CN115805069B - Catalyst for diesel engine based on high-dispersion perovskite catalytic component and preparation method thereof - Google Patents

Abstract

The invention discloses a diesel engine catalyst based on a high-dispersion perovskite catalytic component, which uses La _x Ce _1‑x Mn _y Bi _1‑y O ₃ perovskite-MoO ₃ The composite catalytic material nano particles are used as main catalytic active components and CeO is used as auxiliary material ₂ 、ZrO ₂ 、γ‑Al ₂ O ₃ Cordierite honeycomb ceramics. The catalyst is coated in the DOC, and can efficiently purify PM, HC, CO and other pollutants discharged by the diesel engine. The main catalytic active component has the advantages of sulfur resistance, heat resistance and low cost; the whole catalytic activity of the catalyst is enhanced by increasing the number of the catalytic active sites per unit mass, the complete replacement of noble metal is realized, and perovskite and MoO are contained in the catalyst ₃ The simultaneous addition of (2) can produce a synergistic effect, further improve the catalytic activity of the catalyst and expand the high activity temperature window. The dispersion effect of the perovskite precursor is obviously improved by adopting the preparation of the carbon black adsorption matrix-based first adsorption and then gel, and the nano particles have smaller size, uniform particle size and regular structure.

Description

Diesel engine catalyst based on highly dispersed perovskite catalytic components and preparation method

Technical field

The invention belongs to a vehicle internal combustion engine exhaust pollutant purification technology, and specifically relates to an oxidation catalyst for purifying pollutants such as particulate matter (PM), hydrocarbon (HC) and carbon monoxide (CO) in diesel engine exhaust and its preparation method.

Background technique

Diesel vehicles are currently the main force in heavy-duty, long-distance highway passenger and freight transportation at home and abroad, and have made outstanding contributions to the development of the national economy and the convenience of social life. But at the same time, due to the limitations of combustion methods, the pollutant emissions of diesel vehicles are also relatively serious, prompting most countries in the world to formulate increasingly stringent emission regulations to limit the pollutant emissions of diesel vehicles, which also promotes the use of vehicle diesel engine exhaust. Development, promotion and application of pollutant control technologies. Among the many diesel engine exhaust pollutant control technologies, the diesel oxidation catalyst (DOC) is an effective technology for reducing HC and CO emissions. At present, DOC has almost become a necessary exhaust pollutant purification equipment for vehicle diesel engines. However, traditional DOC requires the coating of catalytic coatings with precious metals as the main catalytically active components. However, precious metal materials have poor performance in PM purification performance, resistance to sulfur poisoning, resistance to thermal aging, and resistance to coking, and the raw materials are expensive, resulting in The operating conditions of modern advanced diesel engines are harsh and the requirements for fuel and lubricity components are extremely stringent. Therefore, the reduction/replacement technology of precious metal catalytic materials in DOC has become a research hotspot at home and abroad.

Substituted perovskites and transition metal oxides have always been the most potential substitute materials for precious metal catalytic materials in DOC. They have excellent sulfur resistance, coking resistance, and sintering resistance, extremely low raw material costs, and can purify HC and CO. The properties are similar to those of precious metal catalytic materials, but their purification efficiency for PM is lower than that of precious metal catalytic materials. On the other hand, to enhance the overall catalytic activity of catalytic materials, in addition to improving the reactivity of the catalytic active sites themselves, increasing the number of catalytic active sites can also achieve obvious effects, while reducing the particle size of the catalytically active component particles in the catalyst, Increasing the specific surface area of active ingredient particles can increase the exposure probability of active ingredients, thereby potentially increasing the number of catalytic active sites. Therefore, the preparation method of high-dispersion, ultra-fine catalytically active ingredient particles has also become the core basic technology for the promotion and application of substituted perovskites and transition metal oxides on DOC. Currently, research on this technology at home and abroad is extremely intense.

Contents of the invention

In view of the above existing technology, the present invention proposes a diesel engine catalyst based on highly dispersed perovskite catalytic components that is easy to operate, saves preparation time and cost, and can significantly improve the dispersion effect of the perovskite precursor. In the process, carbon black is used as the adsorption matrix, and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template prepared by first adsorbing and then gelling steps is used as the La _x Ce _1-x Mn Preparation of _{La x Ce 1 -x} Mn _y Bi _1-y O ₃ type perovskite-molybdenum oxide (MoO ₃ ) composite catalytic material nanoparticles using y Bi 1-y O ₃ type perovskite nanoparticle templates, and as described La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles are the main catalytic active component, CeO ₂ and ZrO ₂ as cocatalysts, and γ-Al ₂ O ₃ as Coating accessories.

In order to solve the above technical problems, the present invention proposes a diesel engine catalyst based on highly dispersed perovskite catalytic components, including a catalytic coating coated on a carrier. The carrier is a 400 mesh cordierite honeycomb ceramic. The catalytic The coating is composed of a main catalytically active component, a co-catalyst and coating auxiliary materials; the co-catalyst is composed of CeO ₂ and ZrO ₂ , and the coating auxiliary material is composed of γ-Al ₂ O ₃ ; the main catalytic active component is composed of ABO ₃ type perovskite-MoO ₃ composite catalytic material nanoparticle composition, in which the mass percentage of ABO ₃ type perovskite and MoO ₃ is 60~90%/40~10%, ABO ₃ type perovskite and MoO ₃ The sum of the mass percentages is 100%; the A-site of the ABO _3- type perovskite is composed of La and Ce, and the B-site is composed of Mn and Bi, forming La _x Ce _1-x Mn _y Bi _1-y O ₃ type Perovskite, where x represents the mole percentage of La at A site in the sum of the moles of Ce and La ions at A site, x=60~90%; y represents Mn at B site in two kinds of Mn and Bi at B site The mole percentage in the sum of ion moles is y=50~80%; at the same time, the mole number of La ions and Ce ions in the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite is The ratio to the sum of the moles of Mn ions and Bi ions is 1:1; the role of the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite in the catalyst is not only the main catalytic active component It is a component and also a nanoparticle template for preparing La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles.

Furthermore, the diesel engine catalyst based on highly dispersed perovskite catalytic components of the present invention, wherein:

In the cocatalyst, the mass percentage of CeO ₂ and ZrO ₂ is 70-90%/10-30%, and the sum of the mass percentages of the two is 100%.

