Preparation method and application of microsphere ceramic particle flue gas denitration catalyst

Abstract

The invention discloses a preparation method and application of a microsphere ceramic particle flue gas denitration catalyst, the catalyst takes a composite oxide of copper oxide and silicon oxide as a carrier, platinum nanoparticles as an active component and vanadium oxide as a cocatalyst, and the catalyst is prepared by a combined method of electrochemical deposition, high-temperature roasting and impregnation loading. Based on the mass of the carrier, the mass percentage content of the active component is 1-3%, and the mass percentage content of the cocatalyst is 5-10%, and the catalyst synthesized by the method has excellent conversion rate and selectivity, can realize efficient removal of nitrogen oxides, and has high economic value and wide market application prospect.

Description

Technical Field

[0001] The invention discloses a preparation method and application of a micron-spherical ceramic particle flue gas denitration catalyst, belonging to the field of environmental protection catalysis. Background Art

[0002] Nitrogen oxides (NO x ) The research background of catalytic reduction involves environmental protection, air quality improvement and the application of catalyst technology. Nitrogen oxides mainly include nitric oxide (NO) and nitrogen dioxide (NO2), which are pollutants produced by combustion processes, industrial emissions, transportation, etc. x Excessive emissions of NO are one of the important factors leading to air pollution and acid rain, and have a wide range of negative impacts on human health, ecosystems and the atmospheric environment. Therefore, how to effectively reduce NO x The emission of pollutants has become an important research topic in the global environmental protection field.

[0003] At present, researchers have developed a variety of catalysts, mainly including: metal oxide catalysts: such as titanium dioxide (TiO2), molybdenum dioxide (MoO3), vanadium oxide (V2O5), etc. They have good catalytic activity and good stability for the catalytic reduction of nitrogen oxides at higher temperatures; transition metal catalysts: such as copper-based catalysts (CuO), iron-based catalysts (Fe2O3), etc. These catalysts can effectively promote the reduction reaction of nitrogen oxides and have relatively low costs; precious metal catalysts: such as platinum (Pt), palladium (Pd), etc. These catalysts have high catalytic activity and selectivity. However, precious metal catalysts have high low-temperature efficiency but high cost, and metal oxide catalysts have low cost but low-temperature oxidation efficiency is not as good as precious metals. Therefore, the research and development of cost-effective and efficient catalysts is one of the key research directions at present. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of low low-temperature reduction efficiency of nitrogen oxides and to provide a preparation method and application of a micron-spherical ceramic particle flue gas denitration catalyst.

[0005] The catalyst uses polyurethane microspheres to form carbon microspheres, then uses electrochemical deposition to deposit copper on the surface of carbon microspheres, then oxidizes at low temperature to form copper oxide, then uses hydrothermal method to wrap silicon oxide on the surface of copper oxide, and then calcines at high temperature to form ceramic microsphere carriers. This method can not only make silicon oxide form uniformly dispersed microsphere ceramic particles, but also use the electron transfer effect of copper oxide to promote the redox performance of active components and co-catalysts. In addition, because it is difficult to deposit silicon oxide on the surface of carbon microspheres by conventional methods, copper is first deposited and then oxidized by electrochemical deposition, and finally silicon oxide is grown by hydrothermal reaction. At the same time, carbon material as the core will also be oxidized to escape into carbon dioxide during the process of silicon oxide calcining to form ceramic particles, thereby avoiding the formation of dense microspheres of silicon oxide wrapped copper oxide particles during high temperature calcination, which affects the specific surface area of ​​the carrier. Finally, the active component platinum and the co-catalyst vanadium oxide are loaded on the surface of the ceramic microsphere carrier by impregnation and redox method, and the excellent low-temperature redox performance of precious metals and the electron transfer effect of vanadium oxide are used to ensure that the microsphere ceramic particle catalyst can reduce nitrogen oxides at low temperature and efficiently.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a flue gas denitration catalyst of micron-spherical ceramic particles, characterized in that: the catalyst uses a composite oxide of copper oxide and silicon oxide as a carrier, platinum nanoparticles as an active component, and vanadium oxide as a co-catalyst, and is prepared by a combined method of electrochemical deposition-high temperature roasting-impregnation loading. Based on the mass of the carrier, the mass percentage of the active component is 1-3%, and the mass percentage of the co-catalyst is 5-10%. The method comprises the following steps:

