Application of cobalt modified spherical cerium oxide catalyst in catalytic decomposition of methyl mercaptan
The catalytic decomposition of methylmercaptan in a fixed bed reactor by cobalt-modified spherical cerium oxide catalyst is solved, and the thermal stability and energy consumption of pure cerium dioxide catalytic decomposition of methylmercaptan at high temperature is achieved, and the low The 100% conversion rate and low-cost catalytic decomposition effect at temperature have good low-temperature activity and environmental protection significance.
Patent Information
- Application Number
- CN202411537714.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-01-07
AI Technical Summary
Pure ceria has poor thermal stability when catalyzed decomposition of methylmercaptan, requires high temperature operation, and has high energy consumption, making it difficult to achieve complete conversion at lower temperatures.
Using a cobalt-modified spherical cerium oxide catalyst, the cobalt-modified spherical cerium oxide catalyst is prepared by dissolving the cerium salt and the cobalt salt in a mixed solution of glacial acetic acid-ethylene glycol, and then pulverizing and filling it in a fixed bed reactor. Catalytic decomposition of methanethiol at 50-400°C.
The catalytic decomposition of methylmercaptan at 225°C is achieved with low temperature activity and low cost, which simplifies the preparation process, reduces energy consumption and has a positive impact on the environment.
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Figure CN119259061A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to use of a cobalt-modified spherical cerium oxide catalyst in catalytic decomposition of methyl mercaptan, and belongs to the technical field of malodorous organic sulfur pollutant treatment. Background Art
[0002] Sulfur-containing volatile organic compounds (S-VOCs) are typical malodorous gases and are considered to be one of the important potential precursor pollutants for the formation of photochemical smog and urban smog. Among them, methyl mercaptan, as a representative S-VOCs, mainly comes from industrial production, sewage treatment and sanitary landfills, etc., and has the characteristics of low olfactory threshold, high toxicity and corrosiveness. Even if the concentration of CH3SH in the environment is very low, it will pose a threat to the human body and the environment. At present, methods for removing methyl mercaptan have been widely used, including adsorption, catalytic decomposition, catalytic oxidation, biological treatment, photocatalytic degradation, etc. Compared with other technologies, catalytic decomposition has high efficiency, produces less waste, and does not require additional additives (eg. O2, H2), and is considered to be one of the most effective ways to remove methyl mercaptan. In recent years, the catalysts for catalytic decomposition of methyl mercaptan mainly include metal elements, metal oxides, zeolite molecular sieves and loaded molecular sieves.
[0003] According to previous studies, transition metal oxide catalysts have attracted widespread attention due to their high activity, low cost and diverse morphologies. Among them, cerium oxide (CeO2) has been widely used in many fields such as propane oxidative dehydrogenation (ODHP), heterogeneous catalytic ozonation, fuel cells, oxygen sensors, etc. Therefore, its application in the field of catalytic decomposition of methyl mercaptan deserves further exploration. However, pure cerium dioxide has poor thermal stability and will sinter at high temperatures, thereby losing its critical oxygen storage / release capacity (OSC), and catalytic decomposition has the disadvantage of high energy consumption. It is necessary to further reduce its operating temperature so that it can achieve complete conversion of methyl mercaptan at a lower temperature. In order to improve the reaction performance of CeO2 carriers, researchers have tried to achieve this goal by doping with other metals. Summary of the invention
[0004] The invention provides a new use of a cobalt-modified spherical cerium oxide catalyst, namely, use of the catalyst in low-temperature catalytic decomposition of methyl mercaptan.
[0005] The cobalt-modified spherical cerium oxide catalyst is prepared by dissolving cerium salt and cobalt salt in deionized water respectively, then dripping the cerium salt solution and the cobalt salt solution into a mixed solution of glacial acetic acid-ethylene glycol in sequence, transferring the mixed solution to a Teflon reactor lining, treating the mixture at 150-200° C. for 200 minutes, cooling the mixture to room temperature, separating the solid from the liquid, washing the solid with deionized water and anhydrous ethanol, and drying and calcining the solid, wherein the molar ratio of Co to Ce is 3:2, and the mixed solution of glacial acetic acid-ethylene glycol is prepared by mixing 1-3 mL of glacial acetic acid and 50-55 mL of ethylene glycol.
[0006] The cobalt-modified spherical cerium oxide catalyst of the present invention is used for catalytic decomposition of methyl mercaptan. Specifically, the gas to be treated containing methyl mercaptan is introduced into a fixed bed reactor, the cobalt-modified spherical cerium oxide catalyst is crushed and screened, and then loaded into the reactor, and methyl mercaptan is catalytically decomposed at normal pressure and a reaction temperature of 50-400° C. The results show that at 225° C., the cobalt-modified spherical cerium oxide catalyst can catalytically decompose methyl mercaptan by 100%.
