Cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene as well as preparation method and application of cobalt-manganese-aluminum composite oxide catalyst

Abstract

The invention discloses a cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene, and a preparation method and application thereof, and belongs to the technical field of catalyst preparation. The preparation method comprises the following steps: carrying out complexation reaction on cobalt salt, manganese salt, aluminum salt, a complexing agent and a surfactant to generate a metal organic framework; and roasting the generated metal organic framework to obtain the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene. The preparation method is simple, the calcination temperature is low, energy consumption is small, and the prepared cobalt-manganese-aluminum composite oxide catalyst is high in oxidation performance, rich in active oxygen, good in toluene degradation performance, capable of keeping the toluene removal rate of 90% or above at the temperature of 200 DEG C, high in stability, easy to operate, capable of saving energy and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and particularly relates to a cobalt-manganese-aluminum composite oxide catalyst, a preparation method thereof, and an application thereof in catalytic combustion of toluene. Background Art

[0002] Volatile Organic Compounds (VOCs) are a major type of air pollutant. The types of VOCs include alkanes, aromatic hydrocarbons, oxygen-containing volatile organic compounds, etc. Automobile exhaust, industrial activities, solvent use, fossil fuel combustion, fuel evaporation, the rubber industry, liquefied petroleum gas use, the petrochemical industry, and coal and biomass combustion are the main sources of atmospheric volatile organic compounds. Toxic and carcinogenic toluene (C7H 10 ) has the general characteristics of VOCs and is often used as a raw material and solvent in chemical synthesis of human activities. In 2017, the International Agency for Research on Cancer of the World Health Organization listed toluene in the list of Group 3 carcinogens. Toluene can not only enter the human body and cause lung diseases, but also act as a precursor for the formation of secondary organic aerosols and ozone, causing air pollution. Therefore, it is urgent to efficiently remove toluene from the atmospheric environment.

[0003] The catalytic combustion method is widely used in the removal of VOCs because of its low reaction temperature, stable reaction, high reaction efficiency, and only non-toxic and harmless CO2 and H2O as reaction products. As a transition metal catalyst, Mn-based catalysts are considered to have great potential for the thermal catalytic oxidation of VOCs because Mn elements are cheap, easy to obtain, environmentally friendly, have diverse structures, strong oxidation properties, and rich oxygen species. However, many limitations have been found in actual research. Single manganese oxides are always limited by small specific surface area, few active sites, and weak adsorption ability for VOCs. Combining with other metals is a good strategy to improve the catalytic activity for VOCs. Some previous studies have proved that catalysts prepared by combining cobalt, manganese, and aluminum elements have good effects in the catalytic combustion of toluene. Xin et al. (Xin, Y., 2024. Achieving deep oxidation of toluene over CoMnO x catalyst:Insight into the collaboration of Co3O4 and MnO x via layered double hydroxides(LDHs) precursor template. Journal of Environmental Chemical Engineering.) prepared Co 1.5 Mn 1.5AlO4, the catalytic temperature T of the prepared catalyst for toluene 90 (the catalytic temperature when the conversion rate is 90%) is 240 °C. The catalytic temperature is high, the energy consumption is high, and the preparation time is long (heating in a water bath at 65 °C for 12 h, drying at 80 °C for 12 h, calcining at 500 °C for 5 h). Ren et al. (Ren, Y., Song, C., Wang, H., Qu, Z., 2024. Accelerated Dual Activationof Lattice Oxygen and Molecule Oxygen over CoMn2O4 Catalysts for VOCOxidation: Promoting the Role of Oxygen Vacancies. ACS Catal.) prepared CoMn2AlO4 spinel and urea-modified CoMn2AlO4 spinel by the hydrothermal method at high temperature, and the catalytic temperature T of the prepared catalyst for toluene 90 is 250 °C and 220 °C respectively. Similarly, the catalytic temperature is relatively high, the preparation process is complex, the preparation cycle is long, and the energy consumption is large (hydrothermal at 200 °C for 24 h, calcining at 600 °C for 4 h, and the second calcining at 400 °C for 4 h). Summary of the Invention

[0004] The purpose of the present invention is to provide a cobalt-manganese-aluminum composite oxide catalyst, a preparation method thereof, and its application in the catalytic combustion of toluene, aiming at the deficiencies of the existing technology. The preparation method has low energy consumption, short cycle, relatively simple process, and the prepared catalyst has a high degradation rate for toluene at relatively low temperatures.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a preparation method of a cobalt-manganese-aluminum composite oxide catalyst for the catalytic combustion of toluene, including: Reacting cobalt salt, manganese salt, aluminum salt, complexing agent and surfactant through complexation reaction to generate metal-organic framework (MOFs); Calcining the generated metal-organic framework to obtain a cobalt-manganese-aluminum composite oxide catalyst.

