A catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide and preparation method thereof

Abstract

The invention discloses a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide and a preparation method thereof. The catalyst comprises the following steps: using a ball milling method to mix Mn with different molar proportions of the substance; 2+ Salt, Ce 3+ Salt, Cu 2+ The salt and the stabilizer citric acid are ball-milled uniformly to obtain a uniform mixture of manganese, cerium and copper; the ball-milled sample is dried in an oven at 30°C-80°C; the sample is calcined at a high temperature of 360°C-400°C for 4h-8h to obtain a nanocatalyst for efficiently degrading toluene. The copper-doped manganese-cerium composite oxide catalyst synthesized by the present invention has good toluene degradation performance, low activation energy, strong oxygen circulation capacity, high stability, simple and safe operation, and energy saving and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and particularly relates to a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide and a preparation method thereof. Background Art

[0002] The emission of volatile organic compounds (VOCs) is one of the important causes of air pollution. Toluene (C7H8), which has toxic and malodorous properties, is the most representative VOCs and is a major source of PM2.5. 2.5 Toluene is a precursor of ozone and has certain damage to the human respiratory system and central nervous system. Toluene mainly comes from the petroleum and chemical industries and has been included in the list of pollutants that need to be controlled and treated in my country. Therefore, it is very important to remove toluene from the atmosphere efficiently.

[0003] The catalytic combustion method can oxidize toluene into green and non-toxic CO2 and H2O by heating. This method has been widely used because of its relatively low heating temperature and environmental friendliness. Manganese (Mn)-based catalyst is a transition metal catalyst. The Mn element is economical, easily available, environmentally friendly, and its oxide has the advantages of multiple valence states and multiple structures. It is a good catalyst for the catalytic combustion of toluene. However, with the continuous deepening of research, some defects have been found: (1) The valence state of manganese-based catalysts is changeable, and the electronic layer structure causes it to easily gain and lose electrons, and its oxygen storage performance is weak; (2) The Mn-O bond energy is large and not easy to break, and the activation energy required for the reaction is high. The cerium (Ce) element has a special 4f electron layer structure, which is easy to form oxygen vacancies; the copper (Cu) element can react with Mn. reaction and reduce the activation energy required for the reaction. Therefore, combining cerium, copper and manganese-based catalysts can effectively improve the above defects, that is, utilizing the excellent oxygen storage and release capacity of Ce to improve the oxygen mobility of the catalyst; utilizing the ability of Cu to accelerate electron transfer to achieve efficient degradation of toluene.

[0004] At present, some studies have confirmed that the catalyst prepared by combining the three elements of manganese, cerium and copper has a good effect on the catalytic combustion of toluene, but the preparation methods of these catalysts have the disadvantages of being complex, high energy consumption and low safety performance. Zhou et al. (Zhou et al. Environmental Science and Pollution Research, 2020) prepared CeO2-CuMnO4 by high-temperature hydrothermal method, which has a good effect on degrading toluene. The preparation method requires the addition of four organic reagents, and the reaction is stirred in the solution, which is costly and energy-intensive (calcined at 600°C). Lu et al. (Lu et al, Journal of Environmental Sciences, 2015) prepared a manganese-cerium-copper catalyst by sol-gel method, which has a good catalytic degradation effect on toluene, but the preparation method has a long cycle (especially overnight drying, more than 12 hours) and high energy consumption (drying at 110°C and calcining at 500°C). Hu Minghua et al. (Hu Minghua, et al. Journal of Jianghan University, 2020) prepared Cu1Mn1Ce3O containing manganese, cerium and copper by coprecipitation. x The catalyst has good low-temperature reducibility and good toluene degradation effect. Its reaction conditions are harsh (the pH value needs to be maintained at 11), the reaction process is complicated, and the energy consumption is high (drying for 12 hours, calcination at 500°C). Summary of the invention

[0005] To overcome the deficiencies in the prior art, the present invention aims to provide a catalyst and a preparation method for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide, which has low energy consumption, short cycle, simple process and high degradation rate for toluene.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide comprises the following steps:

[0008] Mn was prepared by ball milling 2+ Salt, Ce 3+ Salt, Cu 2+ After ball milling with salt and citric acid, drying and calcination, a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide is obtained.