[0008] (1) Preparation of copper-coated carbon materials by electrochemical deposition

[0009] Weighing polyurethane microspheres, placing them in a tubular atmosphere furnace, introducing nitrogen and heating them for carbonization to obtain carbon microsphere powder, then mixing the carbon microsphere powder, polyvinyl alcohol and deionized water in a water bath to obtain a mixed slurry, then pressing the mixed slurry into a sheet, and placing the sheet in an oven to dry and solidify to obtain a carbon cathode; using a copper sheet as a copper anode and a mixed solution of copper sulfate, sulfuric acid and deionized water as an electrolyte, combining the carbon cathode, copper anode, electrolyte and a DC voltage device to form an electrodeposition device and perform electrochemical deposition to obtain a copper-wrapped carbon material;

[0010] (2) Vector preparation

[0011] The copper-coated carbon material obtained in step (1) is placed in a muffle furnace for low-temperature oxidation to obtain a copper oxide-coated carbon material, and then the copper oxide-coated carbon material, silicon salt, and deionized water are evenly mixed and placed in a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the mixture is dried and calcined at high temperature to obtain a silicon oxide-coated copper oxide micron carrier powder;

[0012] (3) Catalyst preparation

[0013] Weigh vanadium salt, monohydrated citric acid and deionized water and mix them evenly to obtain a promoter precursor solution, then place the silicon oxide-coated copper oxide micron carrier powder obtained in step (2) in the promoter precursor solution, dry and then calcine to obtain a mixed powder; then weigh platinum salt and deionized water and mix them evenly to obtain an active component precursor solution, and weigh a reducing agent and deionized water and mix them evenly to obtain a reducing agent solution, immerse the obtained mixed powder in the active component precursor solution, dry and then place it in the reducing agent solution, react and then dry to obtain a catalyst.

[0014] In the technical solution of the present invention: the microscopic diameter of the polyurethane microspheres described in step (1) is 2 to 3 μm, the rate of nitrogen introduction is 20 to 30 mL / min, the temperature of heating and carbonization is 700 to 800°C, the time of heating and carbonization is 2 to 4 hours, and the heating rate is 10 to 20°C / min.

[0015] In the technical scheme of the present invention: the mass ratio of the carbon microsphere powder, polyvinyl alcohol and deionized water described in step (1) is 1: (0.5-2): (2-3), the temperature of the water bath is 80-90° C., the size of the flakes is (20-50)×(20-50)×(2-5) mm, the drying temperature is 30-40° C., and the drying time is 12-24 h.

[0016] In the technical solution of the present invention: the size of the copper sheet described in step (1) is (20-50)×(20-50)×(2-5) mm, and the mass ratio of copper sulfate, sulfuric acid and deionized water is 1:(0.5-1):(300-500).

[0017] In the technical solution of the present invention: the voltage of the electrochemical deposition in step (1) is 1.8 to 2.2 V, and the time of the electrochemical deposition is 12 to 24 hours.

[0018] In the technical solution of the present invention: the temperature of the low-temperature oxidation in step (2) is 200-250° C., and the time of the low-temperature oxidation is 6-12 hours.

[0019] In the technical solution of the present invention: the silicon salt described in step (2) is tetraethyl orthosilicate or butyl orthosilicate, and the mass ratio of the copper oxide-coated carbon material, the silicon salt and deionized water is 1: (2-3): (30-50).

[0020] In the technical scheme of the present invention: the temperature of the hydrothermal reaction in step (2) is 120-140°C, the time of the hydrothermal reaction is 4-6 hours, the temperature of drying is 60-80°C, the time of drying is 12-24 hours, the temperature of high-temperature roasting is 1200-1400°C, and the time of high-temperature roasting is 2-4 hours.

[0021] In the technical scheme of the present invention: the vanadium salt described in step (3) is ammonium metavanadate, the mass ratio of the vanadium salt, citric acid monohydrate and deionized water is 1:(1-3):(20-30), the drying temperature is 60-80°C, the drying time is 6-12h, the roasting temperature is 500-600°C, and the roasting time is 2-4h.

