be molar ratio 4: 1: 3, 28.82g of lactic acid (the number of cerium in cerium acetate, and the number of moles of samarium in samarium acetate) corresponds to 8 times the molar amount relative to the sum of the moles of silver acetate in silver.) using the sintering temperature except for using 600 ° C., Ce 0.8 in the same manner as in example 1 A gray powder containing Sm 0.2 O 2-δ (δ = 0.1) and silver was obtained. The gray powder is referred to as “carbon combustion catalyst C”, and the composite oxide in the powder is referred to as “composite oxide c”.
Ce:Sm:Agがモル比で4:1:3となるように、酢酸銀2.50gを使用し、乳酸28.82g(酢酸セリウム中のセリウムモル数と、酢酸サマリウム中のサマリウムのモル数と、酢酸銀中の銀のモル数との合計に対して8倍のモル量に相当する。)を使用し、焼成温度を600℃とした以外は、実施例1と同様にしてCe0.8Sm0.2O2-δ(δ=0.1)と銀とを含む灰色の粉末を得た。当該灰色の粉末を「カーボン燃焼触媒C」とし、粉末中の複合酸化物を「複合酸化物c」とする。 [Example 3]
Silver acetate 2.50g was used so that Ce: Sm: Ag might be molar ratio 4: 1: 3, 28.82g of lactic acid (the number of cerium in cerium acetate, and the number of moles of samarium in samarium acetate) corresponds to 8 times the molar amount relative to the sum of the moles of silver acetate in silver.) using the sintering temperature except for using 600 ° C., Ce 0.8 in the same manner as in example 1 A gray powder containing Sm 0.2 O 2-δ (δ = 0.1) and silver was obtained. The gray powder is referred to as “carbon combustion catalyst C”, and the composite oxide in the powder is referred to as “composite oxide c”.
カーボン燃焼触媒CのX線回折測定を実施例1と同様にして行った。その結果、複合酸化物cの結晶構造は蛍石型構造であり、カーボン燃焼触媒Cは、複合酸化物cと金属銀の混合物であることが確認された。
次いで、カーボン燃焼触媒Cの粒度分布測定、および比表面積測定を実施例1と同様にして行った。その結果、カーボン燃焼触媒CのD50は12.1μmであり、比表面積は18.5m2/gであった。
また、カーボン燃焼触媒CのTG測定を実施例1と同様にして行った。TG曲線から接線法で求めた燃焼開始温度 Tigは227℃であり、TG曲線の一次微分曲線から求めたピーク温度 Tmは346℃であった。 X-ray diffraction measurement of the carbon combustion catalyst C was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide c was a fluorite structure, and the carbon combustion catalyst C was a mixture of the composite oxide c and metallic silver.
Subsequently, the particle size distribution measurement and the specific surface area measurement of the carbon combustion catalyst C were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst C is 12.1Myuemu, a specific surface area of 18.5 m 2 / g.
Further, TG measurement of the carbon combustion catalyst C was performed in the same manner as in Example 1. The combustion start temperature Tig determined from the TG curve by the tangential method was 227 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 346 ° C.
次いで、カーボン燃焼触媒Cの粒度分布測定、および比表面積測定を実施例1と同様にして行った。その結果、カーボン燃焼触媒CのD50は12.1μmであり、比表面積は18.5m2/gであった。
また、カーボン燃焼触媒CのTG測定を実施例1と同様にして行った。TG曲線から接線法で求めた燃焼開始温度 Tigは227℃であり、TG曲線の一次微分曲線から求めたピーク温度 Tmは346℃であった。 X-ray diffraction measurement of the carbon combustion catalyst C was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide c was a fluorite structure, and the carbon combustion catalyst C was a mixture of the composite oxide c and metallic silver.
Subsequently, the particle size distribution measurement and the specific surface area measurement of the carbon combustion catalyst C were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst C is 12.1Myuemu, a specific surface area of 18.5 m 2 / g.
Further, TG measurement of the carbon combustion catalyst C was performed in the same manner as in Example 1. The combustion start temperature Tig determined from the TG curve by the tangential method was 227 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 346 ° C.