[0006] Optionally, the cobalt salt is selected from one or any several of cobalt chloride, cobalt nitrate, cobalt carbonate, cobalt acetate and cobalt sulfate.

[0007] Optionally, the manganese salt is selected from one or any several of manganese chloride, manganese nitrate, manganese carbonate, manganese acetate and manganese sulfate.

[0008] Optionally, the aluminum salt is selected from one or any several of aluminum chloride, aluminum nitrate, aluminum carbonate, aluminum acetate and aluminum sulfate.

[0009] Optionally, the complexing agent is selected from one or any combination of disodium ethylenediaminetetraacetate, triethanolamine, sodium ethylene diamine tetra (methylene phosphonic acid) and 2-methylimidazole.

[0010] Optionally, the surfactant is selected from one or any combination of triethanolamine, sodium stearate, dodecyl sulfonic acid and cetyltrimethylammonium bromide.

[0011] Further, the molar ratio of the cobalt salt, manganese salt, and aluminum salt is 2:1:1 to 2:3:1.

[0012] Further, the molar ratio of the complexing agent to the sum of the three metal ions of cobalt, manganese, and aluminum is 20:1 to 50:1.

[0013] Further, the molar ratio of the surfactant to the sum of the three metal ions of cobalt, manganese, and aluminum is 1:5 to 1:10.

[0014] Further, the solvent used in the complexation reaction is selected from one or any combination of water, methanol, ethanol, isopropanol, and n-butanol.

[0015] Further, the calcination temperature is 200 - 400 °C, and the calcination time is 2 - 4 h.

[0016] In a second aspect, the present invention provides a cobalt-manganese-aluminum composite oxide catalyst prepared by the preparation method according to any one of the first aspect.

[0017] Further, the specific surface area of the obtained cobalt-manganese-aluminum composite oxide catalyst is 100 - 150 m 2 / g, and the pore diameter is mainly distributed in the range of 2 - 50 nm.

[0018] In a third aspect, the present invention provides the application of the aforementioned cobalt-manganese-aluminum composite oxide catalyst in the catalytic combustion of toluene, wherein the temperature of the catalytic combustion of toluene is 190 - 200 °C.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses the complexation method as the method for preparing the cobalt-manganese-aluminum composite oxide catalyst. The complexation method can uniformly mix cobalt ions, manganese ions, and aluminum ions. The complexing agent fully complexes with metal ions to form a special structure, enhancing the interaction between cobalt, manganese, and aluminum elements, forcing the chemical bond between metal and oxygen to be more easily broken, and enhancing the oxygen supply capacity of the catalyst. The complexation synthesis method is simple, low-cost, has few steps, uses few reagents, and is safe to operate.

[0020] (2) The surfactant can make the three metals disperse better, uniformly mix different metals, make the electronic effect between metal ions more obvious, and enhance the activity of the catalyst for catalytic combustion of toluene.

[0021] (3) The preparation process of the present invention has fewer steps. Compared with the hydrothermal method, it does not need to be heated before calcination, has a short preparation time and low energy consumption. (4) The calcination temperature of the method of the present invention is low and the energy consumption is small. The cobalt-manganese-aluminum composite oxide catalyst can be prepared by calcination at 200-400 °C, while the commonly used calcination temperature at present is mostly above 500 °C.

