A diesel vehicle exhaust purification catalyst, a preparation method and application thereof

Abstract

The application discloses a diesel vehicle exhaust purification catalyst and a preparation method and application thereof. The diesel vehicle exhaust catalyst is prepared by high-temperature calcination of ilmenite, water immersion and dissolution of a titanium-containing solution, addition of the titanium-containing solution into a template agent for hydrothermal crystallization, calcination for removal of the template agent, hydrogenation and the like. The application has the advantages that the effective component Ti in the common mineral ilmenite is used to prepare micropore-mesopore composite TiO2 and a hydrogenation defect type TiO2 catalyst, the crystal form of the catalyst is anatase, the surface layer has an amorphous layer, the catalyst has a micropore-mesopore composite pore structure, and the specific surface area of the catalyst is 655-800 m 2 / g. The catalyst has high propylene and CO catalytic activity without any transition metal or noble metal as an active component, the conversion rate of propylene is above 95% in a temperature range of 150-500 DEG C, and the conversion rate of CO is 100%.

Description

Technical Field

[0001] This invention relates to the field of exhaust gas purification technology, specifically to a diesel vehicle exhaust gas purification catalyst, its preparation method, and its application. Background Technology

[0002] In the coal mining industry, diesel engines are widely used as high-power output devices. While mining machinery (vehicles) constitute a small percentage of the numerous non-road diesel-powered construction machines, they play a crucial role in mining and transportation. Currently, excavators, loaders, and transport vehicles are the main equipment in coal mining, primarily undertaking mining, loading, unloading, and auxiliary transportation tasks, and their role and status in coal production are extremely important. Due to the specific production environment of coal mines, especially the confined space, poor air circulation, and significant safety hazards such as gas leaks in underground work areas, specific explosion-proof requirements are placed on the diesel engines of mining machinery. Research, design, and development of explosion-proof diesel engines have emerged, and trackless rubber-wheeled vehicles powered primarily by explosion-proof diesel engines are now widely used in coal mines. However, due to the special nature of the underground environment and the specific design requirements of explosion-proof diesel engines, the performance of diesel engines in various aspects is relatively degraded, especially in terms of exhaust emissions pollution. Emissions include CO, olefins (VOCs), and NO. x The accumulation of [something] directly endangers the health of coal miners and is also a decisive issue restricting the development of explosion-proof vehicles.

[0003] The current Chinese standard MT 990-2006, "Technical Conditions for Explosion-proof Diesel Engines," stipulates that under the operating conditions specified in MT 220, the volume concentration of harmful gas components in the undiluted exhaust of explosion-proof diesel engines should not exceed 0.1% for carbon monoxide (CO) and 0.1% for nitrogen oxides (NOx). x The volume concentration should not exceed 0.08%. Currently, there are no mature commercially available diesel engine exhaust catalysts with low activation temperature and high catalytic activity in China. Commercially available diesel engine exhaust catalysts only exhibit good catalytic performance above 180℃, which is insufficient to meet the anti-knock performance requirements of diesel engines (the surface temperature of any part of an anti-knock diesel engine must not exceed 150℃). Therefore, it is imperative to develop a diesel engine exhaust treatment catalyst formulation with low activation temperature and high catalytic activity.

[0004] Existing diesel vehicle exhaust catalysts typically use Al2O3, SiO2-Al2O3, zeolite, etc., as supports, with precious metals Pt and Pd as active components. When the loading of the active component in the catalyst is 0.5%-3%, the activation temperature is 190-265℃. The higher the loading of precious metals, the lower the activation temperature. For example, diesel oxidation catalysts (DOC) are used. However, precious metals are expensive, so the cost of the catalyst also limits its practical application. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a diesel vehicle exhaust purification catalyst, its preparation method and application. The catalyst of the present invention can achieve high catalytic activity of propylene and CO without any transition metals or precious metals as active components. The conversion rate of propylene reaches more than 95% and the conversion rate of CO reaches 100% in the temperature range of 150-500℃.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a method for preparing a diesel vehicle exhaust purification catalyst, comprising the following steps:

[0007] 1) Mix ilmenite and concentrated sulfuric acid, calcine to obtain a mixture;

[0008] 2) The mixture is mixed with water and immersed to dissolve titanium-containing solution A;

[0009] 3) Crystallize the titanium-containing solution A, and separate the solid and liquid phases to obtain FeSO4 crystals and solution B;

[0010] 4) Mix solution B with solution P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, with the molecular formula: PEO-PPO-PEO) and perform hydrothermal crystallization treatment to obtain a mixed solution;

[0011] 5) Filter and wash the mixed solution after hydrothermal crystallization in step 4), dry the obtained solid and calcine it to obtain microporous-mesoporous composite TiO2 powder;

[0012] 6) The microporous-mesoporous composite TiO2 powder obtained in step 5) is subjected to surface hydrogenation reduction to obtain hydrogenated TiO2 material.

