Preparation of manganese-cobalt spinel catalyst and its application in catalyzing ozonation of volatile organic compounds at room temperature

Abstract

The application discloses a manganese-cobalt spinel catalyst preparation and application in catalytic ozonation VOCs, belonging to the field of material technology. The application comprises the following steps: manganese salt and cobalt salt are added into water and ultrasonically dissolved, a honeycomb ceramic substrate is grown in the obtained solution, the treated honeycomb ceramic substrate is taken out after the solution becomes light purple; the dipping is repeated for three times; the honeycomb ceramic substrate after the dipping treatment is dried and calcined; the honeycomb ceramic substrate after the calcination is soaked in an acetic acid solution, then the excess solution in the pore is blown away, then the honeycomb ceramic substrate is dipped in a lanthanum salt solution, the excess solution in the pore is blown away after the honeycomb ceramic substrate is taken out, the honeycomb ceramic substrate is dried, and the honeycomb ceramic substrate is calcined again after being heated, so that the manganese-cobalt spinel catalyst is obtained. The manganese-cobalt spinel catalyst prepared by the method has 100% catalytic decomposition activity on toluene, methanol and propylene at room temperature, and has 100% catalytic decomposition activity on ethyl acetate at 53 DEG C. Further simulation of the real environment test results show that the catalytic ozonation decomposition efficiency of the manganese-cobalt spinel catalyst on toluene, xylene and ethyl acetate reaches 100% at room temperature.

Description

Technical Field

[0001] The present invention belongs to the field of material technology, and in particular relates to the preparation of a manganese-cobalt spinel catalyst and its application in the catalytic ozonation of VOCs at room temperature. Background Art

[0002] Volatile organic compounds (VOCs) are primarily emitted from stationary and mobile sources. Stationary sources primarily include industrial emissions from coal-fired power plants and chemical plants, while mobile sources primarily consist of motor vehicle exhaust. Volatile organic compound emissions are a major contributor to air pollution, posing a threat to both human health and the ecological environment. Therefore, finding an effective method for removing VOCs is crucial. Currently, one of the mainstream methods used to remove VOCs is catalytic combustion, which can effectively remove VOCs at high temperatures (500-800°C). However, this method consumes relatively high amounts of energy and is not economical for industrial use. Catalytic ozonation is a novel room-temperature process that decomposes ozone on the catalyst surface into reactive oxygen species with higher oxidizing power, effectively degrading pollutants. With the assistance of a suitable catalyst, ozone can decompose at room temperature and pressure to produce reactive oxygen free radicals, significantly reducing the operating costs and safety risks of industrial VOC waste gas treatment. It also offers three key advantages: high room-temperature activity, high stability, and economic feasibility. However, the development of existing catalysts, especially industrial environmental protection catalysts, is still mainly centered around catalytic oxidation technology. There is currently little research on industrial catalysts for room temperature catalytic ozonation technology, and there is basically no industrial application. This is mainly due to the poor activity of single metal oxides in room temperature catalytic ozonation catalysts, which cannot meet the actual industrial application requirements. Summary of the Invention

[0003] Based on this, the present invention proposes a manganese-cobalt spinel catalyst for preparation and application in the room-temperature catalytic ozonation of VOCs. This invention addresses the problem of insufficient active sites for ozonation using single metal oxide catalysts in existing technologies. By innovatively utilizing in-situ impregnation hydrothermal growth technology, a bimetallic oxide manganese-cobalt spinel monolithic catalyst was developed to meet practical industrial needs.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preparing a manganese-cobalt spinel catalyst comprises the following steps:

[0006] 1) adding manganese salt and cobalt salt to water and dissolving them by ultrasonication, immersing the honeycomb ceramic substrate in the resulting solution, and removing the treated honeycomb ceramic substrate after the solution turns light purple; repeating the immersion three times;

[0007] 2) drying and calcining the honeycomb ceramic substrate after the impregnation treatment;

[0008] 3) The calcined honeycomb ceramic substrate is immersed in an acetic acid solution, and then the excess solution in the pores is blown away, and then immersed in a lanthanum salt solution. After being taken out, the excess solution in the pores is further blown away, and the substrate is dried and calcined again to obtain a manganese cobalt spinel catalyst.

[0009] Furthermore, in step 1), the parameters of the immersion are: temperature 85-95° C., time 4-4.5 hours.

