An integrated water-resistant and sulfur-resistant co oxidation catalyst and a method for preparing the same

Abstract

The application discloses a monolithic water-resistant and sulfur-resistant CO oxidation catalyst and a preparation method thereof. In one aspect, the application provides a monolithic water-resistant and sulfur-resistant CO oxidation catalyst, wherein the mass ratio of components of the catalyst comprises 2.5-12 parts of CuO x , 0.5-5 parts of SnO2, 0.3-3 parts of AgO x , 40-50 parts of TiO2, 10-20 parts of CeO2-TiO2 composite powder, 2-10 parts of a binder and 12-18 parts of a reinforcing agent; and the catalyst has a honeycomb structure. In another aspect, the application provides a preparation method of the monolithic water-resistant and sulfur-resistant CO oxidation catalyst. The application does not use rare noble metals, has better catalytic effect, relatively lower optimal catalytic temperature and excellent water resistance and sulfur resistance.

Description

Technical Field

[0001] This application relates to the field of air pollution control technology, and in particular to an integral water- and sulfur-resistant CO oxidation catalyst and its preparation method. Background Technology

[0002] CO, a significant pollutant, not only poses serious threats to human health but also undergoes photochemical reactions with nitrogen oxides and volatile organic compounds in the air, producing photochemical smog and indirectly damaging the ozone layer. Vehicle exhaust emissions and industrial flue gas emissions from steelmaking are the main pathways for CO pollution. When the CO concentration in the environment exceeds 25 ppm, it can harm human health; exceeding 50 ppm can cause various symptoms of poisoning. Furthermore, industrial flue gas emissions from steelmaking are not only large (flue gas flow rates of 500,000 to 2,000,000 Nm³), but also... 3 Moreover, the CO content is high (5000~10000ppm), posing a great threat to the environment.

[0003] Existing technologies for the harmless treatment of CO in flue gas mainly include chemical solution absorption, physical adsorption, and catalytic oxidation. Among these, catalytic oxidation, which converts CO into non-toxic CO2, is the most energy-efficient and economical method. The core of catalytic oxidation is the oxidation catalyst for CO removal, which mainly includes metal oxide catalysts, mixed metal oxide catalysts, and supported catalysts. Currently, oxides of rare and precious metals such as Pt, Rh, and Pd are widely used. However, these rare and precious metal catalysts are difficult to apply industrially due to their high cost and scarcity.

[0004] Currently, research on oxidation catalysts for CO removal, primarily using non-rare precious metal catalysts, has become a hot topic in this field. Existing non-rare precious metal catalysts mainly employ transition metal oxides, with oxides of elements such as copper, cobalt, manganese, and cerium, as well as mixed metal oxides formed from these elements, being the most widely used. These transition metal oxide catalysts generally have high catalytic temperatures, with optimal catalytic temperatures typically exceeding 250℃. Furthermore, these catalysts exhibit insufficient resistance to sulfur and water. In flue gas containing sulfur and water, they react with sulfur to form sulfates and sulfites, leading to catalyst poisoning and severely impacting catalytic performance.

[0005] Designing a non-rare precious metal-based oxidation catalyst for CO removal with excellent resistance to water and sulfur is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0006] To address at least one of the aforementioned technical problems, and to develop an oxidation catalyst for CO removal that does not employ rare and precious metals, exhibits good catalytic performance, has a relatively low optimal catalytic temperature, and possesses excellent resistance to water and sulfur, this application provides an integral water- and sulfur-resistant CO oxidation catalyst and its preparation method.

[0007] On the one hand, this application provides an integral water- and sulfur-resistant CO oxidation catalyst, wherein the mass ratio of each component of the catalyst includes: 2.5 to 12 parts of CuO. x 0.5-5 parts SnO2, 0.3-3 parts AgO x The catalyst comprises 40-50 parts TiO2, 10-20 parts CeO2-TiO2 composite powder, 2-8 parts binder, and 12-18 parts reinforcing agent; the catalyst has a honeycomb structure.

[0008] Optionally, in the CeO2-TiO2 composite powder, the mass ratio of CeO2 to TiO2 is 1:15~25.

[0009] Optionally, the binder may be attapulgite clay.