[0022] In the technical solution of the present invention: the platinum salt described in step (3) is chloroplatinic acid, the mass ratio of the platinum salt to deionized water is 1: (30-60), the reducing agent is sodium borohydride or potassium borohydride, the mass ratio of the reducing agent to deionized water is 1: (100-200), and the reaction time is 2-4 hours.

[0023] In the technical solution of the present invention, the catalyst prepared by the above method is used in the field of catalytic reduction of nitrogen oxides.

[0024] Beneficial effects:

[0025] (1) The silicon oxide-coated copper oxide ceramic particle carrier has both the mechanical strength of ceramic particles and the rich mesoporous structure on the surface, which enhances the ability of the carrier surface to adsorb and activate reactive molecules;

[0026] (2) Vanadium oxide has excellent electron transfer properties, which can enhance the oxidation performance of the active component platinum and improve the conversion rate of the catalyst for low-temperature reduction of nitrogen oxides;

[0027] (3) The ceramic particle catalyst is evenly distributed at the microscopic interface, which is conducive to maximizing the utilization of active sites;

[0028] (4) The preparation method has a simple process and common raw materials, and has broad market application prospects and high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attached Figure 1 Field emission scanning electron microscope (FE-SEM) image of Example 1;

[0030] Attached Figure 2 Field emission scanning electron microscope (FE-SEM) image of the details of a single sphere in Example 1. DETAILED DESCRIPTION

[0031] The following examples further illustrate the ceramic membrane catalyst and its application in the field of reforming hydrogen production described in the present invention. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0032] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art, and the experimental devices and experimental materials, unless otherwise specified, are all commercially available.

[0033] Example 1

[0034] (1) Preparation of copper-coated carbon materials by electrochemical deposition

[0035] Weigh 50.000g of polyurethane microspheres with a microscopic diameter of 2μm, place them in a tubular atmosphere furnace, introduce nitrogen (at a rate of 20mL / min) and heat (at a rate of 10℃ / min) to 700℃ for carbonization for 4h to obtain carbon microsphere powder, then weigh 5.000g of carbon microsphere powder, 2.500g of polyvinyl alcohol, and 10.000g of deionized water, mix and stir in a water bath at 80℃ to obtain a mixed slurry, and then press the mixed slurry into a sheet with a size of 20×20×5mm The thin slice is placed in an oven at 30°C and dried for 24 hours to solidify to obtain a carbon cathode; a copper sheet with a size of 20×20×5 mm is used as a copper anode, and a mixed solution of 5.000g of copper sulfate, 2.500g of concentrated sulfuric acid with a concentration of 98% and 1500.000g of deionized water is used as an electrolyte. The carbon cathode, the copper anode, the electrolyte, and a DC voltage device are combined to form an electrodeposition device and electrochemical deposition is performed. The voltage of the electrochemical deposition is 1.8V, and the time of the electrochemical deposition is 24 hours to obtain a copper-wrapped carbon material;

[0036] (2) Vector preparation

[0037] The copper-coated carbon material obtained in step (1) is placed in a muffle furnace for low-temperature oxidation at 200° C. for 12 h to obtain a copper oxide-coated carbon material, and then 5.000 g of the copper oxide-coated carbon material, 10.000 g of tetraethyl orthosilicate, and 150.000 g of deionized water are weighed and mixed evenly, and the mixture is placed in a hydrothermal reactor for hydrothermal reaction at 120° C. for 6 h. After the reaction is completed, the mixture is placed in an oven for drying at 60° C. for 12 h, and the mixture is placed in a muffle furnace for high-temperature roasting at 1200° C. for 4 h to obtain a silicon oxide-coated copper oxide micron carrier powder;

[0038] (3) Catalyst preparation

[0039] 0.193 g of ammonium metavanadate, 0.193 g of citric acid monohydrate, and 3.860 g of deionized water were weighed and mixed to obtain a promoter precursor solution. Then 5.000 g of the silicon oxide-coated copper oxide micron carrier powder obtained in step (2) was placed in the promoter precursor solution, dried at 60° C. for 12 h, and then placed in a muffle furnace and calcined at 500° C. for 4 h to obtain a mixed powder; 0.105 g of chloroplatinic acid and 3.150 g of deionized water were weighed and mixed to obtain an active component precursor solution, and 1.000 g of sodium borohydride and 100.000 g of deionized water were weighed and mixed to obtain a sodium borohydride solution. The obtained mixed powder was immersed in the active component precursor solution, dried at 60° C. for 12 h, and then placed in the sodium borohydride solution. After reacting for 4 h, the catalyst was dried to obtain a catalyst (the FE-SEM image of the catalyst is shown in FIG. 1). Figure 1 and Figure 2 shown);

