Catalytic gasoline engine particle trap and preparation method thereof

Abstract

The invention discloses a catalytic gasoline engine particle trap and a preparation method thereof, and belongs to the technical field of catalyst preparation. The particle catalytic converter comprises a particle trap carrier and a coating applied to the carrier. The coating is composed of a first coating and a second coating, the first coating comprises a carrier material and an active noble metal, and the coating is distributed in the wall of the particle trap; the second coating is composed of one or more of boehmite, aluminum oxide, lanthanum modified aluminum oxide, silicon modified aluminum oxide, calcium carbonate and a cerium-zirconium-aluminum compound, has the loose, porous and hydrophobic characteristics, is continuously distributed along the surface of the air inlet channel filtering wall, effectively fills holes in the surface of the air inlet channel wall, and effectively improves the fine particulate matter trapping efficiency. The catalytic trap prepared by the invention has high initial trapping efficiency on particulate matters of more than 10nm, and the preparation method of the catalytic trap is easy to operate, accurate to control, low in equipment requirement and suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts and relates to a catalyst for post-processing exhaust gas of a motor vehicle, in particular to a catalytic gasoline engine particulate filter and a preparation method thereof. Background Art

[0002] In view of the control requirements of particulate matter in exhaust gas (including particulate mass (PM) and particle number (PN), gasoline engine particulate filter (GPF) is considered to be an effective technical means to control its emissions. Due to the structural characteristics of the alternating blocking of the inlet and outlet ends of adjacent channels of GPF, when the engine exhaust gas flows in through the inlet channel, due to the blockage on the opposite side, the airflow can only flow out from the adjacent channel through the holes on the carrier filter wall. At this time, the porous inner wall can capture the particulate matter in the airflow. In order to take into account the purification of gaseous pollutants at the same time, a catalytic coating, namely CGPF, will be coated on it. The capture performance of CGPF mainly depends on the coordination between the coating and its own carrier structure. Compared with normal temperature, the particulate matter emissions of the engine under low temperature conditions (especially 0°C or below) will increase significantly; at the same time, the Euro VII regulations have clearly included PN 10nm and above particulate matter under supervision. At the current stage, PN Introducing particulate matter in the 10-23nm range, in addition to the 23nm requirement, will significantly increase particulate matter emissions, requiring a CGPF with even higher capture efficiency. While CGPFs can increase their efficiency somewhat over time as vehicles run in and mileage increases, OEMs, considering vehicle safety risks, require high initial capture efficiency in the fresh state or at zero kilometers.

[0003] Therefore, how to coordinate the coating with the GPF carrier to achieve gas pollutant purification and meet the future emission regulations for particulate matter emissions above PN 10nm while effectively avoiding excessive increase in back pressure caused by the coating is a difficult problem that technicians in this field need to solve. Summary of the Invention

[0004] The purpose of the present invention is to provide a catalytic gasoline engine particulate filter and a preparation method thereof, which achieves purification of gaseous pollutants through a first coating. At the same time, with the help of the synergistic effect of the second coating and the first coating continuously distributed on the wall of the intake channel, its initial capture efficiency of particulate matter larger than 10nm is improved under the condition of limited increase in back pressure, thereby meeting particulate matter emission requirements.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A catalytic gasoline engine particulate filter and a preparation method thereof. The catalytic filter comprises: a particulate filter carrier and a coating applied to the carrier; the coating comprises a first coating and a second coating, the first coating comprising a carrier material and an active precious metal, the first coating being distributed along the interior of the particulate filter wall; the second coating comprising one or more of boehmite, alumina, lanthanum-modified alumina, silicon-modified alumina, calcium carbonate, and a cerium-zirconium-aluminum composite, the second coating being continuously distributed along the surface of the filter wall of the intake passage, and having loose, porous, and hydrophobic properties.

[0007] Furthermore, the first coating support material comprises one or more of silicon- or lanthanum-modified alumina, a cerium-zirconium composite, and an alkaline earth metal compound.

[0008] Furthermore, the active precious metal in the first coating layer is one or more of platinum, palladium, and rhodium.

[0009] Furthermore, the bulk density of the second coating material is 0.1 to 1 g / cm 3 , its BET specific surface area is 10~300m 2 / g, and its pore volume is 0.5~1.2cm 3 / g.

