JP3758466B2 - Method for producing exhaust gas purifying catalyst - Google Patents

Description

【００４２】
【表２】

【００４３】
表２に示した結果より、酒石酸塩の状態でウォッシュコートした実施例１〜８は、酢酸カリウム、炭酸カリウム、又は硝酸バリウムの状態でウォッシュコートした比較例１〜４よりも、明らかにＮＯ_X 浄化率が向上し、スラリーに溶出したＮＯ_X 吸蔵剤が明らかに少ないことが分かる。
また、酒石酸／吸蔵元素のモル比を３以上にすれば、ＮＯ_X 溶出は、実質的に完全に抑えられることが分かる。
【００４４】
【発明の効果】
ウォッシュコート時にＮＯ_X 吸蔵剤の溶出を防ぐことができ、ＮＯ_X 吸蔵剤が原子レベルで触媒成分に付着することによる触媒性能の低下が解消できる。
【図面の簡単な説明】
【図１】本発明の方法によって得られる排気ガス浄化用触媒のモデル図である。
【図２】本発明の方法によって得られる排気ガス浄化用触媒のモデル図である。
【図３】本発明の方法によって得られる排気ガス浄化用触媒のモデル図である。
【図４】本発明の方法によって得られる排気ガス浄化用触媒のモデル図である。
【図５】本発明の方法によって得られる排気ガス浄化用触媒のモデル図である。
【符号の説明】
１…ＮＯ_X 吸蔵剤
２…触媒成分
３…モノリス基材
４…ＮＯ_X 吸蔵剤と触媒成分の混合粒子
５…付加的触媒成分[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an exhaust gas purification catalyst for purifying exhaust gas discharged from an internal combustion engine such as an automobile, and more particularly to a method for producing a NO _x storage reduction catalyst by washcoat.
[0002]
[Prior art]
As countermeasures for automobile exhaust gas regulations and fuel consumption regulations, it has been proved that a NO _x storage reduction catalyst in which a function of storing NO _x is added to a conventional three-way catalyst is effective.
[0003]
This _the NO _X storage reduction catalyst occludes NO _X under lean oxidizing atmosphere, it was released under a reducing atmosphere temporary stoichiometric-rich, NO by the action of the reducing atmosphere and the catalyst component _Reduce and purify _X.
As the NO _x storage agent, an alkali metal, an alkaline earth metal, or both of these metals are used. As the catalyst component, noble metals such as platinum, gold, ruthenium, rhodium and palladium are used.
Here, if _the NO _X storage agent and catalyst components are mixed in the micro, _the NO _X storage agent reduces the redox capability of the catalyst components, it promotes the sintering of the catalyst components, thereby reducing the purification performance of the catalyst It has been found that
[0004]
For this reason, the present applicant, as an improved NO _x storage reduction catalyst, disclosed in Japanese Patent Application Laid-Open No. 10-258232, is a core portion containing a NO _x storage agent and a catalyst support layer formed on the surface of the core portion. The catalyst which has the microstructure which consists of is proposed.
Exhaust gas purifying catalyst, since _the NO _X storage agent is present near the catalyst component, NO _X catalyst released from _the NO _X storage agent according _the NO _X storage agent and a catalyst component having a microphase separated structure While being effectively reduced by the components, it is possible to suppress a decrease in the catalyst performance as described above due to the action of the NO _x storage agent.
[0005]
Conventionally, the production of a NO _x storage-reduction catalyst having such a microstructure has been carried out, for example, as described in JP-A-7-171399 on a carrier on which a carbonate NO _x storage agent is supported. It has been carried out by wash-coating an aqueous slurry containing components and a binder in a water medium, followed by drying and firing.
[0006]
[Problems to be solved by the invention]
However, during this wash coating, in the carbonate state, a part of the NO _x storage agent elutes in the medium water, so the NO _x storage agent adheres to the catalyst component at the atomic level, and the NO _x storage agent. Has been found to reduce the purification performance of the catalyst.
Therefore, the present invention prevents the elution of the NO _X storage agent during such wash coating, and manufactures a NO _X storage reduction catalyst in which both the NO _X storage agent and the catalyst component are present in the vicinity, but both are separated microscopically. It aims to provide a method.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, there is provided a method for producing an exhaust gas purifying catalyst containing at least one of an alkali metal and an alkaline earth metal as a NO _x storage agent, wherein the NO _x storage agent is brought into contact with tartaric acid to produce tartaric acid. There is provided a method for producing an exhaust gas purifying catalyst, characterized in that after the salt is formed, the tartrate salt is washed on a monolith substrate using water as a medium .
