Method for preparing exhaust gas purifying catalytic device, and exhaust gas purifying catalytic device

Abstract

A method for preparing an exhaust gas purifying catalytic device, comprising: providing a catalytic promoter loaded with a precious metal, and providing an oxide carrier; pulping together the oxide carrier, the catalytic promoter loaded with the precious metal, a binder, a functional regulator and water, to obtain a catalyst slurry; placing the catalyst slurry on a ceramic carrier, and obtaining an exhaust gas purifying catalytic device after the catalyst slurry is dried. The functional regulator comprises at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate.

Description

Preparation method of exhaust purification catalyst and exhaust purification catalyst

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 2024113576997, filed on September 27, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the field of environmental protection, and in particular to a preparation method of exhaust purification catalyst and exhaust purification catalyst. BACKGROUND

[0004] With the rapid development of China's automobile industry, the market share of passenger cars has increased significantly, and the impact of vehicle gasoline engine emissions and pollution on the environment has become increasingly serious. The automobile exhaust purification catalyst is a device that converts pollutants such as carbon monoxide, hydrocarbons, and nitrogen oxides into non-toxic gases such as carbon dioxide and water vapor. The automobile exhaust purification catalyst is generally composed of a honeycomb carrier and a catalytic coating, and the catalytic coating is mainly composed of rare earth oxides, alumina, and other catalytic materials, and noble metal active components. The market competition in the current automobile industry is becoming increasingly fierce, with price wars and intense “involution” that is still rising geometrically. Cost control is a key factor in product research and development and market competitiveness. The amount of noble metal active components, especially Rh, is the main factor determining the cost of automobile exhaust purification catalysts. The noble metal loading of current automobile exhaust purification catalysts still needs to be optimized to further reduce costs. SUMMARY

[0005] By using the preparation method of exhaust purification catalyst and exhaust purification catalyst of one or more embodiments of the present disclosure, the technical problem of how to optimize the noble metal loading of automobile exhaust purification catalysts to reduce costs is solved.

[0006] In a first aspect, the embodiments of the present disclosure provide a preparation method of an exhaust purification catalyst, comprising: providing a catalytic material loaded with noble metal, and providing an oxide carrier; jointly slurrying the oxide carrier, the catalytic material loaded with noble metal, a binder, a functional regulator, and water to obtain a catalyst slurry; and disposing the catalyst slurry on a ceramic carrier, and obtaining the exhaust purification catalyst after the catalyst slurry is dried; wherein the functional regulator comprises at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate.

[0007] In a second aspect, the embodiments of the present disclosure provide an exhaust purification catalyst prepared by the method of any one of the embodiments of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0008] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, further serve to explain the principles of the disclosure.

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the related art, brief introductions will be given to the drawings needed in the embodiments or the related art descriptions. Obviously, those skilled in the art can obtain other drawings from these drawings without any creative effort.

[0010] FIG. 1 is a flowchart of a preparation method of an exhaust gas purification catalyst according to an embodiment of the present disclosure.

[0011] FIG. 2 is a flowchart of providing a support material loaded with a noble metal in a preparation method of an exhaust gas purification catalyst according to an embodiment of the present disclosure. Embodiments of the present disclosure

[0012] To make the objects, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely below with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without any creative effort fall within the scope of the present disclosure.

[0013] Unless otherwise specifically defined, the terms used herein are to be understood as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. If there is a contradiction, the description in the specification shall prevail.

[0014] Unless otherwise specifically stated, the various raw materials, reagents, instruments, and equipment used in the present disclosure can be purchased from the market or can be prepared by existing methods.

[0015] The existing automobile exhaust gas purification catalyst has the technical problem of how to continue to optimize the noble metal load to reduce the cost.

[0016] The technical solutions provided by the embodiments of the present disclosure are to solve the above technical problems, and the general idea is as follows.

[0017] In a first aspect, according to the embodiments of the present disclosure, a preparation method of an exhaust gas purification catalyst is provided. FIG. 1 is a flowchart of a preparation method of an exhaust gas purification catalyst according to an embodiment of the present disclosure. Referring to FIG. 1, the preparation method of the exhaust gas purification catalyst comprises:

[0018] S1: providing a noble metal loaded assistant catalytic material, providing an oxide carrier;

[0019] S2: co-slurrying the oxide carrier, the noble metal loaded assistant catalytic material, a binder, a function regulator, and water to obtain a catalyst slurry; and,

[0020] S3: setting the catalyst slurry on a ceramic carrier, and obtaining an exhaust gas purification catalyst after the catalyst slurry is dried.

[0021] The function regulator comprises at least one of polyhydroxyethyl acrylate and polymethyl hydroxyethyl methacrylate.

[0022] It is easy to understand that the automobile exhaust gas purification catalyst is used to convert the harmful gas in automobile exhaust gas into harmless carbon dioxide, water and nitrogen through oxidation and reduction. Since the harmful gas in automobile exhaust gas mainly includes CO, HC and NOx, the automobile exhaust gas purification catalyst is commonly known as a three-way catalyst.