[0022] (4) The cobalt-manganese-aluminum composite oxide catalyst prepared by the present invention has sufficient reaction sites, a relatively large specific surface area, strong oxidation performance, rich active oxygen, strong stability, and good toluene degradation performance. The catalytic temperature (the catalytic temperature when the conversion rate is 90%) for toluene catalytic combustion is as low as 200 °C, which is lower than the catalytic temperature for toluene degradation of cobalt-manganese-aluminum oxides reported in the prior art under the same test conditions. 90 (The catalytic temperature when the conversion rate is 90%) 90 . Description of the Drawings

[0023] Figure 1 It is the efficiency diagram of toluene catalytic combustion of the catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention; Figure 2 It is the X-ray diffraction (XRD) diagram of the catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention; Figure 3 It is the pore size distribution diagram of the catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention; Figure 4 It is the energy dispersive X-ray spectroscopy (EDX) diagram of the catalyst prepared in Example 1 of the present invention; Figure 5 It is the hydrogen temperature-programmed reduction (H2-TPR) diagram of the catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention; Figure 6 It is the efficiency diagram of toluene catalytic combustion of the catalysts prepared in Examples 1-3 of the present invention; Figure 7 It is the X-ray diffraction (XRD) diagram of the catalysts prepared in Examples 1-3 of the present invention; Figure 8 It is the hydrogen temperature-programmed reduction (H2-TPR) diagram of the catalysts prepared in Examples 1-3 of the present invention; Figure 9 It is the nitrogen isothermal adsorption and desorption curve diagram of the catalysts prepared in Examples 1-3 of the present invention. Detailed Embodiments

[0024] The present invention will be further described below in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0025] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application shall have the ordinary meanings understood by those skilled in the art to which the present invention pertains.

[0026] A preparation method of a cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to the present invention comprises the following steps: (1) Preparing an intermediate: completely dissolving a cobalt salt, a manganese salt, an aluminum salt and a surfactant in a solvent and mixing them evenly, denoted as solution A; completely dissolving a complexing agent in a solvent, denoted as solution B, slowly adding solution A to solution B, and continuously stirring for 4 - 10 h to obtain an intermediate uniformly suspended in the solvent.

[0027] (2) Centrifuging: centrifuging and separating the uniform mixture obtained in step (1), with the centrifuge speed being 10000 - 18000 rpm.

[0028] (3) Drying the intermediate: putting the intermediate obtained by centrifuging into an oven at 60 - 100 °C and drying for 8 - 12 h.

[0029] (4) Roasting to prepare the cobalt-manganese-aluminum composite oxide: roasting the intermediate dried in step (3) in a muffle furnace at 200 - 400 °C for 2 - 4 h, and the resulting solid powder is the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene. Example 1

[0030] Synthesizing Co2Mn 1.5 Al1-MOFs300 nanocatalyst (the molar ratio of cobalt salt, manganese salt, and aluminum salt is 2:1.5:1).

[0031] The specific steps are as follows: (1) Preparing an intermediate: completely dissolving 0.04 mol of cobalt chloride, 0.03 mol of manganese nitrate, 0.02 mol of aluminum acetate and 0.01 mol of dodecylsulfonic acid in methanol and mixing them evenly, denoted as solution A; completely dissolving 3.3 mol of 2-methylimidazole in methanol, denoted as solution B; slowly adding solution A to solution B, and continuously stirring for 8 h to obtain an intermediate uniformly suspended in the solvent.

[0032] (2) Centrifuging: centrifuging and separating the uniform mixture obtained in step (1), with the centrifuge speed being 10000 rpm.

[0033] (3) Drying the intermediate: putting the intermediate obtained by centrifuging in step (2) into an oven at 80 °C and drying for 8 h.

[0034] (4) Roasting to prepare the cobalt-manganese-aluminum composite oxide: roasting the intermediate dried in step (3) in a muffle furnace at 300 °C for 2 h, and the resulting solid powder is Co2Mn 1.5 Al1-MOFs300 nanocatalyst. Example 2

[0035] Synthesis of Co2Mn 1.5 Al1-MOFs 350 nanocatalyst (the molar ratio of cobalt salt, manganese salt, and aluminum salt is 2:1.5:1).