[0010] Optionally, the reinforcing agent is glass fiber.

[0011] On the other hand, this application provides a method for preparing the above-mentioned monolithic water- and sulfur-resistant CO oxidation catalyst, comprising the following steps:

[0012] S1. Calculate the amounts of Cu precursor, Sn precursor and Ag precursor according to the mass ratio, and weigh out Cu precursor, Sn precursor and Ag precursor.

[0013] S2. Preparation of CeO2-TiO2 composite powder;

[0014] S3. Mix the Cu precursor, Sn precursor and Ag precursor weighed in step S1 with the CeO2-TiO2 composite powder prepared in step S2, add organic binder, pore-forming agent, additive and solvent, and then add the formula amount of binder and reinforcing agent, and prepare a slurry by kneading and aging.

[0015] S4. The slurry prepared in step S3 is extruded, dried, and then calcined to obtain an integral water-resistant and sulfur-resistant CO oxidation catalyst.

[0016] Optionally, in step S1, the Cu precursor is selected from at least one of copper acetate and copper nitrate, the Sn precursor is selected from at least one of tin tetrachloride and stannous chloride, and the Ag precursor is selected from at least one of silver nitrate and silver acetate.

[0017] Optionally, in step S2, the preparation of CeO2-TiO2 composite powder includes the following steps: selecting CeO2 powder and TiO2 powder with a particle size of 10~50nm, adding a co-solvent and a solvent, and preparing a slurry; heating to above 90℃ for concentration, then extruding and molding, drying and calcining, with the calcination temperature controlled at 350~500℃ and the holding time at 2~6h; finally crushing and grinding into powder to obtain CeO2-TiO2 composite powder.

[0018] Optionally, in step S3, the organic binder is selected as silica sol.

[0019] Optionally, in step S4, the aging time is more than 48 hours, and the product is dried to a moisture content of less than 2%.

[0020] Optionally, in step S4, the calcination temperature is 550~600℃, and the holding time is more than 4 hours.

[0021] In summary, the present invention has at least one of the following beneficial technical effects:

[0022] 1. This application uses CuO x Using CeO2 as a dual active component of the catalyst, and TiO2 as a stabilizing support and catalyst promoter, can effectively improve the catalytic activity and stability of the catalyst. The introduction of SnO2 can not only stabilize the crystal form of TiO2 as a structural stabilizer, but also act as a catalyst promoter to further improve the catalytic activity and low-temperature catalytic performance of the catalyst.

[0023] 2. The catalyst of this application incorporates AgO. x It can form a synergistic effect with SnO2, improving the catalyst's resistance to sulfur and water. In addition, the CeO2 in this application is integrated into the catalyst system as a composite powder with TiO2 as a support, which can further improve the stability of the active components and enhance the resistance to water and sulfur.

[0024] 3. The preparation method of this application has a relatively simple production process. It does not use precious metal raw materials or toxic oxides such as vanadium. It is supplemented with binders and reinforcing agents to prepare a honeycomb structure with high mechanical strength, high utilization rate of active ingredients, long service life, good reactivity, low pressure drop, and large flue gas volume treatment capacity. Attached Figure Description

[0025] Figure 1 This is an electron micrograph of the catalyst in Example 1 of this application;

[0026] Figure 2 This is an electron micrograph showing the Cu elemental distribution of the catalyst in Example 1 of this application;

[0027] Figure 3This is an electron micrograph showing the Ce elemental distribution of the catalyst in Example 1 of this application;

[0028] Figure 4 This is an electron micrograph showing the O element distribution of the catalyst in Example 1 of this application;

[0029] Figure 5 This is an electron micrograph showing the Ag elemental distribution of the catalyst in Example 1 of this application;

[0030] Figure 6 This is an electron micrograph showing the Sn elemental distribution of the catalyst in Example 1 of this application. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the embodiments.

[0032] This application provides an integral water- and sulfur-resistant CO oxidation catalyst, wherein the mass ratio of each component of the catalyst includes: 2.5 to 12 parts of CuO. x 0.5-5 parts SnO2, 0.3-3 parts AgO x The catalyst comprises 40-50 parts of TiO2, 10-20 parts of CeO2-TiO2 composite powder, 2-10 parts of binder, and 12-18 parts of reinforcing agent; the catalyst has a honeycomb structure.