[0008]
In the present invention, a water-soluble NO _x storage agent is brought into contact with tartaric acid to form a tartrate salt, and then this tartaric acid salt is wash-coated on a monolith substrate.
Alkali metal or alkaline earth metal water-soluble carbonates and acetates, when contacted with tartaric acid, are easily converted to tartrate at room temperature, and this tartaric acid salt is hardly soluble in water. _X Occlusion agent does not elute into aqueous media. Therefore, it is possible to prevent _the NO _X storage agent adheres to the catalyst component eluted.
[0009]
Further, when the tartrate salt is heated to about 180 ° C. or higher, the organic group is scattered, and the oxide, hydroxide, or the like that can exhibit the NO _X storage ability is obtained. Since the manufacturing process of the exhaust gas purifying catalyst generally includes a calcination process of 500 ° C. or higher, it is not necessary to provide the process of scattering the organic group of the tartrate salt.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, at least one of an alkali metal and an alkaline earth metal is used as the NO _x storage agent. Examples of the NO _X storage agent include lithium, sodium, potassium, rubidium, cesium, francium, beryllium, magnesium, calcium, strontium, and barium.
These NO _X storage agents are water-soluble in the form of acetates, carbonates, nitrates, and the like, and if these aqueous solutions are used, the operation of impregnating the carrier is easy and can be uniformly supported on the carrier. .
[0011]
In the present invention, these water-soluble NO _x storage agents are brought into contact with tartaric acid to form a poorly water-soluble tartrate salt, and then the tartaric acid salt is washed to a monolith substrate such as a cordierite honeycomb carrier substrate. Coat. The NO _x storage agent can be brought into contact with this tartaric acid, for example, by simply bringing the NO _x storage agent supported on the carrier into contact with the tartaric acid aqueous solution.
[0012]
The exhaust gas purifying catalyst produced by the method of the present invention contains catalyst components such as platinum, gold, ruthenium, rhodium, palladium, etc., and these catalyst components and NO _x storage agent are monolithic in some embodiments. It can be supported on a substrate.
[0013]
Hereinafter, these aspects will be described with reference to the accompanying drawings.
1-5 illustrate various aspects that can be implemented using the method of the present invention.
FIG. 1 shows an embodiment in which the NO _x storage agent 1 is surrounded by the outer layer of the catalyst component 2.
In this embodiment, a powder composed of particles in which the tartrate salt of the NO _x storage agent is formed on the inside and the catalyst component layer is present on the outside is made into an aqueous slurry using water as a medium, and a binder is added if necessary. Wash it with a coat. By drying and firing, the catalyst component and the NO _x storage agent are fixed to the monolith substrate, and at the same time, the organic group of the tartrate salt of the NO _x storage agent is scattered to obtain the NO _x storage reduction catalyst. .
[0014]
Inside of the NO _X occluding agent can be present only in _the NO _X storage agent, preferably supported on a carrier. This is because the direct contact between the NO _X storage agent and the outside catalyst component can be more effectively prevented. Suitable carriers include alumina, titania, zirconia, include fine powders such as silica, for example, acetates of the NO _X absorbent, impregnated carbonate, an aqueous solution of nitrate into a fine powder of the bearing.
Here, as an example of a method for carrying the NO _X storage agent extremely uniformly and finely, an aqueous solution of NO _X storage agent such as acetate, carbonate, nitrate, etc. is mixed with alumina sol, and the alumina sol is gelled by hydrolysis. Next, the method of drying is mentioned.
[0015]
The catalyst component is preferably present in a state where it is supported on a carrier made of a fine powder of alumina, titania, zirconia, silica or the like. It is possible to prevent direct contact between the catalyst component and _the NO _X storage agent, it is also because catalytic performance surface area of the catalyst component is high is further improved.
The catalyst component layer supported on the outer carrier is, for example, prepared by mixing an aqueous solution of the catalyst component with the carrier fine powder to form a slurry, and coating the slurry on the NO _X storage agent and drying the slurry. Can be formed.
Here, as an example of a method for supporting the catalyst component on the carrier extremely uniformly and finely, an aqueous solution of the catalyst component is mixed with an alumina sol in the same manner as in the case of the NO _X storage agent, and this is mixed with the above NO _X storage agent. And alumina is gelled by hydrolysis and then dried.