[0036] The specific steps are as follows: (1) Preparation of intermediate: Dissolve 0.04 mol of cobalt chloride, 0.03 mol of manganese nitrate, 0.02 mol of aluminum acetate, and 0.01 mol of dodecylsulfonic acid completely in methanol and mix evenly, denoted as solution A; dissolve 1.1 mol of disodium ethylenediaminetetraacetate and 2.2 mol of 2-methylimidazole completely in methanol, denoted as solution B; slowly add solution A to solution B and continuously stir for 8 h to obtain an intermediate uniformly suspended in the solvent.

[0037] (2) Centrifugation: Centrifuge the homogeneous mixture obtained in step (1), and the centrifuge speed is 10000 rpm.

[0038] (3) Drying the intermediate: Put the intermediate obtained by centrifugation in step (2) into an oven at 80 °C and dry for 8 h.

[0039] (4) Calcination to prepare cobalt-manganese-aluminum composite oxide: Calcinate the dried intermediate in step (3) in a muffle furnace at 350 °C for 2 h, and the resulting solid powder is Co2Mn 1.5 Al1-MOFs 350 nanocatalyst. Example 3

[0040] Synthesis of Co2Mn 1.5 Al1-MOFs 400 nanocatalyst (the molar ratio of cobalt salt, manganese salt, and aluminum salt is 2:1.5:1).

[0041] The specific steps are as follows: (1) Preparation of intermediate: Dissolve 0.04 mol of cobalt chloride, 0.03 mol of manganese nitrate, 0.02 mol of aluminum acetate, and 0.01 mol of cetyltrimethylammonium bromide completely in methanol and mix evenly, denoted as solution A; dissolve 1.1 mol of sodium ethylene diamine tetramethylene phosphonate and 2.2 mol of 2-methylimidazole completely in water, denoted as solution B; slowly add solution A to solution B and continuously stir for 8 h to obtain an intermediate uniformly suspended in the solvent.

[0042] (2) Centrifugation: Centrifuge the homogeneous mixture obtained in step (1), and the centrifuge speed is 10000 rpm.

[0043] (3) Drying the intermediate: Put the intermediate obtained by centrifugation in step (2) into an oven at 80 °C and dry for 8 h.

[0044] (4) Calcination to prepare cobalt-manganese-aluminum composite oxide: The intermediate dried in step (3) is calcined in a muffle furnace at 400 °C for 2 h, and the resulting solid powder is Co2Mn 1.5 Al1-MOFs400 nanocatalyst.

[0045] Comparative Example 1 Synthesis of Co2Mn by hydrothermal method 1.5 Al1-HY nanocatalyst (the molar ratio of cobalt salt, manganese salt, and aluminum salt is 2:1.5:1).

[0046] The specific steps are as follows: (1) Preparation of intermediate: 0.04 mol of cobalt chloride, 0.03 mol of manganese nitrate, 0.02 mol of aluminum acetate, and 0.0045 mol of cetyltrimethylammonium bromide are completely dissolved in a solvent and mixed evenly. The pH of the mixed solution is adjusted to 10 using 1 mol / L sodium hydroxide solution. The resulting flocculent substance is hydrothermally treated at 90 °C for 12 h to obtain a homogeneous mixture.

[0047] (2) Centrifugation: The obtained homogeneous mixture is centrifuged, and the centrifuge speed is 4000 rpm.

[0048] (3) Drying the intermediate: The intermediate obtained by centrifugation is placed in an oven at 60 °C and dried for 12 h.

[0049] (4) Calcination to prepare cobalt-manganese-aluminum composite oxide: The intermediate dried in step (3) is calcined in a muffle furnace at 500 °C for 2 h, and the resulting solid powder is Co2Mn 1.5 Al1-HY nanocatalyst.

[0050] Comparative Example 2 Synthesis of Co2Mn by complexation method 1.5 Al1-CA nanocatalyst (the molar ratio of cobalt salt, manganese salt, and aluminum salt is 2:1.5:1).

[0051] The specific steps are as follows: (1) Preparation of intermediate: 0.04 mol of cobalt chloride, 0.03 mol of manganese nitrate, 0.02 mol of aluminum acetate, and 0.162 mol of citric acid are completely dissolved in a solvent and mixed evenly. The molar ratio of citric acid to metal ions is 1.8:1. The mixture is stirred and evaporated to dryness in a water bath at 80 °C to obtain the intermediate.

[0052] (2) Drying the intermediate: The intermediate obtained by centrifugation is placed in an oven at 80 °C and dried for 12 h.