The γ-Al ₂ O ₃ includes pure γ-Al ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol. The pure γ-Al 2 O ₃ powder and aluminum sol are converted into γ-Al ₂ O 3 . The mass percentage of γ-Al ₂ O ₃ converted from the sol is: 80~90%/10~20%, and the sum of the mass percentages of the two is 100%.

The mass percentages of the main catalytic active component, cocatalyst and coating auxiliary materials are 1-5%/4-10%/85-95%, and the sum of the mass percentages of the three is 100%.

The mass percentage of the catalytic coating and the carrier is 15-30%/85-70%, and the sum of the mass percentages of the two is 100%.

The present invention proposes a method for preparing the above-mentioned diesel engine catalyst based on highly dispersed perovskite catalytic components, which includes the following steps:

Step 1. Catalyst composition design: Based on the above-mentioned component ratios, design the following proportions: the mass of La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite and MoO ₃ in the main catalytic active ingredients Percent, La _x Ce _1-x Mn _y Bi _1-y O _3- type perovskite molar percentage of La element and Ce element, molar percentage of Mn element and Bi element, mass percentage of CeO ₂ and ZrO ₂ in the cocatalyst , the mass percentage of pure γ-Al ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol in the γ-Al ₂ O ₃ coating auxiliary materials, the main catalytic active component, co-catalyst and coating The mass percentage of auxiliary materials, and the mass of the catalytic coating that can be produced by the planned configuration of the coating slurry;

Step 2. La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template preparation: According to the proportion of each component designed in step 1 and the planned configuration of the coating slurry, the quality of the catalytic coating can be generated, Calculate _{the mass} of the La _x Ce _{1- x Mn y} Bi _1-y O ₃ type perovskite nanoparticle template in the main catalytic active component and _{the La} The number of moles of La, Ce, Mn and Bi elements in the particle template;

Combine every 433.0g La(NO ₃ ) ₃ ·6H ₂ O to prepare 1 mol of La, every 434.1g of Ce(NO ₃ ) ₃ ·6H ₂ O to prepare 1 mol of Ce, every 173.0g of Mn(CH ₃ COO) ₂ to prepare 1 mol of Mn, and every 485.1 g Bi(NO ₃ ) ₃ ·5H ₂ O to prepare 1 mol Bi, and the number of moles of La, Ce, Mn and Bi elements in the La _x Ce _1-x Mn _y Bi _1-y O _3- type perovskite nanoparticle template _{The preparation of the La} The mass of La(NO ₃ ) ₃ ·6H ₂ O, Ce(NO ₃ ) ₃ ·6H ₂ O, Mn(CH ₃ COO) ₂ , Bi(NO ₃ ) ₃ ·5H ₂ O and glucose used in the mineral nanoparticle template; Weigh the determined masses of La(NO ₃ ) ₃ ·6H ₂ O, Ce(NO ₃ ) ₃ ·6H ₂ O, Mn(CH ₃ COO) ₂ , Bi(NO ₃ ) ₃ ·5H ₂ O, and glucose. And the mass is between 0.8 and 0.8 of the sum of the masses of La(NO ₃ ) ₃ ·6H ₂ O, Ce(NO ₃ ) ₃ ·6H ₂ O, Mn(CH ₃ COO) ₂ and Bi(NO ₃ ) ₃ ·5H ₂ O For carbon black within the range of 1.5 times and with a _D50 particle size not exceeding 500nm, add the above 6 raw materials together into deionized water weighed according to the ratio of 1g carbon black to 30~50mL deionized water, oscillate ultrasonic for 6~8 hours, and then The mixture of the six raw materials and deionized water is heated while ultrasonic oscillation, so that the mixture is evaporated to dryness after 6 to 8 hours and becomes a wet gel; then the wet gel is dried at 80 to 110°C for 6 to 12h, obtain the xerogel; heat the xerogel to 400°C at a rate of 3°C/min in a muffle furnace and keep it for 2h, then heat it up to 700~800°C at a rate of 10°C/min, and calcine In 3 to 4 hours, the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template is obtained;

Step 3. Preparation of the main catalytic active component: According to the proportion of each component designed in step 1 and the mass of the catalytic coating that can be generated by the planned configuration of the coating slurry, calculate the mass of MoO ₃ in the main catalytic active component;

Calculate the mass of (NH ₄ ) ₂ MoO ₄ required to prepare the main catalytic active component by combining the conversion ratio of preparing 144.0g MoO ₃ per 196.0g (NH ₄ ) ₂ MoO ₄ ; weigh the determined mass of (NH ₄ ) ₂ MoO ₄ and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template prepared in step 2, combine the (NH ₄ ) ₂ MoO ₄ and La _x Ce _1-x Mn _y The Bi _1-y O ₃ type perovskite nanoparticle template is added to deionized water weighed according to the ratio of 1g (NH ₄ ) ₂ MoO ₄ to 50 to 500 ml of deionized water, and oscillated with ultrasonic waves to form a slurry; use NaOH or HNO _3. Adjust the pH value of the slurry to be in the range of 4 to 6, and grind the slurry on a grinder until the D ₅₀ particle size is in the range of 800 to 1000 nm, and then heat the slurry while oscillating with ultrasonic waves. Grind the slurry so that the slurry is evaporated to dryness after 4 to 8 hours to become a solid; the evaporated solid is dried at 80 to 110°C for 6 to 12 hours, and then pre-calcinated at 350°C 2h, calcined at 500~550℃ for 2~3h, the powdered and massive solid La _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite-MoO ₃ composite catalytic material nanoparticles obtained after calcination are The main catalytically active component of the catalyst;

Step 4. Preparation of coating slurry: Based on the proportion of each component designed in step 1 and the mass of the catalytic coating produced by the planned configuration of the coating slurry, calculate the mass of CeO ₂ and ZrO ₂ and γ- The quality of Al ₂ O ₃ coating auxiliary materials;