[0010] Furthermore, in step 1), the molar ratio of the manganese salt to the cobalt salt is 7:10.

[0011] Furthermore, the manganese salt is potassium permanganate, the cobalt salt is cobalt nitrate hexahydrate, and the lanthanum salt is lanthanum nitrate hexahydrate.

[0012] Further, in step 2) and step 3),

[0013] The drying parameters are: temperature 150°C, time 6 hours; and / or

[0014] The calcination parameters are: temperature 500° C., time 2.5 hours, and heating rate 10° C. / min.

[0015] Further, in step 3),

[0016] The concentration of the acetic acid solution is 0.1-0.2 mol / L; and / or

[0017] The soaking parameters are: time 1-2 hours; and / or

[0018] The concentration of the lanthanum salt solution is 0.15-0.2 mol / L; and / or

[0019] The parameters of the dipping are: time 10-20 minutes.

[0020] The present invention also provides a manganese-cobalt spinel catalyst prepared by the above preparation method.

[0021] The present invention also provides a use of the manganese-cobalt spinel catalyst in catalytic ozonation of VOCs.

[0022] Catalytic ozonation technology is a novel process that decomposes ozone into reactive oxygen species with higher oxidizing power on a catalyst surface, effectively degrading pollutants. With the help of the catalyst prepared in this invention, ozone can be decomposed to produce reactive oxygen free radicals at room temperature and pressure, significantly reducing the operating costs and safety risks of VOCs waste gas treatment equipment. It offers the advantages of low-temperature, high activity, and economic feasibility.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects:

[0024] The present invention efficiently synthesizes a manganese-cobalt spinel catalyst through a simple in-situ impregnation hydrothermal growth-high-temperature calcination method. The method is simple and efficient and can be applied to industrial large-scale batch preparation of catalysts in the future.

[0025] Under catalytic ozonation conditions, the manganese-cobalt spinel catalyst prepared by the method of the present invention has 100% catalytic decomposition activity for toluene, methanol, and propylene at room temperature, and 100% catalytic decomposition activity for ethyl acetate at 53°C. In addition, the catalyst also has a high removal rate for ozone at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 This is a picture and a scanning electron microscope image of the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention;

[0028] Figure 2 This is the XRD pattern of the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention;

[0029] Figure 3 This is the room temperature catalytic ozonation activity curve of toluene prepared in Example 1 of the present invention;

[0030] Figure 4 The activity curves of the manganese-cobalt spinel monolithic catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention for catalytic ozonation and decomposition of toluene at room temperature are shown;

[0031] Figure 5 The activity curves of the manganese-cobalt spinel monolithic catalysts prepared in Example 1, Comparative Example 3, and Comparative Example 4 of the present invention for the catalytic ozonation decomposition of toluene at room temperature are shown;

[0032] Figure 6 This is the room temperature catalytic ozonolysis activity curve of methanol by the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention;

[0033] Figure 7 This is the room temperature catalytic ozonolysis activity curve of propylene using the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention;

[0034] Figure 8 This is the activity curve of the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention for catalytic ozonation and decomposition of ethyl acetate;

[0035] Figure 9This is the activity curve of the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention for catalytic ozonation and decomposition of methane;

[0036] Figure 10 This is the activity curve of the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention for catalytic ozonation decomposition of mixed gases;

[0037] Figure 11 This is the decomposition activity curve of the manganese-cobalt spinel monolithic catalyst prepared in Example 1 of the present invention to ozone at room temperature and different humidity;

[0038] Figure 12 This is the activity curve of the catalyst of Comparative Example 5 of the present invention for catalytic ozonation decomposition of toluene at room temperature. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0041] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0042] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0043] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0044] The application provides a preparation method of a manganese-cobalt spinel catalyst, which comprises the following steps:

[0045] 1) soluble manganese salt and soluble cobalt salt are added into water and ultrasonically dissolved, and then the water tank with honeycomb ceramic substrate is placed in constant temperature stirring, after the solution becomes light purple, the treated honeycomb ceramic substrate is taken out; the immersion is repeated for three times, so as to realize the purpose of multiple in-situ hydrothermal growth under constant temperature reaction condition;

[0046] 2) the honeycomb ceramic substrate after multiple in-situ hydrothermal growth is dried, and then is placed in a high temperature calcination furnace;

[0047] 3) the calcined honeycomb ceramic substrate is immersed in acetic acid solution, then the excess solution in the pore is blown away, and then the substrate is immersed in soluble lanthanum salt solution, the excess solution in the pore is blown away, and then the substrate is dried and calcined again, so as to obtain the manganese-cobalt spinel catalyst.

