A multifunctional catalytic material of cobalt-manganese-aluminum supported silica aerogel, its preparation method and application

Abstract

A multifunctional catalytic material of silica-supported cobalt-manganese-aluminum aerogel, its preparation method, and its application are disclosed. The silica-supported cobalt-manganese catalyst is prepared using an ultrasonic impregnation method. Aluminum chloride, ethanol, water, and the silica-supported cobalt-manganese catalyst are dissolved by stirring, followed by the addition of 1,2-epoxypropylene, stirring, and then allowed to stand to obtain a gel. The gel is aged with ethanol, then replaced with isopropanol, and the replaced gel material is gradually dried and finally kept at a certain temperature to obtain the silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material. The catalytic material of this invention achieves organic coupling of catalytic cracking and catalytic oxidation, significantly reducing reaction energy consumption and macroscopic pyrolysis temperature through heat complementarity.

Description

Technical Field

[0001] This invention relates to the field of chemical waste salt treatment, specifically to a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material, its preparation method, and its application. Background Technology

[0002] In the rapid development of the fine chemical industry, the problem of waste salt has become increasingly prominent, becoming one of the important factors restricting the sustainable development of the industry. Waste salt, as a product of the evaporation and concentration of high-salt wastewater from the production of pesticides, dyes, and pharmaceutical intermediates, is diverse in type and complex in composition. It not only has wide 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 soil, water sources, and air through infiltration and weathering, thereby affecting ecosystems and human health. Currently, the industry has explored various methods for treating waste salt, including landfilling, 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 uses pyrolysis to convert large-molecule organic matter in waste salt into small-molecule substances and uses high temperatures to volatilize them, thereby achieving waste reduction and harmlessness. Thermal treatment has advantages such as thorough decomposition and short treatment cycle, which is of great significance for reducing the environmental risks of waste salt. However, many challenges still exist in the pyrolysis process of waste salt. On the one hand, poor gas-solid reaction contact is a key factor restricting pyrolysis efficiency. The limited contact area between waste salt and pyrolysis gases leads to poor heat and mass transfer, affecting the decomposition rate and conversion rate of organic matter. On the other hand, high pyrolysis temperatures not only increase energy consumption but may also cause secondary pollution, such as harmful gases and fly ash generated at high temperatures. Furthermore, the complexity of waste salt composition increases the uncontrollability of the pyrolysis process. How to effectively regulate the pyrolysis reaction and improve treatment efficiency and product quality is a pressing issue in the current waste salt treatment field. To address these problems, developing a highly efficient and stable catalyst is crucial for improving the pyrolysis effect of waste salt. The proposed cobalt-manganese-aluminum aerogel multifunctional catalyst supported on silica provides a new approach to waste salt treatment. This catalyst uses silica as a carrier and loads active components such as cobalt, manganese, and aluminum to form a porous aerogel material. This structure not only increases the specific surface area of ​​the catalyst and improves the gas-solid reaction contact efficiency but also facilitates heat and mass transfer, thereby promoting the rapid decomposition of organic matter. Meanwhile, the introduction of active components such as cobalt, manganese, and aluminum endows the catalyst with multiple catalytic functions, such as redox and acid-base catalysis. These functions can work synergistically to improve the selectivity and efficiency of waste salt pyrolysis. Furthermore, the aerogel material possesses good thermal stability and mechanical strength, maintaining stable catalytic performance at high temperatures and extending the catalyst's lifespan. In summary, the development of a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalyst is of great significance for solving problems such as poor gas-solid reaction contact, poor mass transfer, high pyrolysis temperature, and high energy consumption in waste salt pyrolysis. The application of this catalyst is expected to improve waste salt treatment efficiency, reduce energy consumption and secondary pollution risks, and provide strong support for the sustainable development of the fine chemical industry. Summary of the Invention

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

[0004] Technical solution: A method for preparing a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material, comprising the following steps: (1) preparing 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 stirring, drying and keeping warm to obtain silica-supported cobalt-manganese catalyst; (2) stirring and dissolving aluminum chloride, ethanol, water and silica-supported cobalt-manganese catalyst, then adding 1,2-epoxypropane, stirring and standing to obtain gel, wherein the mass ratio of 1,2-epoxypropane, aluminum chloride, ethanol, water and silica-supported cobalt-manganese catalyst is (3-9):(3-9):(3-9):(3-9):1; (3) adding ethanol to the gel for aging, then replacing it with isopropanol, gradient drying the replaced gel material, and finally keeping warm to obtain silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material.

