A composite molecular sieve catalyst for high-efficiency oxidation of carbon monoxide and its preparation method
By introducing Co components onto MCM-41 molecular sieves and combining them with the synergistic effect of Pt, a Pt/Co-MCM-41 composite molecular sieve catalyst was prepared, which solved the problem of easy sintering of the catalyst support and achieved the effect of efficient low-temperature oxidation of carbon monoxide.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2026-03-04
- Publication Date
- 2026-06-30
Smart Images
Figure CN122298478A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of molecular sieve preparation technology, specifically relating to a composite molecular sieve catalyst for high-efficiency carbon monoxide oxidation and its preparation method. Background Technology
[0002] Carbon monoxide (CO) is a colorless, odorless, and toxic gas. Its chemical stability allows it to persist in the environment for extended periods, making it a key pollutant requiring significant pollution control. Major sources of CO emissions include diesel vehicle exhaust and the incomplete combustion of fossil fuels. While CO emissions from diesel vehicle exhaust have decreased significantly in recent years, emissions from the incomplete combustion of fossil fuels, particularly CO produced during the sintering process in the steel industry, have become a focus of research. The volume fraction of CO in the exhaust from this process is approximately 1%. Despite advancements in combustion technology, the problem of fuel residue emissions remains unresolved and continues to impact the environment. Therefore, developing efficient CO treatment technologies is particularly urgent.
[0003] Generally, CO elimination is mainly achieved through two methods: physical and chemical methods. Physical methods primarily include pressure swing adsorption (PSA), high-temperature metal membrane separation, low-temperature polymer membrane separation, and solvent absorption; chemical methods mainly include low-temperature shift reaction, methanation, and catalytic oxidation. Among numerous CO treatment technologies, catalytic oxidation is considered one of the most promising due to its high efficiency and relatively low economic cost. Through the action of a catalyst, CO can be oxidized into harmless carbon dioxide (CO2) at relatively low temperatures, thereby effectively reducing its environmental impact. Researching and developing novel, highly efficient catalysts to improve the performance of catalytic oxidation processes is crucial for achieving CO pollution control.
[0004] The forefront of research in the field of low-temperature catalytic oxidation of CO mainly focuses on the following aspects: optimizing catalyst preparation methods, improving the performance of existing catalysts, in-depth research on the mechanism of catalyst action, and designing industrially applicable catalysts. In the research on optimizing catalyst preparation methods, many studies focus on continuously searching for new supports or modifying existing supports to improve catalytic activity. Heterogeneous reactions mostly occur under harsh conditions, often resulting in sintering between the support and the active phase, shortening the catalyst's lifespan. Therefore, catalyst supports must possess characteristics such as high mechanical strength, good stability, good thermal conductivity, and resistance to sintering under reaction conditions. Finding a novel catalyst support with excellent properties is of great significance. Common catalyst supports mainly include alumina, silica gel, activated carbon, honeycomb ceramics, metal alloys, and zeolites. Currently, there are no reports in the literature on the preparation of Pt-based carbon monoxide oxidation catalysts using modified MCM-41 as a support and their application in the CO oxidation reaction. Summary of the Invention
[0005] The purpose of this invention is to provide a highly efficient composite molecular sieve catalyst for oxidizing carbon monoxide and its preparation method. MCM-41 molecular sieve is used as the catalyst support, Pt is the active component for the catalytic reaction, and Co is the active metal site protectant. Simultaneously, the synergistic effect between Pt and Co is cleverly utilized to effectively improve the low-temperature activity of the catalyst.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for preparing a highly efficient composite molecular sieve catalyst for oxidizing carbon monoxide includes the following steps:
[0008] (1) Commercial MCM-41 molecular sieve and cobalt salt solution were placed in a polytetrafluoroethylene container and ion exchange was carried out at 40~100℃ for 2~6 h. The resulting exchange product was filtered, dried and calcined to obtain Co-MCM-41 molecular sieve.
[0009] (2) The surface of Co-MCM-41 molecular sieve is functionalized by a surface modifier, wherein the surface modifier is at least one of cetyltrimethylammonium bromide, oxalic acid, and polyvinylpyrrolidone;
[0010] (3) Platinum was loaded onto the functionalized molecular sieve, and the resulting solid product was filtered, dried and calcined to obtain the Pt / Co-MCM-41 composite molecular sieve catalyst.
[0011] In step (1), the MCM-41 molecular sieve is at least one of hydrogen-type MCM-41 molecular sieve, sodium-type MCM-41 molecular sieve, and ammonium-type MCM-41 molecular sieve.