[0016]
In order to convert the NO _x storage agent supported in the form of a water-soluble acetate or the like into a water-insoluble tartrate salt, the acetate salt or the like can be simply brought into contact with a tartaric acid aqueous solution. This step can be performed at any stage before and after the formation of the catalyst component layer on the NO _x storage agent. In either case, the step can be performed by dipping or impregnating in an aqueous tartaric acid solution at room temperature. it can.
[0017]
FIG. 2 shows an embodiment in which the NO _x storage agent 1 and the catalyst component 2 form separate particles.
In this embodiment, for example, NO _X storage agent particles and catalyst component particles are respectively prepared in the same manner as described in the embodiment of FIG. 1, and the powder obtained by mixing these particles is brought into contact with an aqueous tartaric acid solution. Change _X storage to tartrate.
Next, the powder is made into an aqueous slurry, and the monolith substrate 3 is wash-coated. Then, it is dried and fired.
[0018]
FIG. 3 shows an embodiment in which the NO _x storage agent 1 and the catalyst component 2 form a two-layer structure on the monolith substrate 3.
In this embodiment, for example, NO _X storage agent particles and catalyst component particles are produced in the same manner as described in the embodiment of FIG. Next, the NO _x storage agent particles are brought into contact with an aqueous tartaric acid solution, the NO _x storage agent is changed to a tartrate salt, washed on the monolith substrate, and the catalyst component particles made into an aqueous slurry are converted into the NO _x storage agent. Washcoat over the top. Then, it is dried and fired.
[0019]
FIG. 4 shows a mode in which the catalyst component and the NO _x storage agent coexist in one particle 4.
In this embodiment, for example, NO _X storage agent particles and catalyst component particles are produced in the same manner as described in the embodiment of FIG. Next, after mixing them, the mixed particles 4 having an appropriate size are brought into contact with an aqueous tartaric acid solution in that state.
Subsequently, it is made an aqueous slurry and wash-coated on a monolith substrate. Then, it is dried and fired.
[0020]
Figure 5 is a preferred embodiment to be added by using on of the NO _X absorbent and the catalyst component carried on the monolith substrate 3, an aqueous solution a further catalyst components by embodiments of FIGS. 1-4 .
Exposure to an aqueous solution without firing those states of FIGS. 1-4, may _the NO _X storage agent and the catalyst component particles are dispersed in an aqueous solution, Therefore, once fired to _the NO _X storage agent It is effective to fix them to a monolith. However, when exposed to an aqueous solution immediately after calcination, the NO _x storage agent changes from tartrate to oxide, so that it elutes into the aqueous solution.
[0021]
However, if the NO _x storage agent is changed to the tartrate again after firing, the elution of the NO _x storage agent can be prevented even when exposed to an aqueous solution.
Examples of such additional catalyst components include rhodium, iridium, etc., and after further converting the NO _X storage agent to a tartrate salt, these are further supported on the NO _X storage agent and the catalyst component in the form of an aqueous solution of these nitrates. can do.
[0022]
The size of each particle in the above description is not particularly limited in order to achieve the object of the present invention. However, in the embodiment shown in FIG. 1, the average of the maximum diameter and the minimum diameter (hereinafter “ The particle diameter is referred to as “particle diameter”.), And the size of the inner particle is 0.1 to 20 μm, and the thickness of the catalyst component layer 3 is 0.01 to 1 μm.
As for each particle | grain shown in FIGS. 2-5, as for the particle diameter, 0.1-20 micrometers is a standard for all, and the thickness of the additional catalyst component layer shown in FIG. 5 is 0.01-1 micrometers. This is a rough guide.
1 to 5 are model diagrams for facilitating understanding of the invention, and are not particularly limited to the shape, relative size, and positional relationship of the illustrated particles.
[0023]
Further, the present invention is, as to change some of the above embodiments, instead of contacting the aqueous solution of tartaric acid in the NO _X absorbent, already the use of _the NO _X storage agent in the state of tartrate, e.g. in is to form the catalyst component layer around the tartrate salt itself of the NO _X absorbent in place of the acetate salt of the NO _X absorbent, the embodiment of FIG. 2-4 embodiment of FIG. 1, _the NO _X storage It includes using tartrate particles instead of particles such as acetate of the agent.
[0024]
In the present invention, the surface of the monolith substrate is coated with these acetates by coating the surface of the monolith substrate with an NO _x storage agent in the form of an aqueous solution of acetate, carbonate, nitrate, and the like. Then, contacting with an aqueous tartaric acid solution converts acetates or the like into tartaric acid salts, and wash-coating the catalyst components.