[0010] Furthermore, the first coating is distributed along the inner wall of the particle trap carrier, and the second coating is continuously distributed along the filter wall surface of the intake passage.

[0011] Furthermore, the length of the second coating layer is 90-100% (relative to the length of the particle collector).

[0012] A method for preparing a catalytic gasoline engine particulate filter comprises the following steps:

[0013] (1) First coating: adding a cerium-zirconium composite material, aluminum oxide, and an alkaline earth metal compound to deionized water and stirring to obtain a suspension slurry; grinding the slurry and loading a precious metal to obtain a precious metal-loaded slurry; adjusting the viscosity of the precious metal-loaded slurry with a regulator to control the solid content of the slurry to 15-35%, and coating the slurry on a particulate filter carrier by vacuum suction coating; and drying at 100-120° C. to obtain a particulate filter catalyst coated with the first coating;

[0014] (2) Second coating: Add the second coating material to deionized water, stir, add a viscosity regulator, control the solid content of the slurry to 3-20%, and obtain a second coating slurry; use vacuum suction coating to coat the second coating slurry along the air inlet end of the particulate filter coated with the first coating; dry at 100-130°C, and calcine at a heating rate of 2-5°C / min to 500-600°C for 1-4h to obtain a catalytic gasoline engine particulate filter; alternatively, the second coating is obtained by directly loading the second coating material in the form of an aerosol and then calcining it.

[0015] Furthermore, the particle size D90 of the first coating slurry in the preparation step (1) is smaller than the particle collector carrier D10; the loading amount of the first coating in the preparation step (1) is 30 to 120 g / L; the loading amount of the second coating in the preparation step (2) is 3 to 30 g / L;

[0016] Furthermore, the regulator is one or more of methyl hydroxyethyl cellulose, aluminum gel, polyethylene glycol, and guar gum.

[0017] The beneficial effects of the present invention are:

[0018] The catalytic gasoline engine particulate filter of the present invention has a coating composed of a first coating and a second coating. The first coating effectively catalytically purifies gaseous pollutants and is distributed within the wall, effectively reducing the coating's impact on back pressure. The second coating is continuously distributed along the surface of the intake duct filter wall, effectively filling the openings (especially large openings) on the intake duct wall surface, thereby improving the capture efficiency of particles larger than 10 nm. At the same time, the coating has loose, porous, and hydrophobic properties, which not only ensures the airflow path and reduces the impact of the outer layer on back pressure, but also reduces or avoids the reduction in particle capture efficiency caused by secondary openings formed by shrinkage of the coating during coating drying and calcination. The preparation method provided by the present invention is easy to operate, precisely controlled, and has low equipment requirements, making it suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the particle trap catalyst of the present invention; in the figure: 1-inlet end wall; 2-outlet end wall; 3-filter wall; 4-first coating; 5-second coating.

[0020] Figure 2 SEM of the coating distribution of the particulate trap catalysts of Example 1 and Example 2.

[0021] Figure 3 Back pressure diagrams of a comparative example particulate trap and a particulate trap according to an embodiment of the present invention.

[0022] Figure 4 The particle trapping efficiency of the comparative example particle trap and the particle trap according to the embodiment of the present invention for particulate matter (PN-23nm).

[0023] Figure 5 The particle trapping efficiency of the comparative example particle trap and the particle trap according to the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. These specific embodiments are intended to further illustrate the present invention and are not intended to limit the present invention in any way.

[0025] See also Figure 1 A catalytic gasoline engine particulate filter and its preparation method, the catalyst filter comprising: a particulate filter carrier, a coating applied to the carrier; the coating comprising a first coating and a second coating, the first coating comprising a carrier material and an active precious metal, the coating being distributed along the inner wall of the particulate filter; the second coating being continuously distributed along the surface of the filter wall of the intake duct, effectively filling the openings on the intake duct wall.

[0026] The principle of the present invention is:

[0027] To achieve gaseous pollutant purification and effectively reduce the impact of the catalytic coating on backpressure, the first coating layer is distributed as micropores within the wall. While the larger openings on the inlet wall surface of the GPF carrier or its catalyst facilitate airflow and contribute to backpressure, they also cause particulate matter to overflow from the airflow, resulting in low particle capture efficiency. The present invention utilizes a second coating layer of porous material to effectively achieve loose filling of the wall surface openings. Furthermore, the material's hydrophobicity and low bulk density prevent particle overflow caused by secondary openings formed by shrinkage of the coating material during drying or high temperatures. Combined with the synergistic effect of the first and second layers, multiple particle interception is achieved, thereby improving the initial capture efficiency of particles larger than 10nm.