[0033] The preparation method of the above-mentioned monolithic water-resistant and sulfur-resistant CO oxidation catalyst of this application includes the following steps:

[0034] S1. Calculate the amounts of Cu precursor, Sn precursor and Ag precursor according to the mass ratio, and weigh out Cu precursor, Sn precursor and Ag precursor.

[0035] S2. Preparation of CeO2-TiO2 composite powder;

[0036] S3. Mix the Cu precursor, Sn precursor and Ag precursor weighed in step S1 with the CeO2-TiO2 composite powder prepared in step S2, add organic binder, pore-forming agent, additive and solvent, and then add the formula amount of binder and reinforcing agent, and prepare a slurry by kneading and aging.

[0037] S4. The slurry prepared in step S3 is extruded, dried, and then calcined to obtain an integral water-resistant and sulfur-resistant CO oxidation catalyst.

[0038] Prior to this application, existing non-rare precious metal catalysts for treating CO in flue gas were mainly copper-manganese and aluminum-cerium catalysts. These catalysts often incorporate cobalt and other transition metal oxides as catalyst promoters to enhance catalytic activity. Aluminum-cerium catalysts are primarily used for treating automotive exhaust gases, which have low flow rates and relatively low CO content; copper-manganese catalysts are mainly used for treating industrial flue gases, which have high flow rates and relatively high CO content.

[0039] Existing copper-manganese catalysts often incorporate transition metal oxides, such as cobalt, cerium, nickel, and tin, as catalyst promoters to enhance catalytic activity. However, steelmaking flue gas in industrial processes has a high CO content and generally low temperatures (typically 120-150°C), making it difficult to apply sufficient temperature to existing catalysts. Furthermore, these transition metal oxide-based catalysts often fall short in treating steelmaking flue gas. This is primarily because steelmaking flue gas contains a certain amount of SO₂. x Water vapor and other substances can easily cause catalyst poisoning.

[0040] This application uses TiO2 as a stable support and loads CuO. x The active component, CeO2-TiO2 composite powder, serves as another active component. Under the influence of TiO2's high specific surface area and good stability, CuO... x The stability of the dual active components formed with CeO2 is significantly improved, and the water and sulfur resistance is greatly enhanced; in addition, this application introduces AgO x Together with SnO2, they can form a synergistic effect to block SO2. x The reaction between water and the active components of the catalyst inhibits catalyst poisoning, thereby significantly improving the catalyst's resistance to water and sulfur. Furthermore, the introduction of SnO2, in addition to inhibiting catalyst poisoning, also acts as a catalyst promoter within the TiO2 framework system, enhancing the catalytic activity of the dual-active components.

[0041] The following are preparation examples and embodiments of this application.

[0042] The main raw materials used in the preparation examples and embodiments of this application are all commercially available.

[0043] The following are preparation examples of this application.

[0044] Preparation Example 1

[0045] The preparation of CeO2-TiO2 composite powder in this example includes the following steps:

[0046] S3-1c: Select CeO2 powder and TiO2 powder with a particle size of 10~50nm, mix them in a ratio of 1:15 to obtain composite powder, and then add ammonia water and deionized water according to the mass ratio of composite powder: ammonia water: deionized water of 3:1:1, and mix thoroughly to prepare a slurry.

[0047] S3-2c, heat to 90~95℃ and concentrate into a paste, then extrude into a mold, dry to a moisture content of less than 2%, and then calcine. The calcination temperature is controlled at 350~400℃ and the holding time is 2h to obtain the sintered material.

[0048] S3-3c: The sintered material is crushed and ground into powder with a particle size of less than 200 mesh to obtain CeO2-TiO2 composite powder.

[0049] Preparation Example 2

[0050] The difference between this preparation example and Preparation Example 1 is that CeO2 powder and TiO2 powder are mixed in a ratio of 1:18.

[0051] Preparation Example 3

[0052] The difference between this preparation example and Preparation Example 1 is that CeO2 powder and TiO2 powder are mixed in a ratio of 1:19.