[0040] (4) Catalytic activity test

[0041] Take 1 mL of 20-40 mesh catalyst, pour it into a quartz tube with an inner diameter of 6 mm, fix it with quartz wool and wire mesh, place the quartz tube in a tubular furnace, and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tubular furnace. The intake components are: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), and the rest are N2. The total gas flow rate is 500 mL / min, and the temperature is set to 160°C. The flue gas analyzer determines the NO concentration before and after the reaction. The efficiency of the catalyst in removing NO at 160°C for 3 minutes is 94.2%.

[0042] Example 2

[0043] (1) Preparation of copper-coated carbon materials by electrochemical deposition

[0044] 50.000 g of polyurethane microspheres with a microscopic diameter of 3 μm were weighed and placed in a tubular atmosphere furnace, nitrogen was introduced (at a rate of 30 mL / min) and the temperature was increased (at a rate of 20 °C / min) to 800 °C for carbonization for 2 h to obtain carbon microsphere powder. Then 5.000 g of carbon microsphere powder, 10.000 g of polyvinyl alcohol and 15.000 g of deionized water were weighed and mixed and stirred in a 90 °C water bath to obtain a mixed slurry. The mixed slurry was then pressed into a thin film with a size of 50 × 50 × 2 mm. The sheet is placed in an oven at 40°C and dried for 12 hours to solidify to obtain a carbon cathode; a copper sheet with a size of 50×50×2 mm is used as a copper anode, and a mixed solution of 5.000 g of copper sulfate, 5.000 g of concentrated sulfuric acid with a concentration of 98% and 2500.000 g of deionized water is used as an electrolyte, and the carbon cathode, the copper anode, the electrolyte, and a DC voltage device are combined to form an electrodeposition device and electrochemical deposition is performed, the voltage of the electrochemical deposition is 2.2 V, and the time of the electrochemical deposition is 12 hours, to obtain a copper-wrapped carbon material;

[0045] (2) Vector preparation

[0046] The copper-coated carbon material obtained in step (1) is placed in a muffle furnace for low-temperature oxidation at 250° C. for 6 hours to obtain a copper oxide-coated carbon material, and then 5.000 g of the copper oxide-coated carbon material, 15.000 g of butyl orthosilicate, and 250.000 g of deionized water are weighed, mixed evenly, and placed in a hydrothermal reactor for hydrothermal reaction at 140° C. for 4 hours. After the reaction is completed, the mixture is placed in an oven for drying at 80° C. for 24 hours, and then placed in a muffle furnace for high-temperature roasting at 1400° C. for 2 hours to obtain a silicon oxide-coated copper oxide micron carrier powder;

[0047] (3) Catalyst preparation

[0048] 0.643 g of ammonium metavanadate, 1.929 g of citric acid monohydrate, and 19.290 g of deionized water were weighed and mixed to obtain a promoter precursor solution, and then 5.000 g of the silicon oxide-coated copper oxide micron carrier powder obtained in step (2) was placed in the promoter precursor solution, dried at 80° C. for 6 h, and then placed in a muffle furnace and calcined at 600° C. for 2 h to obtain a mixed powder; 0.315 g of chloroplatinic acid and 18.900 g of deionized water were weighed and mixed to obtain an active component precursor solution, and 1.000 g of potassium borohydride and 200.000 g of deionized water were weighed and mixed to obtain a potassium borohydride solution, and the obtained mixed powder was immersed in the active component precursor solution, dried at 80° C. for 6 h, and then placed in the potassium borohydride solution, reacted for 2 h, and then dried to obtain a catalyst;

[0049] (4) Catalytic activity test

[0050] Take 1 mL of 20-40 mesh catalyst, pour it into a quartz tube with an inner diameter of 6 mm, fix it with quartz wool and wire mesh, place the quartz tube in a tubular furnace, and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tubular furnace. The intake components are: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), and the rest are N2. The total gas flow rate is 500 mL / min, and the temperature is set to 160°C. The flue gas analyzer determines the NO concentration before and after the reaction. The efficiency of the catalyst in removing NO at 160°C for 3 minutes is 98.2%.

