Preparation method of tail gas purification catalyst and tail gas purification catalyst

Abstract

The invention relates to a preparation method of a tail gas purification catalyst. The preparation method comprises the following steps: providing a catalytic aid material loaded with noble metal, and providing an oxide carrier; pulping the oxide carrier and the co-catalysis material together with a binder, a function regulator and water to obtain catalyst slurry; the catalyst slurry is arranged on a ceramic carrier, the tail gas purification catalyst is obtained after the catalyst slurry is dried, and the function regulator comprises at least one of poly (hydroxyethyl acrylate) and poly (hydroxyethyl methacrylate). According to the application, in the process of preparing the precious metal-loaded co-catalysis material into the slurry, a function regulator is added, the function regulator comprises at least one of poly (hydroxyethyl acrylate) and poly (hydroxyethyl methacrylate), and it is found in actual research that poly (hydroxyethyl acrylate) and poly (hydroxyethyl methacrylate) can inhibit agglomeration of precious metal, so that the precious metal can be effectively prevented from being agglomerated; therefore, the noble metal can keep higher catalytic efficiency, and the loading capacity of the noble metal can be further reduced.

Description

Technical Field

[0001] The present application relates to the field of environmental protection, and in particular to automobile exhaust purification. Background Art

[0002] With the rapid development of my country's automobile industry, the market share of passenger cars has increased significantly, and the impact of emissions and pollution from gasoline engines on the environment has become increasingly serious. Automobile exhaust purification catalysts are the main strategy for converting pollutants such as carbon monoxide, hydrocarbons, and nitrogen oxides into non-toxic gases such as carbon dioxide and water vapor. Automobile exhaust purification catalysts are generally composed of honeycomb carriers and catalytic coatings, which are mainly composed of rare earth oxides, alumina and other catalytic materials and precious metal active components. At present, the market competition in the automobile industry is becoming increasingly fierce, the price war is full of smoke, and the intensity of "involution" is still rising geometrically. Cost control is a key factor in product research and development and improving market competitiveness. The amount of precious metal active components such as Pt, Pd, and Rh, especially the amount of Rh, is the main factor determining the cost of the exhaust treatment system. The current precious metal loading of automobile exhaust purification catalysts still needs to be optimized to further reduce costs. Summary of the invention

[0003] The embodiments of the present application provide a method for preparing an exhaust gas purification catalyst and an exhaust gas purification catalyst to solve the technical problem that the precious metal loading amount of the automobile exhaust gas purification catalyst still needs to be further optimized.

[0004] In a first aspect, an embodiment of the present application provides a method for preparing an exhaust gas purification catalyst, the method for preparing an exhaust gas purification catalyst comprising the following steps:

[0005] Providing a catalyst-promoting material loaded with precious metals and an oxide carrier;

[0006] Slurrying the oxide carrier and the catalyst promoter material together with a binder, a functional regulator and water to obtain a catalyst slurry;

[0007] The catalyst slurry is placed on a ceramic carrier, and after the catalyst slurry is dried, the exhaust gas purification catalyst is obtained.

[0008] Wherein, the functional regulator includes at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate.

[0009] In some embodiments of the present application, the catalyst promoter material includes at least one of ZrO2 and CeO2; and / or,

[0010] The oxide support comprises lanthanum-modified alumina; and / or,

[0011] The binder is at least one of zirconium acetate, pseudo-boehmite, polyvinyl alcohol and polyethylene glycol; and / or,

[0012] The weight average molecular weight of the macromolecule in the functional regulator is 500-1000.

[0013] In some embodiments of the present application, the catalytic promoter material further comprises at least one of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide, and aluminum oxide; and / or,

[0014] The oxide carrier further comprises at least one of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide and calcium oxide; and / or,

[0015] In the oxide carrier, the content of lanthanum oxide is not higher than 10%, and the content of aluminum oxide is not lower than 85%.

[0016] In some embodiments of the present application, in the catalyst slurry, the mass ratio of the catalytic promoter material to the oxide carrier is 1:1-4; and / or,

[0017] The solid content of the catalyst slurry is 10% to 50%; and / or,

[0018] The catalyst slurry comprises 1% to 8% of a binder in terms of mass percentage of the catalyst slurry; and / or,

[0019] The catalyst slurry includes 5% to 10% of the functional regulator in terms of mass percentage of the catalyst slurry.

[0020] In some embodiments of the present application, the noble metal is Rh, and the step of providing a catalyst promoter material loaded with the noble metal comprises the following steps:

[0021] Providing a mixed solution including a Rh precursor and magnesium acetate;

[0022] The catalyst promoter material is immersed in the mixed solution and then calcined to obtain a catalyst promoter material loaded with precious metals.

[0023] Wherein, based on the mass percentage of the Rh precursor, the amount of magnesium acetate is 0.5% to 2%.

[0024] In a second aspect, an embodiment of the present application provides an exhaust gas purification catalyst, which is an exhaust gas purification catalyst prepared by the method described in any embodiment of the first aspect.