[0053] Preparation Example 4

[0054] The difference between this preparation example and Preparation Example 1 is that CeO2 powder and TiO2 powder are mixed in a ratio of 1:20.

[0055] Preparation Example 5

[0056] The difference between this preparation example and Preparation Example 1 is that CeO2 powder and TiO2 powder are mixed in a ratio of 1:25.

[0057] The following are embodiments of this application. Example 1

[0058] The preparation method of the monolithic water- and sulfur-resistant CO oxidation catalyst in this embodiment includes the following steps:

[0059] S1, based on 2.5 kg of CuO x 0.5 kg SnO2, 0.3 kg AgO x The catalyst composition consists of 40 kg of TiO2 (particle size 20-50 μm), 10 kg of CeO2-TiO2 composite powder, 2 kg of attapulgite clay, and 12 kg of chopped glass fiber; CuO is added according to the specified proportions. x Calculate the precursor dosage based on the SnO2:AgOx mass ratio, and weigh out copper acetate, stannous chloride, and silver nitrate.

[0060] S2. Select the CeO2-TiO2 composite powder from Preparation Example 1;

[0061] S3. Mix the copper acetate, stannous chloride, and silver nitrate weighed in step S1, and the CeO2-TiO2 composite powder and TiO2 weighed according to the formula in step S2. Add 1 kg of stearic acid and stir the dry powder for 10 min. Then add 3 kg of glycerol as a solvent, add water, and knead for 15 min. Then add 3 kg of silica sol and 1 kg of oxalic acid, heat to 90°C, and dehumidify to a moisture content of less than 35%. Add the formula amount of attapulgite clay and chopped glass fiber, stir thoroughly, add 2 kg of methylcellulose and 1 kg of PEO, knead for 15 min, and then age for 48 h to obtain the slurry.

[0062] S4. The slurry from step S3 is extruded and dried to a moisture content of less than 2%, and then calcined at a temperature of 550~600℃ for 4 hours to obtain an integral water-resistant and sulfur-resistant CO oxidation catalyst.

[0063] The catalyst in this embodiment was examined by electron microscopy, and the results are as follows: Figures 1-6 As shown. Based on Figure 1 It can be seen that the catalyst in this application has a highly porous honeycomb structure and a high specific surface area. Based on... Figures 2-6 As can be seen, the active component CuO in this embodiment x The distribution of CeO2 is relatively uniform, while CeO2 is more uniformly distributed in the catalyst due to the composite powder and TiO2 framework. The distribution of O element is relatively dense and uniform due to the active group and TiO2 framework. The content of Ag and Sn elements, which inhibit catalyst poisoning and play a stabilizing and promoting role of active components, is small, but the distribution is relatively uniform. Example 2

[0064] The difference between this embodiment and Embodiment 1 is that in step S1, 12 kg of CuO is used. x 5kg SnO2, 3kg AgO x The catalyst composition consisted of 50 kg of TiO2 (particle size 20~50 μm), 20 kg of CeO2-TiO2 composite powder, 10 kg of attapulgite clay, and 18 kg of chopped glass fiber. Example 3

[0065] The difference between this embodiment and Embodiment 1 is that in step S1, 7 kg of CuO is used. x 4kg SnO2, 1kg AgO xThe catalyst composition consisted of 45 kg of TiO2 (particle size 20~50 μm), 15 kg of CeO2-TiO2 composite powder, 8 kg of attapulgite clay, and 12 kg of chopped glass fiber. Example 4

[0066] The difference between this embodiment and Example 3 is that, in step S2, the CeO2-TiO2 composite powder of Preparation Example 2 is used. Example 5

[0067] The difference between this embodiment and Example 3 is that, in step S2, the CeO2-TiO2 composite powder of Example 3 is selected. Example 6

[0068] The difference between this embodiment and Example 3 is that, in step S2, the CeO2-TiO2 composite powder of Preparation Example 4 is selected. Example 7

[0069] The difference between this embodiment and Example 3 is that, in step S2, the CeO2-TiO2 composite powder of Preparation Example 5 is selected. Example 8

[0070] The difference between this embodiment and embodiment 5 is that, in step S1, TiO2 with a particle size of 10~50nm is selected.

