Silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material as well as preparation method and application thereof

Abstract

The invention discloses a silicon dioxide loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material as well as a preparation method and application thereof. A silicon dioxide loaded cobalt-manganese catalyst is prepared by utilizing an ultrasonic impregnation method; stirring and dissolving aluminum chloride, ethanol, water and the silicon dioxide supported cobalt-manganese catalyst, then adding 1, 2-epoxypropane, stirring and standing to obtain gel; and adding ethanol into the gel for aging, then replacing with isopropanol, carrying out gradient drying on the replaced gel material, and finally carrying out heat preservation to obtain the silicon dioxide loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material. The catalytic material bifunctional catalyst provided by the invention realizes organic coupling of catalytic cracking and catalytic oxidation, and reaction energy consumption and macroscopic pyrolysis temperature are greatly reduced through heat complementation.

Description

Technical Field

[0001] The invention relates to the field of chemical waste salt treatment, and in particular to a silicon dioxide-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material and a preparation method and application thereof. Background Art

[0002] In the rapid development of the fine chemical industry, the problem of waste salt has become increasingly prominent and has become one of the important factors restricting the sustainable development of the industry. Waste salt, as a product of evaporation and concentration of high-salt wastewater in the production process of pesticides, dyes, pharmaceutical intermediates, etc., has a wide variety of types and complex components. It not only has a wide range of sources, but also contains a large number of toxic and harmful substances, posing a serious threat to the environment. If these waste salts are not properly treated, they will not only occupy a large amount of land resources, but may also pollute the soil, water sources and air through infiltration, weathering and other channels, thereby affecting the ecosystem and human health. For the treatment of waste salt, the industry has explored a variety of methods, including landfill, salt washing, thermal treatment and oxidation. Among them, thermal treatment has attracted much attention due to its significant advantages in treatment effect. This method mainly converts macromolecular organic matter in waste salt into small molecular substances through pyrolysis process, and uses high temperature to volatilize it, thereby achieving waste reduction and harmlessness. The thermal treatment method has the advantages of thorough decomposition and short treatment cycle, which is of great significance for reducing the environmental risks of waste salt. However, there are still many challenges in the pyrolysis process of waste salt. On the one hand, poor contact between gas and solid reaction is a key factor restricting the efficiency of pyrolysis. The limited contact area between waste salt and pyrolysis gas leads to poor heat and mass transfer, which affects the decomposition rate and conversion rate of organic matter. On the other hand, the high pyrolysis temperature not only increases energy consumption, but also may cause secondary pollution, such as harmful gases and fly ash produced at high temperature. In addition, the complexity of waste salt composition also increases the uncontrollability of the pyrolysis process. How to effectively regulate the pyrolysis reaction and improve the treatment efficiency and product quality is an urgent problem to be solved in the current field of waste salt treatment. In view of the above problems, the development of an efficient and stable catalyst has become the key to improving the pyrolysis effect of waste salt. The introduction of a multifunctional catalyst of cobalt-manganese-aluminum aerogel supported by silica provides a new idea for waste salt treatment. The catalyst uses silica as a carrier and forms an aerogel material with a porous structure by loading active components such as cobalt, manganese, and aluminum. This structure not only increases the specific surface area of ​​the catalyst and improves the contact efficiency of the gas-solid reaction, but also facilitates the conduct of heat and mass transfer, thereby promoting the rapid decomposition of organic matter. At the same time, the introduction of active components such as cobalt, manganese, and aluminum gives the catalyst a variety of catalytic functions, such as redox, acid-base catalysis, etc. These functions can work synergistically to improve the selectivity and efficiency of waste salt pyrolysis. In addition, aerogel materials also have good thermal stability and mechanical strength, can maintain stable catalytic performance at high temperatures, and extend the service life of the catalyst. In summary, the research and development of silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalysts is of great significance for solving the problems of poor gas-solid contact, poor mass transfer, high pyrolysis temperature, and high energy consumption in the pyrolysis process of waste salt. The application of this catalyst is expected to improve the efficiency of waste salt treatment, reduce energy consumption and the risk of secondary pollution, and provide strong support for the sustainable development of the fine chemical industry. Summary of the invention

[0003] Technical problem to be solved: In view of the above technical problem, the present invention provides a silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material and a preparation method and application thereof.