[0012] In step (1), the cobalt salt solution is at least one of cobalt acetate solution, cobalt nitrate solution, and cobalt sulfate solution. Further, the concentration of the cobalt salt solution is 0.01~0.15 mol / L, preferably 0.01~0.07 mol / L.
[0013] In step (1), the ratio of the MCM-41 molecular sieve to the cobalt salt solution is 1 g: 10~100 mL.
[0014] In step (2), the specific steps for functionalizing the surface of Co-MCM-41 molecular sieve are as follows: Co-MCM-41 molecular sieve is ultrasonically dispersed in a water / oxalic acid mixture, then a surface modifier is added, and the mixture is stirred at 30~80℃ for 1~8 h. The resulting product is then filtered and dried.
[0015] Furthermore, the ratio of the Co-MCM-41 molecular sieve to the water / oxalic acid mixture is 1 g: 200~400 mL; the mass ratio of the Co-MCM-41 molecular sieve to the surface modifier is 1:2~3.
[0016] In step (3), the platinum is derived from at least one of ammonium chloroplatinate, potassium chloroplatinate, and chloroplatinic acid.
[0017] In step (3), the specific method for loading platinum onto the functionalized molecular sieve is as follows: add at least one of ammonium chloroplatinate, potassium chloroplatinate, and chloroplatinic acid to the functionalized molecular sieve and stir at room temperature for 10-14 h.
[0018] In step (3), the roasting temperature is 500~650℃ and the time is 2~6 h.
[0019] In step (3), the loading of platinum in the Pt / Co-MCM-41 composite molecular sieve catalyst is 0.5~2.0 wt.%.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0021] 1. The Pt / Co-MCM-41 composite molecular sieve catalyst synthesized in this invention uses MCM-41 molecular sieve as the catalyst support, Pt as the catalytically active component, and Co as the active metal site protectant. Simultaneously, it cleverly utilizes the synergistic effect between the Pt and Co components to effectively improve the low-temperature activity of the catalyst. Compared with existing technologies, it effectively slows down the sintering and agglomeration of Pt and exhibits a certain degree of water and sulfur resistance stability.
[0022] 2. The Pt / Co-MCM-41 composite molecular sieve catalyst synthesized by the method of the present invention has good thermal stability and high efficiency in low-temperature carbon monoxide oxidation activity. At around 90℃, the conversion rate of carbon monoxide reaches 100%. Attached Figure Description
[0023] Figure 1 The diagram shows the carbon monoxide oxidation activity of the products in Examples 1-4 of this invention.
[0024] Figure 2 The diagram shows the carbon monoxide oxidation activity of the products from Example 1 and Comparative Examples 1 and 2 of this invention. Detailed Implementation
[0025] Example 1
[0026] A method for preparing a highly efficient composite molecular sieve catalyst for oxidizing carbon monoxide includes the following steps:
[0027] (1) Dissolve 3 g of cobalt acetate in 200 mL of deionized water to obtain a cobalt acetate solution (0.06 mol / L), add 2 g of ammonium type MCM-41 molecular sieve, place it in a polytetrafluoroethylene beaker, exchange at 80℃ for 4 h, filter, dry and calcine the exchange product to obtain Co-MCM-41 molecular sieve.
[0028] (2) Weigh 1 g of Co-MCM-41 molecular sieve and ultrasonically disperse it into 300 mL of water / oxalic acid (v / v=1) mixture. Then add 2.8 g of polyvinylpyrrolidone and 0.15 g of cetyltrimethylammonium bromide in sequence. Stir continuously at 70°C for 1 h. Filter the resulting solid product and dry it.
[0029] (3) Add 0.02 g of chloroplatinic acid to the above-mentioned dried solid product, stir continuously at room temperature for 12 h, and finally filter, dry, and calcine at 400℃ for 4 h to obtain Pt / Co-MCM-41 composite molecular sieve catalyst.
[0030] Example 2
[0031] A method for preparing a highly efficient composite molecular sieve catalyst for oxidizing carbon monoxide includes the following steps:
[0032] (1) Dissolve 1.5 g of cobalt acetate in 200 mL of deionized water to obtain a cobalt acetate solution (0.03 mol / L). Add 2 g of ammonium type MCM-41 molecular sieve and place it in a polytetrafluoroethylene beaker. Exchange the solution at 80℃ for 4 h. Filter, dry and calcine the exchange product to obtain Co-MCM-41 molecular sieve.