[0048] In the following preferred embodiment of the application, the repeated immersion refers to that the manganese salt and the cobalt salt are added into water and ultrasonically dissolved to prepare a solution, and then the honeycomb ceramic substrate after the previous immersion treatment is placed in the new solution for new immersion treatment. Specifically,

[0049] The manganese salt and the cobalt salt are added into water and ultrasonically dissolved, and the honeycomb ceramic substrate is immersed in the obtained solution, after the solution becomes light purple, the honeycomb ceramic substrate after the first treatment is taken out;

[0050] The manganese salt and the cobalt salt are added into water and ultrasonically dissolved, and the honeycomb ceramic substrate after the first treatment is immersed in the obtained solution, after the solution becomes light purple, the honeycomb ceramic substrate after the second treatment is taken out;

[0051] The manganese salt and the cobalt salt are added into water and ultrasonically dissolved, and the honeycomb ceramic substrate after the second treatment is immersed in the obtained solution, after the solution becomes light purple, the honeycomb ceramic substrate after the third treatment is taken out.

[0052] During the three times, the preparation mode and the amount of the manganese salt and the cobalt salt are the same.

[0053] The reason why the solution becomes light purple is that the potassium permanganate aqueous solution is purple, the cobalt nitrate aqueous solution is pink, and the solution obtained after the two are mixed and ultrasonically dissolved in water is purple red. After the honeycomb ceramic carrier is immersed in the purple red solution for reaction, the concentration of free cobalt ions in the solution is reduced due to the reduction of potassium permanganate and the interaction between cobalt ions and the substrate material, so that the color of the solution becomes light, that is, the immersion process will consume potassium permanganate and cobalt nitrate, so the color of the solution will become light.

[0054] In a preferred embodiment of the present application, in step 1), the parameters of the three immersions are as follows: temperature 85-95℃, time 4-4.5 hours. For example, in the following embodiments of the present application, the effect is verified by taking the immersion temperature of 86℃ and the immersion time of 4.5 hours.

[0055] In a preferred embodiment of the present application, in step 1), the molar ratio of the manganese salt and the cobalt salt is 7:10.

[0056] In a preferred embodiment of the present application, the manganese salt, the cobalt salt and the lanthanum salt are all hydrates, such as potassium permanganate hydrate, cobalt nitrate hydrate, and lanthanum nitrate hydrate. For example, in the following embodiments of the present application, the effect is verified by taking potassium permanganate, cobalt nitrate hexahydrate, and lanthanum nitrate hexahydrate.

[0057] In a preferred embodiment of the present application, in steps 2) and 3),

[0058] The parameters of the drying are as follows: temperature 150℃, time 6 hours;

[0059] The parameters of the calcination are as follows: temperature 500℃, time 2.5 hours, and heating rate 10℃ / min.

[0060] In a preferred embodiment of the present application, in step 3),

[0061] The concentration of the acetic acid solution is 0.1-0.2mol / L. For example, in the following embodiments of the present application, the effect is verified by taking the concentration of the acetic acid solution of 0.1mol / L.

[0062] The parameters of the soaking are as follows: time 1-2 hours. For example, in the following embodiments of the present application, the effect is verified by taking the soaking time of 1 hour;

[0063] The concentration of the lanthanum salt solution is 0.15-0.2mol / L. For example, in the following embodiments of the present application, the effect is verified by taking the concentration of the lanthanum salt solution of 0.15mol / L.

[0064] The parameters of the immersion are as follows: time 10-20 minutes. For example, in the following embodiments of the present application, the effect is verified by taking the soaking time of 10 minutes.

[0065] The manganese-cobalt spinel catalyst is prepared by the above preparation method.