[0004] Technical solution: A method for preparing a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material, comprising the following steps: (1) preparing a silica-supported cobalt-manganese catalyst by ultrasonic impregnation: weighing manganese acetate and cobalt chloride according to 3wt.%-9wt.% of the mass of silica and dissolving them in water, wherein the molar ratio of cobalt to manganese is 1:(0.5-3), stirring evenly, adding silica, stirring at room temperature, ultrasonicating after the stirring, drying and keeping warm to obtain a silica-supported cobalt-manganese catalyst; (2) stirring and dissolving aluminum chloride, ethanol, water and the silica-supported cobalt-manganese catalyst, then adding 1,2-propylene oxide, stirring and standing to obtain a gel, wherein the mass ratio of 1,2-propylene oxide, aluminum chloride, ethanol, water and the silica-supported cobalt-manganese catalyst is (3-9):(3-9):(3-9):(3-9):1; (3) adding ethanol to the gel for aging, replacing it with isopropanol, gradient drying the replaced gel material, and finally keeping warm to obtain a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material.

[0005] Preferably, the weighed mass of the manganese acetate and cobalt chloride is 5 wt.% of the silicon dioxide.

[0006] Preferably, in the above step (1), the molar ratio of cobalt to manganese is 1:1; the ultrasonic hertz is 40KHz, and the ultrasonic time is 10-40min; the drying temperature is 60-100°C, and the drying time is 8-16h; and the insulation time at 500-700°C is 4-6h.

[0007] Preferably, in the above step (2), the mass ratio of 1,2-propylene oxide, aluminum chloride, ethanol, water and silica-supported cobalt manganese catalyst is 3:3:6:6:1.

[0008] Preferably, in the above step (3), the aging temperature is 25-70°C, and the aging time is 24-72h; the replacement temperature is 25-60°C, and the time is 9-24h; the gradient drying temperature is 2-5 points within 50-200°C, and the drying time at each temperature point is 1-4h; and the insulation time at 500-700°C is 4-6h.

[0009] The silicon dioxide-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material prepared by the method.

[0010] The above-mentioned silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material is used for pyrolysis at medium and low temperatures to remove volatile organic matter in waste salt.

[0011] Preferably, the mass ratio of the above-mentioned waste salt and the silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material is 10:2.

[0012] Beneficial effects: 1. The inner layer of the catalytic material of the present invention is a silica-loaded metal active site with a large specific surface area, which provides a core site for catalytic oxidation. 2. The outer layer of the catalytic material of the present invention is an aluminum aerogel layer with dense pores, excellent temperature resistance and good mass transfer and heat transfer effects. 3. The double-layer structure of the catalytic material of the present invention protects the internal active metal sites and effectively shields the external erosion and interference of the active metal sites. 4. The bifunctional catalyst of the catalytic material of the present invention realizes the organic coupling of catalytic cracking and catalytic oxidation, and greatly reduces the reaction energy consumption and macroscopic pyrolysis temperature through heat complementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a removal rate diagram of the embodiments of the present invention and the comparative example.

[0014] Figure 2 It is a graph of the removal rate of waste salt pyrolysis temperature in the embodiments of the present invention and the comparative example.

[0015] Figure 3 This is the X-ray diffraction diagram of the material obtained in Example 1 of the present invention. The peak position in the figure is consistent with Al 2 O 3 The diffraction data of the standard card is consistent, indicating that the obtained material contains Al 2 O 3 The aerogel layer protects the active sites in the inner layer and promotes the coordinated oxidation and acid-base reactions. DETAILED DESCRIPTION

[0016] Example 1

[0017] (1) Preparation of silica-supported cobalt-manganese catalyst by ultrasonic impregnation method: 0.0879 g of manganese acetate and 0.085 g of cobalt chloride were weighed according to 3% by mass of silica, dissolved in distilled water, stirred evenly, and then 5.78 g of silica was added thereto. The mixture was stirred at room temperature overnight. After stirring, ultrasonic treatment was performed at 40 kHz for 30 min, and the mixture was transferred to an electric heated forced air drying oven and dried at 80° C. for 12 h. Finally, the mixture was kept warm in a muffle furnace at 500° C. for 5 h to obtain a silica-supported cobalt-manganese catalyst, which was ground into powder for later use.

[0018] (2) Weigh 11.35 g of aluminum chloride and add 22.7 g of 1,2-propylene oxide, 22.7 g of anhydrous ethanol, 22.7 g of deionized water and 3.78 g of silica-supported cobalt manganese catalyst thereto, stir to dissolve, then add 22.7 g of 1,2-propylene oxide to the mixed solution, stir and remove the rotor to wait for gelation.

[0019] (3) After adding anhydrous ethanol to the gel for aging for 24 hours, it was replaced with isopropanol twice, the first replacement was 3 hours, and the second replacement was 6 hours. The replaced gel material was placed in an electric heated forced air drying oven for gradient drying at 60°C, 80°C, 100°C, 120°C, and 150°C, and finally placed in a muffle furnace at 550°C for 5 hours to obtain a silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalyst.