[0013] According to the method of the present invention, in step 1), the calcination temperature is 200-300℃, the calcination time is 4-6h; and / or the concentration of concentrated sulfuric acid is 5-10mol / L, wherein the mass ratio of ilmenite to concentrated sulfuric acid is 10:(11.76~15.68). During calcination, the iron and titanium in the ilmenite are converted into soluble iron and titanium. Preferably, the ilmenite powder is pre-ground to 200-400 mesh. When the concentrated sulfuric acid of the above concentration and the ilmenite of the above particle size are set within a certain mass ratio range, the leaching efficiency of iron and titanium can be optimized.

[0014] According to the method of the present invention, in step 2), the water leaching includes: leaching at 25-100°C with a mixture-to-water mass ratio of 1:(3-5), and stirring for 0.5-3 hours; preferably, the mixture-to-water mass ratio is 1:5. During the water leaching, the ferric sulfate, titanium sulfate, and titanium oxysulfate generated in the calcined mixture dissolve in the water, and the dissolution efficiency is optimal within the above-mentioned temperature and mass ratio range. The titanium-containing solution A is mainly a mixture of TiOSO4, Ti(SO4)2, and FeSO4. Preferably, Ti... 4 + The concentration is 1–1.2 mol / L, Fe 2+ The concentration is 0.5–1 mol / L.

[0015] According to the method of the present invention, in step 3), the crystallization temperature is 0-6℃; the main components of solution B are TiOSO4 and Ti(SO4)2, Ti 4+ The concentration is 2.5-4 mol / L.

[0016] According to the method of the present invention, in step 4), the mass ratio of ilmenite to P123 is 10:5-7, for example 10:6.3. In step 4), P123 is added as a template agent to induce the formation of pore structures.

[0017] In a specific implementation, P123 is dissolved in a solvent and stirred at room temperature until completely dissolved to prepare a P123 solution. The solvent is preferably anhydrous ethanol or water.

[0018] According to the method of the present invention, in step 4), the crystallization temperature is 100-120℃ and the crystallization time is 12-24h, more preferably 110-120℃ for 20-24h; hydrothermal crystallization is used to prepare microporous-mesoporous TiO2. Preferably, the P123 solution and solution B are mixed, stirred at 90-100℃ for 20-30min, and then subjected to hydrothermal crystallization treatment.

[0019] According to the method of the present invention, in step 5), the calcination temperature is 450-650℃, for example 500℃, the calcination time is 3-8h, for example 5h, and the heating rate is 3-10℃ / min, for example 5℃ / min; in a specific embodiment, the washing includes washing multiple times with deionized water and anhydrous ethanol, and the drying includes drying the obtained solid at 80-100℃ for 6-10h. In this step, drying and dehydration are performed, and calcination removes the template agent.

[0020] According to the method of the present invention, in step 6), the surface hydrogenation reduction includes: hydrogenation at 450-600°C in a fixed bed under normal pressure, for example 1-2 atmospheres, 5-100% H2 atmosphere, with a hydrogen flow rate of 50-200 ml / min and a hydrogenation time of 2-12 h, and then cooling to room temperature.

[0021] In another aspect, the present invention also provides a catalyst prepared by the above-described preparation method.

[0022] The catalyst according to the present invention has an anatase crystal form, an amorphous surface layer, and a uniform microporous-mesoporous composite pore structure with a specific surface area of ​​655-800 m². 2 / g, of which the mesoporous pore volume is 0.28-0.60cm³ 3 / g, pore size 2-20nm; micropore volume 0.04-0.12cm³ 3 / g, with a pore size of 0.2-1.5nm and a micropore ratio of 10%-30%.