Also by these methods, the object of the present invention, such as preventing the elution of the NO _x storage agent at the wash coat stage, can be achieved.
[0025]
【Example】
Example 1
While stirring an isopropyl alcohol solution in which aluminum isopropoxide (Al (OC ₃ H ₇ ) ₃ ) and potassium acetate (KCH ₃ CO ₂ ) are stirred, water is dropped into the solution to hydrolyze the aluminum isopropoxide, An alumina gel containing potassium was produced. This alumina gel was dried at 120 ° C. for 2 hours, and then heated at 800 ° C. in air for 5 hours, so that it was supported on alumina having an average particle diameter of about 2.7 μm containing 10.5% by mass of potassium. It was to obtain a _the NO _X storage agent.
[0026]
Next, the NO _x storage agent is dispersed in an isopropyl alcohol solution in which aluminum isopropoxide is dissolved, and a dinitrodiammine platinum nitric acid aqueous solution is dropped while stirring the slurry, and at the same time, water necessary for hydrolysis is added, Aluminum isopropoxide was hydrolyzed and an alumina gel containing platinum was coated on the NO _x storage agent.
Next, this slurry was dried at 120 ° C. for 2 hours and heated in air at 480 ° C. for 5 hours to obtain a catalyst powder having a catalyst component layer around the NO _X storage agent (hereinafter referred to as NO _X storage). The powder comprising the agent, the catalyst component, and the carrier is referred to as “catalyst powder”).
[0027]
This catalyst powder had an average particle size of about 2.9 μm and contained 8.7% by mass of potassium and 2.0% by mass of platinum (the balance being alumina).
130.0 g of this catalyst powder was put into 500 cc H ₂ O in which 43.46 g of tartaric acid had been previously dissolved, and stirred for 15 minutes. After stirring, the mixture was centrifuged and the supernatant was discarded. The powder obtained was dried at 120 ° C. for 2 hours to produce potassium hydrogen tartrate (KHC ₄ H ₄ O ₆ ). Here, the ratio of potassium (K) contained in the catalyst powder to the tartaric acid added was 1: 1 as the molar ratio of K / tartaric acid.
[0028]
Example 2
130.0 g of the catalyst powder containing potassium, platinum, and alumina support obtained in the same manner as in Example 1 was put into 500 cc of H ₂ O in which 86.92 g of tartaric acid had been dissolved in advance, and then for 15 minutes. Stir. After this stirring, the supernatant was discarded by centrifugation, and the resulting powder was dried at 120 ° C. for 2 hours to produce potassium hydrogen tartrate (KHC ₄ H ₄ O ₆ ). Here, the ratio of potassium contained in the catalyst powder to the tartaric acid added was 1: 2 in molar ratio of K / tartaric acid.
[0029]
Example 3
130.0 g of the catalyst powder containing potassium, platinum, and alumina support obtained in the same manner as in Example 1 was put into 500 cc of H ₂ O in which 130.39 g of tartaric acid had been dissolved in advance, and then for 15 minutes. Stir. After this stirring, the supernatant was discarded by centrifugation, and the resulting powder was dried at 120 ° C. for 2 hours to produce potassium hydrogen tartrate (KHC ₄ H ₄ O ₆ ). Here, the ratio of potassium contained in the catalyst powder to the tartaric acid added was 1: 3 in terms of a molar ratio of K / tartaric acid.
[0030]
Example 4
130.0 g of the catalyst powder containing potassium, platinum, and alumina support obtained in the same manner as in Example 1 was put into 500 cc H ₂ O in which 178.85 g of tartaric acid had been dissolved in advance, and the mixture was stirred for 15 minutes. Stir. After this stirring, the supernatant was discarded by centrifugation, and the resulting powder was dried at 120 ° C. for 2 hours to produce potassium hydrogen tartrate (KHC ₄ H ₄ O ₆ ). Here, the ratio of potassium contained in the catalyst powder to the tartaric acid added was 1: 4 as the molar ratio of K / tartaric acid.
[0031]
Example 5
130.0 g of the catalyst powder containing potassium, platinum, and alumina support obtained in the same manner as in Example 1 was put into 500 cc of H ₂ O in which 217.31 g of tartaric acid had been dissolved in advance, and then for 15 minutes. Stir. After this stirring, the supernatant was discarded by centrifugation, and the resulting powder was dried at 120 ° C. for 2 hours to produce potassium hydrogen tartrate (KHC ₄ H ₄ O ₆ ). Here, the ratio of potassium contained in the catalyst powder to the tartaric acid added was 1: 5 in the molar ratio of K / tartaric acid.