[0028] The particle collectors used in the following examples all have specifications of Φ132.1*127 (mm), a mesh size of 300 cpsi, a wall thickness of 8 mil, an average pore size of 19.8 μm, a D10 of 12.3 μm, and a porosity of 68%.

[0029] Example 1-Comparison

[0030] The catalytic filter trap is prepared as follows:

[0031] (1) Preparation of coating slurry: 510 g of cerium-zirconium composite material (cerium content 30%), 175 g of lanthanum-modified alumina and 65 g of barium hydroxide octahydrate were added to deionized water in sequence and stirred to obtain a suspension. The suspension was ground to a slurry particle size D90 of 2.3 μm; the noble metal content was 5 g / ft 3 @0:3:2 (platinum: palladium: rhodium) loads rhodium and palladium in sequence, rhodium and palladium are added in the form of nitrates; aluminum glue is used to adjust the slurry viscosity to 650cps and the solid content to 27%;

[0032] (2) The coating slurry was applied from the air inlet and outlet of the particle collector respectively according to a vacuum suction coating method with a loading amount of 100 g / L and a 1:1 partition coating length; after drying, it was calcined at a temperature of 550°C for 2 hours.

[0033] Example 2

[0034] The catalytic filter trap is prepared as follows:

[0035] (1) First coating: 612.7 g of cerium-zirconium composite material (cerium content 30%), 142.6 g of lanthanum-modified alumina, and 38.1 g of barium acetate were added to a certain amount of deionized water, stirred to obtain a suspension, and ground to a slurry particle size D90 of 2.3 μm; the precious metal content was 5 g / ft 3 Rhodium and palladium were sequentially loaded in a 0:3:2 ratio (platinum:palladium:rhodium), with rhodium and palladium added in the form of nitrates; aluminum gel was used to adjust the slurry to a viscosity of 900 cps and a solid content of 20.3%; the coating slurry was applied to the particulate filter from the air inlet and outlet using a vacuum suction coating method at a loading of 50 g / L and a 1:1 zone coating length; and the particulate filter catalyst was dried at 120°C to obtain a first-coated particulate filter catalyst.

[0036] (2) Second coating: 42.63 g of lanthanum-modified alumina was added to a certain amount of deionized water, stirred, and then methyl hydroxyethyl cellulose was added to adjust the slurry viscosity to 350 cps and the solid content to 3.8%. The slurry was coated from the air inlet end of the particulate filter coated with the first coating at a loading of 9 g / L by vacuum suction coating; the coating height was 120 mm; the lanthanum-modified alumina was dried at 120 ° C and then calcined at 550 ° C for 2 h to obtain a catalyst with particles distributed along the wall of the air inlet duct. The D90 of the lanthanum-modified alumina used was 24.3 μm and the bulk density was 0.18 g / cm 3 , with a specific surface area of ​​200m 2 / g, pore volume 0.68cm 3 / g.

[0037] Example 3

[0038] The catalytic filter trap is prepared as follows:

[0039] (1) The catalyst obtained according to Example 2 is the first coating layer of this embodiment;

[0040] (2) Second coating: 42.63 g of lanthanum-modified alumina was added to a certain amount of deionized water, stirred, and then methyl hydroxyethyl cellulose was added to adjust the slurry viscosity to 400 cps. The solid content was controlled to 4.9%. The slurry was coated from the air inlet end of the particulate collector coated with the first coating at a loading amount of 12 g / L using a vacuum suction coating method; the coating height was 123 mm; the catalyst was dried at 120°C and then calcined at 550°C for 2 h to obtain a catalyst with particles distributed along the wall of the air inlet duct. The second coating material used was the same as that used for the second coating in Example 2.