Calculation of the mass percentage of Al _{2 O 3} in aluminum sol based on the preparation of 172.1g CeO ₂ per 434.2g Ce(NO ₃ ) ₃ ·6H ₂ O, the preparation of 123.2g ZrO ₂ per 429.3g Zr(NO ₃ ) ₄ ·5H 2 O Calculate the mass of Ce(NO ₃ ) ₃ ·6H ₂ O, Zr(NO ₃ ) ₄ ·5H ₂ O and aluminum sol required to prepare the coating slurry; in addition, the average molecular weight of 5 to 15 g per 100 g of catalytic coating is 20000 polyethylene glycol ratio, calculate the mass of polyethylene glycol required to prepare the catalytic coating; weigh the determined masses of Ce(NO ₃ ) ₃ ·6H ₂ O and Zr(NO ₃ ) ₄ ·5H ₂ O, pure γ-Al ₂ O ₃ powder, aluminum sol, polyethylene glycol with a molecular weight of 20000, and the La _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite-MoO prepared in step 3 ₃ Composite catalytic material nanoparticles, add the above 6 raw materials together into deionized water with a mass equivalent to 5 to 15 times the mass of the planned catalytic coating, oscillate with ultrasonic waves to form a slurry; adjust the above with NaOH or HNO ₃ The pH value of the slurry is in the range of 5 to 7, and the slurry is ground on a grinder until the D ₅₀ particle size is in the range of 800 to 1000 nm, and then the ground slurry is ground at 50 to 70°C Stir for 48 to 72 hours to obtain the coating slurry;

Step 5. Coat the catalytic coating on the carrier: design the mass of the carrier to be coated with the catalytic coating; weigh the carrier with the determined mass, and immerse the carrier in the coating at 50-70°C. layer of slurry, and ensure that the upper end surface of the carrier is slightly higher than the slurry level; after the slurry naturally lifts and fills all the pores of the carrier, the carrier is taken out of the slurry, and the residual fluid in the pores is blown away. At 80 Dry at ~110°C for 4 to 16 hours, then roast at 500 to 600°C for 2 to 4 hours; repeat the above impregnation, drying and roasting processes 2 to 3 times to obtain a diesel engine catalyst based on highly dispersed perovskite catalytic components.

The diesel engine catalyst based on the highly dispersed perovskite catalytic component prepared by the present invention is packaged as a diesel oxidation catalytic converter (DOC), and the diesel oxidation catalytic converter is installed in the diesel engine exhaust passage to achieve PM and HC removal in the diesel engine exhaust. and efficient oxidation and purification of CO.

Compared with the prior art, the beneficial effects of the present invention are:

The preparation method of first adsorbing and then gelling based on carbon black adsorption matrix is not only easy to operate, saves preparation time and cost, but also can significantly improve the dispersion effect of perovskite precursor, which is beneficial to the preparation of smaller scale, uniform particle size and regular structure. La _x Ce _1-x Mn _y Bi _1-y O _3- type perovskite nanoparticles. Using La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticles as ultrafine particle templates, highly dispersed La _x Ce _1-x Mn _y Bi _1-y O ₃ type can be further prepared Perovskite-MoO ₃ composite catalytic material nanoparticles. The main catalytic active component of La _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite-MoO ₃ composite catalytic material nanoparticles has the advantages of resistance to sulfur, anti-coking, heat resistance and low cost, and can significantly increase the unit mass. The number of catalytic active sites and the improvement of the catalytic activity of the catalytic active sites improve the overall pollutant purification performance of DOC, realize the complete replacement of precious metal materials in DOC, and significantly reduce the raw material cost of the catalyst. In addition, the main catalytic active component of the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles is La _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite. The simultaneous addition of MoO ₃ can produce a synergistic effect, further improving the overall catalytic activity of the catalyst and expanding the high activity temperature window.

Description of the drawings

Figure 1 is a schematic diagram of the engine exhaust PM, HC and CO purification performance evaluation system.

Among them: 1-dynamometer; 2-coupling; 3-test diesel engine; 4-intake air flow meter; 5-intake processor; 6-injector; 7-fuel injection control system; 8-exhaust Sampling port A; 9-Temperature sensor A; 10-Diesel oxidation catalytic converter (DOC); 11-Temperature sensor B; 12-Exhaust gas sampling port B; 13-Selective catalytic reduction catalyst; 14-Diesel particulate trap ; 15-exhaust sampling mechanism; 16-engine exhaust analyzer; 17-exhaust gas filter; 18-air pump.

Figure 2 is an engine evaluation system using the diesel engine exhaust PM, HC and CO purification performance. When the diesel engine exhaust temperature is 300°C and the air speed is 50000h ^-1 , the catalyst described in Examples 1 to 3 has a positive effect on the diesel engine exhaust gas. Purification efficiency of PM, HC and CO.

Figure 3 is an engine evaluation system using the diesel engine exhaust PM, HC and CO purification performance. When the diesel engine exhaust temperature is 400°C and the air speed is 100000h ^-1 , the catalyst described in Examples 1 to 3 has a positive effect on the diesel engine exhaust gas. Purification efficiency of PM, HC and CO.

Figure 4 shows the use of the diesel engine exhaust PM, HC and CO purification performance engine evaluation system during the European Steady State Test Cycle (ESC) test. purification efficiency.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples, but the following examples in no way limit the present invention.

The diesel engine catalyst based on highly dispersed perovskite catalytic components of the present invention includes a catalytic coating coated on a carrier. The carrier is a 400-mesh cordierite honeycomb ceramic. The catalytic coating is composed of a main catalytic active component and a cocatalyst. and coating auxiliary materials; the cocatalyst is composed of CeO ₂ and ZrO ₂ , and the coating auxiliary material is composed of γ-Al ₂ O _3. Each component and its content is as follows:

(1) La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles are used as the main catalytically active component, and the La _x Ce _1-x Mn _y Bi _1- The mass percentage of _{yO3 type} perovskite and _MoO3 is: 60~90%/40~10%, and the sum of the mass percentages is 100%.

(2) In the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite, the molar percentage of La element and Ce element is: 60~90%/10~40%, and the sum of molar percentages is 100%; the mole percentage of Mn element and Bi element is: 50~80%/20~50%, the sum of mole percentages is 100%; and the sum of the moles of La element and Ce element is equal to the mole of Mn element and Bi element The sum of the numbers is equal; the role of the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite in the catalyst is not only a component of the main catalytic active component, but also a component for preparing La _x Ce _{1 -x} Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles nanoparticle template.

(3) CeO ₂ and ZrO ₂ are used as cocatalysts, and the mass percentages of CeO ₂ and ZrO ₂ are: 70-90%/10-30%, and the sum of the mass percentages is 100%.