[0066] The manganese-cobalt spinel catalyst is applied in catalyzing the ozone oxidation of VOCs, which include toluene, methanol, propylene, ethyl acetate, methane, ozone and mixed gas. In the application, the test conditions are as follows: the flow rate of test gas is 100 mL / min, the flow rate of oxygen is 0-30 mL / min (such as 0 mL / min or 30 mL / min), the ozone concentration is 17-700 ppm (such as 17 ppm or 700 ppm), the flow rate of N2 as the balance gas is 36.7-50 mL / min (such as 36.7 mL / min or 50 mL / min), the concentration of test gas is 100 ppm, the flow rate of test gas is 20-33.3 mL / min (such as 20 mL / min or 33.3 mL / min), the volume space velocity is 600-18950 h -1 (600 h -1 , 2400 h -1 or 18950 h -1 ), the test temperature is room temperature-400℃ (such as room temperature, 53℃ or 400℃).

[0067] In the present application, "room temperature" refers to 25±2℃ unless otherwise specified.

[0068] In the present application, all raw materials are commercially available.

[0069] The technical solutions of the present application are further illustrated by the following examples.

[0070] Example 1

[0071] Preparation of a manganese-cobalt spinel catalyst:

[0072] Potassium permanganate and cobalt nitrate hexahydrate were mixed in a molar ratio of 7:10 and added to water for dissolution under ultrasonic stirring (the concentration of potassium permanganate in the obtained solution was 0.032 mol / L, and the concentration of cobalt nitrate hexahydrate was 0.048 mol / L); the fully mixed solution was added to a water tank containing a honeycomb ceramic substrate and stirred at 86°C for 4.5 hours. After the solution turned light purple, the solution was discharged from the drain port. The solution was prepared three times and hydrothermal growth was repeated at 86°C for 4.5 hours. After the in-situ hydrothermal growth reaction was completed, the reaction solution was discharged, the solution in the pores was blown out, and the substrate was placed in an oven for 1 hour. The obtained monolithic catalyst was dried at 50°C for 6 hours, and then calcined at 500°C for 2.5 hours at a heating rate of 10°C / min; the monolithic catalyst was immersed in a 0.1mol / L acetic acid solution for 60 minutes, and then the excess solution in the pores was blown away. After being taken out, it was immersed in a 0.15mol / L lanthanum nitrate hexahydrate solution for 10 minutes, and then the excess solution in the pores was blown away. It was placed in an oven and dried at 150°C for 6 hours; finally, the monolithic catalyst was calcined at a constant temperature of 500°C for 2.5 hours at a heating rate of 10°C / min to obtain a manganese cobalt spinel monolithic stone catalyst (MC-500°C).

[0073] Comparative Example 1

[0074] The same as Example 1, except that the calcination temperature was adjusted from 500° C. to 600° C. to obtain a manganese-cobalt spinel monolithic catalyst (MC-600° C.).

[0075] Comparative Example 2

[0076] The same as Example 1, except that the calcination temperature was adjusted from 500° C. to 700° C., to obtain a manganese-cobalt spinel monolithic catalyst (MC-700° C.).

[0077] Comparative Example 3

[0078] The same as Example 1, except that the molar ratio of potassium permanganate and cobalt nitrate hexahydrate is adjusted from 7:10 to 3:10, to obtain a manganese-cobalt spinel monolithic catalyst.

[0079] Comparative Example 4

[0080] The same as Example 1, except that the molar ratio of potassium permanganate and cobalt nitrate hexahydrate was adjusted from 7:10 to 5:10, to obtain a manganese-cobalt spinel monolithic catalyst.

[0081] Comparative Example 5

[0082] Commercially available manganese oxide (MnO) and manganese dioxide (MnO2) catalysts were purchased from Aladdin (CAS: 1344-43-0) and Xianfeng Nano (CAS: 1313-13-9), respectively.

[0083] For the prepared manganese-cobalt spinel catalyst, the following Figure 1-2 The structural morphology of the catalyst was characterized. Figure 1 Scanning electron microscopy images show that the prepared manganese-cobalt spinel monolithic catalyst has no clear morphology and its surface elements are evenly distributed. Figure 2 From the XRD pattern, it can be seen that the characteristic peaks of Mn and Co metals do not appear in the manganese-cobalt spinel catalyst, indicating that the metallic manganese in the catalyst is highly dispersed or the content is below the detection limit, or the obtained metal oxide is calcined at a low temperature and it is difficult to form a good crystal structure.