[比較例1]
撹拌機を備えた1L(リットル)ビーカー中で、Ce:Smがモル比で4:1になるように、炭酸セリウム56.8gと炭酸サマリウム11.1gを100mLのイオン交換水に加えて得られた懸濁液に、炭酸アンモニウム99.0gとクエン酸131.5gを加え、設定温度を80℃とし2時間撹拌を継続した。この懸濁液の撹拌を続けながら、Ce:Sm:Agがモル比で4:1:5となるように、炭酸銀28.6gとクエン酸29.0gを懸濁液に投入し、さらに2時間撹拌を継続して、セリウムとサマリウムおよび銀を含むスラリーを得た。 [Comparative Example 1]
Obtained by adding 56.8 g of cerium carbonate and 11.1 g of samarium carbonate to 100 mL of ion-exchanged water in a 1 L (liter) beaker equipped with a stirrer so that Ce: Sm is a molar ratio of 4: 1. To this suspension, 99.0 g of ammonium carbonate and 131.5 g of citric acid were added, the set temperature was 80 ° C., and stirring was continued for 2 hours. While continuing to stir the suspension, 28.6 g of silver carbonate and 29.0 g of citric acid were added to the suspension so that the Ce: Sm: Ag molar ratio was 4: 1: 5. Stirring was continued for a time to obtain a slurry containing cerium, samarium and silver.
撹拌機を備えた1L(リットル)ビーカー中で、Ce:Smがモル比で4:1になるように、炭酸セリウム56.8gと炭酸サマリウム11.1gを100mLのイオン交換水に加えて得られた懸濁液に、炭酸アンモニウム99.0gとクエン酸131.5gを加え、設定温度を80℃とし2時間撹拌を継続した。この懸濁液の撹拌を続けながら、Ce:Sm:Agがモル比で4:1:5となるように、炭酸銀28.6gとクエン酸29.0gを懸濁液に投入し、さらに2時間撹拌を継続して、セリウムとサマリウムおよび銀を含むスラリーを得た。 [Comparative Example 1]
Obtained by adding 56.8 g of cerium carbonate and 11.1 g of samarium carbonate to 100 mL of ion-exchanged water in a 1 L (liter) beaker equipped with a stirrer so that Ce: Sm is a molar ratio of 4: 1. To this suspension, 99.0 g of ammonium carbonate and 131.5 g of citric acid were added, the set temperature was 80 ° C., and stirring was continued for 2 hours. While continuing to stir the suspension, 28.6 g of silver carbonate and 29.0 g of citric acid were added to the suspension so that the Ce: Sm: Ag molar ratio was 4: 1: 5. Stirring was continued for a time to obtain a slurry containing cerium, samarium and silver.
得られたスラリーを105℃に設定した乾燥機で一昼夜乾燥し、水分を除去して得られた乾燥物をアルミナ製の匣鉢に移し、保持する焼成時間を10時間とした他は実施例1と同様にして焼成した。得られた焼成物を乳鉢で解砕し、Ce0.8Sm0.2O2-δ(δ=0.1)の組成を有する複合酸化物と銀とを含む灰色の粉末を得た。当該灰色の粉末を「カーボン燃焼触媒D」とし、粉末中の複合酸化物を「複合酸化物d」とする。
The obtained slurry was dried for a whole day and night in a drier set at 105 ° C., and the dried product obtained by removing moisture was transferred to an alumina mortar, and the calcining time for holding was 10 hours. It fired in the same manner. The obtained fired product was pulverized in a mortar to obtain a gray powder containing silver and a composite oxide having a composition of Ce 0.8 Sm 0.2 O 2-δ (δ = 0.1). The gray powder is referred to as “carbon combustion catalyst D”, and the composite oxide in the powder is referred to as “composite oxide d”.
カーボン燃焼触媒DのX線回折測定を実施例1と同様にして行った。その結果、複合酸化物dの結晶構造は蛍石型構造であり、カーボン燃焼触媒Dは、複合酸化物dと金属銀の混合物であることが確認された。
次いで、カーボン燃焼触媒Dの粒度分布測定、および比表面積測定を実施例1と同様にして行った。その結果、カーボン燃焼触媒DのD50は3.0μmであり、比表面積は61.6m2/gであった。
また、カーボン燃焼触媒DのTG測定を実施例1と同様にして行った。図1にカーボン燃焼触媒CのTG曲線を示す。TG曲線から接線法で求めた燃焼開始温度 Tigは257℃であり、TG曲線の一次微分曲線から求めたピーク温度Tmは379℃であった。 X-ray diffraction measurement of the carbon combustion catalyst D was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide d was a fluorite structure, and the carbon combustion catalyst D was a mixture of the composite oxide d and metallic silver.
Subsequently, the particle size distribution measurement and specific surface area measurement of the carbon combustion catalyst D were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst D is 3.0 [mu] m, a specific surface area of 61.6m 2 / g.
Further, TG measurement of the carbon combustion catalyst D was performed in the same manner as in Example 1. FIG. 1 shows a TG curve of the carbon combustion catalyst C. The combustion start temperature Tig determined from the TG curve by the tangential method was 257 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 379 ° C.