Examples 1 to 5 correspond to the embodiment of FIG.
[0032]
Example 6
Alumina gel containing platinum by hydrolyzing aluminum isopropoxide by adding dropwise the dinitrodiammine platinum nitric acid aqueous solution while stirring the isopropyl alcohol solution in which aluminum isopropoxide is dissolved, and simultaneously adding water necessary for hydrolysis. Was generated.
Next, this slurry was dried at 120 ° C. for 2 hours, and then heated at 480 ° C. in air for 5 hours to obtain 130 g of powder carrying 1.5 g of platinum on alumina.
[0033]
To this powder, 15.0 g of potassium carbonate (K ₂ CO ₃ ) was mixed, put into 500 cc of H ₂ O in which 97.68 g of tartaric acid had been dissolved in advance, and stirred for 15 minutes. After this stirring, the supernatant is discarded by centrifugation, and the resulting powder is dried at 120 ° C. for 2 hours to produce potassium hydrogen tartrate (KHC ₄ H ₄ O ₆ ), which contains the catalyst component and NO _X storage agent. A catalyst powder was obtained. Here, the ratio of potassium contained in the catalyst powder to the tartaric acid added was 1: 3 in terms of a molar ratio of K / tartaric acid.
The catalyst powder obtained in this example consists of separate particles of porous alumina particles with an average particle size of about 2.5 μm incorporating platinum and potassium hydrogen tartrate particles with an average particle size of about 3.0 μm. It was observed.
[0034]
Example 7
56.6 g of barium nitrate (Ba (NO ₂ ) ₃ ) was mixed with 130 g of powder obtained by supporting 1.5 g of platinum obtained in the same manner as in Example 6 on alumina, and 97.46 g of tartaric acid was previously added. The solution was put into 500 cc of dissolved H ₂ O and stirred for 15 minutes. After this stirring, the supernatant was discarded by centrifugation, and the obtained powder was dried at 120 ° C. for 2 hours to produce barium hydrogen tartrate (BaC ₄ H ₄ O ₆ ). Here, the ratio of potassium contained in the obtained catalyst powder to the tartaric acid added was 1: 3 in terms of a Ba / tartaric acid molar ratio.
The catalyst powder obtained in this example is composed of separate particles of porous alumina particles having an average particle diameter of about 2.5 μm incorporating platinum and barium tartrate particles having an average particle diameter of about 1.9 μm. Was observed.
[0035]
Example 8
To 130 g of powder obtained by supporting 1.5 g of platinum obtained in the same manner as in Example 6 on alumina, 28.3 g of barium nitrate (Ba (NO ₂ ) ₃ ) and 10.6 g of potassium acetate (CH ₃ COOK) were obtained. ) Was added to 500 cc H ₂ O in which 93.22 g of tartaric acid had been dissolved in advance, and stirred for 15 minutes. After this stirring, the supernatant is discarded by centrifugation, and the resulting powder is dried at 120 ° C. for 2 hours, and barium hydrogen tartrate (BaC ₄ H ₄ O ₆ ) and potassium hydrogen tartrate (BaC ₄ H ₄ O ₆ ) are added. Generated. Here, the ratio of potassium contained in the catalyst powder to the tartaric acid added was 1: 3 in terms of a molar ratio of (Ba + K) / tartaric acid.
The catalyst powder obtained in this example was composed of porous alumina particles having an average particle diameter of about 2.5 μm incorporating platinum, barium tartrate particles having an average particle diameter of about 1.9 μm, and an average particle diameter of about 3 It was observed to consist of discrete particles of 2 μm potassium hydrogen tartrate particles.
Examples 6 to 8 correspond to the embodiment of FIG.
[0036]
Relatively 1
In the middle step of Example 1, the average diameter is about 2.9 μm, and the catalyst particles containing 8.7% by mass of potassium and 2.0% by mass of platinum (the balance is alumina) are used as they are without being treated with tartaric acid. did.
[0037]
Relatively 2
The mixture on the alumina carrying platinum and potassium carbonate in the intermediate step of Example 6 was used as it was without being treated with tartaric acid.
[0038]
Relatively 3
A mixture of alumina supporting platinum and barium nitrate in the intermediate step of Example 7 was used as it was without being treated with tartaric acid.
[0039]
Relatively 4
The mixture of alumina supporting platinum, barium nitrate and potassium acetate in the intermediate step of Example 8 was used as it was without being treated with tartaric acid.