[0041] Example 4

[0042] The catalytic filter trap is prepared as follows:

[0043] (1) The catalyst obtained according to Example 2 is the first coating layer of this embodiment;

[0044] (2) Second coating: 42.63 g of lanthanum-modified alumina was added to a certain amount of deionized water, stirred, and then methyl hydroxyethyl cellulose was added to adjust the slurry viscosity to 500 cps. The solid content was controlled to 6.2%. The slurry was coated from the air inlet end of the particulate collector coated with the first coating at a loading amount of 15 g / L using a vacuum suction coating method; the coating height was 119 mm; the catalyst was dried at 120°C and then calcined at 550°C for 2 h to obtain a catalyst with particles distributed along the wall of the air inlet duct. The second coating material used was the same as that used for the second coating in Example 2.

[0045] Example 5

[0046] The catalytic gasoline engine particulate filter according to Example 4 was obtained after calcining at 1000° C. for 10 hours.

[0047] Example 6

[0048] The catalytic filter trap is prepared as follows:

[0049] (1) First coating: 334.2 g of cerium-zirconium composite material (cerium content 40%), 77.8 g of lanthanum-modified alumina, and 20.8 g of barium acetate were added to a certain amount of deionized water, stirred to obtain a suspension, and ground to a slurry particle size D90 of 1.3 μm; according to the precious metal content of 10 g / ft 3 Rhodium and palladium were sequentially loaded in a 0:7:3 (platinum:palladium:rhodium) ratio, with rhodium and palladium added as nitrates; methyl hydroxyethyl cellulose was used to adjust the slurry viscosity to 620 cps and the solid content to 22.7%; vacuum suction coating was used at a loading of 80 g / L and a 1:1 zone coating ratio, with the coating slurry applied from the air inlet and outlet of the particulate filter; and the catalyst was dried at 120°C to obtain a particulate filter catalyst coated with the first coating layer.

[0050] (2) Second coating: 15.032 g of lanthanum-modified alumina A and 22.55 g of lanthanum-modified alumina were added to deionized water in succession. After stirring, methyl hydroxyethyl cellulose was added to adjust the slurry viscosity to 560 cps and the solid content to 4.8%. The slurry was coated from the air inlet end of the particulate filter coated with the first coating at a loading of 12 g / L by vacuum suction coating. The coating height was 119 mm. The lanthanum-modified alumina A was dried at 120 ° C and then calcined at 550 ° C for 2 h to obtain a catalyst with particles distributed along the wall of the air inlet duct. The lanthanum-modified alumina A used had a D90 of 5.8 μm and a bulk density of 0.16 g / cm 3 , with a specific surface area of ​​250m 2 / g, pore volume 0.86cm 3 / g; Lanthanum modified alumina B: D90 is 26.1μm, bulk density is 0.14g / cm 3 , with a specific surface area of ​​291m 2 / g, pore volume 0.61cm 3 / g

[0051] Example 7

[0052] The catalytic filter trap is prepared as follows:

[0053] (1) First coating: 278.5 g of cerium-zirconium composite material (cerium content 30%), 64.8 g of lanthanum-modified alumina, and 17.3 g of barium acetate were added to a certain amount of deionized water, stirred to obtain a suspension, and ground to a slurry particle size D90 of 2.5 μm; the precious metal content was 3 g / ft 3 Rhodium and palladium were loaded sequentially in a 0:2:1 ratio (platinum:palladium:rhodium), with rhodium and palladium added as nitrates. Methyl hydroxyethyl cellulose was used to adjust the slurry to a viscosity of 850 cps and a solid content of 32%. The coating slurry was applied to the air inlet of the particulate filter using a vacuum suction coating method at a loading of 70 g / L. The coating height was 110 mm, and the catalyst was dried at 120°C to obtain a particulate filter catalyst coated with the first coating layer.

[0054] (2) Second coating:

[0055] 62.64 g of lanthanum-modified alumina was added to a certain amount of deionized water and stirred. Methyl hydroxyethyl cellulose was then added to adjust the slurry viscosity to 460 cps and the solid content to 7.1%. The slurry was coated from the air inlet end of the particulate collector coated with the first coating at a loading amount of 18 g / L using a vacuum suction coating method; the coating height was 123 mm; the mixture was dried at 120°C and then calcined at 550°C for 2 h to obtain a catalyst with particles distributed along the wall of the air inlet duct. The second coating material used was the same as that used for the second coating in Example 2.