[0023] It is easy to understand that the automobile exhaust gas purification catalyst generally includes a ceramic carrier and a noble metal loaded assistant catalytic material. In some embodiments, the noble metal loaded assistant catalytic material is arranged on the surface of the ceramic carrier. The noble metal is an active catalytic component for purifying automobile exhaust gas, and generally includes at least one of Pt, Pd and Rh, and can also include other noble metals. The assistant catalytic material generally has a high specific surface area, which provides abundant loading sites for the noble metal. For example, γ-Al2O3 is a common component of the assistant catalytic material. The assistant catalytic material can also generally contain oxygen storage materials, such as some rare earth oxide materials, which can absorb oxygen when the environmental oxygen content is high and release oxygen when the environmental oxygen content is low, so that the exhaust gas purification work of the automobile exhaust gas purification catalyst can be stably carried out in an environment with fluctuating oxygen content.

[0024] It is easy to understand that the noble metal loaded assistant catalytic material needs to be arranged on the ceramic carrier, and one way is to coat the noble metal loaded assistant catalytic material on the ceramic carrier after the noble metal loaded assistant catalytic material is made into a catalyst slurry. However, in the related art, the noble metal particles may agglomerate during the process of making the assistant catalytic material loaded with noble metal into a slurry. This leads to a decrease in the catalytic efficiency of a part of the noble metal, and thus leads to an increase in the loading amount of the noble metal in order to achieve good catalytic effect, and thus leads to a high cost of the exhaust gas purification catalyst in the related art.

[0025] In some embodiments of the present disclosure, a functional regulator is added during the process of preparing the slurry of the noble metal loaded promoter material, the functional regulator including at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate. In actual research, it is found that the polyhydroxyethyl acrylate and the polyhydroxyethyl methacrylate can respectively inhibit the agglomeration of the noble metal, so that the noble metal can maintain a high catalytic efficiency, and thus the loading amount of the noble metal can be reduced, and thus the cost of the exhaust purification catalyst can be reduced.

[0026] It is easy to understand that, after the catalyst slurry is arranged on the ceramic carrier, the catalyst slurry forms a catalytic layer on the surface of the ceramic carrier after the catalyst slurry is dried, so that the catalytic layer is loaded with the noble metal.

[0027] In addition, it should be noted that, in some embodiments of the present disclosure, the ceramic carrier can be a ceramic carrier without any coating, or can be a ceramic carrier whose surface has been arranged with a catalytic layer including the noble metal loaded promoter material.

[0028] For example, in an embodiment, the surface of the ceramic carrier has been arranged with a catalytic layer including the Pt and Pd loaded promoter material, and the catalytic layer including the Pt and Pd loaded promoter material can be formed on the surface of the ceramic carrier by steps S1-S3 in the present disclosure, and then the catalytic layer including the Rh loaded promoter material can be continuously prepared on the ceramic carrier by steps S1-S3 in the present disclosure.

[0029] In some embodiments of the present disclosure, the promoter material includes at least one of ZrO2 and CeO2; and / or,

[0030] The oxide carrier includes modified alumina; and / or,

[0031] The binder includes at least one of zirconium acetate, pseudo-boehmite, polyvinyl alcohol and polyethylene glycol; and / or,

[0032] The weight average molecular weight of the macromolecule in the functional regulator is 500-1000.

[0033] It is easy to understand that ZrO2 and CeO2 have a structure that can provide a high specific surface area in a micro sense, for dispersing the noble metal and having the effect of improving the catalytic activity of the noble metal. In addition, ZrO2 and CeO2 have high thermal stability, and can inhibit the structural collapse of the oxide carrier under high temperature conditions.

[0034] It is easy to understand that the modified alumina can be lanthanum-modified alumina, which refers to alumina loaded with lanthanum oxide. The thermal stability of alumina loaded with lanthanum oxide can be improved, and lanthanum modification of alumina can inhibit the change of the crystal phase of alumina at high temperature, thereby improving the aging resistance of the lanthanum-modified alumina. The lanthanum modification of alumina can be realized by impregnating a lanthanum salt precursor solution on the alumina and then sintering.

[0035] As an example, the weight average molecular weight of the macromolecule in the functional regulator can be 500, 600, 700, 800, 900, or 1000.

[0036] In some embodiments of the present disclosure, the promoter material further comprises at least one of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide, and aluminum oxide; and / or,

[0037] The oxide carrier further comprises at least one of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide; and / or,

[0038] In the oxide carrier, the mass content of lanthanum oxide is not higher than 10%, and the mass content of aluminum oxide is not lower than 85%.

[0039] It is easy to understand that by further adding lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide, and aluminum oxide, etc. in the promoter material, the thermal stability and specific surface area of the promoter material can be further increased.

[0040] It is easy to understand that by further adding neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide, etc. in the oxide carrier, the change of the crystal phase of the alumina at high temperature can be further inhibited, the aging resistance of the alumina can be improved, and in addition, the specific surface area of the alumina can be increased, thereby helping to increase the dispersibility of the noble metal and further increasing its catalytic activity.