(4) Use γ-Al ₂ O ₃ as a coating auxiliary material, and the γ-Al ₂ O ₃ comes from pure γ-Al ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol, The mass percentage of the pure γ-Al ₂ O ₃ powder and the γ-Al ₂ O ₃ converted from the aluminum sol is: 80-90%/10-20%, and the sum of the mass percentages is 100%.

(5) The catalytic coating of the catalyst of the present invention is composed of the main catalytic active component, co-catalyst and coating auxiliary materials, and the mass percentage of the main catalytic active component, co-catalyst and coating auxiliary materials is: 1 to 5%/ 4～10%/85～95%, the sum of mass percentages is 100%.

(6) The catalyst of the present invention is composed of the catalytic coating and 400 mesh cordierite honeycomb ceramics, and the 400 mesh cordierite honeycomb ceramic is the carrier of the catalyst of the present invention, and the catalytic coating needs to be coated on the On the carrier, the mass percentage range of the catalytic coating and the carrier is: 15-30%/85-70%, and the sum of the mass percentages is 100%.

The invention proposes a catalyst for diesel engines based on highly dispersed perovskite catalytic components, which is suitable for the purification of PM, HC and CO in diesel engine exhaust. It uses carbon black as the adsorption matrix and adopts the steps of first adsorption and then gelation to prepare La. _x Ce _{1- x} Mn _y Bi _1-y O ₃ type perovskite nanoparticles, using the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticles as templates to prepare La _x Ce _{1 -x} Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles, and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalysis The material nanoparticles are the main catalytically active component, CeO ₂ and ZrO ₂ are used as cocatalysts, and γ-Al ₂ O ₃ is used as coating auxiliary materials. The specific process mainly includes the following 5 steps:

(1) Catalyst composition design;

(2) La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template preparation;

(3) Preparation of main catalytic active ingredients;

(4) Coating slurry preparation;

(5) Coat the catalytic coating on the carrier.

The technical solution of the present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings. It should be noted that the embodiments are illustrative rather than restrictive, and the content covered by the present invention is not limited to the following embodiments.

Diesel engine catalysts based on highly dispersed perovskite catalytic components include: La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles, CeO ₂ , ZrO ₂ , γ-Al ₂ O ₃ and 400 mesh cordierite honeycomb ceramics.

La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles are used as the main catalytically active component, and the La _x Ce _1-x Mn _y Bi _1-y O ₃ The mass percentages of type perovskite and MoO ₃ are: 60~90%/40~10%, and the sum of the mass percentages is 100%.

In the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite, the mole percentages of La element and Ce element are: 60~90%/10~40%, and the sum of the mole percentages is 100%; The mole percentages of Mn element and Bi element are: 50~80%/20~50%, and the sum of mole percentages is 100%; and the sum of the moles of La element and Ce element is the sum of the moles of Mn element and Bi element. Equal; the role of the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite in the catalyst is not only a component of the main catalytic active component, but also a component for preparing La _x Ce _1-x Mn Nanoparticle template for _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles.

CeO ₂ and ZrO ₂ are used as cocatalysts, and the mass percentages of CeO ₂ and ZrO ₂ are: 70-90%/10-30%, and the sum of the mass percentages is 100%.

γ-Al ₂ O ₃ is used as a coating auxiliary material, and the γ-Al ₂ O ₃ comes from pure γ-Al ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol. The mass percentage of γ-Al ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol is: 80~90%/10~20%, and the sum of the mass percentages is 100%.

The catalytic coating of the catalyst of the present invention is composed of the main catalytic active component, co-catalyst and coating auxiliary materials, and the mass percentage of the main catalytic active component, co-catalyst and coating auxiliary materials is: 1~5%/4~10 %/85~95%, the sum of mass percentages is 100%.

The catalyst of the present invention is composed of the catalytic coating and 400 mesh cordierite honeycomb ceramics, and the 400 mesh cordierite honeycomb ceramic is the carrier of the catalyst of the present invention, and the catalytic coating needs to be coated on the carrier, And the mass percentage range of the catalytic coating and the carrier is: 15-30%/85-70%, and the sum of the mass percentages is 100%.

The preparation method of the catalyst of the present invention is described in detail below through specific examples.

Example 1

(1) Catalyst composition design

The following ratios are designed respectively: La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite The mass percentage of ore and MoO ₃ is: 90%/10%, the mole percentage of La element and Ce element in La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite is: 60%/40%, The molar percentage of Mn element and Bi element is: 50%/50%, the mass percentage of CeO ₂ and ZrO ₂ in the cocatalyst is: 70%/30%, pure γ-Al in γ-Al ₂ O ₃ coating accessories The mass percentage of ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol is: 80%/20%, and the mass percentage of the main catalytic active component, co-catalyst and coating auxiliary materials is: 1%/ 4%/95%, and the planned configuration of coating slurry can produce 2000g of catalytic coating.

(2) La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template preparation

Weigh 14.6g La(NO ₃ ) ₃ ·6H ₂ O, 9.8g Ce(NO ₃ ) ₃ ·6H ₂ O, 4.9g Mn(CH ₃ COO) ₂ , 13.7g Bi(NO ₃ ) ₃ ·5H ₂ O , 40g glucose and 60g carbon black with a median particle size (D ₅₀ particle size) of 452nm, add the 6 raw materials to 3L deionized water, oscillate ultrasonic for 6 hours, and then heat the 6 raw materials and the The mixture of deionized water was evaporated to dryness after 8 hours to form a wet gel; the wet gel was then dried at 80°C for 12 hours to obtain a dry gel; the dry gel was heated in a muffle furnace The temperature is raised to 400°C at a rate of 3°C/min and maintained for 2 hours, and then heated to 800°C for 3 hours at a rate of 10°C/min to prepare La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template.

(3) Preparation of main catalytic active ingredients

Weigh 2.7g (NH ₄ ) ₂ MoO ₄ and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template prepared in step (2), and add the two raw materials to 1350 ml. In ionized water, ultrasonic oscillation forms a slurry; use NaOH or HNO ₃ to adjust the pH value of the slurry in the range of 4 to 6, and grind the slurry on a grinder until the D ₅₀ particle size is 800 ~1000nm range, and then heat the ground slurry while ultrasonic oscillation, so that the slurry evaporates to dryness and becomes solid after 8 hours. The evaporated solid was dried at 80°C for 12 hours, then pre-calcinated at 350°C for 2 hours, and calcined at 500°C for 3 hours to become powdery and block solids. The powdery and massive solids obtained after the calcination are La _x Ce _1-x Mny _{Bi 1- y} O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles.