[0023] In another aspect, the present invention provides the application of the catalyst prepared by the above preparation method, for the catalytic oxidation of propylene and CO in the exhaust gas of explosion-proof diesel vehicles.

[0024] In this article, "room temperature" refers to the same as the ambient temperature, such as 15℃-30℃.

[0025] Compared with existing technologies, this invention has the following advantages: This invention involves high-temperature calcination of ilmenite, water leaching to extract a titanium-containing solution, hydrothermal crystallization of the titanium-containing solution with a template agent, calcination to remove the template agent to prepare TiO2 material, and hydrogenation to prepare an explosion-proof diesel vehicle exhaust catalyst. The defective TiO2 obtained by this invention has an anatase crystal form, an amorphous surface layer, and a microporous-mesoporous composite pore structure with a specific surface area of ​​655-800 m². 2 / g. The method of this invention is simple, utilizing the effective component Ti in the common mineral ilmenite to prepare microporous-mesoporous composite TiO2, and hydrogenating to prepare defective TiO2 catalysts.

[0026] The defective TiO2 catalyst for treating explosion-proof diesel vehicle exhaust described in this invention, compared to traditional Pt / Al2O3 catalysts, does not use precious metals or other active components, significantly reducing costs. It also has a larger specific surface area, which is beneficial for gas diffusion. Propylene conversion reaches over 95% and CO conversion reaches 100% within the temperature range of 150-500℃. The numerous oxygen vacancies formed after hydrogenation serve as both active and adsorption sites, facilitating oxygen conduction and the adsorption, desorption, and activation of reactant gases. Simultaneously, the small amount of S remaining after TiO2 preparation from ilmenite provides acidic sites for the defective TiO2. The acidity and redox properties of hydrogenated TiO2 complement each other, thereby improving the catalyst's activity. This invention not only fills the gap in the field of defective catalysts for treating explosion-proof diesel vehicle exhaust but also provides a new approach to the synthesis of explosion-proof diesel vehicle exhaust catalysts, ushering in a new era of synthesis of explosion-proof diesel vehicle exhaust catalysts without the need for active components. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation method of a diesel vehicle exhaust purification catalyst, as exemplified by the present invention.

[0028] Figure 2 The image shows the X-ray powder diffraction pattern of the diesel vehicle exhaust purification catalyst prepared in Example 2 of this invention. Figure 3 The figure shows the nitrogen adsorption-desorption isotherm of the diesel vehicle exhaust gas treatment catalyst prepared in Example 2 of the present invention. The two lines in the figure are the desorption curve (top) and the adsorption curve (bottom).

[0029] Figure 4 This diagram illustrates the relationship between temperature and the conversion rates of CO and C3H6 when the catalyst prepared in Example 2 of this invention is used to catalyze the exhaust gas of an explosion-proof diesel vehicle. Detailed Implementation

[0030] The present invention will be further described below with reference to the embodiments. However, the present invention is not limited to the listed embodiments, but should also include equivalent improvements and modifications of the technical solutions defined in the appended claims of the present invention.

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] In the following examples and comparative examples:

[0033] (1) Main raw materials

[0034] The ilmenite was purchased from the Panzhihua Magnetite Mine in Sichuan Province. Unless otherwise specified, other chemical reagents were manufactured by Sinopharm and were all of analytical grade.

[0035] (2) Characterization and testing

[0036] The crystal structure of the prepared diesel vehicle exhaust gas treatment catalyst was determined by XRD analysis using Bruker's D8 ADVANCE from Germany, with a scan rate ranging from 0.5° / min to 5° / min.

[0037] The pore structure and mesopore size of the prepared diesel vehicle exhaust gas treatment catalyst were determined by N2 adsorption method using an ASAP 2020 physical adsorption instrument from Micromeritics, USA, with N2 as the adsorption medium.

[0038] The morphology of the prepared hydrogenated TiO2 denitration catalyst was determined by TEM using a JEMARM 200F transmission electron microscope manufactured by JEOL Corporation of Japan.

[0039] The following examples illustrate the preparation method and application of the diesel vehicle exhaust purification catalyst of the present invention.