[0007] The beneficial effects of the present invention are as follows: The preparation method of the cobalt-modified spherical cerium oxide catalyst of the present invention is simple, low in cost and short in preparation time; The cobalt-modified spherical cerium oxide catalyst of the present invention has excellent low-temperature activity, can completely catalyze the decomposition of methyl mercaptan at a relatively low temperature (225°C), has good low-temperature activity, and is of great significance for improving the adverse effects of methyl mercaptan on the environment. Therefore, the present invention has certain application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Figure 1 The catalytic activity comparison diagram of catalysts prepared by different methods; Figure 2 This is a low-temperature activity test diagram of the cobalt-modified spherical cerium oxide catalyst in Example 1. DETAILED DESCRIPTION
[0009] The present invention is further described in detail below by way of examples, but the protection scope of the present invention is limited to the contents described above. The methods in the implementation are conventional methods unless otherwise specified, and the reagents are conventional reagents or reagents prepared according to conventional methods unless otherwise specified; Example 1: Preparation and application of cobalt-modified spherical cerium oxide catalyst 1. Weigh 2 g of Ce(NO3)3·6H2O and dissolve it in 2 mL of deionized water to obtain a cerium nitrate solution. Then, according to the Co:Ce molar ratio of 6:4, add 4.78 g of Co(NO3)2·6H2O to 2 mL of deionized water to obtain a cobalt nitrate solution. 2. Add 2 mL of glacial acetic acid to 52 mL of ethylene glycol, stir and mix to obtain a glacial acetic acid-ethylene glycol mixture, and then dropwise add the cerium nitrate solution and the cobalt nitrate solution prepared in step (1) into the glacial acetic acid-ethylene glycol mixture, and continue stirring for 30 min. 3. The mixed solution was transferred to a Teflon reactor liner and placed in a 180°C oven for heating for 200 min. After cooling to room temperature, the reactor liner was removed and centrifuged to obtain a precipitate. The precipitate was washed with deionized water and anhydrous ethanol for 3 times each, and dried in a 60°C oven for 12 h. The dried powder was then placed in a crucible, transferred to a muffle furnace, and calcined at 500°C in air for 2 h (heating rate of 5°C / min) to obtain a cobalt-modified spherical cerium oxide catalyst. At the same time, the catalysts of Comparative Examples 1-6 were prepared as controls, wherein the steps for preparing the catalysts of Comparative Examples 1-6 were the same as those described above, and the difference between Comparative Example 1 and Comparative Example 2 was that the amount of cobalt nitrate added in step 1 was 2.12 g and 1.81 g; the difference between Comparative Example 3 was that no cobalt nitrate solution was prepared in step 1-2, and a CeO2-S catalyst was prepared; the difference between Comparative Examples 4, 5 and 6 was that cobalt nitrate was replaced with lanthanum nitrate in step 1, and the addition amounts were 0.50 g, 1.34 g and 3.01 g, respectively; 4. The catalyst prepared by the above method is used in catalytic degradation of methyl mercaptan The gas to be treated containing 5000 ppm of methyl mercaptan is introduced into a fixed bed reactor, the catalyst is crushed and sieved to 40-60 mesh, 200 mg is taken and loaded into the reactor, and a catalytic degradation reaction is carried out at normal pressure and 250-450°C; The results are as follows Figure 1 As shown, the conversion rate of methyl mercaptan by the catalyst of Example 1 at 250° C. reaches 100%, and the temperature for catalytic decomposition of methyl mercaptan is significantly lower than that of the catalysts prepared in Comparative Examples 1-6; 5. Experiment on catalytic decomposition of methyl mercaptan by the catalyst of Example 1 at 50-250°C, using the same method as step 4; Results Figure 2 In Example 1, the activity of the cobalt-modified spherical cerium oxide catalyst gradually increases with the increase of temperature. When the temperature reaches 225°C, the conversion rate of methyl mercaptan reaches 100%.
Claims
1. Application of a cobalt-modified spherical cerium oxide catalyst in catalytic decomposition of methyl mercaptan; The cobalt-modified spherical cerium oxide catalyst is prepared by dropping a cerium salt solution and a cobalt salt solution into a mixture of glacial acetic acid and ethylene glycol in sequence under stirring, treating at 150-200° C. for 200 minutes, separating the solid from the liquid, washing the solid with deionized water and anhydrous ethanol, and drying and calcining.
2. The use according to claim 1, characterized in that: The molar ratio of Co to Ce is 3:
2.
3. The use according to claim 1, characterized in that: The glacial acetic acid-ethylene glycol mixed solution is prepared by mixing 1-3 mL of glacial acetic acid and 50-55 mL of ethylene glycol.
4. The use according to claim 1, characterized in that: Complete catalytic decomposition of methyl mercaptan at 225-250°C.