[0025] In some embodiments of the present application, the exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, wherein the front-stage catalyst includes a first ceramic carrier, a first catalytic layer arranged on the first ceramic carrier, and a second catalytic layer arranged on the first catalytic layer, the precious metal loaded on the first catalytic layer includes at least one of Pt and Pd, and the precious metal loaded on the second catalytic layer includes Rh,

[0026] The rear-stage catalyst includes a second ceramic carrier and a third catalytic layer arranged on the second ceramic carrier. The precious metal loaded on the third catalytic layer includes at least one of Pt and Pd.

[0027] In some embodiments of the present application, the catalyst-promoting material of the first catalyst layer includes CeO2-ZrO2-Co3O4-M1 x O y , wherein M1 is at least one of La, Pr, Nd, and Y; and / or,

[0028] The catalyst-promoting material of the second catalyst layer includes CeO2-ZrO2-Al2O3-M2 x O y , wherein M2 is at least one of La and Y; and / or,

[0029] The catalyst-promoting material of the third catalyst layer includes CeO2-ZrO2-M3 x O y , wherein M3 is at least one of La, Pr, Nd, Y, and Al.

[0030] In some embodiments of the present application, the mass percentage of each component in the catalyst-promoting material of the first catalyst layer is: CeO2 is 65% to 80%, ZrO2 is 10% to 30%, Co3O4 is 1% to 5%, M1 x O y 2% to 5%; and / or,

[0031] The mass percentage of each component in the catalyst-promoting material of the second catalyst layer is: CeO2 is 55% to 70%, ZrO2 is 10% to 25%, Al2O3 is 5% to 15%, M2 x O y 2% to 5%; and / or,

[0032] The mass percentages of the components in the catalyst-promoting material of the third catalyst layer are: CeO2 is 20% to 45%, ZrO2 is 50% to 70%, M3 x O y 3% to 10%; and / or,

[0033] The catalytic material of the first catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 600μmol / g; and / or,

[0034] The catalyst-promoting material of the second catalyst layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 600μmol / g; and / or,

[0035] The catalytic material of the third catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 800μmol / g; and / or,

[0036] The lanthanum-modified alumina has a specific surface area of ​​not less than 110 m2 after aging at 1000°C for 4 hours. 2 / g; and / or,

[0037] The pore density of the first ceramic carrier is 300 to 450 per square inch, and the wall thickness is ≤8 mil.

[0038] In some embodiments of the present application, the noble metals loaded on the first catalytic layer include Pt and Pd, wherein the loading amount of Pt is 20 to 100 g / ft 3 , Pd loading is 0~30g / ft 3 and / or,

[0039] In the second catalytic layer, the Rh loading is 0.1 to 15 g / ft 3 and / or,

[0040] The noble metals loaded on the third catalytic layer include Pt and Pd, wherein the loading amount of Pt is 10 to 50 g / ft 3 , Pd loading is 0~20g / ft 3 .

[0041] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0042] The preparation method of the exhaust gas purification catalyst provided in the embodiment of the present application includes adding a functional regulator during the process of preparing a slurry from a catalytic promoter material loaded with precious metals. The functional regulator includes at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate. In actual research, it was found that polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate can inhibit the agglomeration of precious metals, thereby maintaining a high catalytic efficiency of the precious metals, thereby reducing the loading amount of the precious metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0045] Figure 1 A schematic flow chart of a method for preparing an exhaust gas purification catalyst provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0047] Unless otherwise specified, the terms used herein should be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. In the event of a conflict, this specification takes precedence.

[0048] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0049] The existing automobile exhaust purification catalyst has a technical problem that the precious metal loading capacity still needs to be further optimized.

[0050] The technical solution provided by the embodiments of the present application is to solve the above technical problems, and the overall idea is as follows:

[0051] In the first aspect, the present invention provides a method for preparing an exhaust gas purification catalyst. Figure 1 The preparation method of the exhaust gas purification catalyst comprises the following steps:

[0052] S1: providing a catalyst-promoting material loaded with precious metals and an oxide carrier;

[0053] S2: slurrying the oxide support and the catalyst promoter material together with a binder, a functional regulator and water to obtain a catalyst slurry;

[0054] S3: placing the catalyst slurry on a ceramic carrier, and after the catalyst slurry is dried, obtaining the exhaust gas purification catalyst.

[0055] Wherein, the functional regulator includes at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate.

[0056] It is easy to understand that the automobile exhaust purification catalyst is used to convert harmful gases in automobile exhaust into harmless carbon dioxide, water and nitrogen through oxidation and reduction. Since the harmful gases in automobile exhaust are mainly CO, HC and NOx, the automobile exhaust purification catalyst is commonly known as a three-way catalytic converter.

[0057] It is easy to understand that the automobile exhaust purification catalyst generally includes a ceramic carrier and a co-catalyst material loaded with precious metals, wherein the co-catalyst material loaded with precious metals is arranged on the surface of the ceramic carrier. Precious metals are active catalytic components for purifying automobile exhaust, generally at least one of Pt, Pd, and Rh, and may also include other precious metals. Co-catalyst materials usually have a high specific surface area, which provides abundant loading sites for precious metals. For example, γ-Al2O3 is a common main component of co-catalyst materials. Co-catalyst materials usually also contain oxygen storage materials, such as some rare earth oxide materials. These oxygen storage materials can absorb oxygen when the ambient oxygen content is high, and can release oxygen when the ambient oxygen content is low, so that the exhaust purification work of the automobile exhaust purification catalyst can be carried out stably in an environment with fluctuating oxygen content.