[0041] In some embodiments of the present disclosure, in the catalyst slurry, the mass ratio of the promoter material loaded with noble metal to the oxide carrier is 1:1-4; and / or,

[0042] The solid content of the catalyst slurry is 10%-50%; and / or,

[0043] The amount of the binder is 1%-8% in terms of the mass percentage of the catalyst slurry, i.e. the catalyst slurry comprises 1%-8% of the binder; and / or,

[0044] The amount of the functional regulator is 5%-10% in terms of the mass percentage of the catalyst slurry, i.e. the catalyst slurry comprises 5%-10% of the functional regulator.

[0045] As an example, the mass ratio of the promoter material to the oxide support can be 1:1, 1:2, 1:3, 1:4.

[0046] As an example, the mass content of the binder in the catalyst slurry can be 1%, 3%, 5%, 7%, 8%.

[0047] As an example, the mass content of the functional regulator in the catalyst slurry can be 5%, 6%, 7%, 8%, 9%, 10%.

[0048] FIG. 2 is a schematic diagram of a process for providing a promoter material loaded with noble metal in a preparation method of a tail gas purification catalyst according to an embodiment of the present disclosure. In some embodiments of the present disclosure, the noble metal in the promoter material loaded with noble metal is Rh. As shown in FIG. 2, the process for providing the promoter material loaded with noble metal includes:

[0049] S11: providing a mixed solution including a Rh precursor and magnesium acetate; and,

[0050] S12: calcining the promoter material after being immersed in the mixed solution including the Rh precursor and the magnesium acetate to obtain the promoter material loaded with noble metal;

[0051] wherein the amount of the magnesium acetate is 0.5% to 2% in terms of the mass percentage of the Rh precursor.

[0052] When the promoter material is loaded with the noble metal Rh, the magnesium acetate can be complexed with the Rh precursor to regulate the generation rate of Rh, thereby regulating the metal morphology of Rh and improving the dispersion performance and catalytic capacity of Rh.

[0053] It should be noted that steps S11 and S12 are preferred embodiments for preparing the oxide support loaded with Rh, and the noble metal in the present disclosure is not limited to Rh.

[0054] In a second aspect, the present disclosure also provides a tail gas purification catalyst prepared by the method of any one of the embodiments of the first aspect.

[0055] The tail gas purification catalyst is realized based on the method of any one of the embodiments of the first aspect, and the specific implementation of the tail gas purification catalyst can refer to the above embodiments and the common general knowledge in the art. Since the tail gas purification catalyst adopts some 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 repeated here.

[0056] In some embodiments of the present disclosure, the exhaust 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 disposed on the first ceramic carrier, and a second catalytic layer disposed on the first catalytic layer, the noble metal loaded on the first catalytic layer comprises at least one of Pt and Pd, and the noble metal loaded on the second catalytic layer comprises Rh; and the rear-stage catalyst comprises a second ceramic carrier and a third catalytic layer disposed on the second ceramic carrier, the noble metal loaded on the third catalytic layer comprises at least one of Pt and Pd.

[0057] It should be noted that the exhaust purification catalyst with the above-mentioned front-stage catalyst and rear-stage catalyst structure has a good purification effect on high-concentration pollutants generated by the engine during transient start-stop, and is particularly suitable for hybrid electric vehicles that frequently start and stop. The front-stage catalyst can concentrate the treatment of pollutants generated during start-stop, and the rear-stage catalyst can catalyze the pollutants that have not been fully reacted.

[0058] It should be noted that in some embodiments of the present disclosure, the first catalytic layer, the second catalytic layer, and the third catalytic layer are all prepared by the method of the first aspect of the present disclosure.

[0059] In some embodiments of the present disclosure, the first catalytic layer comprises CeO2-ZrO2-Co3O4-M1 x O y , M1 is at least one of La, Pr, Nd, and Y; and / or,

[0060] The second catalytic layer comprises CeO2-ZrO2-Al2O3-M2 x O y , wherein M2 is at least one of La and Y; and / or,

[0061] The third catalytic layer comprises CeO2-ZrO2-M3 x O y , wherein M3 is at least one of La, Pr, Nd, Y, and Al.

[0062] CeO2-ZrO2-Co3O4-M1 x O y has a good promotion effect on the catalytic activity of the noble metals Pt and Pd in the first catalytic layer. CeO2-ZrO2-Al2O3-M2 x O y has a large specific surface area, which is conducive to the good dispersion of Rh.

[0063] In some embodiments of the present disclosure, the mass percentage of each component in the first catalytic layer is: CeO2 is 65%~80%, ZrO2 is 10%~30%, Co3O4 is 1%~5%, M1 x O y is 2%~5%; and / or,

[0064] The mass percentage of each component in the second catalytic layer is: CeO2 is 55%~70%, ZrO2 is 10%~25%, Al2O3 is 5%~15%, M2 x O y is 2%~5%; and / or,

[0065] The mass percentage of each component in the third catalytic layer is: CeO2 is 20%~45%, ZrO2 is 50%~70%, M3 x O y is 3%~10%; and / or,

[0066] The specific surface area of the first catalytic layer is not less than 50 m 2 / g, and the oxygen storage capacity is not less than 600 μmol / g; and / or,

[0067] The specific surface area of the second catalytic layer is not less than 50 m 2 / g, and the oxygen storage capacity is not less than 600 μmol / g; and / or,

[0068] The specific surface area of the third catalytic layer is not less than 50 m 2 / g, and the oxygen storage capacity is not less than 800 μmol / g; and / or,

[0069] The specific surface area of the modified alumina is not less than 110 m 2 / g; and / or,

[0070] The pore density of the first ceramic carrier is 300 / ft2~450 / ft2, and the wall thickness is ≤8 mil.