[0040] Example 1

[0041] The preparation method of the diesel vehicle exhaust purification catalyst of the present invention is as follows: Figure 1 The process, as shown, specifically includes:

[0042] Ilmenite was ground to 200 mesh. Ilmenite powder and 5 mol / L concentrated sulfuric acid were mixed at a mass ratio of 10:11.76 and calcined in a muffle furnace at 200℃ for 4 hours to obtain the mixture.

[0043] The above mixture was mixed with water at room temperature and stirred, then leached at 25°C at a mixture-to-water mass ratio of 1:3 for 0.5 hours with stirring. The resulting titanium-containing solution was then dissolved, and insoluble matter was removed by filtration. The titanium-containing solution was a mixture of TiOSO4, Ti(SO4)2, and FeSO4, denoted as solution A. 4+ The concentration is 1 mol / L, Fe 2+ The concentration is 0.5 mol / L.

[0044] Solution A was placed in a refrigerator at 3°C ​​for two days to crystallize. The resulting FeSO4·7H2O crystals were obtained by filtration and stored in a sealed container. The filtrate mainly consisted of TiOSO4 and Ti(SO4)2, and was denoted as solution B.

[0045] P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, with the molecular formula PEO-PPO-PEO) was dissolved in anhydrous ethanol at a mass ratio of ilmenite to P123 of 10:6.3. The solution was stirred at room temperature until completely dissolved to prepare solution C.

[0046] Solution C was poured into solution B, stirred at 90°C for 30 minutes, and then poured into a stainless steel reactor with a polytetrafluoroethylene liner. The mixture was then hydrothermally crystallized at 100°C for 12 hours.

[0047] The crystallized mixed solution was filtered, washed three times each with deionized water and anhydrous ethanol, and the resulting solid was dried at 80℃ for 8 hours. Finally, it was calcined in a muffle furnace at 500℃ for 5 hours with a heating rate of 5℃ / min. This yielded microporous-mesoporous composite TiO2 powder.

[0048] The above-mentioned microporous-mesoporous composite TiO2 powder was subjected to surface hydrogenation reduction. Under normal pressure and a 100% H2 atmosphere, hydrogenation was carried out in a fixed bed at 450℃ with a hydrogen flow rate of 100 ml / min for 12 h, followed by cooling to room temperature. Hydrogenated TiO2 powder was obtained. The prepared defective microporous-mesoporous composite TiO2 catalyst exhibited anatase crystal structure with an amorphous surface layer and a composite pore structure, possessing a specific surface area of ​​655 m². 2 / g, of which the mesoporous pore volume is 0.28cm³ 3 / g, pore size 2nm; micropore volume 0.04cm³ 3 / g, with a pore size of 0.2nm and a micropore ratio of 23.2%.

[0049] Example 2

[0050] Ilmenite was ground to 200 mesh. Ilmenite powder and 7 mol / L concentrated sulfuric acid were mixed at a mass ratio of 10:12.43 and calcined in a muffle furnace at 250℃ for 5 hours to obtain the mixture.

[0051] The above mixture was mixed with water at room temperature and stirred, then leached at 50°C at a mixture-to-water mass ratio of 1:4 for 0.5 hours with stirring. The resulting titanium-containing solution was then dissolved, and insoluble matter was removed by filtration. The titanium-containing solution was mainly a mixture of TiOSO4, Ti(SO4)2, and FeSO4, denoted as solution A. 4+ The concentration was 1.1 mol / L, Fe 2+ The concentration is 0.6 mol / L.

[0052] Solution A was placed in a refrigerator at 0°C for two days to crystallize. The resulting FeSO4·7H2O crystals were obtained by filtration and stored in a sealed container. The filtrate mainly consisted of TiOSO4 and Ti(SO4)2, and was denoted as solution B.

[0053] Dissolve P123 in anhydrous ethanol, with the amount of P123 added according to a mass ratio of ilmenite to P123 of 10:5. Stir at room temperature until completely dissolved to prepare solution C.

[0054] Solution C was poured into solution B, stirred at 90°C for 30 minutes, and then poured into a stainless steel reactor with a polytetrafluoroethylene liner. The mixture was then hydrothermally crystallized at 110°C for 24 hours.

[0055] The crystallized mixed solution was filtered, washed three times each with deionized water and anhydrous ethanol, and the resulting solid was dried at 90℃ for 8 hours. Finally, it was calcined in a muffle furnace at 450℃ for 8 hours with a heating rate of 3℃ / min. This yielded a microporous-mesoporous composite TiO2 material.