次いで、カーボン燃焼触媒Dの粒度分布測定、および比表面積測定を実施例1と同様にして行った。その結果、カーボン燃焼触媒DのD50は3.0μmであり、比表面積は61.6m2/gであった。
また、カーボン燃焼触媒DのTG測定を実施例1と同様にして行った。図1にカーボン燃焼触媒CのTG曲線を示す。TG曲線から接線法で求めた燃焼開始温度 Tigは257℃であり、TG曲線の一次微分曲線から求めたピーク温度Tmは379℃であった。 X-ray diffraction measurement of the carbon combustion catalyst D was performed in the same manner as in Example 1. As a result, it was confirmed that the crystal structure of the composite oxide d was a fluorite structure, and the carbon combustion catalyst D was a mixture of the composite oxide d and metallic silver.
Subsequently, the particle size distribution measurement and specific surface area measurement of the carbon combustion catalyst D were performed in the same manner as in Example 1. As a result, D 50 carbon combustion catalyst D is 3.0 [mu] m, a specific surface area of 61.6m 2 / g.
Further, TG measurement of the carbon combustion catalyst D was performed in the same manner as in Example 1. FIG. 1 shows a TG curve of the carbon combustion catalyst C. The combustion start temperature Tig determined from the TG curve by the tangential method was 257 ° C., and the peak temperature Tm determined from the first derivative curve of the TG curve was 379 ° C.
カーボン燃焼触媒Aとカーボン燃焼触媒DのTG測定結果より求めた燃焼開始温度Tigとピーク温度Tmを比較すると、両者は同一組成であるにも拘らず、カーボン燃焼開始温度とピーク温度はともに、実施例1の製造方法で製造したカーボン燃焼触媒Aの方が低い値を示している。したがって、カーボン燃焼触媒AをDPFに使用した方が、フィルターに捕集されたカーボンを主成分とする浮遊粒子状物質は、より低温で燃焼し始めることになる。これは、乳酸を使用した実施例1の製造方法では、原料粉末が完全に溶媒である水に溶解するので、生成物である複合酸化物中で、セリウムとサマリウムが均一に分布しているためであると考えられる。
Comparing the combustion start temperature Tig and the peak temperature Tm obtained from the TG measurement results of the carbon combustion catalyst A and the carbon combustion catalyst D, both the carbon combustion start temperature and the peak temperature were implemented even though they were the same composition. The carbon combustion catalyst A produced by the production method of Example 1 shows a lower value. Therefore, when the carbon combustion catalyst A is used for the DPF, the suspended particulate matter mainly composed of carbon collected by the filter starts to burn at a lower temperature. This is because, in the manufacturing method of Example 1 using lactic acid, since the raw material powder is completely dissolved in water as a solvent, cerium and samarium are uniformly distributed in the composite oxide as a product. It is thought that.
本発明に係る乳酸を使用した製造方法により得られる排気ガス浄化用触媒は、カーボン燃焼開始温度およびピーク温度が低く、ディーゼル燃料を用いる内燃機関の排気ガス浄化触媒として有用である。
なお、2010年11月30日に出願された日本特許出願2010-267451号の明細書、特許請求の範囲、図面及び要約書の全内容をここに引用し、本発明の明細書の開示として、取り入れるものである。 The exhaust gas purifying catalyst obtained by the production method using lactic acid according to the present invention has a low carbon combustion start temperature and peak temperature, and is useful as an exhaust gas purifying catalyst for an internal combustion engine using diesel fuel.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2010-267451 filed on November 30, 2010 are cited herein as disclosure of the specification of the present invention. Incorporated.
なお、2010年11月30日に出願された日本特許出願2010-267451号の明細書、特許請求の範囲、図面及び要約書の全内容をここに引用し、本発明の明細書の開示として、取り入れるものである。 The exhaust gas purifying catalyst obtained by the production method using lactic acid according to the present invention has a low carbon combustion start temperature and peak temperature, and is useful as an exhaust gas purifying catalyst for an internal combustion engine using diesel fuel.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2010-267451 filed on November 30, 2010 are cited herein as disclosure of the specification of the present invention. Incorporated.