[0020] Example 2

[0021] (1) A silica-supported cobalt-manganese catalyst was prepared by ultrasonic impregnation method. 0.1466 g of manganese acetate and 0.1423 g of cobalt chloride were weighed according to 5% by mass of silica, dissolved in distilled water, stirred evenly, and 5.78 g of silica was added thereto. The mixture was stirred at room temperature overnight. After stirring, ultrasonic treatment was performed at 40 kHz for 30 min, and the mixture was transferred to an electric heated blast drying oven and dried at 80° C. for 12 h. Finally, the mixture was kept warm in a muffle furnace at 500° C. for 5 h to obtain a silica-supported cobalt-manganese catalyst, which was ground into powder for later use.

[0022] (2) Weigh 11.35 g of aluminum chloride and add 22.7 g of anhydrous ethanol, 22.7 g of deionized water and 3.78 g of silica-supported cobalt manganese catalyst thereto, stir to dissolve, then add 22.7 g of 1,2-propylene oxide to the mixed solution, stir and remove the rotor to wait for gelation.

[0023] (3) After adding anhydrous ethanol to the gel for aging for 24 hours, it was replaced with isopropanol twice, the first replacement was 3 hours, and the second replacement was 6 hours. The replaced gel material was placed in an electric heated forced air drying oven for gradient drying at 60°C, 80°C, 100°C, 120°C, and 150°C, and finally placed in a muffle furnace at 550°C for 5 hours to obtain a silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalyst.

[0024] Example 3

[0025] (1) A silica-supported cobalt-manganese catalyst was prepared by ultrasonic impregnation method. 0.2052 g of manganese acetate and 0.1993 g of cobalt chloride were weighed according to 7% by mass of silica, dissolved in distilled water, stirred evenly, and then 5.78 g of silica was added thereto. The mixture was stirred at room temperature overnight. After stirring, ultrasonic treatment was performed at 40 kHz for 30 min, and the mixture was transferred to an electric heated blast drying oven and dried at 80° C. for 12 h. Finally, the mixture was kept warm in a muffle furnace at 500° C. for 5 h to obtain a silica-supported cobalt-manganese catalyst, which was ground into powder for later use.

[0026] (2) Weigh 11.35 g of aluminum chloride and add 22.7 g of anhydrous ethanol, 22.7 g of deionized water and 3.78 g of silica-supported cobalt manganese catalyst thereto, stir to dissolve, then add 22.7 g of 1,2-propylene oxide to the mixed solution, stir and remove the rotor to wait for gelation.

[0027] (3) After adding anhydrous ethanol to the gel for aging for 24 hours, it was replaced with isopropanol twice, the first replacement was 3 hours, and the second replacement was 6 hours. The replaced gel material was placed in an electric heated forced air drying oven for gradient drying at 60°C, 80°C, 100°C, 120°C, and 150°C, and finally placed in a muffle furnace at 550°C for 5 hours to obtain a silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalyst.

[0028] Comparative Example 1

[0029] The silica-supported cobalt-manganese catalyst was prepared by ultrasonic impregnation method. Manganese acetate and cobalt chloride were weighed and dissolved in distilled water according to the theoretical loading of 3%. After stirring, 5.78g silica was added and stirred at room temperature overnight. After stirring, 40KHz ultrasonic was applied for 30min, and the catalyst was transferred to an electric heating blast drying oven at 80℃ for 12h, and finally kept warm in a muffle furnace at 500℃ for 5h to obtain the silica-supported cobalt-manganese catalyst.

[0030] Comparative Example 2

[0031] The silica-supported cobalt-manganese catalyst was prepared by ultrasonic impregnation method. Manganese acetate and cobalt chloride were weighed according to the theoretical loading amount of 5% and dissolved in distilled water. After stirring evenly, 5.78g of silica was added thereto and stirred at room temperature overnight. After stirring, ultrasound was applied at 40KHz for 30min, and the catalyst was transferred to an electric blast drying oven and dried at 80°C for 12h. Finally, the catalyst was kept warm in a muffle furnace at 500°C for 5h to obtain the silica-supported cobalt-manganese catalyst.

[0032] Separation Example:

[0033] The waste water solution after pyrolysis is filtered, the catalyst after catalytic pyrolysis is dried, and placed in a muffle furnace for high-temperature calcination at 550°C for 5 hours.

[0034] Embodiment and comparative example performance test:

[0035] Conduct a test on the removal of industrial waste salt. Weigh 7g of industrial waste salt and place it in a crucible. Sieve the catalysts of each embodiment and comparative example through a 120-140 mesh, add the catalysts of each embodiment and comparative example to the waste salt and mix them evenly, wherein the mass ratio of waste salt to silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material is 10:0.5-10:4, and perform a pyrolysis experiment at 400°C in a tubular furnace with an air flow rate of 100mL / min, 5°C / min, and a heat preservation time of 60min. Take a certain amount of pyrolyzed waste salt for TOC detection, and calculate the removal rate.