[0056] Microporous-mesoporous composite TiO2 powder was subjected to surface hydrogenation reduction. Hydrogenation was carried out in a fixed bed at 550℃ under normal pressure and a 100% H2 atmosphere, with a hydrogen flow rate of 100 ml / min for 6 h, followed by cooling to room temperature to obtain hydrogenated TiO2 powder. The resulting defective microporous-mesoporous composite TiO2 catalyst exhibited anatase crystal structure with an amorphous surface layer and a composite pore structure, possessing a specific surface area of ​​798.8 m². 2 / g, of which the mesoporous pore volume is 0.60cm³ 3 / g, pore size 10.7nm; micropore volume 0.12cm³ 3 / g, with a pore size of 1.0nm and a micropore ratio of 29.6%.

[0057] Figure 2 X-ray powder diffraction pattern of the diesel vehicle exhaust purification catalyst prepared in an embodiment of the present invention.

[0058] Example 3

[0059] First, ilmenite is ground to 300 mesh. Ilmenite powder and 10 mol / L concentrated sulfuric acid are mixed at a mass ratio of ilmenite to concentrated sulfuric acid of 10:15.68 and calcined in a muffle furnace at a temperature of 200℃ for 4 hours to obtain a mixture.

[0060] The above mixture was mixed with water at room temperature and stirred, then leached at 100°C at a mixture-to-water mass ratio of 1:5 for 0.5 hours with stirring. The resulting titanium-containing solution was then dissolved, and insoluble matter was removed by filtration. The titanium-containing solution was a mixture of TiOSO4, Ti(SO4)2, and FeSO4, denoted as solution A. 4+The concentration was 1.2 mol / L, Fe 2+ The concentration is 1 mol / L.

[0061] Solution A was placed in a refrigerator at 6°C for two days to crystallize. The resulting FeSO4·7H2O crystals were obtained by filtration and stored in a sealed container. The filtrate mainly consisted of TiOSO4 and Ti(SO4)2, and was denoted as solution B.

[0062] Dissolve P123 in anhydrous ethanol, with the amount of P123 added according to a mass ratio of ilmenite to P123 of 10:7. Stir at room temperature until completely dissolved to prepare solution C.

[0063] Solution C was poured into solution B, stirred at 100°C for 20 minutes, and then poured into a stainless steel reactor with a polytetrafluoroethylene liner. Hydrothermal crystallization was carried out at 120°C for 12 hours.

[0064] The crystallized mixed solution was filtered, washed three times each with deionized water and anhydrous ethanol, and the resulting solid was dried at 100℃ for 8 hours. Finally, it was calcined in a muffle furnace at 650℃ for 3 hours with a heating rate of 10℃ / min to obtain microporous-mesoporous composite TiO2 powder.

[0065] Microporous-mesoporous composite TiO2 powder was subjected to surface hydrogenation reduction. Hydrogenation was carried out in a fixed bed at 600℃ under normal pressure and a 5% H2 atmosphere, with a hydrogen flow rate of 100 ml / min for 2 h, followed by cooling to room temperature to obtain hydrogenated TiO2 powder. The resulting defective microporous-mesoporous composite TiO2 catalyst exhibited anatase crystal structure with an amorphous surface layer and a composite pore structure, possessing a specific surface area of ​​732.4 m². 2 / g, of which the mesoporous pore volume is 0.44cm³ 3 / g, pore size 5.6nm; micropore volume 0.08cm³ 3 / g, with a pore size of 1.5nm and a micropore ratio of 10.6%.

[0066] Comparative Example 1

[0067] Unlike Example 1, the hydrothermal crystallization temperature is 180°C.

[0068] Comparative Example 2:

[0069] Unlike Example 1, the hydrogenation temperature was 300°C.

[0070] Comparative Example 3:

[0071] Unlike Example 1, commercially available titanium dioxide was used for hydrogenation, and the specific hydrogenation steps were the same as in Example 1.

[0072] The catalysts prepared in Examples 1-3 and Comparative Examples 1-3 of this invention were granulated (40-60 mesh) for catalytic oxidation of propylene and CO (exhaust gas from explosion-proof diesel vehicles). The space velocity was 60,000 h⁻¹. -1 The concentrations were: propylene 800 ppm, CO 1000 ppm, O2 2%, and N2 as a mixed gas. Performance data for each catalyst are shown in Table 1 below.