[0040]
-Evaluation method-
The catalyst powders of Examples 1 to 8 and Comparative Examples 1 to 3 are dispersed in ion-exchanged water containing a binder to prepare a slurry for wash coat, and each catalyst is coated on a monolith test piece having a diameter of 30 mm and a length of 50 mm. did.
These were evaluated for NO _x purification rates in the model gas shown in Table 1. Specifically, pretreatment was performed by flowing a rich gas at 500 ° C. for 10 minutes, the temperature was lowered while alternately flowing the rich gas and the lean gas for 2 minutes, and the NO _x purification rate was measured for the lean gas at 350 ° C. Further, the amount of potassium eluted in the water of the slurry was measured during the wash coating. These results are shown in Table 2.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
From the results shown in Table 2, Examples 1-8, which were wash-coated in the tartrate state, were clearly more NO _x than Comparative Examples 1-4, which were wash-coated in the state of potassium acetate, potassium carbonate, or barium nitrate. It can be seen that the purification rate is improved and the NO _x storage agent eluted in the slurry is clearly less.
Further, it can be seen that if the tartaric acid / occlusion element molar ratio is 3 or more, the NO _x elution can be suppressed substantially completely.
[0044]
【The invention's effect】
It is possible to prevent elution of the NO _X absorbent during washcoat decrease in catalytic performance due to _the NO _X storage agent adheres to the catalyst components at the atomic level can be solved.
[Brief description of the drawings]
FIG. 1 is a model diagram of an exhaust gas purification catalyst obtained by the method of the present invention.
FIG. 2 is a model diagram of an exhaust gas purification catalyst obtained by the method of the present invention.
FIG. 3 is a model diagram of an exhaust gas purifying catalyst obtained by the method of the present invention.
FIG. 4 is a model diagram of an exhaust gas purifying catalyst obtained by the method of the present invention.
FIG. 5 is a model diagram of an exhaust gas purifying catalyst obtained by the method of the present invention.
[Explanation of symbols]
1 ... NO _X absorbent 2 ... catalyst components 3 ... monolith substrate 4 ... NO _X occluding agent and mixing particles 5 ... additional catalyst component of the catalyst component

Claims (9)

A method of manufacturing a catalyst for purifying exhaust gases containing at least one alkali metal and alkaline earth metal as _the NO _X storage agent, after the tartrate said _the NO _X storage agent in contact with tartaric acid, the tartaric acid A method for producing an exhaust gas purifying catalyst, characterized in that a salt is coated on a monolith substrate using water as a medium . The exhaust gas according to claim 1, wherein the NO _x storage agent surrounded by the outer layer of the catalyst component is brought into contact with tartaric acid to form tartrate, and then the catalyst component and the tartrate are washcoated with water as a medium on a monolith substrate. A method for producing a gas purification catalyst. The exhaust gas according to claim 1, wherein the NO _x storage agent particles mixed with the catalyst component particles are brought into contact with tartaric acid to form tartrate, and then the catalyst component and the tartrate are washed on a monolith substrate using water as a medium. A method for producing a gas purification catalyst. The NO _x storage agent coexisting in the catalyst component and one particle is brought into contact with tartaric acid to form tartrate, and then the catalyst component and the tartrate are washed on a monolith substrate using water as a medium. The manufacturing method of the catalyst for exhaust-gas purification | cleaning of description. The NO After the _X absorbent wash-coated with water as a medium, a method of producing an exhaust gas purifying catalyst according to the catalyst components to claim 1 washcoat water as a medium. The NO _x storage agent and the catalyst component on the monolith substrate that is wash-coated with water as a medium by the method according to any one of claims 1 to 5 are calcined, and then the NO _x storage agent is contacted with tartaric acid, A method for producing an exhaust gas purifying catalyst, wherein the additional catalyst component is wash-coated using water as a medium . In any one of the methods of claims 1 to 5, wherein _the NO _X storage agent instead be brought into contact with the tartaric acid, the preparation of the catalyst for purifying exhaust gases, which comprises using a tartrate salt of the NO _X absorbent Method. A method of manufacturing a catalyst for purifying exhaust gases containing at least one alkali metal and alkaline earth metal as _the NO _X storage agent was the _the NO _X storage agent carried on the monolith substrate is changed to tartrate Thereafter, a method for producing an exhaust gas purifying catalyst, wherein the catalyst component is supported by a wash coat using water as a medium . NO _x The method for producing an exhaust gas purifying catalyst according to any one of claims 1 to 6, wherein the molar ratio of tartaric acid to the storage agent is 3 or more.

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