[0071] In some embodiments of the present disclosure, the noble metal supported on the first catalytic layer includes Pt and Pd, the loading amount of Pt is 20 g / ft 3 ~100 g / ft 3 , and the loading amount of Pd is 0~30 g / ft 3 ; and / or,

[0072] In the second catalytic layer, the loading amount of Rh is 0.1 g / ft 3 ~15 g / ft 3 ; and / or,

[0073] The noble metal supported on the third catalytic layer includes Pt and Pd, wherein the loading of Pt is 10 g / ft ~ 50 g / ft 3 , and the loading of Pd is 0 ~ 20 g / ft 3 .

[0074] For example, in the first catalytic layer, the loading of Pt can be 20 g / ft 3 , 400 g / ft 3 , 600 g / ft 3 , 800 g / ft 3 , 100 g / ft 3 , and the loading of Pd can be 0 g / ft 3 , 5 g / ft 3 , 10 g / ft 3 , 15 g / ft 3 , 20 g / ft 3 , 25 g / ft 3 , 30 g / ft 3 .

[0075] For example, in the second catalytic layer, the loading of Rh can be 0.1 g / ft 3 , 0.3 g / ft 3 , 0.9 g / ft 3 , 3 g / ft 3 , 9 g / ft 3 , 15 g / ft 3 .

[0076] For example, in the third catalytic layer, the loading of Pt can be 10 g / ft 3 , 20 g / ft 3 , 30 g / ft 3 , 40 g / ft 3 , 50 g / ft 3 , and the loading of Pd can be 0 g / ft 3 , 5 g / ft 3 , 10 g / ft 3 , 15 g / ft 3 , 20 g / ft 3 .

[0077] The technical solutions of the present disclosure are further described below in combination with specific examples. It should be understood that these examples are only used to illustrate the present disclosure and not to limit the scope of the present disclosure. The experimental methods not specified in the following examples are generally determined according to the industry standards. If there is no corresponding industry standard, the general international standards, conventional conditions, or the conditions suggested by the manufacturers are followed.

[0078] Example 1

[0079] The present example provides a method for preparing a tail gas purification catalyst, which comprises:

[0080] The oxide raw materials for preparing the CeO2-ZrO2-La2O3-promoted catalyst material are weighed, and the mass percentage of each component in the oxide raw materials for preparing the CeO2-ZrO2-Al2O3-Y2O3-promoted catalyst material is as follows: CeO2 is 35%, ZrO2 is 60%, and La2O3 is 5%.

[0081] The lanthana-modified alumina, which is used as the oxide carrier, is weighed, and the content of lanthanum oxide in the lanthana-modified alumina is 8%.

[0082] The platinum nitrate solution is prepared according to a loading amount of 30 g / ft 3 The palladium nitrate solution is prepared according to a loading amount of 10 g / ft 3

[0083] The oxide raw materials for preparing the CeO2-ZrO2-La2O3-promoted catalyst material, the platinum nitrate solution, and the palladium nitrate solution are mixed and evaporated to dryness, to obtain a mixture, which is then calcined at 600°C to obtain the CeO2-ZrO2-La2O3-promoted catalyst material loaded with Pt and Pd.

[0084] The CeO2-ZrO2-La2O3-promoted catalyst material loaded with Pt and Pd, the oxide carrier, the pseudoboehmite, the hydroxyethyl acrylate, and water are jointly ball-milled to obtain a catalyst slurry. In the catalyst slurry, the mass ratio of the CeO2-ZrO2-La2O3-promoted catalyst material loaded with Pt and Pd to the oxide carrier is 1:1, the mass content of the pseudoboehmite is 5%, the mass content of the hydroxyethyl acrylate is 5%, and the solid content of the catalyst slurry is 30%.

[0085] The catalyst slurry is coated onto the ceramic carrier, which is dried and then calcined at 700°C to obtain the tail gas purification catalyst.

[0086] Example 2

[0087] The present example provides a method for preparing a tail gas purification catalyst, which comprises:

[0088] The oxide raw materials for preparing the CeO2-ZrO2-Al2O3-Y2O3-promoted catalyst material are weighed, and the mass percentage of each component in the oxide raw materials for preparing the CeO2-ZrO2-Al2O3-Y2O3-promoted catalyst material is as follows: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%.