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

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

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

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

[0009] The above method yields a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material.

[0010] The above-mentioned silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material is used in the pyrolysis removal of volatile organic compounds from waste salt at medium and low temperatures.

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

[0012] Beneficial effects: 1. The inner layer of the catalytic material of this invention consists of silica-supported metal active sites with a large specific surface area, providing a core site for catalytic oxidation. 2. The outer layer of the catalytic material of this invention is an aluminum aerogel layer with dense pores, exhibiting excellent temperature resistance and good mass and heat transfer effects. 3. The bilayer structure of the catalytic material of this invention protects the internal active metal sites, effectively shielding them from external erosion and interference. 4. The bifunctional catalyst of this invention achieves organic coupling of catalytic cracking and catalytic oxidation, significantly reducing reaction energy consumption and macroscopic pyrolysis temperature through heat complementarity. Attached Figure Description

[0013] Figure 1 This is an embodiment of the present invention and a comparative removal rate diagram.

[0014] Figure 2 This is a graph showing the waste salt pyrolysis temperature and removal rate of embodiments and comparative examples of the present invention.

[0015] Figure 3 This is the X-ray diffraction pattern of the material obtained in Example 1 of the present invention. The peak positions in the figure match the diffraction data of the Al2O3 standard card, indicating that the obtained material contains an Al2O3 aerogel layer, which protects the inner active sites and promotes the coordinated progress of oxidation and acid-base reactions. Detailed Implementation

[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% of the mass of silica, dissolved in distilled water, stirred evenly, and then 5.78 g of silica was added. The mixture was stirred overnight at room temperature. After stirring, the mixture was ultrasonicated at 40 kHz for 30 min and then transferred to an electric heating drying oven at 80 ℃ for 12 h. Finally, the mixture was kept at 500 ℃ in a muffle furnace for 5 h to obtain silica-supported cobalt-manganese catalyst, which was then ground into powder for later use.

[0018] (2) Weigh 11.35g of aluminum chloride and add 22.7g of 12-epoxypropane, 22.7g of anhydrous ethanol, 22.7g of deionized water and 3.78g of silica-supported cobalt-manganese catalyst. Stir to dissolve, then add 22.7g of 1,2-epoxypropane to the mixed solution, stir and remove the rotor to gel.

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

[0020] Example 2

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

[0022] (2) Weigh 11.35g of aluminum chloride and add 22.7g of anhydrous ethanol, 22.7g of deionized water and 3.78g of silica-supported cobalt-manganese catalyst to it. Stir to dissolve, then add 22.7g of 1,2-epoxypropane to the mixed solution. After stirring, remove the rotor to allow it to gel.

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

[0024] Example 3

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

[0026] (2) Weigh 11.35g of aluminum chloride and add 22.7g of anhydrous ethanol, 22.7g of deionized water and 3.78g of silica-supported cobalt-manganese catalyst to it. Stir to dissolve, then add 22.7g of 1,2-epoxypropane to the mixed solution. After stirring, remove the rotor to allow it to gel.

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

[0028] Comparative Example 1

[0029] A silica-supported cobalt-manganese catalyst was prepared by ultrasonic impregnation. Manganese acetate and cobalt chloride were weighed at 3% of the theoretical loading and dissolved in distilled water. After stirring evenly, 5.78 g of silica was added and stirred overnight at room temperature. After stirring, the mixture was ultrasonicated at 40 kHz for 30 min and then transferred to an electric heating drying oven at 80 °C for 12 h. Finally, it was kept at 500 °C in a muffle furnace for 5 h to obtain the silica-supported cobalt-manganese catalyst.

[0030] Comparative Example 2

[0031] A silica-supported cobalt-manganese catalyst was prepared by ultrasonic impregnation. Manganese acetate and cobalt chloride were weighed at 5% of the theoretical loading and dissolved in distilled water. After stirring evenly, 5.78 g of silica was added and stirred overnight at room temperature. After stirring, the mixture was ultrasonicated at 40 kHz for 30 min and then transferred to an electric heating drying oven at 80 °C for 12 h. Finally, it was kept at 500 °C in a muffle furnace for 5 h to obtain the silica-supported cobalt-manganese catalyst.