[0073] Table 1

[0074]

[0075]

[0076] Note: T90 refers to the temperature at which the catalytic efficiency reaches 90%.

[0077] As shown in Table 1, the optimal synergistic setting of crystallization time and temperature in Example 2 of this invention resulted in the lowest T90 temperature, and lower temperatures are better. Comparative Example 1, with a hydrothermal temperature of 180°C, did not yield a microporous-mesoporous composite structure, only a mesoporous structure; therefore, its T90 temperature was higher than that of the examples of this invention. Comparative Example 2, with a hydrogenation temperature of 300°C, produced a catalyst with fewer surface defects and lower activity, resulting in a high T90 temperature. Comparative Example 3, using titanium dioxide as a raw material, had a small specific surface area and lacked a regular pore structure, resulting in poor activity and a high T90 temperature.

[0078] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are within the spirit and scope of the present invention.

Claims

1. A method for preparing a diesel vehicle exhaust purification catalyst, characterized in that: Includes the following steps: 1) Mix ilmenite and concentrated sulfuric acid, then calcine to obtain a mixture; 2) The mixture is mixed with water and immersed to dissolve titanium-containing solution A; 3) Crystallize the titanium-containing solution A, and separate the solid and liquid phases to obtain FeSO4 crystals and solution B; 4) Mix solution B and solution P123 and perform hydrothermal crystallization treatment to obtain a mixed solution; the hydrothermal crystallization temperature is 100-120℃ and the crystallization time is 12-24h; 5) Filter and wash the mixed solution after hydrothermal crystallization in step 4), dry the obtained solid and calcine it to obtain microporous-mesoporous composite TiO2 powder; 6) The microporous-mesoporous composite TiO2 powder obtained in step 5) is subjected to surface hydrogenation reduction to obtain hydrogenated TiO2 material; the surface hydrogenation reduction includes: hydrogenation in a fixed bed at 450-600℃ under normal pressure and 5-100% H2 atmosphere, with a hydrogen flow rate of 50-200 ml / min and a hydrogenation time of 2-12 h, and then cooling to room temperature.

2. The method for preparing the diesel vehicle exhaust purification catalyst according to claim 1, characterized in that: In step 1), the calcination temperature is 200-300℃ and the calcination time is 4-6h; and / or the concentration of concentrated sulfuric acid is 5-10mol / L, wherein the mass ratio of ilmenite to concentrated sulfuric acid is 10:(11.76~15.68), and the ilmenite is pre-ground to 200-400 mesh.

3. The method for preparing the diesel vehicle exhaust purification catalyst according to claim 1, characterized in that: In step 2), the water immersion includes: immersion at 25-100℃ with a mass ratio of mixture to water of 1:(3~5) and stirring for 0.5-3h; and / or, in step 3), the crystallization temperature is 0-6℃.

4. The method for preparing the diesel vehicle exhaust purification catalyst according to claim 1, characterized in that: In step 4), the mass ratio of ilmenite to P123 is 10:5-7.

5. The method for preparing the diesel vehicle exhaust purification catalyst according to claim 1, characterized in that: In step 5), the calcination temperature is 450-650℃, the calcination time is 3-8h, and the heating rate is 3-10℃ / min; the washing includes washing multiple times with deionized water and anhydrous ethanol; and the drying includes drying the obtained solid at 80-100℃ for 6-10h.

6. A diesel vehicle exhaust purification catalyst prepared by the preparation method according to any one of claims 1-5.

7. The catalyst according to claim 6, characterized in that: The catalyst has an anatase crystal form with an amorphous surface layer and a uniform microporous-mesoporous composite pore structure, with a specific surface area of ​​655-800 m². 2 / g, of which the mesoporous pore volume is 0.28-0.60cm³ 3 / g, pore size 2-20nm; micropore volume 0.04-0.12cm³ 3 / g, with a pore size of 0.2-1.5nm and a micropore ratio of 10%-30%.

8. The application of a diesel vehicle exhaust purification catalyst prepared by any one of claims 1-5, wherein it is used for the catalytic oxidation of propylene and CO in the exhaust gas of an explosion-proof diesel vehicle.

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