[0033] (2) Weigh 1 g of Co-MCM-41 molecular sieve and ultrasonically disperse it into 350 mL of water / oxalic acid (v / v=1) mixture. Then add 1.86 g of polyvinylpyrrolidone and 0.35 g of cetyltrimethylammonium bromide in sequence. Stir continuously at 60°C for 3 h. Filter the resulting solid product and dry it.
[0034] (3) Add 0.02 g of chloroplatinic acid to the above-mentioned dried solid product, stir continuously at room temperature for 12 h, and finally filter, dry, and calcine at 400℃ for 4 h to obtain Pt / Co-MCM-41 composite molecular sieve catalyst.
[0035] Example 3
[0036] A method for preparing a highly efficient composite molecular sieve catalyst for oxidizing carbon monoxide includes the following steps:
[0037] (1) Dissolve 2.3 g of cobalt acetate in 200 mL of deionized water to obtain a cobalt acetate solution (0.04 mol / L), add 2 g of ammonium type MCM-41 molecular sieve, place in a polytetrafluoroethylene beaker, exchange at 80℃ for 4 h, filter, dry and calcine the exchange product to obtain Co-MCM-41 molecular sieve.
[0038] (2) Weigh 1 g of Co-MCM-41 molecular sieve and ultrasonically disperse it into 200 mL of water / oxalic acid (v / v=1) mixture. Then add 2.8 g of polyvinylpyrrolidone and 0.2 g of cetyltrimethylammonium bromide in sequence. Stir continuously at 50°C for 5 h. Filter the resulting solid product and dry it.
[0039] (3) Add 0.02 g of chloroplatinic acid to the above-mentioned dried solid product, stir continuously at room temperature for 12 h, and finally filter, dry, and calcine at 400℃ for 4 h to obtain Pt / Co-MCM-41 composite molecular sieve catalyst.
[0040] Example 4
[0041] A method for preparing a highly efficient composite molecular sieve catalyst for oxidizing carbon monoxide includes the following steps:
[0042] (1) Dissolve 3.7 g of cobalt acetate in 200 mL of deionized water to obtain a cobalt acetate solution (0.07 mol / L), add 2 g of ammonium type MCM-41 molecular sieve, place in a polytetrafluoroethylene beaker, exchange at 80℃ for 4 h, filter, dry and calcine the exchange product to obtain Co-MCM-41 molecular sieve.
[0043] (2) Weigh 1 g of Co-MCM-41 molecular sieve and ultrasonically disperse it into 400 mL of water / oxalic acid alcohol (v / v=1) mixture. Then add 2 g of polyvinylpyrrolidone and 0.3 g of cetyltrimethylammonium bromide in sequence. Stir continuously at 80°C for 2 h. Filter the resulting solid product and dry it.
[0044] (3) Add 0.02 g of chloroplatinic acid to the above-mentioned dried solid product, stir continuously at room temperature for 12 h, and finally filter, dry, and calcine at 400℃ for 4 h to obtain Pt / Co-MCM-41 composite molecular sieve catalyst.
[0045] Comparative Example 1
[0046] Comparative Example 1 differs from Example 1 in that no ion exchange was performed; all other steps were the same as in Example 1. Specifically:
[0047] (1) Weigh 1 g of MCM-41 molecular sieve and ultrasonically disperse it into 300 mL of water / oxalic acid (v / v=1) mixture. Then add 2.8 g of polyvinylpyrrolidone and 0.15 g of cetyltrimethylammonium bromide in sequence. Stir continuously at 70 °C for 1 h. Filter the resulting solid product and dry it.
[0048] (2) Add 0.02 g of chloroplatinic acid to the above-mentioned dried solid product, stir continuously at room temperature for 12 h, and finally filter, dry, and calcine at 400℃ for 4 h to obtain Pt / MCM-41 molecular sieve catalyst.
[0049] Comparative Example 2
[0050] Comparative Example 2, compared to Example 1, did not add chloroplatinic acid; all other steps were the same as in Example 1. Specifically:
[0051] (1) Dissolve 3 g of cobalt acetate in 200 mL of deionized water to obtain a cobalt acetate solution (0.06 mol / L), add 2 g of ammonium type MCM-41 molecular sieve, place it in a polytetrafluoroethylene beaker, exchange at 80℃ for 4 h, filter, dry and calcine the exchange product to obtain Co-MCM-41 molecular sieve.
[0052] (2) Weigh 1 g of Co-MCM-41 molecular sieve and ultrasonically disperse it into 300 mL of water / oxalic acid (v / v=1) mixture. Then add 2.8 g of polyvinylpyrrolidone and 0.15 g of cetyltrimethylammonium bromide in sequence. Stir continuously at 70 °C for 1 h. Filter the obtained solid product, dry it, and calcine it at 400 °C for 4 h to obtain Co-MCM-41 molecular sieve catalyst.