(4) Coating slurry preparation

Weigh 141.3g Ce(NO ₃ ) ₃ ·6H ₂ O, 83.6g Zr(NO ₃ ) ₄ ·5H ₂ O, 1520g pure γ-Al ₂ O ₃ powder, and 1900g Al ₂ O _3. The mass content is 20%. of aluminum sol, 300g of polyethylene glycol with a molecular weight of 20,000 and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles prepared in step (3), and the The above 6 kinds of raw materials are added to 10kg of deionized water together, and ultrasonic vibration is used to form a slurry; use NaOH or HNO ₃ to adjust the pH value of the slurry to be in the range of 5 to 7, and grind the slurry on a grinder Grind until the D ₅₀ particle size is in the range of 800 to 1000 nm, and then stir the ground slurry at 70°C for 48 hours to obtain a coating slurry.

(5) Apply the catalytic coating to the carrier

Weigh 1kg of the carrier, immerse the carrier in the coating slurry at 70°C, and ensure that the upper end surface of the carrier is slightly higher than the slurry level; wait for the slurry to naturally rise and fill all the pores of the carrier , take out the carrier from the slurry, blow off the residual fluid in the channels, dry at 110°C for 4h, and then bake at 500°C for 4h. Repeat the above impregnation, drying and roasting process three times to obtain a diesel engine catalyst based on highly dispersed perovskite catalytic components.

Example 2

(1) Catalyst composition design

The following ratios are designed respectively: La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite The mass percentage of ore and MoO ₃ is: 60%/40%, the mole percentage of La element and Ce element in La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite is: 90%/10%, The molar percentage of Mn element and Bi element is: 80%/20%, the mass percentage of CeO ₂ and ZrO ₂ in the cocatalyst is: 90%/10%, pure γ-Al in γ-Al ₂ O ₃ coating accessories The mass percentage of ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol is: 90%/10%, and the mass percentage of the main catalytic active component, co-catalyst and coating auxiliary materials is: 5%/ 10%/85%, and the planned configuration of coating slurry can produce 2000g of catalytic coating.

(2) La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template preparation

Weigh 85.7g La(NO ₃ ) ₃ ·6H ₂ O, 9.6g Ce(NO ₃ ) ₃ ·6H ₂ O, 30.4g Mn(CH ₃ COO) ₂ , 21.3g Bi(NO ₃ ) ₃ ·5H ₂ O , 80g glucose and 120g carbon black with a median particle size (D ₅₀ particle size) of 373nm, add the 6 raw materials to 3.6L deionized water, oscillate ultrasonic for 8 hours, and then heat the 6 raw materials while oscillating ultrasonic and deionized water, so that the mixture is evaporated to dryness after 6 hours to become a wet gel; then the wet gel is dried at 80°C for 12 hours to obtain a dry gel; the dry gel is dried in a muffle Raise the temperature in the furnace to 400°C at a rate of 3°C/min and maintain it for 2 hours, and then raise the temperature to 700°C for 4 hours at a rate of 10°C/min to prepare La _x Ce _1-x Mn _y Bi _1-y O Type ₃ perovskite nanoparticle template.

(3) Preparation of main catalytic active ingredients

Weigh 54.4g (NH ₄ ) ₂ MoO ₄ and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template prepared in step (2), and add 3000 ml of the two raw materials. In ionized water, ultrasonic oscillation forms a slurry; use NaOH or HNO ₃ to adjust the pH value of the slurry in the range of 4 to 6, and grind the slurry on a grinder until the D ₅₀ particle size is 800 ~1000nm range, and then heat the ground slurry while ultrasonic oscillation, so that the slurry evaporates to dryness and becomes a solid after 4 hours. The evaporated solid was dried at 110°C for 6 hours, then pre-calcinated at 350°C for 2 hours, and then calcined at 550°C for 2 hours to become powdery and block solids. The powdery and massive solids obtained after the calcination are La _x Ce _{1- x Mny} Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles.

(4) Coating slurry preparation

Weigh 454.1g Ce(NO ₃ ) ₃ ·6H ₂ O, 69.7g Zr(NO ₃ ) ₄ ·5H ₂ O, 1530g pure γ-Al ₂ O ₃ powder, and 850g Al ₂ O _3. The mass content is 20%. Aluminum sol, 100g polyethylene glycol with a molecular weight of 20,000 and La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles prepared in step (3), and the The above 6 kinds of raw materials are added to 30kg of deionized water together, and ultrasonic oscillation is used to form a slurry; NaOH or HNO ₃ is used to adjust the pH value of the slurry to be in the range of 5 to 7, and the slurry is placed on a grinder Grind until the D ₅₀ particle size is in the range of 800 to 1000 nm, and then stir the ground slurry at 50°C for 72 hours to obtain a coating slurry.

(5) Apply the catalytic coating to the carrier

Weigh 1kg of the carrier, immerse the carrier in the coating slurry at 50°C, and ensure that the upper end surface of the carrier is slightly higher than the slurry level; wait for the slurry to naturally rise and fill all the pores of the carrier , take out the carrier from the slurry, blow off the residual fluid in the channels, dry at 80°C for 16h, and then bake at 600°C for 2h. Repeat the above impregnation, drying and roasting process twice to obtain a diesel engine catalyst based on highly dispersed perovskite catalytic components.

Example 3

(1) Catalyst composition design

The following ratios are designed respectively: La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite The mass percentage of ore and MoO ₃ is: 80%/20%, the mole percentage of La element and Ce element in La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite is: 80%/20%, The molar percentage of Mn element and Bi element is: 60%/40%, the mass percentage of CeO ₂ and ZrO ₂ in the cocatalyst is: 80%/20%, pure γ-Al in γ-Al ₂ O ₃ coating auxiliary materials The mass percentage of ₂ O ₃ powder and γ-Al ₂ O ₃ converted from aluminum sol is: 80%/20%, and the mass percentage of the main catalytic active component, co-catalyst and coating auxiliary materials is: 3%/ 7%/90%, and the planned configuration of coating slurry can produce 2000g of catalytic coating.