[0089] The lanthana-modified alumina, which is used as the oxide carrier, is weighed, and the mass content of lanthanum oxide in the lanthana-modified alumina is 5%.​

[0090] According to the loading amount of 5g / ft 3 Rh nitrate solution was prepared according to the loading amount of 5g / ft

[0091] The oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3, the Rh nitrate solution and the magnesium acetate were mixed and evaporated to dryness to obtain a mixture, and then the mixture was calcined at 600°C to obtain the Rh-loaded promoter material.

[0092] The Rh-loaded promoter material, the oxide carrier, the zirconium acetate, the polyhydroxyethyl methacrylate and the water were co-ball milled to obtain a catalyst slurry. In the catalyst slurry, the mass ratio of the Rh-loaded promoter material to the oxide carrier was 1:4, the mass content of the zirconium acetate was 6%, the mass content of the polyhydroxyethyl methacrylate was 9%, and the solid content of the catalyst slurry was 4%.

[0093] The catalyst slurry was coated onto the ceramic carrier, the ceramic carrier was dried and then calcined at 700°C to obtain the tail gas purification catalyst.

[0094] Example 3

[0095] The difference between this example and Example 2 is that the mixture does not contain magnesium acetate.

[0096] The present example provides a preparation method of a tail gas purification catalyst, which comprises:

[0097] The oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3 was weighed, and the mass percentage of each component in the oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3 was as follows: CeO2 was 65%, ZrO2 was 20%, Al2O3 was 10%, and Y2O3 was 5%.

[0098] Lanthanum-modified alumina was weighed as the oxide carrier, and the mass content of lanthanum oxide in the lanthanum-modified alumina was 7%.

[0099] Rh nitrate solution was prepared according to the loading amount of 5g / ft 3 Rh nitrate solution was prepared according to the loading amount of 5g / ft

[0100] The oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3 and the Rh nitrate solution were mixed and evaporated to dryness to obtain a mixture, and then the mixture was calcined at 600°C to obtain the Rh-loaded promoter material.

[0101] The Rh-loaded promoter material, the oxide carrier, zirconium acetate, polyhydroxyethyl methacrylate and water are co-ball milled to prepare a catalyst slurry. In the catalyst slurry, the mass ratio of the Rh-loaded promoter material to the oxide carrier is 1:1-4, the mass content of zirconium acetate is 8%, the mass content of polyhydroxyethyl methacrylate is 10%, and the solid content of the catalyst slurry is 50%.

[0102] The catalyst slurry is coated on the ceramic carrier, the ceramic carrier is calcined at 700℃ after drying the moisture to obtain the tail gas purification catalyst.

[0103] Example 4

[0104] The embodiment provides a tail gas purification catalyst, the tail gas purification catalyst comprising a front-stage catalyst and a rear-stage catalyst, the front-stage catalyst comprising 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 noble metal loaded on the first catalytic layer comprising at least one of Pt and Pd, and the noble metal loaded on the second catalytic layer comprising Rh.

[0105] The rear-stage catalyst comprises a second ceramic carrier and a third catalytic layer arranged on the second ceramic carrier, and the noble metal loaded on the third catalytic layer comprising Pt and Pd.

[0106] The promoter material of the first catalytic layer comprises CeO2-ZrO2-Co3O4-M1 x O y , wherein M1 x O y consisting of La2O3 and Nd2O3 in a mass ratio of 1:1, and the mass percentage of each component in the promoter material of the first catalytic layer is as follows: CeO2 is 75%, ZrO2 is 20%, Co3O4 is 3%, and M1 x O y is 2%,

[0107] The promoter material of the second catalytic layer comprises CeO2-ZrO2-Al2O3-Y2O3, and the mass percentage of each component in the promoter material of the second catalytic layer is as follows: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%,

[0108] The promoter material of the third catalytic layer comprises CeO2-ZrO2-Pr2O3, and the mass percentage of each component in the promoter material of the third catalytic layer is as follows: CeO2 is 35%, ZrO2 is 60%, and Pr2O3 is 5%.

[0109] The oxide carrier in the first, second and third catalytic layers respectively further comprises modified alumina, the modified alumina is lanthanum-modified alumina, the lanthanum-modified alumina further comprises silica and calcium oxide in a mass ratio of 1:1, and in the modified alumina, the mass content of lanthanum oxide is 5%, the mass content of silica is 2%, and the mass content of calcium oxide is 2%. In the first, second and third catalytic layers, the mass ratio of the noble metal loaded on the promoter material and the modified alumina in the oxide carrier is 1:4.

[0110] The specific surface area of the promoter material in the first catalytic layer is not less than 50 m 2 / g after aging at 1000℃ for 4h, and the oxygen storage capacity is not less than 600 μmol / g, the specific surface area of the promoter material in the second catalytic layer is not less than 50 m 2 / g after aging at 1000℃ for 4h, and the oxygen storage capacity is not less than 600 μmol / g, and the specific surface area of the promoter material in the third catalytic layer is not less than 50 m 2 / g after aging at 1000℃ for 4h, and the oxygen storage capacity is not less than 800 μmol / g, the specific surface area of the lanthanum-modified alumina is not less than 110 m 2 / g after aging at 1000℃ for 4h.