[0053] (3) Calcination to prepare cobalt-manganese-aluminum composite oxide: The intermediate dried in step (2) is calcined in a muffle furnace at 360 °C for 2 h, and the resulting solid powder is Co2Mn 1.5Al1-CA nanocatalyst.

[0054] Comparative Example 3 Synthesis of Co2Mn by coprecipitation method 1.5 Al1-PC nanocatalyst (the molar ratio of cobalt salt, manganese salt, and aluminum salt is 2:1.5:1).

[0055] The specific steps are as follows: (1) Preparation of intermediate: Dissolve 0.04 mol of cobalt chloride, 0.03 mol of manganese nitrate, and 0.02 mol of aluminum acetate completely in water and mix evenly to obtain Solution A. Dissolve 0.04 mol of sodium carbonate and 0.144 mol of sodium hydroxide completely in water. Slowly mix Solution A and Solution B simultaneously, stir at 70 °C in a water bath for 5 h, and centrifuge and wash to obtain the intermediate.

[0056] (2) Drying the intermediate: Put the centrifuged intermediate into an oven at 70 °C and dry for 12 h.

[0057] (3) Calcining to prepare cobalt-manganese-aluminum composite oxide: Calcinate the dried intermediate in step (2) in a muffle furnace at 550 °C for 6 h, and the resulting solid powder is Co2Mn 1.5 Al1-PC nanocatalyst.

[0058] Figure 1 This is the efficiency diagram of the cobalt-manganese-aluminum composite oxide catalyst prepared in Example 1 of the present invention and Comparative Examples 1-3 for catalytic combustion of toluene. The reaction conditions are: 10,000 ppm of toluene, an air space velocity of 66,000 ml·g -1 ·h -1 , and 0.05 g of the catalyst. It can be Figure 1 seen that compared with the catalysts prepared by other common methods, the cobalt-manganese-aluminum composite oxide prepared by the method of the present invention has good catalytic activity for toluene, good oxidation performance, sufficient oxygen storage, and can stably degrade toluene at a lower temperature. T 90 is as low as 200 °C, lower than the T reported in the prior art 90 .

[0059] Figure 2 This is the X-ray diffraction (XRD) pattern of the cobalt-manganese-aluminum composite oxide catalyst prepared in Example 1 of the present invention and Comparative Examples 1-3. It can be Figure 1 seen that in Example 1, there are main characteristic peaks of Co2AlO4 at 19.0°, and main characteristic peaks of CoMnAlO4 at 31.4°, 37.1°, 38.8°, 49.9°, 56.0°, and 65.3°. Compared with Comparative Examples 1-3, the characteristic peak signal in Example 1 is strong, the peak width is narrow, and the crystallinity is high, indicating that cobalt-manganese-aluminum mainly exists in the form of spinel.

[0060] Figure 3 This is the pore size distribution diagram of the cobalt-manganese-aluminum composite oxide catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention. As can be seen from Figure 3 it, the pore sizes of the catalysts prepared in Example 1 of the present invention are mainly distributed in the range of 2-50 nm, and the average pore size is in the range of 10-30 nm.

[0061] Figure 4 This is the energy dispersive X-ray spectroscopy (EDX) diagram of the cobalt-manganese-aluminum composite oxide catalyst prepared in Example 1 of the present invention. As can be seen from Figure 4 it, the cobalt, manganese, and aluminum metal elements are evenly distributed, and the dispersion degrees of the light spots of different colors represent the dispersion degrees of the corresponding metal elements respectively.

[0062] Figure 5 This is the hydrogen temperature-programmed reduction (H2-TPR) diagram of the catalysts prepared in Example 1 and Comparative Examples 1-3 of the present invention. As can be seen from Figure 5 it, the oxidation ability of Example 1 is significantly stronger than that of Comparative Examples 1-3. The position of the hydrogen consumption peak for reduction in Example 1 increases significantly at 236 °C. At this temperature, there is no obvious hydrogen consumption peak for reduction in the spectra of Comparative Examples 1-3.