[0058] It is easy to understand that the catalyst-promoting material loaded with precious metals needs to be placed on a ceramic carrier. One way is to make the catalyst-promoting material loaded with precious metals into a slurry and then apply it to the ceramic carrier. However, in the process of making the catalyst-promoting material loaded with precious metals into a slurry, the precious metal particles may agglomerate. This leads to a decrease in the catalytic efficiency of some precious metals, and then the loading amount of precious metals has to be increased in order to achieve a good catalytic effect.

[0059] In the process of preparing a slurry from a catalytic promoter material loaded with precious metals, the present application adds a functional regulator, wherein the functional regulator includes at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate. In actual research, it is found that polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate can inhibit the agglomeration of precious metals, thereby maintaining a high catalytic efficiency of the precious metals, thereby reducing the loading amount of the precious metals.

[0060] In addition, it should be noted that the ceramic carrier described in the present application may be a ceramic carrier without any coating, or may be a ceramic carrier having a catalytic promoter coating loaded with precious metals on the surface. As an example, in one embodiment, a catalytic promoter coating loaded with Pt and Pd is already provided on the surface of the ceramic carrier, and a catalytic promoter coating loaded with Rh can be further prepared on the ceramic carrier through steps S1-S3 of the present application.

[0061] In some embodiments of the present application, the catalyst promoter material includes at least one of ZrO2 and CeO2; and / or,

[0062] The oxide support comprises lanthanum-modified alumina; and / or,

[0063] The binder is at least one of zirconium acetate, pseudo-boehmite, polyvinyl alcohol and polyethylene glycol; and / or,

[0064] The weight average molecular weight of the macromolecule in the functional regulator is 500-1000.

[0065] It is easy to understand that ZrO2 and CeO2 can provide a microscopic high specific surface area structure, disperse precious metals, and enhance the catalytic activity of precious metals. In addition, ZrO2 and CeO2 have high thermal stability, which can inhibit the structural collapse of oxide carriers under high temperature conditions.

[0066] It is easy to understand that lanthanum-modified alumina refers to alumina loaded with lanthanum oxide. The thermal stability of alumina doped with lanthanum can be improved. Lanthanum modification of alumina can inhibit the change of the crystal phase of alumina at high temperature and improve the aging resistance of alumina. Lanthanum modification of alumina can be performed by impregnating alumina with a lanthanum salt precursor solution and then sintering.

[0067] As an example, the weight average molecular weight of the polymer in the functional regulator can be 500, 600, 700, 800, 900, or 1000.

[0068] In some embodiments of the present application, the catalytic promoter material further comprises at least one of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide, and aluminum oxide; and / or,

[0069] The oxide carrier further comprises at least one of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide and calcium oxide; and / or,

[0070] In the oxide carrier, the content of lanthanum oxide is not higher than 10%, and the content of aluminum oxide is not lower than 85%.

[0071] It is easy to understand that further adding lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide, aluminum oxide and other substances to the co-catalyst material can further increase the thermal stability and specific surface area of ​​the co-catalyst material.

[0072] It is easy to understand that further adding neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, calcium oxide and other substances to the oxide carrier can further inhibit the change of the crystal phase of aluminum oxide at high temperature and improve the aging resistance of aluminum oxide. In addition, it can also increase the specific surface area of ​​aluminum oxide, thereby helping to increase the dispersion of precious metals and thus increase their catalytic activity.

[0073] In some embodiments of the present application, in the catalyst slurry, the mass ratio of the catalytic promoter material to the oxide carrier is 1:1-4; and / or,

[0074] The solid content of the catalyst slurry is 10% to 50%; and / or,

[0075] The catalyst slurry comprises 1% to 8% of a binder in terms of mass percentage of the catalyst slurry; and / or,

[0076] The catalyst slurry includes 5% to 10% of the functional regulator in terms of mass percentage of the catalyst slurry.

[0077] As an example, the mass ratio of the promoter material to the oxide carrier may be 1:1, 1:2, 1:3, or 1:4.

[0078] As an example, the content of the binder in the catalyst slurry may be 1%, 3%, 5%, 7%, or 8%.

[0079] As an example, the content of the functional regulator in the catalyst slurry may be 5%, 6%, 7%, 8%, 9%, or 10%.

[0080] In some embodiments of the present application, the noble metal is Rh, and the step of providing a catalyst promoter material loaded with the noble metal comprises the following steps:

[0081] S11: providing a mixed solution including a Rh precursor and magnesium acetate;

[0082] S12: immersing the promoter material in the mixed solution and then calcining to obtain a promoter material loaded with precious metals.

[0083] Wherein, based on the mass percentage of the Rh precursor, the amount of magnesium acetate is 0.5% to 2%.

[0084] When the precious metal Rh is loaded, magnesium acetate can complex with the Rh precursor to regulate the generation rate of Rh, thereby regulating the Rh metal morphology and improving the Rh dispersion performance and catalytic ability.

[0085] It should be noted that step S11 and step S12 are preferred embodiments for preparing an oxide support loaded with Rh, and the noble metal described in this application is not limited to Rh.