[0053] Composite catalyst performance testing
[0054] The catalysts prepared in Examples 1-4 and Comparative Examples 1-2 were tested for carbon monoxide oxidation activity in a fixed-bed reactor. The catalyst dosage was 0.2 g, the reaction mixture consisted of CO (50,000 ppm), O2 (10 vol%), and N2 as the equilibrium gas. The reaction temperature was 50-200 °C, and the reaction space velocity was 480,000 h⁻¹. -1 .
[0055] Figure 1This comparison of the carbon monoxide oxidation activities of the products in Examples 1-4 shows that the catalyst activity initially increased and then decreased with increasing cobalt acetate solution concentration during ion exchange, reaching its peak at a concentration of 0.06 mol / L (Example 1). Initially, with increasing concentration, the amount of Co ions introduced increased, strengthening the synergistic effect between Pt and Co components and effectively improving the low-temperature activity of the catalyst (Example 1 > Example 3 > Example 2). However, with further increases in the amount of Co ions introduced, the synergistic effect was somewhat suppressed (Example 4).
[0056] Figure 2 The comparison of the carbon monoxide oxidation activities of the products in Example 1 and Comparative Examples 1 and 2 shows that the synergistic effect of introducing Co ions through ion exchange with Pt significantly improves the low-temperature activity of the catalyst. This not only lowers the temperature at which carbon monoxide is completely converted but also increases its conversion rate at low temperatures. Comparative Example 2 further illustrates that without the addition of Pt, the catalyst activity is very poor; the addition of Pt significantly improves the catalyst activity, indicating that the synergistic effect between Pt and Co promotes the reaction.
Claims
1. A method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide, characterized in that, Includes the following steps: (1) MCM-41 molecular sieve and cobalt salt solution were placed in a polytetrafluoroethylene container and ion exchange was carried out at 40~100℃ for 2~6 h. The exchange product was filtered, dried and calcined to obtain Co-MCM-41 molecular sieve. (2) The surface of Co-MCM-41 molecular sieve is functionalized by a surface modifier, wherein the surface modifier is at least one of cetyltrimethylammonium bromide, oxalic acid, and polyvinylpyrrolidone; (3) Platinum was loaded onto the functionalized molecular sieve, and the resulting solid product was filtered, dried and calcined to obtain the Pt / Co-MCM-41 composite molecular sieve catalyst.
2. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 1, characterized in that, In step (1), the MCM-41 molecular sieve is at least one of hydrogen-type MCM-41 molecular sieve, sodium-type MCM-41 molecular sieve, and ammonium-type MCM-41 molecular sieve, and the cobalt salt solution is at least one of cobalt acetate solution, cobalt nitrate solution, and cobalt sulfate solution.
3. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 1, characterized in that, In step (1), the concentration of the cobalt salt solution is 0.01~0.15 mol / L, and the ratio of the MCM-41 molecular sieve to the cobalt salt solution is 1 g: 10~100 mL.
4. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 3, characterized in that, The concentration of the cobalt salt solution is 0.01~0.07 mol / L.
5. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 1, characterized in that, In step (2), the specific steps for functionalizing the surface of Co-MCM-41 molecular sieve are as follows: Co-MCM-41 molecular sieve is ultrasonically dispersed in a water / oxalic acid mixture, then a surface modifier is added, and the mixture is stirred at 30~80℃ for 1~8 h. The resulting product is then filtered and dried.
6. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 5, characterized in that, The ratio of Co-MCM-41 molecular sieve to water / oxalic acid mixture is 1 g: 200~400 mL; the mass ratio of Co-MCM-41 molecular sieve to surface modifier is 1: 2~3.
7. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 1, characterized in that, In step (3), the specific method for loading platinum onto the functionalized molecular sieve is as follows: add at least one of ammonium chloroplatinate, potassium chloroplatinate, and chloroplatinic acid to the functionalized molecular sieve and stir at room temperature for 10-14 h.
8. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 1, characterized in that, In step (3), the roasting temperature is 500~650℃ and the time is 2~6 h.
9. The method for preparing a high-efficiency composite molecular sieve catalyst for oxidizing carbon monoxide according to claim 1, characterized in that, In step (3), the loading of platinum in the Pt / Co-MCM-41 composite molecular sieve catalyst is 0.5~2.0 wt.%.
10. The Pt / Co-MCM-41 composite molecular sieve catalyst obtained by the preparation method according to any one of claims 1 to 9.