[0056] Example 8

[0057] The catalytic filter trap is prepared as follows:

[0058] (1) First coating: 305.2 g of cerium-zirconium composite material (cerium content 40%), 104.9 g of lanthanum-modified alumina, and 39.1 g of octahydrate and barium hydroxide were added to deionized water in sequence, stirred to obtain a suspension, and ground to a slurry particle size D90 of 1.8 μm; the precious metal content was 3 g / ft 3Rhodium and palladium were sequentially loaded in a 0:2:1 ratio (platinum:palladium:rhodium), with rhodium and palladium added as nitrates; methyl hydroxyethyl cellulose was used to adjust the slurry viscosity to 505 cps and the solid content to 23.3%; vacuum suction coating was used to apply the coating slurry to the air inlet and outlet of the particulate filter at a loading of 70 g / L and a coating length partitioned at 1:1; and the particulate filter catalyst was dried at 120°C to obtain a first-coated particulate filter catalyst.

[0059] (2) Second coating: 62.6 g of cerium-zirconium-aluminum composite (cerium content 12.5%, aluminum content 50%) was added to a certain amount of deionized water, stirred, and then methyl hydroxyethyl cellulose was added to adjust the slurry viscosity to 350 cps, and the solid content was controlled to 7.7%. The slurry was coated from the air inlet end of the particulate filter coated with the first coating at a loading amount of 20 g / L by vacuum suction coating, and the coating height was 120 mm. After drying at 120 ° C, the catalyst was calcined at 550 ° C for 2 h to obtain a catalyst with particles distributed along the wall of the air inlet duct. The D90 of the cerium-zirconium-aluminum composite used was 16.3 μm, and the bulk density was 0.80 g / cm 3 , with a specific surface area of ​​85m 2 / g, pore volume 0.56cm 3 / g.

[0060] Example 9

[0061] The catalytic filter trap is prepared as follows:

[0062] (1) First coating: 334.2 g of cerium-zirconium composite material (cerium content 35%), 77.8 g of lanthanum-modified alumina, and 20.8 g of barium acetate were added to a certain amount of deionized water, stirred to obtain a suspension, and ground to a slurry particle size D90 of 1.5 μm; according to the precious metal content of 5 g / ft 3 Rhodium and platinum were sequentially loaded in a 4:0:1 (platinum:palladium:rhodium) ratio, with rhodium and platinum added in the form of nitrates; methyl hydroxyethyl cellulose was used to adjust the slurry viscosity to 550 cps and the solid content to 24.1%; the coating slurry was applied from the air inlet and outlet of the particulate filter using a vacuum suction coating method with a coating load of 80 g / L and a coating height partitioning of 1:1. After drying at 120°C, the slurry was calcined at 550°C for 2 hours to obtain a particulate filter catalyst coated with a first coating layer;

[0063] (2) Second coating: will have 292m 2 / g high specific surface area boehmite is formed into particle-aerosol through a loading device and loaded from the catalyst inlet end face to obtain a catalyst with a coating distributed along the wall of the inlet channel. The boehmite used has a D90 of 21.4μm, a bulk density of 0.16g / ml, and a pore volume of 1.0cm 3 / g; the outer layer loading is 7g / L;

[0064] Example 10

[0065] The catalytic gasoline engine particulate filter according to Example 8 has a second coating loading of 5 g / L, a lanthanum-modified alumina having a D90 of 40.3 μm, and a bulk density of 0.28 g / cm 3 , specific surface area 183m 2 / g, pore volume 0.83cm 3 / g;

[0066] Example 11 - Backpressure and capture efficiency test

[0067] (1) Backpressure test

[0068] The catalytic gasoline engine particulate filter obtained in the embodiment was subjected to back pressure tests at room temperature (25±5°C) and cold flow (600CMH) using super flow equipment. Figure 3 As shown, compared with the catalytic gasoline engine particulate filter of the prior art (Example 1), the back pressure of the particulate filter of the present invention is slightly increased; under the same first coating condition, the back pressure of the particulate filter increases with the increase of the second coating amount; the back pressure of the particulate filter is affected by both the first coating and the second coating.

[0069] (2) Capture efficiency test

[0070] The catalytic gasoline engine particulate filter (CGPF) obtained in the embodiment was used on a National VI 1.5T GDI vehicle to conduct a WLTC vehicle emission test in accordance with the GB18352.6-2016 "Light-duty Vehicle Pollutant Emission Limits and Measurement Methods (China Sixth Phase)" standard. The vehicle post-treatment was a close-coupled layout of three-way catalyst (TWC) + CGPF; the tested CGPF was in a fresh or zero-kilometer state. The original exhaust of particulate matter (23nm, 10nm) and the corresponding tail exhaust of particulate matter after CGPF were collected respectively. The capture efficiency results of the particulate matter (23nm, 10nm) were as follows: Figure 4 、 Figure 5 shown.