[0086] In a second aspect, an embodiment of the present application provides an exhaust gas purification catalyst, which is an exhaust gas purification catalyst prepared by the method described in any embodiment of the first aspect.

[0087] The exhaust gas purification catalyst is implemented based on the method described in any embodiment of the first aspect. The specific implementation of the exhaust gas purification catalyst can refer to the above embodiments and common knowledge in the field. Since the exhaust gas purification catalyst adopts part or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0088] In some embodiments of the present application, the exhaust gas purification catalyst includes a front-stage catalyst and a rear-stage catalyst, wherein the front-stage catalyst includes a first ceramic carrier, a first catalytic layer arranged on the first ceramic carrier, and a second catalytic layer arranged on the first catalytic layer, the precious metal loaded on the first catalytic layer includes at least one of Pt and Pd, and the precious metal loaded on the second catalytic layer includes Rh,

[0089] The rear-stage catalyst includes a second ceramic carrier and a third catalytic layer arranged on the second ceramic carrier. The precious metal loaded on the third catalytic layer includes at least one of Pt and Pd.

[0090] It should be noted that the exhaust gas purification catalyst with the above-mentioned front-stage catalyst and rear-stage catalyst structure has a good purification effect on the high-concentration pollutants generated by the engine during instantaneous start-stop, and is particularly suitable for hybrid vehicles with frequent start-stop. The front-stage catalyst can centrally treat the pollutants generated during the start-stop process, and the rear-stage catalyst catalyzes the pollutants that have not fully reacted.

[0091] It should be noted that the first catalytic layer, the second catalytic layer and the third catalytic layer of the present application are all prepared by the method described in the first aspect of the present application.

[0092] In some embodiments of the present application, the catalyst-promoting material of the first catalyst layer includes CeO2-ZrO2-Co3O4-M1 x O y , wherein M1 is at least one of La, Pr, Nd, and Y; and / or,

[0093] The catalyst-promoting material of the second catalyst layer includes CeO2-ZrO2-Al2O3-M2 x O y , wherein M2 is at least one of La and Y; and / or,

[0094] The catalyst-promoting material of the third catalyst layer includes CeO2-ZrO2-M3 x O y , wherein M3 is at least one of La, Pr, Nd, Y, and Al.

[0095] CeO2-ZrO2-Co3O4-M1 x O y It has a good effect on improving the catalytic activity of Pt and Pd in ​​the first catalytic layer.

[0096] CeO2-ZrO2-Al2O3-M2 x O y It has a larger specific surface area, which is conducive to the good dispersion of Rh.

[0097] In some embodiments of the present application, the mass percentage of each component in the catalyst-promoting material of the first catalyst layer is: CeO2 is 65% to 80%, ZrO2 is 10% to 30%, Co3O4 is 1% to 5%, M1 x O y 2% to 5%; and / or,

[0098] The mass percentage of each component in the catalyst-promoting material of the second catalyst layer is: CeO2 is 55% to 70%, ZrO2 is 10% to 25%, Al2O3 is 5% to 15%, M2 x O y 2% to 5%; and / or,

[0099] The mass percentages of the components in the catalyst-promoting material of the third catalyst layer are: CeO2 is 20% to 45%, ZrO2 is 50% to 70%, M3 x O y 3% to 10%; and / or,

[0100] The catalytic material of the first catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 600μmol / g; and / or,

[0101] The catalyst-promoting material of the second catalyst layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 600μmol / g; and / or,

[0102] The catalytic material of the third catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 800μmol / g; and / or,

[0103] The lanthanum-modified alumina has a specific surface area of ​​not less than 110 m2 after aging at 1000°C for 4 hours. 2 / g; and / or,

[0104] The pore density of the first ceramic carrier is 300 to 450 per square inch, and the wall thickness is ≤8 mil.

[0105] In some embodiments of the present application, the noble metals loaded on the first catalytic layer include Pt and Pd, wherein the loading amount of Pt is 20 to 100 g / ft 3 , Pd loading is 0~30g / ft 3 and / or,

[0106] In the second catalytic layer, the Rh loading is 0.1 to 15 g / ft 3 and / or,

[0107] The noble metals loaded on the third catalytic layer include Pt and Pd, wherein the loading amount of Pt is 10 to 50 g / ft 3 , Pd loading is 0~20g / ft 3 .

[0108] As an example, in the first catalytic layer, the Pt loading can be 20 g / ft 3 , 400g / ft 3 , 600g / ft 3 , 800g / ft 3 , 100g / ft 3 , the Pd loading can be 0g / ft 3 , 5g / ft 3 , 10g / ft 3 , 15g / ft 3 , 20g / ft 3 , 25g / ft 3 , 30g / ft 3 .

[0109] As an example, in the second catalytic layer, the Rh loading can be 0.1 g / ft 3 , 0.3g / ft 3 , 0.9g / ft 3 , 3g / ft 3 , 9g / ft 3 , 15g / ft 3 .

[0110] As an example, in the third catalytic layer, the Pt loading can be 10 g / ft 3 , 20g / ft 3 , 30g / ft 3 , 40g / ft 3 , 50g / ft 3 , the Pd loading can be 0g / ft 3 , 5g / ft 3 , 10g / ft 3 , 15g / ft 3 , 20g / ft 3 .