(2) La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template preparation

Weigh 54.7g La(NO ₃ ) ₃ ·6H ₂ O, 13.7g Ce(NO ₃ ) ₃ ·6H ₂ O, 16.4g Mn(CH ₃ COO) ₂ , 30.7g Bi(NO ₃ ) ₃ ·5H ₂ O , 60g glucose and 120g carbon black with a median particle size ( _D50 particle size) of 373nm. Add the 6 raw materials to 4.8L deionized water, oscillate ultrasonically for 7 hours, and then heat the 6 raw materials while oscillating ultrasonically. and deionized water, so that the mixture is evaporated to dryness after 7 hours to become a wet gel; then the wet gel is dried at 80°C for 12 hours to obtain a dry gel; the dry gel is dried in a muffle Raise the temperature in the furnace to 400°C at a rate of 3°C/min and maintain it for 2 hours, and then raise the temperature to 800°C for 3 hours at a rate of 10°C/min to prepare La _x Ce _1-x Mn _y Bi _1-y O Type ₃ perovskite nanoparticle template.

(3) Preparation of main catalytic active ingredients

Weigh 16.3g (NH ₄ ) ₂ MoO ₄ and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite nanoparticle template prepared in step (2), and add the two raw materials to 1600 ml. In ionized water, ultrasonic oscillation forms a slurry; use NaOH or HNO ₃ to adjust the pH value of the slurry in the range of 4 to 6, and grind the slurry on a grinder until the D ₅₀ particle size is 800 ~1000nm range, and then heat the ground slurry while ultrasonic oscillation, so that the slurry evaporates to dryness and becomes a solid after 6 hours. The evaporated solid was dried at 100°C for 8 hours, then pre-calcinated at 350°C for 2 hours, and then calcined at 550°C for 2 hours to become powdery and block solids. The powdery and massive solids obtained after the calcination are La _x Ce _{1- x Mny} Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles.

(4) Coating slurry preparation

Weigh 282.6g Ce(NO ₃ ) ₃ ·6H ₂ O, 97.6g Zr(NO ₃ ) ₄ ·5H ₂ O, 1440g pure γ-Al ₂ O ₃ powder, and 1800g Al ₂ O _3. The mass content is 20%. of aluminum sol, 200g of polyethylene glycol with a molecular weight of 20,000 and the La _x Ce _1-x Mn _y Bi _1-y O ₃ type perovskite-MoO ₃ composite catalytic material nanoparticles prepared in step (3), and the resulting The above 6 raw materials are added to 20kg of deionized water together, and ultrasonic oscillation is used to form a slurry; NaOH or HNO ₃ is used to adjust the pH value of the slurry to be in the range of 5 to 7, and the slurry is placed on a grinder Grind until the D ₅₀ particle size is in the range of 800 to 1000 nm, and then stir the ground slurry at 60°C for 60 hours to obtain a coating slurry.

(5) Apply the catalytic coating to the carrier

Weigh 1kg of the carrier, immerse the carrier in the coating slurry at 60°C, and ensure that the upper end surface of the carrier is slightly higher than the slurry level; wait for the slurry to naturally rise and fill all the pores of the carrier , take out the carrier from the slurry, blow off the residual fluid in the channels, dry at 100°C for 8 hours, and then bake at 550°C for 3 hours. Repeat the above impregnation, drying and roasting processes three times to obtain a diesel engine catalyst based on highly dispersed perovskite catalytic components.

The diesel engine exhaust PM, HC and CO purification performance engine evaluation system shown in Figure 1 was used to evaluate the diesel engine exhaust PM, HC and CO purification performance of the catalysts prepared in Examples 1 to 3. Before the test, the catalysts prepared in Examples 1 to 3 need to be separately cut and combined into a monolithic catalyst, and the cut and combined monolithic catalysts must be packaged. The test method is:

(1) Steady-state working condition test: use the dynamometer 1 and the coupling 2 to control the torque and speed of the test engine 3, and adjust the fuel supply speed of the injector 6 to the diesel engine through the fuel injection control system 7 to control the engine exhaust The ratios of air flow and catalyst volume were 50000h ^-1 and 100000h ^-1 respectively, and the average exhaust gas temperatures in the diesel oxidation catalytic converter (DOC) 10 were controlled to 300°C and 400°C respectively to evaluate PM, HC and CO purification performance. . The intake air flow measurement value of the intake air flow meter 4 provides feedback parameters for the control strategy of the fuel injection control system; and the air intake processor 5 provides clean air with a specific temperature and humidity for the engine. Temperature sensor A9 and temperature sensor B11 respectively measure the exhaust gas temperatures at both ends of the DOC 10. The average exhaust gas temperature in the DOC 10 can be obtained by averaging the two temperatures. The exhaust samples before and after DOC10 treatment enter the exhaust sampling mechanism 15 and the engine exhaust analyzer 16 through the exhaust sampling port A8 and the exhaust sampling port B12 respectively for PM, HC and CO specific emission analysis. The exhaust gas after composition analysis is purified of particulate pollutants through the exhaust filter 17 and then discharged out of the laboratory by the air pump 18 . At the same time, after the remaining exhaust gas from the test engine 3 is purified through the selective catalytic reduction catalytic converter 13 and the diesel particulate trap 14, it is also purified of particulate pollutants through the exhaust filter 17 and then discharged from the air pump 18. laboratory. Using the diesel engine exhaust PM, HC and CO purification performance engine evaluation system, the average exhaust temperature in DOC is 300°C and the airspeed is 50000h ^-1 , and the average exhaust temperature in DOC is 400°C and the airspeed is 100000h. ^-1 , the purification efficiency of diesel engine exhaust PM, HC and CO by the catalysts prepared in Examples 1 to 3 is shown in Figure 2 and Figure 3 respectively.

(2) ESC test: The above-mentioned diesel engine exhaust PM, HC and CO purification performance engine evaluation system is used, and in accordance with the national standard GB 17691-2005 "Vehicle Compression Ignition, Gaseous Fuel Ignition Engine and Automotive Exhaust Pollutant Emissions" The purification effect of the catalysts prepared in Examples 1 to 3 on diesel engine exhaust PM, HC and CO was evaluated according to the ESC test procedures specified in Limit Values and Measurement Methods (China III, IV, and V Stages), as shown in Figure 4.