[0036] Conduct a test on the removal of industrial waste salt. Weigh 7g of industrial waste salt and place it in a crucible. Sieve the catalysts of each embodiment and comparative example through a 120-140 mesh. Add the catalysts of each embodiment and comparative example to the waste salt and mix them evenly. The mass ratio of waste salt to silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material is 10:2. Pyrolysis experiments are performed at 300°C, 350°C, 400°C, 450°C, and 500°C in a tubular furnace with an air flow rate of 100mL / min, 5°C / min, and a heat preservation time of 60min. Take a certain amount of pyrolyzed waste salt for TOC detection and calculate the removal rate.

[0037] like Figure 1 As shown, the catalysts of the embodiments of the present invention are higher than those of the comparative examples in the entire temperature range, and the removal efficiency reaches more than 90% at a ratio of 10:1, while the comparative examples are all below 90%. The removal efficiency of the catalysts of the embodiments of the present invention is significantly higher than that of the comparative examples.

[0038] like Figure 2 As shown, the removal rates of the catalysts of various embodiments of the present invention in the pyrolysis temperature range of 300-500°C are all above 90%. When the temperature is 450°C, the removal rate of the comparative example is about 85%. When the temperature is 500°C, the removal rate of the comparative example is about 84%, which are much lower than the removal rates of the embodiments of the present invention, indicating that the catalysts of the present invention can maintain good catalytic pyrolysis effects at relatively low temperatures.

[0039] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. For ordinary technicians in this technical field, after knowing the contents recorded in the present invention, they can make several equivalent changes and substitutions without departing from the principle of the present invention. These equivalent changes and substitutions should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing a multifunctional catalytic material of cobalt-manganese-aluminum aerogel supported by silica, characterized in that the steps include: (1) A silica-supported cobalt-manganese catalyst is prepared by ultrasonic impregnation method: manganese acetate and cobalt chloride are weighed and dissolved in water according to 3wt.%-9wt.% of the mass of silica, wherein the molar ratio of cobalt to manganese is 1:(0.5-3), and after stirring evenly, silica is added, and stirred at room temperature. After stirring, ultrasonic treatment is performed, and the silica-supported cobalt-manganese catalyst is kept warm after drying. (2) Aluminum chloride, ethanol, water and the silica-supported cobalt-manganese catalyst are stirred and dissolved, and then 1,2-propylene oxide is added, and the mixture is stirred and allowed to stand to obtain a gel, wherein the mass ratio of 1,2-propylene oxide, aluminum chloride, ethanol, water and the silica-supported cobalt-manganese catalyst is (3-9):(3-9):(3-9):(3-9):

1. (3) After aging the gel by adding ethanol, the gel material is replaced by isopropanol, and the replaced gel material is gradient dried. Finally, the gel material is kept warm to obtain a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material.

2. The method for preparing the multifunctional catalytic material of silica-supported cobalt-manganese-aluminum aerogel according to claim 1, characterized in that: The weighed mass of the manganese acetate and cobalt chloride is 5 wt.% of the silicon dioxide.

3. The method for preparing the multifunctional catalytic material of silica-supported cobalt-manganese-aluminum aerogel according to claim 1, characterized in that: In the step (1), the molar ratio of cobalt to manganese is 1:1; the ultrasonic hertz is 40 KHz, and the ultrasonic time is 10-40 minutes; the drying temperature is 60-100°C, and the drying time is 8-16 hours; and the insulation time at 500-700°C is 4-6 hours.

4. The method for preparing the multifunctional catalytic material of silica-supported cobalt-manganese-aluminum aerogel according to claim 1, characterized in that: In the step (2), the mass ratio of 1,2-propylene oxide, aluminum chloride, ethanol, water and silica-supported cobalt manganese catalyst is 3:3:6:6:

1.

5. The method for preparing the multifunctional catalytic material of silica-supported cobalt-manganese-aluminum aerogel according to claim 1, characterized in that: In the step (3), the aging temperature is 25-70°C and the aging time is 24-72h; the replacement temperature is 25-60°C and the time is 9-24h; the gradient drying temperature is 2-5 points within 50-200°C, and the drying time at each temperature point is 1-4h; and the insulation time at 500-700°C is 4-6h.

6. A multifunctional catalytic material of cobalt manganese aluminum aerogel supported on silica obtained by the method according to any one of claims 1 to 5.

7. Use of the silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material according to claim 6 in removing volatile organic compounds from waste salt by pyrolysis at medium and low temperatures.

8. The use according to claim 7, characterized in that: The mass ratio of the waste salt to the silica-loaded cobalt-manganese-aluminum aerogel multifunctional catalytic material is 10:2.

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