[0111] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0112] Example 1

[0113] This embodiment provides a method for preparing an exhaust gas purification catalyst, which is specifically as follows:

[0114] Weigh the oxide raw material for preparing the catalyst promoter material CeO2-ZrO2-La2O3, wherein the mass percentage of each component in the oxide raw material is: CeO2 is 35%, ZrO2 is 60%, and La2O3 is 5%;

[0115] Weighing lanthanum-modified alumina as an oxide carrier, wherein the content of lanthanum oxide is 8%;

[0116] According to 30g / ft 3 Prepare platinum nitrate solution at a loading of 10 g / ft 3 Prepare palladium nitrate solution with a loading amount of ;

[0117] The oxide raw material, the platinum nitrate solution and the palladium nitrate solution are mixed and then the water is evaporated to obtain a mixture, and then the mixture is calcined at 600° C. to obtain a catalyst-promoting material loaded with Pt and Pd;

[0118] The co-catalytic material, the oxide carrier, pseudo-boehmite, poly(hydroxyethyl acrylate) and water are ball-milled together to obtain a catalyst slurry, wherein the mass ratio of the co-catalytic material to the oxide carrier is 1:1, the content of pseudo-boehmite is 5%, the content of poly(hydroxyethyl acrylate) is 5%, and the solid content of the catalyst slurry is 30%;

[0119] The catalyst slurry is coated on a ceramic carrier, and after drying the water, the ceramic carrier is calcined at 700° C. to obtain the exhaust gas purification catalyst.

[0120] Example 2

[0121] This embodiment provides a method for preparing an exhaust gas purification catalyst, which is specifically as follows:

[0122] Weighing oxide raw materials for preparing the catalyst promoter material CeO2-ZrO2-Al2O3-Y2O3, wherein the mass percentage of each component in the oxide raw materials is: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%;

[0123] Weighing lanthanum-modified alumina as an oxide carrier, wherein the content of lanthanum oxide is 5%;

[0124] According to 5g / ft 3 Prepare rhodium nitrate solution with a loading amount of ;

[0125] The oxide raw material, the rhodium nitrate solution and magnesium acetate are mixed and then the water is evaporated to obtain a mixture, and then the mixture is calcined at 600° C. to obtain a promoter material loaded with Rh;

[0126] The promoter material, the oxide carrier, zirconium acetate, poly(hydroxyethyl methacrylate) and water are ball-milled together to obtain a catalyst slurry, wherein the mass ratio of the promoter material to the oxide carrier is 1:4, the content of zirconium acetate is 6%, the content of poly(hydroxyethyl methacrylate) is 9%, and the solid content of the catalyst slurry is 4%;

[0127] The catalyst slurry is coated on a ceramic carrier, and after drying the water, the ceramic carrier is calcined at 700° C. to obtain the exhaust gas purification catalyst.

[0128] Example 3

[0129] The difference between this embodiment and embodiment 2 is only that: the mixture does not contain magnesium acetate.

[0130] This embodiment provides a method for preparing an exhaust gas purification catalyst, which is specifically as follows:

[0131] Weighing oxide raw materials for preparing the catalyst promoter material CeO2-ZrO2-Al2O3-Y2O3, wherein the mass percentage of each component in the oxide raw materials is: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%;

[0132] Weighing lanthanum-modified alumina as an oxide carrier, wherein the content of lanthanum oxide is 7%;

[0133] According to 5g / ft 3 Prepare rhodium nitrate solution with a loading amount of ;

[0134] The oxide raw material and the rhodium nitrate solution are mixed and then evaporated to dryness to obtain a mixture, and then the mixture is calcined at 600° C. to obtain a promoter material loaded with Rh;

[0135] The promoter material, the oxide carrier, zirconium acetate, poly(hydroxyethyl methacrylate) and water are ball-milled together to obtain a catalyst slurry, wherein the mass ratio of the promoter material to the oxide carrier is 1:1-4, the content of zirconium acetate is 8%, the content of poly(hydroxyethyl methacrylate) is 10%, and the solid content of the catalyst slurry is 50%;

[0136] The catalyst slurry is coated on a ceramic carrier, and after drying the water, the ceramic carrier is calcined at 700° C. to obtain the exhaust gas purification catalyst.

[0137] Example 4

[0138] The present embodiment provides an exhaust gas purification catalyst, the exhaust gas purification catalyst comprising a front-stage catalyst and a rear-stage catalyst, wherein the front-stage catalyst comprises a first ceramic carrier, a first catalytic layer arranged on the first ceramic carrier, and a second catalytic layer arranged on the first catalytic layer, the precious metal loaded on the first catalytic layer comprises at least one of Pt and Pd, the precious metal loaded on the second catalytic layer comprises Rh,

[0139] The rear-stage catalyst includes a second ceramic carrier and a third catalytic layer arranged on the second ceramic carrier. The precious metals loaded on the third catalytic layer include Pt and Pd.