[0084] Application Example 1

[0085] The manganese-cobalt spinel catalyst prepared in Example 1 was used to catalyze the ozonation of VOCs at room temperature. Figure 3 The room temperature catalytic ozonolysis activity of toluene over manganese cobalt spinel catalyst was tested. The test conditions were as follows: toluene was used as the test gas, the total gas flow rate was controlled at 100 mL / min, the oxygen flow rate was 30 mL / min, the ozone concentration was 700 ppm, the balance gas flow rate of N2 was 36.7 mL / min, the toluene concentration was 100 ppm (the original toluene concentration in the gas cylinder was 500 ppm), the toluene flow rate was 33.3 mL / min, and the volume space velocity was 2400 h / min. -1 The toluene concentration in the tail gas is detected and analyzed by gas chromatography, and the ozone concentration is detected by an ozone detector. Figure 3 The catalyst activity curve shows that the catalyst exhibits 100% toluene catalytic ozonation activity at room temperature, and the catalyst activity does not decrease after 20 hours, and can still maintain 100% toluene decomposition activity, showing good catalytic stability.

[0086] Application Example 2

[0087] Figure 4 The room temperature catalytic ozonation decomposition activity of toluene of the manganese cobalt spinel catalyst prepared in Example 1, Comparative Example 1, and Comparative Example 2 was tested. The test conditions were as follows: the test gas was toluene, the total gas flow rate was controlled to 100 mL / min, the oxygen flow rate was 30 mL / min, the ozone concentration was 700 ppm, the N2 balance gas flow rate was 36.7 mL / min, the toluene concentration was 100 ppm (the original toluene concentration in the gas cylinder was 300 ppm), the toluene flow rate was 33.3 mL / min, and the volume space velocity was 2400 h -1 .from Figure 4 The catalyst activity curve shows that the manganese-cobalt spinel catalyst (MC-600°C) prepared in Comparative Example 1 exhibits 100% catalytic ozonation activity for toluene for only 2 h, and the catalytic activity significantly decreases after more than 2 h. The manganese-cobalt spinel catalyst (MC-700°C) prepared in Comparative Example 2 exhibits even worse performance, and exhibits 100% catalytic ozonation activity for toluene for less than 1 h, and the catalytic activity significantly decreases after more than 1 h.

[0088] Application Example 3

[0089] Figure 5 The manganese-cobalt spinel catalyst prepared in Example 1, Comparative Example 3, and Comparative Example 4 was tested for room-temperature catalytic ozonation decomposition activity for toluene, and the test conditions were as follows: the test gas was toluene, the total gas flow was controlled to be 100 mL / min, the oxygen flow was 30 mL / min, the ozone concentration was 700 ppm, N2 was used as the balancing gas, the flow was 36.7 mL / min, the toluene concentration was 100 ppm (the original toluene concentration in the gas cylinder was 300 ppm), the toluene flow was 33.3 mL / min, and the volume space velocity was 2400 h-1. -1 The toluene concentration in the tail gas was detected and analyzed by gas chromatography, and the ozone concentration was detected by an ozone detector. From the catalyst activity curve, it can be seen that the manganese-cobalt spinel catalyst prepared in Comparative Example 3 exhibits 90% catalytic ozonation activity for toluene for only about 1 h, and loses the catalytic activity after more than 1 h. The manganese-cobalt spinel catalyst prepared in Comparative Example 4 exhibits extremely unstable catalytic ozonation activity for toluene, and directly loses the activity after 4 h of catalysis. Figure 5

[0090] Application Example 4

[0091] Figure 6 The manganese-cobalt spinel catalyst prepared in Example 1 was tested for room-temperature catalytic ozonation decomposition activity for methanol, and the test conditions were as follows: the test gas was methanol, the total gas flow was controlled to be 100 mL / min, the oxygen flow was 30 mL / min, the ozone concentration was 700 ppm, N2 was used as the balancing gas, the flow was 50 mL / min, the methanol concentration was 100 ppm (the original methanol concentration in the gas cylinder was 500 ppm), the gas flow was 20 mL / min, and the volume space velocity was 2400 h-1. -1 The methanol concentration in the tail gas was detected and analyzed by gas chromatography, and the ozone concentration was detected by an ozone detector. From the catalyst activity curve, it can be seen that the manganese-cobalt spinel catalyst prepared in Example 1 exhibits 100% catalytic ozonation activity for methanol at room temperature, and the catalyst activity does not decrease after 24 h, and still can maintain 100% methanol decomposition activity, showing good stability. Figure 6