In summary, coating the catalyst prepared in the present invention in DOC can effectively purify PM, HC, CO and other pollutants emitted by diesel engines. The main catalytic active component of composite catalytic material nanoparticles has the advantages of sulfur resistance, heat resistance, and low cost. It also enhances the overall catalytic activity of the catalyst by increasing the number of catalytic active sites per unit mass, achieving complete replacement of precious metals, and among them, perovskite and MoO The simultaneous addition of ₃ can produce a synergistic effect, further improving the catalytic activity of the catalyst and expanding the high activity temperature window. The preparation method of first adsorption and then gelation based on the carbon black adsorption matrix significantly improves the dispersion effect of the perovskite precursor, which is beneficial to the preparation of composite catalytic material nanoparticles with smaller scale, uniform particle size and regular structure.

Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative and not restrictive. Those of ordinary skill in the art will not Under the inspiration of the present invention, many changes can be made without departing from the spirit of the present invention, and these all fall within the protection of the present invention.

Claims (7)

1. The catalyst for the diesel engine based on the high-dispersion perovskite catalytic component comprises a catalytic coating coated on a carrier, wherein the carrier is 400-mesh cordierite honeycomb ceramic, and the catalytic coating consists of a main catalytic active component, a cocatalyst and a coating auxiliary material; the catalyst promoter is composed of CeO ₂ And ZrO(s) ₂ The coating auxiliary material consists of gamma-Al ₂ O ₃ Composition; the method is characterized in that:

the main catalytic active component is formed by ABO ₃ perovskite-MoO ₃ Composite catalytic material nanoparticle composition, wherein, ABO ₃ Perovskite and MoO ₃ The mass percentage of (a) is 60-90%/40-10%, ABO ₃ Perovskite and MoO ₃ The sum of the mass percentages of the components is 100 percent;

the ABO ₃ The A site of perovskite is composed of La and Ce, the B site is composed of Mn and Bi, la is formed _x Ce _1-x Mn _y Bi _1-y O ₃ A perovskite type, wherein x represents the mole percentage ratio of La at the A position in the sum of the mole numbers of Ce and La at the A position, and x=60-90%; y represents the mole percentage ratio of Mn at the B site in the sum of the mole numbers of Mn and Bi at the B site, and y=50-80%; at the same time, the La _x Ce _1-x Mn _y Bi _1-y O ₃ The ratio of the sum of the mole numbers of La ions and Ce ions to the sum of the mole numbers of Mn ions and Bi ions in the perovskite is 1:1; the La is _x Ce _1-x Mn _y Bi _1-y O ₃ The role of the perovskite in the catalyst is not only one component of the main catalytic active ingredient, but also the preparation of La _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite-MoO ₃ Nanoparticle templates of composite catalytic material nanoparticles.

2. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as claimed in claim 1, wherein: in the cocatalyst, the CeO ₂ And ZrO(s) ₂ The mass percentage of the catalyst is 70-90%/10-30%, and the sum of the mass percentages of the catalyst and the catalyst is 100%.

3. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as claimed in claim 1, wherein: said gamma-Al ₂ O ₃ Comprising gamma-Al derived from pure material ₂ O ₃ Powder and gamma-Al converted from aluminium sol ₂ O ₃ The pure gamma-Al ₂ O ₃ Powder and gamma-Al converted from aluminium sol ₂ O ₃ The mass percentage of (3) is as follows: 80-90%/10-20%, the sum of the mass percentages of the two is 100%.

4. The catalyst for diesel engine based on highly dispersed perovskite catalytic component as claimed in claim 1, wherein: the mass percentage of the main catalytic active component, the cocatalyst and the coating auxiliary material is 1-5%/4-10%/85-95%, and the sum of the mass percentages of the main catalytic active component, the cocatalyst and the coating auxiliary material is 100%.

5. A catalyst for diesel engines based on highly dispersed perovskite catalytic components according to any one of claims 1 to 4, characterized in that: the mass percentage of the catalytic coating and the carrier is 15-30%/85-70%, and the sum of the mass percentages of the catalytic coating and the carrier is 100%.

6. A process for the preparation of a catalyst for diesel engines based on highly dispersed perovskite catalytic components as claimed in any one of claims 1 to 5, characterized in that: the specific process comprises the following steps:

step 1, designing a catalyst composition:

according to the proportions of the components in any one of claims 1 to 5, the following proportions are respectively designed: la in main catalytic active ingredient _x Ce _1-x Mn _y Bi _1-y O ₃ Perovskite and MoO ₃ In mass percent of La _x Ce _1-x Mn _y Bi _1-y O ₃ Mole percent of La element and Ce element in perovskite, mole percent of Mn element and Bi element, and CeO in cocatalyst ₂ And ZrO(s) ₂ In mass percent of gamma-Al ₂ O ₃ Pure gamma-Al in coating auxiliary material ₂ O ₃ Powder and gamma-Al converted from aluminium sol ₂ O ₃ The mass percentage of the main catalytic active component, the cocatalyst and the coating auxiliary material, and the mass of the catalytic coating which can be generated by planning to configure the coating slurry;

step 2, la _x Ce _1-x Mn _y Bi _1-y O ₃ Preparing a perovskite nanoparticle template:

calculating La in the main catalytic active component according to the proportion of each component designed in the step 1 and the quality of the catalytic coating which can be generated by planning to configure coating slurry _x Ce _1-x Mn _y Bi _1-y O ₃ Quality of perovskite nanoparticle template and La _x Ce _1-x Mn _y Bi _{1- y} O ₃ The mole number of La, ce, mn and Bi elements in the perovskite nano particle template;

bind to each 433.0g La (NO) ₃ ) ₃ ·6H ₂ O preparation of 1mol La, per 434.1g Ce (NO) ₃ ) ₃ ·6H ₂ O preparation of 1mol Ce per 173.0g Mn (CH) ₃ COO) ₂ Preparation of 1mol Mn per 485.1g Bi (NO ₃ ) ₃ ·5H ₂ O preparation of 1mol Bi and La _x Ce _{1- x} Mn _y Bi _1-y O ₃ The La is prepared by calculating the conversion ratio of the sum of the mole numbers of La, ce, mn and Bi elements in the perovskite nanoparticle template to the mole number of glucose used to be 1:1-2 and the weight of 180.2g per mole of glucose _x Ce _{1- x} Mn _y Bi _1-y O ₃ La (NO) for perovskite nanoparticles ₃ ) ₃ ·6H ₂ O、Ce(NO ₃ ) ₃ ·6H ₂ O、Mn(CH ₃ COO) ₂ 、Bi(NO ₃ ) ₃ ·5H ₂ Mass of O and glucose;