[0071] from Figure 4 、 Figure 5It can be seen that compared with Example 1 used for comparison, Examples 2 to 10 of the present invention have a 20-30% improvement in the capture efficiency of 23nm and 10nm particles. The improvement in capture efficiency is due to the filling of the wall openings by the wall distribution of the second coating and the synergy between the first and second coatings. From Examples 2 to 4, it can be seen that the particle capture efficiency of the collector increases with the increase of the second coating load. Among them, Example 4 has a capture efficiency of 97% for particles larger than 10nm, and its capture efficiency remains at a considerable level after aging at 1000°C (Example 5); from the examples, it can be seen that compared with 23nm particles, its capture efficiency for particles larger than 10nm is 1-3% higher; by adjusting the first and second coatings, a high initial capture efficiency for particles larger than 10nm can be achieved.

Claims

1. A catalytic gasoline engine particulate filter, characterized in that: The catalytic trap includes a particulate trap support and a coating applied to the support; the coating is composed of a first coating and a second coating, the first coating comprising a support material and an active precious metal, and the second coating being composed of one or more of boehmite, alumina, lanthanum-modified alumina, silicon-modified alumina, calcium carbonate, and a cerium-zirconium-aluminum composite; The first coating layer is distributed along the inner wall of the particle trap carrier, and the second coating layer is continuously distributed along the filter wall surface of the intake passage.

2. The catalytic gasoline engine particulate filter according to claim 1, characterized in that: The support material of the first coating layer comprises one or more of silicon- or lanthanum-modified alumina, a cerium-zirconium composite, and an alkaline earth metal compound.

3. The catalytic gasoline engine particulate filter according to claim 1, characterized in that: The active precious metal of the first coating layer is one or more of platinum, palladium and rhodium.

4. The catalytic gasoline engine particulate filter according to claim 1, characterized in that: The bulk density of the second coating material is 0.1 to 1 g / cm 3 , its BET specific surface area is 10~300m 2 / g, and its pore volume is 0.5~1.2cm 3 / g.

5. The catalytic gasoline engine particulate filter according to claim 1, characterized in that: The second coating layer has loose porous and hydrophobic properties.

6. The catalytic gasoline engine particulate filter according to claim 1, characterized in that: The length of the second coating layer is 90-100% of the length of the particle collector.

7. A method for preparing a catalytic gasoline engine particulate filter according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Preparation of the first coating The cerium-zirconium composite material, aluminum oxide and alkaline earth metal compound are added into deionized water and stirred to obtain a suspension slurry; The slurry is ground and loaded with precious metal to obtain a slurry loaded with precious metal; The viscosity of the slurry after loading the precious metal is adjusted by a regulator to control the solid content of the slurry to be 15-35%, and the slurry is coated on the particle collector carrier by vacuum suction coating; drying at 100-120° C. to obtain a particulate filter catalyst coated with a first coating; (2) Preparation of the second coating The second coating material is added to deionized water, stirred, and then a viscosity regulator is added to control the solid content of the slurry to 3-20% to obtain a second coating slurry; Using a vacuum suction coating method, the second coating slurry is applied along the air inlet end of the particulate filter coated with the first coating; After drying at 100-130° C., the mixture is calcined at a heating rate of 2-5° C. / min to 500-600° C. for 1-4 hours to obtain a catalytic gasoline engine particulate filter. or The second coating layer is obtained by directly loading the second coating material in the form of aerosol and then calcining it.

8. The method for preparing a catalytic gasoline engine particulate filter according to claim 7, characterized in that: The particle size D90 of the first coating slurry is smaller than the particle collector carrier D10; the loading amount of the first coating is 30 to 120 g / L.

9. The method for preparing a catalytic gasoline engine particulate filter according to claim 7, characterized in that: The second coating loading amount is 3 to 30 g / L.

10. The method for preparing a catalytic gasoline engine particulate filter according to any one of claims 7 to 9, characterized in that: The regulator is one or more of methyl hydroxyethyl cellulose, aluminum gel, polyethylene glycol, and guar gum.

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