Claims (10)
- (A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物とを、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物とを、乳酸の水溶液で溶解して溶液を製造する溶解工程と、
前記溶液を乾燥焼成する乾燥焼成工程とを有することを特徴とする、セリウムとセリウムを除く希土類元素とを含有する複合酸化物と銀および/または銀の酸化物とを含む排気ガス浄化用触媒の製造方法。 (A) A silver-containing compound, a cerium-containing compound, and a rare-earth element-containing compound excluding cerium, or (B) a silver-containing compound and a rare-earth element-containing compound excluding cerium and cerium are dissolved in an aqueous solution of lactic acid. A dissolution process for producing the solution,
An exhaust gas purifying catalyst comprising a composite oxide containing cerium and a rare earth element excluding cerium and silver and / or a silver oxide, characterized by comprising a drying and firing step for drying and firing the solution. Production method. - 前記複合酸化物が、LnxCe1-xO2-δ(但し、Lnは、セリウムを除く希土類元素から選ばれる少なくとも1種の元素を示し、xは、0<x<0.5であり、δは、酸素欠損量を示し、0<δ<0.25である。)で表される請求項1に記載の排気ガス浄化用触媒の製造方法。 The composite oxide is Ln x Ce 1-x O 2-δ (where Ln represents at least one element selected from rare earth elements excluding cerium, and x is 0 <x <0.5) , Δ represents the amount of oxygen deficiency, and 0 <δ <0.25.) The method for producing an exhaust gas purifying catalyst according to claim 1.
- 銀含有化合物、セリウム含有化合物、およびセリウムを除く希土類元素含有化合物が、いずれも酢酸塩である請求項1または2に記載の排気ガス浄化用触媒の製造方法。 The method for producing an exhaust gas purifying catalyst according to claim 1 or 2, wherein the silver-containing compound, the cerium-containing compound, and the rare-earth element-containing compound excluding cerium are all acetates.
- セリウムを除く希土類元素がサマリウムである請求項1~3のいずれか1項に記載の排気ガス浄化用触媒の製造方法。 The method for producing an exhaust gas purification catalyst according to any one of claims 1 to 3, wherein the rare earth element excluding cerium is samarium.
- 前記乾燥焼成工程の後、さらに解砕・粉砕工程を有する請求項1~4のいずれか1項に記載の排気ガス浄化用触媒の製造方法。 The method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 4, further comprising a crushing and pulverizing step after the drying and firing step.
- 前記乾燥焼成工程における焼成温度が、335~800℃である請求項1~5のいずれか1項に記載の排気ガス浄化用触媒の製造方法。 The method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 5, wherein a firing temperature in the drying and firing step is 335 to 800 ° C.
- セリウムとセリウムを除く希土類元素とを含有する複合酸化物に含まれるセリウムのモル数(Ce)とセリウムを除く希土類元素のモル数(Ln)との和である(Ce+Ln)に対する、銀および/または銀の酸化物に含まれる銀のモル数である(Ag)の比率を、(Ag)/(Ce+Ln)と表すとき、(Ag)/(Ce+Ln)が、1/9~9/1である請求項1~6のいずれか1項に記載の排気ガス浄化用触媒の製造方法。 Silver with respect to (Ce + Ln), which is the sum of the number of moles of cerium (Ce) and the number of moles of rare earth elements excluding cerium (Ln) contained in the composite oxide containing cerium and rare earth elements excluding cerium, and When the ratio of (Ag), which is the number of moles of silver contained in the silver oxide, is expressed as (Ag) / (Ce + Ln), (Ag) / (Ce + Ln) is 1/9 to The method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 6, wherein the ratio is 9/1.
- (A)銀含有化合物と、セリウム含有化合物と、セリウムを除く希土類元素含有化合物、または(B)銀含有化合物と、セリウムおよびセリウムを除く希土類元素含有化合物に含まれる、銀のモル数をAgm、セリウムのモル数をCem、及びセリウムを除く希土類元素のモル数をLnmと表し、乳酸の水溶液に含まれる乳酸のモル数をLamと表すとき、Lam/(Agm+Cem+Lnm)が、10/1~0.1/1である請求項1~7のいずれか1項に記載の排気ガス浄化用触媒の製造方法。 (A) and the silver-containing compound, a cerium-containing compound, rare earth-containing compound excluding cerium, or (B) a silver-containing compound, contained in the rare earth-containing compound excluding cerium and cerium, the number of moles of silver Ag m represents the number of moles of cerium Ce m, and the number of moles of rare earth elements excluding cerium and Ln m, to represent the number of moles of lactic acid contained in the aqueous solution of lactic acid and La m, La m / (Ag m + Ce m The method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 7, wherein + Ln m ) is 10/1 to 0.1 / 1.
- 銀および/または銀の酸化物に含まれる金属銀の含有率が70~100モル%である請求項1~8のいずれか1項に記載の排気ガス浄化用触媒の製造方法。 The method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 8, wherein the content of metallic silver contained in silver and / or silver oxide is 70 to 100 mol%.
- 請求項1~9のいずれかの製造方法で製造された触媒を、フィルター媒体に担持させたことを特徴とする排気ガス浄化装置。 An exhaust gas purifying apparatus, wherein the catalyst produced by the production method according to any one of claims 1 to 9 is supported on a filter medium.
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