[0140] The catalyst-promoting material of the first catalyst layer includes CeO2-ZrO2-Co3O4-M1 x O y , where M1 x O y The catalyst layer is composed of La2O3 and Nd2O3 in a mass ratio of 1:1. The mass percentages of the components in the catalyst-promoting material of the first catalyst layer are: CeO2 is 75%, ZrO2 is 20%, Co3O4 is 3%, M1 x O y 2%,

[0141] The catalyst-promoting material of the second catalyst layer includes CeO2-ZrO2-Al2O3-Y2O3, and the mass percentage of each component in the catalyst-promoting material of the second catalyst layer is: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%.

[0142] The catalytic promoter material of the third catalytic layer includes CeO2-ZrO2-Pr2O3, and the mass percentage of each component in the catalytic promoter material of the third catalytic layer is: CeO2 is 35%, ZrO2 is 60%, and Pr2O3 is 5%.

[0143] The first catalytic layer, the second catalytic layer and the third catalytic layer also include modified alumina, which is lanthanum-modified alumina, wherein the lanthanum-modified alumina also includes silicon dioxide and calcium oxide in a mass ratio of 1:1, wherein the content of lanthanum oxide in the modified alumina is 5%, the content of silicon dioxide is 2%, and the content of calcium oxide is 2%; in the first catalytic layer, the second catalytic layer and the third catalytic layer, the mass ratio of the co-catalytic material and the modified alumina is 1:4.

[0144] The catalytic material of the first catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, the oxygen storage capacity is not less than 600μmol / g, and the specific surface area of ​​the second catalytic layer is not less than 50m after aging at 1000°C for 4h. 2 / g, the oxygen storage capacity is not less than 600μmol / g, and the specific surface area of ​​the catalytic promoter material of the third catalytic layer is not less than 50m after aging at 1000°C for 4h. 2 / g, an oxygen storage capacity of not less than 800 μmol / g, and a specific surface area of ​​not less than 110 m2 after aging at 1000°C for 4 hours. 2 / g.

[0145] The first ceramic carrier has a pore density of 350 per square inch and a wall thickness of 8 mil.

[0146] The precious metals loaded on the first catalytic layer include Pt and Pd, wherein the loading amount of Pt is 30 g / ft 3 , Pd loading is 10g / ft 3 In the second catalytic layer, the Rh loading is 8 g / ft 3 The precious metals loaded on the third catalytic layer include Pt and Pd, wherein the loading amount of Pt is 20 g / ft 3 , the Pd loading is 5g / ft 3 .

[0147] This embodiment also provides a method for preparing the above-mentioned exhaust gas purification catalyst, which is specifically as follows:

[0148] Preparation of the front stage catalyst:

[0149] A first platinum nitrate solution and a first palladium nitrate solution are prepared according to the Pt and Pd loading amounts of the first catalyst layer, raw materials are weighed according to the composition of the promoter material of the first catalyst layer, and the raw materials are mixed with the first platinum nitrate solution and the first palladium nitrate solution, and then the water is evaporated to obtain a first mixture, and then the first mixture is calcined at 500° C. to obtain a first oxide loaded with Pt and Pd;

[0150] The first oxide is ball-milled with polyvinyl alcohol, polyhydroxyethyl acrylate and water to obtain a first catalyst slurry, wherein the content of polyvinyl alcohol in the first catalyst slurry is 3%, the content of polyhydroxyethyl acrylate is 6%, and the solid content of the first catalyst slurry is 20%;

[0151] Applying the first catalyst slurry onto a first ceramic carrier, drying the water, and calcining the first ceramic carrier at 700° C. to form a first catalytic layer on the first ceramic carrier;

[0152] A rhodium nitrate solution is prepared according to the Rh loading amount of the second catalytic layer. The composition of the promoter material of the second catalytic layer is obtained by weighing raw materials and mixing them with the rhodium nitrate solution and magnesium acetate, and then evaporating the water to obtain a second mixture, and then calcining the second mixture at 500° C. to obtain a second oxide loaded with Rh;

[0153] The second oxide is ball-milled with polyethylene glycol, polyhydroxyethyl acrylate and water to obtain a second catalyst slurry, wherein the content of polyethylene glycol in the second catalyst slurry is 4%, the content of polyhydroxyethyl acrylate is 5%, and the solid content of the second catalyst slurry is 30%;

[0154] The second catalyst slurry is coated on the surface of the first ceramic carrier, namely the first catalyst layer, and the first ceramic carrier is calcined at 700° C. after drying the water to obtain a front-stage catalyst.

[0155] Preparation of post-stage catalyst:

[0156] A second platinum nitrate solution and a second palladium nitrate solution are prepared according to the Pt and Pd loading amounts of the third catalytic layer, raw materials are weighed according to the composition of the promoter material of the third catalytic layer, and the raw materials are mixed with the second platinum nitrate solution and the second palladium nitrate solution, and then the water is evaporated to obtain a third mixture, and then the third mixture is calcined at 500° C. to obtain a third oxide loaded with Pt and Pd;

[0157] The third oxide is ball-milled with pseudo-boehmite, poly(hydroxyethyl acrylate) and water to obtain a third catalyst slurry, wherein the content of polyethylene glycol in the third catalyst slurry is 4%, the content of poly(hydroxyethyl acrylate) is 5%, and the solid content of the third catalyst slurry is 30%;

[0158] The third catalyst slurry is coated on the second ceramic carrier, and after drying the water, the second ceramic carrier is calcined at 700° C. to obtain a rear-stage catalyst.