[0111] The first ceramic carrier has a pore density of 350 per square inch and a wall thickness of 8 mil.

[0112] The noble metal loaded on the first catalytic layer comprises Pt and Pd, the loading amount of Pt is 30 g / ft 3 , and the loading amount of Pd is 10 g / ft 3 , in the second catalytic layer, the loading amount of Rh is 8 g / ft 3 , the noble metal loaded on the third catalytic layer comprises Pt and Pd, the loading amount of Pt is 20 g / ft 3 , and the loading amount of Pd is 5 g / ft 3 .

[0113] The embodiment also provides a preparation method of the exhaust gas purification catalyst, which comprises the following steps:

[0114] Preparation of the pre-stage catalyst:

[0115] First platinum nitrate solution and first palladium nitrate solution are prepared according to the Pt loading amount and the Pd loading amount of the first catalytic layer, and oxide raw materials for preparing the promoter material of the first catalytic layer are weighed according to the composition of the promoter material of the first catalytic layer, the oxide raw materials for preparing the promoter material of the first catalytic layer, the first platinum nitrate solution and the first palladium nitrate solution are mixed and then evaporated to dryness, to obtain a first mixture, and then the first mixture is calcined at 500℃ to obtain the first oxide loaded with Pt and Pd.

[0116] The first oxide, polyvinyl alcohol, polyhydroxyethyl acrylate and water are co-ball milled to prepare a first catalyst slurry. In the first catalyst slurry, the mass content of polyvinyl alcohol is 3%, the mass content of polyhydroxyethyl acrylate is 6%, and the solid content of the first catalyst slurry is 20%.

[0117] The first catalyst slurry is coated on the first ceramic carrier, the first ceramic carrier is calcined at 700°C after drying the moisture, and a first catalytic layer is formed on the first ceramic carrier.

[0118] A rhodium nitrate solution is prepared according to the Rh loading amount of the second catalytic layer, and oxide raw materials are weighed according to the composition of the second catalytic layer. The oxide raw materials for preparing the second catalytic layer, the rhodium nitrate solution and magnesium acetate are mixed and evaporated to dryness, to obtain a second mixture, which is then calcined at 500°C to obtain a second oxide loaded with Rh.

[0119] The second oxide, polyethylene glycol, polyhydroxyethyl acrylate and water are co-ball milled to prepare a second catalyst slurry. In the second catalyst slurry, the mass content of polyethylene glycol is 4%, the mass content of polyhydroxyethyl acrylate is 5%, and the solid content of the second catalyst slurry is 30%.

[0120] The second catalyst slurry is coated on the surface of the first ceramic carrier, i.e. on the first catalytic layer, and the first ceramic carrier is calcined at 700°C after drying the moisture, to obtain a front-stage catalytic converter.

[0121] Preparation of a rear-stage catalytic converter:

[0122] Second platinum nitrate solution and second palladium nitrate solution are prepared according to the Pt loading amount and the Pd loading amount of the third catalytic layer, and oxide raw materials are weighed according to the composition of the third catalytic layer. The oxide raw materials for preparing the third catalytic layer, the second platinum nitrate solution and the second palladium nitrate solution are mixed and evaporated to dryness, to obtain a third mixture, which is then calcined at 500°C to obtain a third oxide loaded with Pt and Pd.

[0123] The third oxide, pseudoboehmite, polyhydroxyethyl acrylate and water are co-ball milled to prepare a third catalyst slurry. In the third catalyst slurry, the mass content of polyethylene glycol is 4%, the mass content of polyhydroxyethyl acrylate is 5%, and the solid content of the third catalyst slurry is 30%.

[0124] The third catalyst slurry is coated on the second ceramic carrier, and the second ceramic carrier is calcined at 700°C after drying the moisture, to obtain a rear-stage catalytic converter.

[0125] Preparation of an exhaust gas purification catalytic converter:

[0126] Assembling the front-stage catalyst and the rear-stage catalyst, to obtain the exhaust gas purification catalyst.

[0127] Comparative Example 1

[0128] The only difference between this comparative example and Example 1 is that the catalyst slurry does not contain a functional modifier.

[0129] This comparative example provides a method for preparing an exhaust gas purification catalyst, which comprises:

[0130] The oxide raw material for preparing the catalytic material CeO2-ZrO2-La2O3 is weighed, and the mass percentage of each component in the oxide raw material for preparing the catalytic material CeO2-ZrO2-La2O3 is as follows: CeO2 is 35%, ZrO2 is 60%, and La2O3 is 5%.

[0131] The lanthana-modified alumina, which is an oxide carrier, is weighed, and the content of lanthana in the lanthana-modified alumina is 8%.

[0132] The platinum nitrate solution is prepared according to a loading amount of 30 g / ft 3 , and the palladium nitrate solution is prepared according to a loading amount of 10 g / ft 3 .