[0051] Example 3

[0052] (1) Preparation of copper-coated carbon materials by electrochemical deposition

[0053] 50.000 g of polyurethane microspheres with a microscopic diameter of 2 μm were weighed and placed in a tubular atmosphere furnace, nitrogen was introduced (at a rate of 20 mL / min) and the temperature was increased (at a rate of 15 °C / min) to 750 °C for carbonization for 3 h to obtain carbon microsphere powder. Then 5.000 g of carbon microsphere powder, 10.000 g of polyvinyl alcohol and 15.000 g of deionized water were weighed and mixed and stirred in a water bath at 85 °C to obtain a mixed slurry. The mixed slurry was then pressed into a thin film with a size of 50 × 50 × 2 mm. The sheet is placed in an oven at 35°C and dried for 18 hours to solidify to obtain a carbon cathode; a copper sheet with a size of 50×50×2 mm is used as a copper anode, and a mixed solution of 5.000g of copper sulfate, 5.000g of concentrated sulfuric acid with a concentration of 98% and 2500.000g of deionized water is used as an electrolyte, and the carbon cathode, the copper anode, the electrolyte, and a DC voltage device are combined to form an electrodeposition device and electrochemical deposition is performed, the voltage of the electrochemical deposition is 2.2V, and the time of the electrochemical deposition is 12 hours, to obtain a copper-wrapped carbon material;

[0054] (2) Vector preparation

[0055] The copper-coated carbon material obtained in step (1) is placed in a muffle furnace for low-temperature oxidation at 250° C. for 6 h to obtain a copper oxide-coated carbon material, and then 5.000 g of the copper oxide-coated carbon material, 15.000 g of butyl orthosilicate, and 250.000 g of deionized water are weighed, mixed evenly, and placed in a hydrothermal reactor for hydrothermal reaction at 130° C. for 5 h. After the reaction is completed, the mixture is placed in an oven for drying at 80° C. for 18 h, and placed in a muffle furnace for high-temperature roasting at 1300° C. for 3 h to obtain a silicon oxide-coated copper oxide micron carrier powder;

[0056] (3) Catalyst preparation

[0057] 0.643 g of ammonium metavanadate, 1.929 g of citric acid monohydrate, and 19.290 g of deionized water were weighed and mixed to obtain a promoter precursor solution, and then 5.000 g of the silicon oxide-coated copper oxide micron carrier powder obtained in step (2) was placed in the promoter precursor solution, dried at 80° C. for 6 h, and then placed in a muffle furnace and calcined at 600° C. for 2 h to obtain a mixed powder; 0.315 g of chloroplatinic acid and 18.900 g of deionized water were weighed and mixed to obtain an active component precursor solution, and 1.000 g of potassium borohydride and 200.000 g of deionized water were weighed and mixed to obtain a potassium borohydride solution, and the obtained mixed powder was immersed in the active component precursor solution, dried at 80° C. for 6 h, and then placed in the potassium borohydride solution, reacted for 2 h, and then dried to obtain a catalyst;

[0058] (4) Catalytic activity test

[0059] Take 1 mL of 20-40 mesh catalyst, pour it into a quartz tube with an inner diameter of 6 mm, fix it with quartz wool and wire mesh, place the quartz tube in a tubular furnace, and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tubular furnace. The intake components are: NO (500 ppm), NH3 (500 ppm), O2 (11 vol.%), and the rest are N2. The total gas flow rate is 500 mL / min, and the temperature is set to 160°C. The flue gas analyzer determines the NO concentration before and after the reaction. The efficiency of the catalyst in removing NO at 160°C for 3 minutes is 96.0%.