[0071] Comparative Example 1

[0072] This application selects Example 31 of the invention patent with publication number CN116237060A and invention titled "A Wide-Temperature Sulfur-Resistant CO Oxidation Catalyst and Its Preparation Method and Application" as Comparative Example 1 of this application.

[0073] Comparative Example 2

[0074] This application selects Example 2 of the invention patent with publication number [number] and invention title [name] entitled "A Water-Resistant Non-Precious Metal Catalyst for Removing Carbon Monoxide from Sulfur and Its Preparation Method" as Comparative Example 2 of this application.

[0075] Comparative Example 3

[0076] The difference between this comparative example and Example 8 is that no attapulgite clay was added.

[0077] Comparative Example 4

[0078] The difference between this comparative example and Example 8 is that, in step S1, an equal amount of SnO2 is used to replace AgOx.

[0079] Comparative Example 5

[0080] The difference between this comparative example and Example 8 is that, in step S1, an equal amount of AgOx is used to replace SnO2.

[0081] Comparative Example 6

[0082] The difference between this comparative example and Example 8 is that, in step S2, the CeO2-TiO2 composite powder is replaced with equal amounts and proportions of CeO2 powder and TiO2 powder.

[0083] The CO catalytic effect of the products of Examples 1-8 and Comparative Examples 1-6 was tested in experiments.

[0084] Configure simulated flue gas according to the following concentration ratio: H2O (12%), SO2 (30ppm), CO (5000ppm), O2 (16%), with the remainder being nitrogen.

[0085] Catalytic beds were prepared by filling them with catalysts from Examples 1-8 and Comparative Examples 1-6, respectively, to prepare experimental catalytic beds.

[0086] The simulated flue gas volume space velocity is 10000 h⁻¹. -1 The CO removal rate was tested at initial flue gas temperatures of 140℃, 160℃, 180℃, 200℃, 220℃ and 240℃, respectively.

[0087] The results are shown in Table 1 below.

[0088] Table 1. Test results of Examples 1-8 and Comparative Examples 1-6

[0089] 140℃（%） 160℃（%） 180℃（%） 200℃（%） 220℃（%） 240℃（%） Example 1 72.4 83.3 87.6 90.2 90.8 91.6 Example 2 72.7 83.6 87.7 90.4 90.9 91.7 Example 3 73.4 84.2 88.2 91.1 91.6 92.2 Example 4 74.1 85.1 89.1 92.3 93.0 93.5 Example 5 74.9 85.9 89.5 92.6 93.2 93.8 Example 6 74.6 85.4 89.2 92.4 92.9 93.5 Example 7 73.3 84.2 88.5 91.4 91.8 92.1 Example 8 84.8 90.3 92.2 93.6 94.2 94.6 Comparative Example 1 63.4 71.2 76.9 81.8 84.5 86.6 Comparative Example 2 50.8 60.2 67.4 74.8 80.8 84.2 Comparative Example 3 76.3 83.6 87.4 90.1 91.6 92.8 Comparative Example 4 61.2 68.3 73.6 77.7 80.1 82.2 Comparative Example 5 64.9 73.8 80.2 84.4 87.9 89.4 Comparative Example 6 72.7 80.6 85.1 88.2 90.1 91.2

[0090] As can be seen from the data in Table 1, the catalysts prepared in Examples 1-8 of this application, when the flue gas contains sulfur oxides and water vapor, can achieve a CO removal rate of over 70% at temperatures below 240°C, and exhibit excellent catalytic performance at temperatures between 200 and 240°C, with a CO removal rate exceeding 90%. In contrast, the catalysts in Comparative Examples 1-6 show a significant difference compared to the catalysts of this application. Therefore, the catalysts of this application exhibit superior low-temperature catalytic performance compared to existing technologies, and their sulfur and water resistance are significantly improved.

[0091] The data in Table 1, comparing the data of Examples 1 to 8 of this application, shows that after optimizing the catalyst ratio, the catalytic effect is significantly improved, as are the water resistance and sulfur resistance. Furthermore, after optimizing the CeO2-TiO2 composite powder ratio, the performance of the catalyst can be further improved.