[0092] Application Example 5 ​​

[0093] Figure 7 The manganese cobalt spinel catalyst prepared in Example 1 was tested for catalytic ozonolysis activity of propylene at room temperature. The test conditions were as follows: the test gas was propylene, the total gas flow was controlled at 100 mL / min, the oxygen flow was 30 mL / min, the ozone concentration was 700 ppm, N2was used as the balance gas at a flow rate of 50 mL / min, the propylene concentration was 100 ppm (the original ethyl acetate concentration in the cylinder was 500 ppm), the gas flow was 20 mL / min, and the volume space velocity was 600 h -1 -1. The propylene concentration in the tail gas was detected and analyzed by gas chromatography, and the ozone concentration was detected by an ozone detector. From -1 the catalyst activity curve, it can be seen that the catalyst prepared in Example 1 exhibited 100% catalytic ozonolysis activity of propylene at room temperature, and the catalyst activity did not decrease after 24 h, and still maintained 100% propylene decomposition activity, showing good stability. When the volume space velocity was 2400 h -1 -1, the catalyst prepared in Example 1 exhibited a significant decrease in activity after 4 h at room temperature, and reached a stable state after 8 h, maintaining about 40% propylene decomposition activity. Figure 7 -1

[0094] Application Example 6

[0095] Figure 8 The manganese cobalt spinel catalyst prepared in Example 1 was tested for catalytic ozonolysis activity of ethyl acetate. The test conditions were as follows: the test gas was ethyl acetate, the total gas flow was controlled at 50 mL / min, the oxygen flow was 30 mL / min, the ozone concentration was 700 ppm, N2was used as the balance gas at a flow rate of 10 mL / min, the ethyl acetate concentration was 100 ppm (the original ethyl acetate concentration in the cylinder was 500 ppm), and the volume space velocity was 2400 h -1 -1. The ethyl acetate concentration in the tail gas was detected and analyzed by gas chromatography, and the ozone concentration was detected by an ozone detector. From Figure 8 the catalyst activity curve, it can be seen that the catalyst exhibited 100% catalytic ozonolysis activity of ethyl acetate at 53°C.

[0096] Application Example 7

[0097] Figure 9 ​​The manganese cobalt spinel catalyst prepared in Example 1 was tested for catalytic ozonation decomposition activity of methane. The test conditions were as follows: the test gas was methane, the total gas flow was controlled at 100 mL / min, the oxygen flow was 30 mL / min, the ozone concentration was 700 ppm, N2was used as the balance gas at a flow rate of 50 mL / min, the methane concentration was 100 ppm (the original methane concentration in the gas cylinder was 500 ppm), the volume space velocity was 2400 h -1 The methane concentration in the tail gas was detected and analyzed by gas chromatography, and the ozone concentration was detected by an ozone detector. From Figure 9 The catalyst activity curve showed that the catalyst could exhibit 100% catalytic ozonation activity of methane at 400°C.

[0098] Application Example 8

[0099] Figure 10 The manganese cobalt spinel catalyst prepared in Example 1 was tested for catalytic ozonation decomposition activity of mixed gas. The test conditions were as follows: the test gas was 40 ppm toluene, 30 ppm ethyl acetate, and 30 ppm xylene, the total gas flow was controlled at 100 mL / min, the oxygen flow was 30 mL / min, the ozone concentration was 700 ppm, N2was used as the balance gas at a flow rate of 33.7 mL / min, the volume space velocity was 2400 h -1 The VOCs concentration in the tail gas was detected and analyzed by gas chromatography, and the ozone concentration was detected by an ozone detector. From Figure 10 The catalyst activity curve showed that the catalyst could exhibit 100% catalytic ozonation activity of xylene in the mixed gas for 13 hours, and the degradation of toluene could be maintained at 100% for 14 hours. The degradation of ethyl acetate could be maintained at 100% for 16 hours. The test results showed that the catalyst had good room temperature catalytic ozonation decomposition activity for mixed components.