[0133] The oxide raw material for preparing the catalytic material CeO2-ZrO2-La2O3, the platinum nitrate solution, and the palladium nitrate solution are mixed and evaporated to dryness, to obtain a mixture, and then the mixture is calcined at 600°C to obtain a catalytic material loaded with Pt and Pd;

[0134] The catalytic material loaded with Pt and Pd, the oxide carrier, the pseudoboehmite, and water are jointly ball-milled to prepare a catalyst slurry. In the catalyst slurry, the mass ratio of the catalytic material loaded with Pt and Pd to the oxide carrier is 1:1, the mass content of the pseudoboehmite is 5%, and the solid content of the catalyst slurry is 30%.

[0135] The catalyst slurry is coated onto the ceramic carrier, the ceramic carrier is calcined at 700°C after drying the water, to obtain an exhaust gas purification catalyst.

[0136] Comparative Example 2

[0137] The only difference between this comparative example and Example 2 is that the catalyst slurry does not contain a functional modifier.

[0138] This comparative example provides a method for preparing an exhaust gas purification catalyst, which comprises:

[0139] The oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3 is weighed, and the mass percentage of each component in the oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3 is as follows: CeO2 is 65%, ZrO2 is 20%, Al2O3 is 10%, and Y2O3 is 5%.

[0140] The lanthanum-modified alumina serving as the oxide carrier is weighed, and the content of lanthanum oxide in the lanthanum-modified alumina is 5%.

[0141] The rhodium nitrate solution is prepared according to a loading amount of 5 g / ft 3 .

[0142] The oxide raw material for preparing the promoter material CeO2-ZrO2-Al2O3-Y2O3, the rhodium nitrate solution, and the magnesium acetate are mixed and evaporated to dryness, to obtain a mixture, and then the mixture is calcined at 600°C to obtain the promoter material loaded with Rh.

[0143] The promoter material loaded with Rh, the oxide carrier, zirconium acetate, and water are collectively ball-milled to obtain a catalyst slurry. In the catalyst slurry, the mass ratio of the promoter material loaded with Rh to the oxide carrier is 1:4, the mass content of the zirconium acetate is 6%, and the solid content of the catalyst slurry is 4%. The catalyst slurry is coated onto a ceramic carrier, the ceramic carrier is calcined at 700°C after drying the water, to obtain the exhaust gas purification catalyst.

[0144] Related experiments and effect data:

[0145] The noble metal dispersion of the exhaust gas purification catalysts of Examples 1 to 4 and Comparative Examples 1 to 2 is tested.

[0146] The method for testing the noble metal dispersion is as follows:

[0147] 200 mg of the sample is pretreated in an H2 stream at a temperature of 450°C for 1 h, and the flow rate of the H2 is 30 mL / min. Then the sample is cooled to room temperature in a He stream and placed in an ethanol-dry ice mixture at -78°C. Subsequently, a constant dose of CO is pulsed into the sample until no CO consumption is detected. Assuming that only one CO molecule is adsorbed per noble metal atom, the adsorption rate of the CO molecules is calculated, which is defined as the dispersion of the noble metal in the catalyst layer. For Example 4, the noble metal dispersion is the average of the front-stage catalyst and the rear-stage catalyst.

[0148] The THC (total carbon compounds) light-off temperature, CO light-off temperature, and NO light-off temperature of the exhaust gas purification catalysts of Examples 1 to 4 and Comparative Examples 1 to 2 are tested according to the national standard GB / T 34248-2017.

[0149] The test results are shown in Table 1.

[0150] Table 1

[0151]

[0152] As can be seen from Table 1, the THC light-off temperature, CO light-off temperature and NO light-off temperature of Examples 1-4 are at a low level, and the noble metal dispersion is at a high level. Compared with Example 1, the noble metal dispersion of Comparative Example 1 is significantly reduced, which may be because the functional regulator is not added in the preparation process of Comparative Example 1. The THC light-off temperature, CO light-off temperature and NO light-off temperature of Comparative Example 1 are all higher, which may be because the noble metal dispersion is too low to reduce the catalytic efficiency. Compared with Example 2, the functional regulator is not added in the preparation process of Comparative Example 2, and the test results show the same rule. In summary, in some embodiments of the present disclosure, the addition of the functional regulator can effectively increase the dispersion of the noble metal, thereby increasing the catalytic efficiency of the three-way catalyst.

[0153] The above technical solutions provided by the embodiments of the present disclosure have the following advantages compared with related art:

[0154] The preparation method of the tail gas purification catalyst provided by the embodiments of the present disclosure, in the process of preparing the slurry of the catalytic material loaded with noble metal, by adding a functional regulator, the functional regulator includes at least one of polyhydroxyethyl acrylate and polymethyl hydroxyethyl methacrylate, it is found in actual research that polyhydroxyethyl acrylate and polymethyl hydroxyethyl methacrylate can inhibit the agglomeration of noble metal, so that the noble metal can maintain a high catalytic efficiency, thereby the load of noble metal can be reduced, and the cost of the tail gas purification catalyst can be reduced.