[0092] As can be seen from the comparison of the data in Table 1 between Example 8 of this application and Comparative Examples 4-6, the catalyst of this application, with the addition of SnO2 and AgO... x There is a clear synergistic effect, with SnO2 replacing AgO x Or with AgO x Replacing SnO2 significantly reduces the catalyst's resistance to water and sulfur. Furthermore, the catalyst in this application, by pre-loading CeO2 with TiO2 before adding it to the catalyst system, exhibits superior catalytic performance, as well as better resistance to water and sulfur. The applicant believes that pre-loading CeO2 with TiO2 can substantially improve the stability and anti-poisoning properties of the CeO2 active component in the catalyst system.

[0093] The applicant tested the durability and abrasion resistance of the combined catalysts in this application. Catalytic beds filled with the catalysts from Examples 1-8 of this application operated continuously for 30 days, exhibiting very stable catalytic performance without any decrease in catalytic efficiency or catalyst failure. Catalysts A and B from Examples 1-8 of this application were filled into a 1m diameter duct and flowed at 5000m... 2 With an airflow of / h and continuous wear for 30 days, the wear loss rate of the catalyst was less than 0.5%, while in Example 8 with added attapulgite clay, the wear loss rate was less than 0.2%. It can be seen that the honeycomb catalyst of this application has extremely excellent wear resistance.

[0094] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An integral water- and sulfur-resistant CO oxidation catalyst, characterized in that, The catalyst components are proportioned in the following mass ratios: 2.5 to 12 parts CuO. x 0.5-5 parts SnO2, 0.3-3 parts AgO x The catalyst comprises 40-50 parts TiO2, 10-20 parts CeO2-TiO2 composite powder, 2-10 parts binder, and 12-18 parts reinforcing agent; the catalyst has a honeycomb structure; the catalyst uses TiO2 as a stable support and supports CuO. x The active component, CeO2-TiO2 composite powder, serves as another active component. Under the influence of TiO2's high specific surface area and good stability, CuO... x The dual-active component is formed with CeO2; the binder is attapulgite clay.

2. The monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 1, characterized in that, In the CeO2-TiO2 composite powder, the mass ratio of CeO2 to TiO2 is 1:15~25.

3. The monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 1, characterized in that, The reinforcing agent is glass fiber.

4. A method for preparing the monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 1, characterized in that, Includes the following steps: S1. Calculate the amounts of Cu precursor, Sn precursor and Ag precursor according to the mass ratio, and weigh out Cu precursor, Sn precursor and Ag precursor. S2. Preparation of CeO2-TiO2 composite powder; S3. The Cu precursor, Sn precursor and Ag precursor weighed in step S1 are mixed with the CeO2-TiO2 composite powder prepared in step S2 and the prescribed amount of TiO2. Organic binder, pore-forming agent, stearic acid and solvent are added, and then the prescribed amount of binder and reinforcing agent are added. After mixing and aging, a slurry is prepared. S4. The slurry prepared in step S3 is extruded, dried, and then calcined to obtain an integral water-resistant and sulfur-resistant CO oxidation catalyst.

5. The preparation method of the monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 4, characterized in that, In step S1, the Cu precursor is selected from at least one of copper acetate and copper nitrate, the Sn precursor is selected from at least one of tin tetrachloride and stannous chloride, and the Ag precursor is selected from at least one of silver nitrate and silver acetate.

6. The preparation method of the monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 4, characterized in that, In step S2, the preparation of CeO2-TiO2 composite powder includes the following steps: selecting CeO2 powder and TiO2 powder with a particle size of 10~50nm, adding co-solvent and solvent, and preparing a slurry; heating to above 90℃ for concentration, then extruding and molding, drying and calcining, with the calcination temperature controlled at 350~500℃ and the holding time 2~6h; finally crushing and grinding into powder to obtain CeO2-TiO2 composite powder.

7. The preparation method of the monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 4, characterized in that, In step S3, the organic binder is selected as silica sol.

8. The preparation method of the monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 4, characterized in that, In step S3, the aging time is more than 48 hours, and the product is dried to a moisture content of less than 2%.

9. The preparation method of the monolithic water- and sulfur-resistant CO oxidation catalyst according to claim 4, characterized in that, In step S4, the calcination temperature is 550~600℃ and the holding time is more than 4 hours.

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