weighing La (NO) of determined mass ₃ ) ₃ ·6H ₂ O、Ce(NO ₃ ) ₃ ·6H ₂ O、Mn(CH ₃ COO) ₂ 、Bi(NO ₃ ) ₃ ·5H ₂ O, glucose and a mass of La (NO) ₃ ) ₃ ·6H ₂ O、Ce(NO ₃ ) ₃ ·6H ₂ O、Mn(CH ₃ COO) ₂ Bi (NO) ₃ ) ₃ ·5H ₂ In the range of 0.8 to 1.5 times the sum of O masses and D ₅₀ Carbon black having a particle diameter of not more than 500nm, and adding 1g of carbon to the above 6 raw materials togetherIn the deionized water weighed according to the proportion of 30-50 mL of deionized water, carrying out ultrasonic oscillation for 6-8 h, and then heating the mixture of the 6 raw materials and the deionized water while carrying out ultrasonic oscillation, so that the mixture is evaporated to dryness after 6-8 h to form wet gel; drying the wet gel at 80-110 ℃ for 6-12 hours to obtain xerogel; heating the xerogel to 400 ℃ in a muffle furnace at a speed of 3 ℃/min and keeping for 2 hours, heating to 700-800 ℃ at a speed of 10 ℃/min, and calcining for 3-4 hours to obtain La _x Ce _1-x Mn _y Bi _1-y O ₃ A perovskite nanoparticle template;

step 3, preparing main catalytic active components:

calculating MoO in the main catalytic active component according to the proportion of each component designed in the step 1 and the quality of the catalytic coating which can be generated by planning to configure coating slurry ₃ Is the mass of (3); combined with each 196.0g (NH) ₄ ) ₂ MoO ₄ Preparation of 144.0g MoO ₃ The conversion ratio of (C) to (C) is calculated to obtain the (NH) required for the preparation of the main catalyst active ingredient ₄ ) ₂ MoO ₄ Is the mass of (3);

weighing the (NH) ₄ ) ₂ MoO ₄ La obtained by the preparation of step 2 _x Ce _1-x Mn _y Bi _1-y O ₃ A perovskite nanoparticle template, and the (NH ₄ ) ₂ MoO ₄ And La (La) _x Ce _1-x Mn _y Bi _1-y O ₃ Perovskite nanoparticle template addition was performed according to 1g (NH ₄ ) ₂ MoO ₄ In the deionized water which is weighed according to the proportion of 50-500 ml of deionized water, carrying out ultrasonic oscillation to form slurry; by NaOH or HNO ₃ Adjusting the pH of the slurry to a pH in the range of 4 to 6 and grinding the slurry on a grinder to a pH D ₅₀ The particle size is in the range of 800-1000 nm, and the ground slurry is heated while ultrasonic oscillation is carried out, so that the slurry is evaporated to dryness after 4-8 hours and becomes solid;

drying the dried solid at 80-110 ℃ for 6-12 h, presintering at 350 ℃ for 2h, and calcining at 500-550 ℃ for 2 ultra-high3h, la of powdery and massive solids obtained after calcination _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite-MoO ₃ The composite catalytic material nano particles are the main catalytic active components of the catalyst;

step 4, preparing coating slurry:

calculating CeO required for preparing the catalytic coating according to the proportions of the components designed in the step 1 and the quality of the catalytic coating which can be generated by planning to configure the coating slurry ₂ And ZrO(s) ₂ Quality of (C) and gamma-Al ₂ O ₃ The quality of the coating auxiliary materials;

bind per 434.2g Ce (NO) ₃ ) ₃ ·6H ₂ O preparation 172.1g CeO ₂ Each 429.3g of Zr (NO) ₃ ) ₄ ·5H ₂ O preparation 123.2gZrO ₂ Al in aluminum sol ₂ O ₃ Calculated out the mass percent of Ce (NO) required for preparing the coating slurry ₃ ) ₃ ·6H ₂ O、Zr(NO ₃ ) ₄ ·5H ₂ O and the mass of the aluminum sol; in addition, the mass of polyethylene glycol consumed for preparing the catalytic coating is calculated according to the proportion of 5-15 g of polyethylene glycol with average molecular weight of 20000 required for each 100g of the catalytic coating;

weighing Ce (NO) with determined mass ₃ ) ₃ ·6H ₂ O、Zr(NO ₃ ) ₄ ·5H ₂ O, pure gamma-Al ₂ O ₃ Powder, aluminum sol, polyethylene glycol with molecular weight of 20000 and La prepared in step 3 _x Ce _1-x Mn _y Bi _1-y O ₃ perovskite-MoO ₃ The 6 raw materials are added into deionized water with the mass 5-15 times of the mass of the catalytic coating to be prepared together to form slurry by ultrasonic oscillation; by NaOH or HNO ₃ Adjusting the pH of the slurry to a pH in the range of 5 to 7 and grinding the slurry on a grinder to a pH D ₅₀ The grain diameter is in the range of 800-1000 nm, and the ground slurry is stirred for 48-72 h at the temperature of 50-70 ℃ to obtain coating slurry;

step 5, coating a catalytic coating on the carrier:

designing the quality of the support to which the catalytic coating is to be applied; weighing the carrier with determined mass, immersing the carrier in the coating slurry at 50-70 ℃ and ensuring that the upper end surface of the carrier is slightly higher than the slurry level; after the slurry naturally lifts all pore canals filled with the carrier, the carrier is taken out from the slurry, residual fluid in the pore canals is blown off, the slurry is dried for 4 to 16 hours at the temperature of 80 to 110 ℃, and then the slurry is baked for 2 to 4 hours at the temperature of 500 to 600 ℃; repeating the processes of dipping, drying and roasting for 2-3 times to obtain the catalyst for the diesel engine based on the high-dispersion perovskite catalytic component.

7. Use of a diesel engine catalyst based on highly dispersed perovskite catalytic components as defined in any one of claims 1 to 5, prepared according to the preparation method of claim 6, packaged as a Diesel Oxidation Catalyst (DOC), said diesel oxidation catalyst being mounted in a diesel exhaust passage for efficient oxidation purification of PM, HC and CO in diesel exhaust.