[0155] Various embodiments of the present disclosure can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit to the scope of the present disclosure. Therefore, it should be considered that the described range has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has 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., and single numbers within the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0156] In the present disclosure, the orientation words such as "upper" and "lower" are specifically the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the present disclosure, the terms "comprise", "contain" and the like mean "including but not limited to". Moreover, the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the elements defined by the statement "comprise" do not exclude the presence of other identical elements in the process, method, article or device including the elements. In this paper, the relationship 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 any such actual relationship or order between the entities or operations. In this paper, the "and / or" describes the association relationship of the associated objects, which means that there can be three relationships. For example, A and / or B can represent the following cases: A exists alone, A and B exist together, and B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that any one of the three associated objects can exist alone, or any at least two of them exist together. For example, for A, and / or B, and / or C, it means that any one of A, B and C exists alone, or any two of them exist together, or all three of them exist together. In this paper, "at least one" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or similar expressions mean any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0157] The above description is only a specific embodiment of the present disclosure, which enables those skilled in the art to understand or implement the present disclosure. Various modifications of these embodiments will be apparent to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A method for preparing an exhaust gas purification catalyst, comprising: providing a noble metal loaded promoter material, and providing an oxide carrier; co-slurrying the oxide carrier, the noble metal loaded promoter material, a binder, a function regulator, and water to obtain a catalyst slurry; and, arranging the catalyst slurry on a ceramic carrier, and obtaining the exhaust gas purification catalyst after the catalyst slurry is dried; wherein the function regulator comprises at least one of polyhydroxyethyl acrylate and polyhydroxyethyl methacrylate.

2. The method of manufacturing an exhaust gas purifying catalyst according to claim 1, wherein, the binder comprises at least one of zirconium acetate, pseudo-boehmite, polyvinyl alcohol, and polyethylene glycol; and / or, the binder is used in an amount of 1%-8% by mass percentage of the catalyst slurry; and / or, the high molecular in the function regulator has a weight average molecular weight of 500-1000; and / or, the function regulator is used in an amount of 5%-10% by mass percentage of the catalyst slurry.

3. The method of manufacturing an exhaust gas purifying catalyst according to claim 1, wherein, the noble metal in the noble metal loaded promoter material is Rh, and the providing of the noble metal loaded promoter material comprises: providing a mixed solution comprising a Rh precursor and magnesium acetate; and, immersing the promoter material in the mixed solution comprising the Rh precursor and magnesium acetate, and calcining to obtain the noble metal loaded promoter material; wherein the magnesium acetate is used in an amount of 0.5%-2% by mass percentage of the Rh precursor. 4.An exhaust gas purification catalyst prepared by the method of any one of claims 1-3.

5. The exhaust gas purifying catalyst according to claim 4, wherein 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 noble metal loaded on the first catalytic layer comprises at least one of Pt and Pd, and the noble metal loaded on the second catalytic layer comprises Rh; the rear-stage catalyst comprises a second ceramic carrier and a third catalytic layer arranged on the second ceramic carrier, the noble metal loaded on the third catalytic layer comprises at least one of Pt and Pd.

6. The exhaust gas purifying catalyst according to claim 4, wherein The first catalytic layer includes a CeO2-ZrO2-Co3O4-M1 x O y wherein M1 is at least one of La, Pr, Nd, Y; and / or, The second catalytic layer includes a CeO2-ZrO2-Al2O3-M2 x O y wherein M2 is at least one of La, Y; and / or, The third catalytic layer includes a CeO2-ZrO2-M3 x O y wherein M3 is at least one of La, Pr, Nd, Y, Al.

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

8. The exhaust gas purifying catalyst according to claim 6, wherein the oxide carrier in the first catalytic layer and the oxide carrier in the third catalytic layer each comprises modified alumina, the modified alumina comprises alumina and lanthanum oxide, and the modified alumina further comprises at least one of neodymium oxide, magnesium oxide, barium oxide, silicon dioxide, and calcium oxide.

9. The exhaust gas purifying catalyst according to claim 8, wherein The specific surface area of the first catalytic layer is not less than 50 m 2 / g, and the oxygen storage capacity is not less than 600 μmol / g; and / or The specific surface area of the second catalytic layer is not less than 50 m 2 / g after the second catalytic layer is aged at 1000 ℃ for 4 h, and the oxygen storage capacity is not less than 600 μmol / g; and / or, The specific surface area of the third catalytic layer is not less than 50 m 2 / g after the aging of the third catalytic layer at 1000 ℃ for 4 h, and the oxygen storage capacity is not less than 800 μmol / g; and / or, The modified alumina has a specific surface area of not less than 110 m 2 / g; and / or, the first ceramic carrier has a pore density of 300 pores / in2-450 pores / in2, and a wall thickness ≤8 mil.

10. The exhaust gas purifying catalyst according to claim 5, wherein The noble metal supported on the first catalytic layer includes Pt and Pd, wherein the loading of Pt is 20-100 g / ft 3 , the loading of Pd is 0-30 g / ft 3 ; and / or, The loading amount of Rh in the second catalytic layer is 0.1 g / ft 3 15 g / ft 3 ; and / or, The noble metal supported on the third catalytic layer includes Pt and Pd, wherein the loading of Pt is 10 g / ft 3 ~50 g / ft 3 , and the loading of Pd is 0~20 g / ft 3 .

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