[0100] Application Example 9

[0101] Figure 11 The manganese cobalt spinel catalyst prepared in Example 1 was tested for decomposition activity of ozone at room temperature and different humidity. The test conditions were as follows: the test gas was 17 ppm ozone, the total flow rate was 1.2 L / min, the space velocity was 18950 h -1 , the air balance gas, the test temperature was 25°C, and the ozone concentration in the tail gas was detected by an ozone detector. From Figure 11It can be seen from the catalyst activity curve that the catalyst can achieve more than 85% ozone removal at room temperature when the humidity is 1% and can maintain basically unchanged for 13 hours, which shows that the catalyst has a good removal rate under dry gas conditions. At a humidity of 25%, it can achieve more than 81% ozone removal at room temperature and can maintain basically unchanged for 6 hours. At a humidity of 50%, it can achieve more than 71% ozone removal at room temperature and can maintain basically unchanged for 6 hours. At a humidity of 75%, it can achieve more than 55% ozone removal at room temperature and can maintain basically unchanged for 6 hours. This shows that the catalyst still has a certain removal rate for ozone under different humidity conditions.

[0102] Application Example 10

[0103] Figure 12 The activity of commercial manganese oxide and manganese dioxide catalysts in comparative example 5 for catalytic ozonation and decomposition of toluene at room temperature was tested. The test conditions were as follows: the test gas was 100 ppm toluene, the total gas flow rate was controlled to 100 mL / min, the oxygen flow rate was 30 mL / min, the ozone concentration was 700 ppm, the N2 balance gas flow rate was 33.7 mL / min, and the volume space velocity was 2400 h -1 The concentration of VOCs in the exhaust gas is detected and analyzed by gas chromatography, and the concentration of ozone is detected by an ozone detector. Figure 12 The catalyst activity curves show that the commercial manganese oxide (MnO) catalyst's toluene degradation activity reaches 0% after 4 hours, while the toluene degradation activity of the commercial manganese dioxide (MnO2) catalyst drops below 10% after 24 hours. These test results demonstrate that the manganese-cobalt spinel monolith exhibits superior room-temperature catalytic ozonolysis activity compared to single manganese oxide (MnO or MnO2) catalysts.

[0104] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for catalyzing the ozonation of VOCs using a manganese-cobalt spinel catalyst, characterized in that: The preparation method of the manganese-cobalt spinel catalyst comprises the following steps: 1) Add manganese salt and cobalt salt to water and dissolve them by ultrasonication. Immerse the honeycomb ceramic substrate in the resulting solution. After the solution turns light purple, remove the treated honeycomb ceramic substrate. Repeat the immersion process. 2) drying and calcining the honeycomb ceramic substrate after the impregnation treatment; 3) immersing the calcined honeycomb ceramic substrate in an acetic acid solution, then blowing away excess solution in the pores, then immersing it in a lanthanum salt solution, removing it, further blowing away excess solution in the pores, drying it, and heating and calcining it again to obtain a manganese-cobalt spinel catalyst; The repeated impregnation means that each time the manganese salt and the cobalt salt are added to water and ultrasonically dissolved to prepare a solution, and then the honeycomb ceramic substrate treated by the previous impregnation treatment is placed in the new solution for a new round of impregnation treatment, and this complete process is repeated three times; The VOCs include: one or more of toluene, methanol, propylene and ethyl acetate; During the application process, the test conditions are as follows: test gas flow rate of 100 mL / min, oxygen flow rate of 30 mL / min, ozone concentration of 17-700 ppm, N2 as balance gas flow rate of 36.7-50 mL / min, test gas concentration of 100 ppm, test gas flow rate of 20-33.3 mL / min, volume space velocity of 600-18950 h -1 , the test temperature is room temperature.

2. The use according to claim 1, characterized in that In step 1), the parameters of the immersion are: temperature 85-95° C., time 4-4.5 hours.

3. The use according to claim 1, characterized in that In step 1), the molar ratio of the manganese salt to the cobalt salt is 7:

10.

4. The use according to claim 1, characterized in that The manganese salt is potassium permanganate, the cobalt salt is cobalt nitrate hexahydrate, and the lanthanum salt is lanthanum nitrate hexahydrate.

5. The use according to claim 1, characterized in that In steps 2) and 3), The drying parameters are: temperature 150°C, time 6 hours; and / or The calcination parameters are: temperature 500° C., time 2.5 hours, and heating rate 10° C. / min.

6. The use according to claim 1, characterized in that In step 3), The concentration of the acetic acid solution is 0.1-0.2 mol / L; and / or The soaking parameters are: time 1-2 hours; and / or The concentration of the lanthanum salt solution is 0.15-0.2 mol / L; and / or The parameters of the dipping are: time 10-20 minutes.

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