[0063] Figure 6 This is the efficiency diagram of catalytic combustion of toluene by the cobalt-manganese-aluminum composite oxide catalysts prepared in Examples 1-3 of the present invention. The reaction conditions are as follows: toluene at 10000 ppm, an air space velocity of 66000 ml·g -1 ·h -1 , and 0.05 g of the catalyst. As can be seen from Figure 6 it, Examples 1-3 can all maintain a conversion rate of over 90% at 200 °C, and adjusting the preparation conditions within the specified range has no significant effect on the catalytic activity of the catalyst.

[0064] Figure 7 This is the X-ray diffraction (XRD) diagram of the cobalt-manganese-aluminum composite oxide catalysts prepared in Examples 1-3 of the present invention. As can be seen from Figure 7 it, Examples 1-3 all have the main characteristic peak of Co2AlO4 at 19.0°, and the main characteristic peaks of CoMnAlO4 at 31.4°, 37.1°, 38.8°, 49.9°, 56.0°, and 65.3°.

[0065] Figure 8 This is the hydrogen temperature-programmed reduction (H2-TPR) diagram of the cobalt-manganese-aluminum composite oxide catalysts prepared in Examples 1-3 of the present invention. As can be seen from Figure 8 it, the reduction hydrogen consumption peak temperature of Example 1 is relatively low, which corresponds to Figure 6 this.

[0066] Figure 9This is the nitrogen isothermal adsorption and desorption curve of the cobalt-manganese-aluminum composite oxide catalyst prepared in Examples 1-3 of the present invention. From Figure 9 It can be seen that the curves of Examples 1-3 are similar, all belonging to the Type IV adsorption isotherm and showing an H3-type hysteresis loop, indicating that the structures of the three examples are similar.

[0067] The present invention provides a preparation method of a cobalt-manganese-aluminum composite oxide catalyst with low cost, simple operation, good recyclability, and environmental friendliness. The obtained cobalt-manganese-aluminum composite oxide catalyst has good oxidation performance and sufficient oxygen storage. At 200 °C, it can maintain a toluene removal rate of over 90%, has good activity, and is energy-saving and environmentally friendly.

[0068] If the ratio of the amounts of cobalt, manganese, and aluminum in the present invention is exceeded, the prepared nano-catalyst T 90 has a high temperature and a low toluene degradation efficiency.

[0069] The present invention has been published with preferred embodiments, but it is not intended to limit the present invention. Any technical solutions obtained by adopting equivalent substitution or equivalent transformation schemes fall within the protection scope of the present invention.

Claims

1. A method for preparing a cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene, characterized in that: include: The cobalt salt, the manganese salt, the aluminum salt, the complexing agent and the surfactant are reacted to form a metal organic framework; The generated metal organic framework is calcined to obtain a cobalt manganese aluminum composite oxide catalyst.

2. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The complexing agent is selected from one or any combination of disodium ethylenediaminetetraacetate, triethanolamine, sodium ethylenediaminetetramethylenephosphate and 2-methylimidazole.

3. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The surfactant is selected from one or any combination of triethanolamine, sodium stearate, dodecyl sulfonic acid and hexadecyltrimethylammonium bromide.

4. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The molar ratio of the cobalt salt, the manganese salt and the aluminum salt is 2:1:1 to 2:3:

1.

5. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The molar ratio of the complexing agent to the sum of the three metal ions of cobalt, manganese and aluminum is 20:1-50:

1.

6. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The molar ratio of the surfactant to the sum of the three metal ions of cobalt, manganese and aluminum is 1:5-1:

10.

7. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The solvent used in the complexation reaction is selected from one or any combination of water, methanol, ethanol, isopropanol and n-butanol.

8. The method for preparing the cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to claim 1, characterized in that: The calcination temperature is 200~400℃ and the calcination time is 2~4h.

9. The cobalt-manganese-aluminum composite oxide catalyst prepared by the method for preparing a cobalt-manganese-aluminum composite oxide catalyst for catalytic combustion of toluene according to any one of claims 1 to 8, characterized in that: The specific surface area of ​​the catalyst is 100-150 m 2 / g, pore size is 2~50nm.

10. Use of the cobalt-manganese-aluminum composite oxide catalyst in catalytic combustion of toluene according to claim 9, characterized in that: The temperature of toluene catalytic combustion is 190~200℃.

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