[0159] Preparation of exhaust gas purification catalyst:

[0160] The front-stage catalyst and the rear-stage catalyst are assembled to obtain an exhaust gas purification catalyst.

[0161] Comparative Example 1

[0162] The only difference between this comparative example and Example 1 is that the catalyst slurry does not contain a functional regulator.

[0163] This comparative example provides a method for preparing an exhaust gas purification catalyst, which is as follows:

[0164] Weighing oxide raw materials for preparing the catalytic promoter material CeO2-ZrO2-La2O3, wherein the mass percentage of each component in the oxide raw materials is: CeO2 is 35%, ZrO2 is 60%, and La2O3 is 5%;

[0165] Weighing lanthanum-modified alumina as an oxide carrier, wherein the content of lanthanum oxide is 8%;

[0166] According to 30g / ft 3 Prepare platinum nitrate solution at a loading of 10 g / ft 3 Prepare palladium nitrate solution with a loading amount of ;

[0167] The oxide raw material, the platinum nitrate solution and the palladium nitrate solution are mixed and then the water is evaporated to obtain a mixture, and then the mixture is calcined at 600° C. to obtain a catalyst-promoting material loaded with Pt and Pd;

[0168] The co-catalytic material, the oxide carrier, pseudo-boehmite and water are ball-milled together to obtain a catalyst slurry, wherein the mass ratio of the co-catalytic material to the oxide carrier is 1:1, the content of the pseudo-boehmite is 5%, and the solid content of the catalyst slurry is 30%;

[0169] The catalyst slurry is coated on a ceramic carrier, and after drying the water, the ceramic carrier is calcined at 700° C. to obtain the exhaust gas purification catalyst.

[0170] Comparative Example 2

[0171] The only difference between this comparative example and Example 2 is that the catalyst slurry does not contain a functional regulator.

[0172] This comparative example provides a method for preparing an exhaust gas purification catalyst, which is as follows:

[0173] Weighing oxide raw materials for preparing the catalyst promoter material CeO2-ZrO2-Al2O3-Y2O3, wherein the mass percentage of each component in the oxide raw materials is: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%;

[0174] Weighing lanthanum-modified alumina as an oxide carrier, wherein the content of lanthanum oxide is 5%;

[0175] According to 5g / ft 3 Prepare rhodium nitrate solution with a loading amount of ;

[0176] The oxide raw material, the rhodium nitrate solution and magnesium acetate are mixed and then the water is evaporated to obtain a mixture, and then the mixture is calcined at 600° C. to obtain a promoter material loaded with Rh;

[0177] The promoter material, the oxide carrier, zirconium acetate and water are ball-milled together to obtain a catalyst slurry, wherein the mass ratio of the promoter material to the oxide carrier is 1:4, the content of zirconium acetate is 6%, and the solid content of the catalyst slurry is 4%;

[0178] The catalyst slurry is coated on a ceramic carrier, and after drying the water, the ceramic carrier is calcined at 700° C. to obtain the exhaust gas purification catalyst.

[0179] Related experiments and effect data:

[0180] The noble metal dispersion test was performed on the exhaust gas purification catalysts of Examples 1 to 4 and Comparative Examples 1 to 2.

[0181] The method for precious metal dispersion test is as follows:

[0182] Take 200 mg of sample and pretreat it at 450°C in H2 flow for 1 h, with a H2 flow rate of 30 mL / min. Then the sample is cooled to room temperature in He gas and placed in an ethanol-dry ice mixture at -78°C. Subsequently, a constant dose of CO pulse is injected into the sample until CO consumption is no longer detected. Assuming that only one CO molecule is adsorbed per noble metal atom, the adsorption rate of the CO molecule is calculated and defined as the dispersion of the noble metal in the catalyst. For Example 4, the noble metal dispersion is the average value of the front-stage catalyst and the rear-stage catalyst.

[0183] According to the national standard GB / T 34248-2017, the exhaust gas purification catalysts of Examples 1 to 4 and Comparative Examples 1 to 2 were tested for THC (total carbon compound) ignition temperature, CO ignition temperature, and NO ignition temperature.

[0184] The above test results are shown in Table 1.

[0185] Table 1

[0186]

[0187] As can be seen from Table 1, the THC ignition temperature, CO ignition temperature, and NO ignition temperature of Examples 1 to 4 are all at a relatively low level, and the precious metal dispersion is at a relatively high level. Compared with Example 1, the precious metal dispersion of Comparative Example 1 is significantly reduced, which may be because no functional regulator was added during the preparation process of Comparative Example 1. The THC ignition temperature, CO ignition temperature, and NO ignition temperature of Comparative Example 1 are all relatively high, which may be because the precious metal dispersion is too low, resulting in a decrease in its catalytic efficiency. Compared with Example 2, no functional regulator was added during the preparation process of Comparative Example 2, and its test results showed the same rule. In summary, the functional regulator added in the present application can effectively increase the dispersion of precious metals, thereby increasing the catalytic efficiency of the three-way catalyst.

[0188] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0189] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. refer to "including but not limited to". Moreover, the terms "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "including..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of these three associated objects can exist alone, or any at least two of them exist at the same time. For example, for A, and / or B, and / or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, ab (i.e. a and b), ac, bc, or abc, wherein a, b, and c can be single or multiple, respectively.