[0032] Separation Example:

[0033] The wastewater after pyrolysis was dissolved and filtered, the catalyst after catalytic pyrolysis was dried, and then calcined in a muffle furnace at 550°C for 5 hours.

[0034] Example and comparative performance tests:

[0035] Industrial waste salt removal tests were conducted. 7g of industrial waste salt was weighed and placed in a crucible. The catalysts from each example and comparative example were sieved through a 120-140 mesh sieve. The catalysts from each example and comparative example were then added to the waste salt and mixed uniformly. The mass ratio of waste salt to silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material was 10:0.5 to 10:4. Pyrolysis experiments were conducted at 400℃ in a tube furnace with an air flow rate of 100mL / min, 5℃ / min, and a holding time of 60min. A certain amount of the pyrolyzed waste salt was taken for TOC analysis, and the removal rate was calculated.

[0036] Industrial waste salt removal tests were conducted. 7g of industrial waste salt was weighed and placed in a crucible. The catalysts from each example and comparative example were sieved through a 120-140 mesh sieve. The catalysts from each example and comparative example were added to the waste salt and mixed evenly. The mass ratio of waste salt to silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material was 10:2. Pyrolysis experiments were conducted at 300℃, 350℃, 400℃, 450℃, and 500℃ in a tube furnace with an air flow rate of 100mL / min, 5℃ / min, and a holding time of 60min. A certain amount of the pyrolyzed waste salt was taken for TOC analysis, and the removal rate was calculated.

[0037] like Figure 1 As shown, the catalysts of the embodiments of the present invention are higher than those of the comparative examples across the entire temperature range, and the removal rate 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 catalysts of the various embodiments of the present invention have a removal rate of over 90% in the pyrolysis temperature range of 300-500℃. At a temperature of 450℃, the removal rate of the comparative example is about 85%, and at a temperature of 500℃, the removal rate of the comparative example is about 84%, all of which are much lower than the removal rates of the embodiments of the present invention. This indicates that the catalysts of the present invention can maintain good catalytic pyrolysis effect at lower temperatures.

[0039] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for preparing a silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material, characterized in that the steps include... include: (1) Preparation of silica-supported cobalt-manganese catalyst by ultrasonic impregnation: Manganese acetate and cobalt chloride were weighed according to 3wt.%-9wt.% of the mass of silica and dissolved in water, wherein the molar ratio of cobalt to manganese was 1:(0.5-3). After stirring evenly, silica was added and stirred at room temperature. After stirring, ultrasonication was performed, and after drying, the mixture was kept at 500-700℃ for 4-6 hours to obtain silica-supported cobalt-manganese catalyst; (2) Aluminum chloride, ethanol, water and silica-supported cobalt-manganese catalyst were mixed. Stir to dissolve, then add 1,2-epoxypropane, stir and let stand to obtain gel. The mass ratio of 1,2-epoxypropane, aluminum chloride, ethanol, water and silica-supported cobalt-manganese catalyst is (3-9):(3-9):(3-9):(3-9):1; (3) After adding ethanol to the gel for aging, use isopropanol to replace it, and then dry the replaced gel material in a gradient. Finally, keep it at 500-700℃ for 4-6h to obtain silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material.

2. The preparation method of the silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material according to claim 1, characterized in that, The manganese acetate and cobalt chloride are weighed out to be 5 wt.% of silicon dioxide.

3. The preparation method of the silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material according to claim 1, characterized in that, In step (1), the molar ratio of cobalt to manganese is 1:1; the ultrasonic hertz is 40 kHz; the ultrasonic time is 10-40 min; the drying temperature is 60-100℃; and the drying time is 8-16 h.

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

1.

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

6. The silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material prepared by any one of the methods described in claims 1-5.

7. The application of the silica-supported cobalt-manganese-aluminum aerogel multifunctional catalytic material of claim 6 in the pyrolysis removal of volatile organic compounds from waste salt at medium and low temperatures.

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

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