Claims

1. A method for preparing a micron-spherical ceramic particle flue gas denitration catalyst, characterized in that: The catalyst uses a composite oxide of copper oxide and silicon oxide as a carrier, platinum nanoparticles as an active component, and vanadium oxide as a co-catalyst. It is prepared by a combined method of electrochemical deposition-high temperature calcination-impregnation loading. Based on the mass of the carrier, the mass percentage of the active component is 1-3%, and the mass percentage of the co-catalyst is 5-10%. The method comprises the following steps: (1) Preparation of copper-coated carbon materials by electrochemical deposition Weighing polyurethane microspheres, placing them in a tubular atmosphere furnace, introducing nitrogen and heating them for carbonization to obtain carbon microsphere powder, then mixing the carbon microsphere powder, polyvinyl alcohol and deionized water in a water bath to obtain a mixed slurry, then pressing the mixed slurry into a sheet, and placing the sheet in an oven to dry and solidify to obtain a carbon cathode; using a copper sheet as a copper anode and a mixed solution of copper sulfate, sulfuric acid and deionized water as an electrolyte, combining the carbon cathode, copper anode, electrolyte and a DC voltage device to form an electrodeposition device and perform electrochemical deposition to obtain a copper-wrapped carbon material; (2) Vector preparation The copper-coated carbon material obtained in step (1) is placed in a muffle furnace for low-temperature oxidation to obtain a copper oxide-coated carbon material, and then the copper oxide-coated carbon material, silicon salt, and deionized water are evenly mixed and placed in a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the mixture is dried and calcined at high temperature to obtain a silicon oxide-coated copper oxide micron carrier powder; (3) Catalyst preparation Weigh vanadium salt, monohydrated citric acid and deionized water and mix them evenly to obtain a promoter precursor solution, then place the silicon oxide-coated copper oxide micron carrier powder obtained in step (2) in the promoter precursor solution, dry and then calcine to obtain a mixed powder; then weigh platinum salt and deionized water and mix them evenly to obtain an active component precursor solution, and weigh a reducing agent and deionized water and mix them evenly to obtain a reducing agent solution, immerse the obtained mixed powder in the active component precursor solution, dry and then place it in the reducing agent solution, react and then dry to obtain a catalyst.

2. The preparation method according to claim 1, characterized in that: The microscopic diameter of the polyurethane microspheres described in step (1) is 2 to 3 μm, the rate of nitrogen introduction is 20 to 30 mL / min, the temperature of heating and carbonization is 700 to 800° C., the time of heating and carbonization is 2 to 4 hours, and the heating rate is 10 to 20° C. / min.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the carbon microsphere powder, polyvinyl alcohol and deionized water in step (1) is 1: (0.5-2): (2-3), the temperature of the water bath is 80-90° C., the size of the flakes is (20-50)×(20-50)×(2-5) mm, the drying temperature is 30-40° C., and the drying time is 12-24 h.

4. The preparation method according to claim 1, characterized in that: The size of the copper sheet described in step (1) is (20-50)×(20-50)×(2-5) mm, and the mass ratio of copper sulfate, sulfuric acid and deionized water is 1:(0.5-1):(300-500).

5. The preparation method according to claim 1, characterized in that: The voltage of the electrochemical deposition in step (1) is 1.8 to 2.2 V, and the time of the electrochemical deposition is 12 to 24 hours.

6. The preparation method according to claim 1, characterized in that: The temperature of the low-temperature oxidation in step (2) is 200-250° C., and the time of the low-temperature oxidation is 6-12 hours.

7. The preparation method according to claim 1, characterized in that: The silicon salt described in step (2) is tetraethyl orthosilicate or butyl orthosilicate, and the mass ratio of the copper oxide-coated carbon material, the silicon salt and the deionized water is 1: (2-3): (30-50).

8. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (2) is 120-140° C., the time of the hydrothermal reaction is 4-6 hours, the temperature of the drying is 60-80° C., the time of the drying is 12-24 hours, the temperature of the high-temperature calcination is 1200-1400° C., and the time of the high-temperature calcination is 2-4 hours.

9. The preparation method according to claim 1, characterized in that: The vanadium salt described in step (3) is ammonium metavanadate, and the mass ratio of the vanadium salt, citric acid monohydrate and deionized water is 1:(1-3):(20-30). The drying temperature is 60-80°C, the drying time is 6-12h, the roasting temperature is 500-600°C, and the roasting time is 2-4h.

10. The preparation method according to claim 1, characterized in that: The platinum salt described in step (3) is chloroplatinic acid, the mass ratio of the platinum salt to deionized water is 1: (30-60), the reducing agent is sodium borohydride or potassium borohydride, the mass ratio of the reducing agent to deionized water is 1: (100-200), and the reaction time is 2-4 hours.

11. Use of the catalyst prepared by the method of claim 1 in the field of catalytic reduction of nitrogen oxides.

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