[0190] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing an exhaust gas purification catalyst, characterized in that: The preparation method of the exhaust gas purification catalyst comprises the following steps: Providing a catalyst-promoting material loaded with precious metals and an oxide carrier; Slurrying the oxide carrier and the catalyst promoter material together with a binder, a functional regulator and water to obtain a catalyst slurry; The catalyst slurry is placed on a ceramic carrier, and after the catalyst slurry is dried, the exhaust gas purification catalyst is obtained. Wherein, the functional regulator includes at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate.

2. The method for preparing an exhaust gas purification catalyst according to claim 1, characterized in that: The binder is at least one of zirconium acetate, pseudo-boehmite, polyvinyl alcohol and polyethylene glycol; and / or, The amount of the binder is 1% to 8% based on the mass percentage of the catalyst promoter material; and / or, The weight average molecular weight of the macromolecule in the functional regulator is 500 to 1000; and / or, Calculated by the mass percentage of the catalytic promoter material, the dosage of the functional regulator is 5% to 10%.

3. The method for preparing an exhaust gas purification catalyst according to claim 1, characterized in that: The noble metal is Rh, and the step of providing a catalyst promoter material loaded with the noble metal comprises the following steps: Providing a mixed solution including a Rh precursor and magnesium acetate; The catalyst promoter material is immersed in the mixed solution and then calcined to obtain a catalyst promoter material loaded with precious metals. Wherein, based on the mass percentage of the Rh precursor, the amount of magnesium acetate is 0.5% to 2%.

4. An exhaust gas purification catalyst, characterized in that: The exhaust gas purification catalyst is an exhaust gas purification catalyst prepared by the method according to any one of claims 1 to 3.

5. The exhaust gas purification catalyst according to claim 4, characterized in that: The exhaust gas purification catalyst comprises a front-stage catalyst and a rear-stage catalyst, wherein the front-stage catalyst comprises a first ceramic carrier, a first catalytic layer arranged on the first ceramic carrier, and a second catalytic layer arranged on the first catalytic layer, the precious metal loaded on the first catalytic layer comprises at least one of Pt and Pd, and the precious metal loaded on the second catalytic layer comprises Rh, The rear-stage catalyst includes a second ceramic carrier and a third catalytic layer arranged on the second ceramic carrier. The precious metal loaded on the third catalytic layer includes at least one of Pt and Pd.

6. The exhaust gas purification catalyst according to claim 4, characterized in that: The catalyst-promoting material of the first catalyst layer includes CeO2-ZrO2-Co3O4-M1 x O y , wherein M1 is at least one of La, Pr, Nd, and Y; and / or, The catalyst-promoting material of the second catalyst layer includes CeO2-ZrO2-Al2O3-M2 x O y , wherein M2 is at least one of La and Y; and / or, The catalyst-promoting material of the third catalyst layer includes CeO2-ZrO2-M3 x O y , wherein M3 is at least one of La, Pr, Nd, Y, and Al.

7. The exhaust gas purification catalyst according to claim 6, characterized in that: The mass percentages of the components in the catalyst-promoting material of the first catalyst layer are: CeO2 is 65% to 80%, ZrO2 is 10% to 30%, Co3O4 is 1% to 5%, M1 x O y 2% to 5%; and / or, The mass percentage of each component in the catalyst-promoting material of the second catalyst layer is: CeO2 is 55% to 70%, ZrO2 is 10% to 25%, Al2O3 is 5% to 15%, M2 x O y 2% to 5%; and / or, The mass percentages of the components in the catalyst-promoting material of the third catalyst layer are: CeO2 is 20% to 45%, ZrO2 is 50% to 70%, M3 x O y It is 3% to 10%.

8. The exhaust gas purification catalyst according to claim 6, characterized in that: The first catalytic layer and the third catalytic layer further include modified alumina, wherein the modified alumina includes alumina and lanthanum oxide, and the modified alumina further includes at least one of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide.

9. The exhaust gas purification catalyst according to claim 6, characterized in that: The catalytic material of the first catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 600μmol / g; and / or, The catalyst-promoting material of the second catalyst layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 600μmol / g; and / or, The catalytic material of the third catalytic layer has a specific surface area of ​​not less than 50 m2 after aging at 1000°C for 4 hours. 2 / g, oxygen storage capacity is not less than 800μmol / g; and / or, The lanthanum-modified alumina has a specific surface area of ​​not less than 110 m2 after aging at 1000°C for 4 hours. 2 / g; and / or, The pore density of the first ceramic carrier is 300 to 450 per square inch, and the wall thickness is ≤8 mil.

10. The exhaust gas purification catalyst according to claim 5, characterized in that: The noble metals loaded on the first catalytic layer include Pt and Pd, wherein the loading amount of Pt is 20 to 100 g / ft 3 , Pd loading is 0~30g / ft 3 and / or, In the second catalytic layer, the Rh loading is 0.1 to 15 g / ft 3 and / or, The noble metals loaded on the third catalytic layer include Pt and Pd, wherein the loading amount of Pt is 10 to 50 g / ft 3 , Pd loading is 0~20g / ft 3 .

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