[0009] Furthermore, Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of the salt is controlled at 5:0.2:0.5 to 5:2:1.5.

[0010] Furthermore, citric acid and Mn 2+The molar ratio of the salt is controlled at 1:1 to 5:1.

[0011] Furthermore, Mn 2+ Salt, Ce 3+ Salt, Cu 2+ The salt and citric acid are dry ball milled at a drying temperature of 30°C-80°C for 0.5h-1h.

[0012] Furthermore, the rotation speed of the dry ball milling is 400 rpm-600 rpm, and the time is 10 min-30 min.

[0013] Furthermore, the calcination temperature is 360°C-400°C, and the calcination time is 4h-8h.

[0014] Furthermore, Mn 2+ The salt is (CH3COO)2Mn or Mn(NO3)2.

[0015] Furthermore, Ce 3+ The salt is Ce(NO3)3·6H2O or Ce(CH3COO)3·4H2O.

[0016] Furthermore, Cu 2+ The salt is Cu(NO3)2·3H2O or Cu(CH3COO)2.

[0017] A catalyst for catalytic combustion of toluene using a copper-doped manganese-cerium composite oxide prepared according to the method described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention adopts ball milling-calcination method as a method for preparing copper-doped manganese-cerium composite oxide catalyst. The ball milling method can 2+ Salt, Ce 3+ Salt and Cu 2+ The salts are mixed evenly, and the solid phase reaction provided by ball milling reduces the loss of Mn, Ce, and Cu ions, increasing the yield. 3+ The radius changes in the direction of decreasing, getting closer to the radius of other metal ions, reducing the ionic bond energy, making it easier to break chemical bonds, and prone to redox reactions, thereby generating a copper-doped manganese-cerium composite oxide catalyst. Ball milling is used for mixing, which is simple, low-cost, with fewer steps and less reagents. 2+ Salt, Ce 3+ Salt and Cu 2+ After adding three salts and stabilizer citric acid, the ball mill can be started. No other reagents, such as liquid solvents, need to be added, and the operation is safe. The existing technology requires gradually adding reagents into the solution, mixing under continuous stirring, pressurizing, etc.

[0020] Furthermore, the ball milling time in the present invention is short, requiring only 10 minutes at least, while other mixing methods require much more than 30 minutes.

[0021] Furthermore, the drying time is short and the energy consumption is low. The present invention adopts dry ball milling, and the raw materials for ball milling contain only a very small amount of bound water, so the drying temperature is low and the drying time is short. Compared with the currently commonly used solution method of adding a large amount of solvent, the drying time is much shorter.

[0022] Furthermore, the calcination temperature is low and the energy consumption is small. The invention can prepare the copper-doped manganese-cerium composite oxide by calcination at 320°C-380°C, while the commonly used calcination temperature is mostly above 500°C.

[0023] The copper-doped manganese-cerium composite oxide prepared by the invention has a T 90 The catalytic temperature at a conversion rate of 90% is as low as 260°C, which is lower than the T of the manganese-cerium-copper catalyst for toluene degradation under the same test conditions reported in existing studies. 90 The copper-doped manganese-cerium composite oxide prepared by the invention has good stability and cyclability. 90 The temperature can be maintained for more than 48 hours without changing. The activation energy of the obtained copper-doped manganese-cerium composite oxide is as low as 96.6 kJ / mol, which is about 30 kJ / mol lower than that of the manganese-cerium composite oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the efficiency diagram of the catalytic combustion of toluene by the copper-doped manganese-cerium composite oxide prepared by the method;

[0025] Figure 2 This is the conversion efficiency diagram of toluene catalytic combustion of copper-doped manganese-cerium composite oxide (Mn:Ce:Cu=5:1:1) at 260℃;

[0026] Figure 3 X-ray diffraction (XRD) patterns of manganese-cerium composite oxide (Mn:Ce=5:1) and copper-doped manganese-cerium composite oxide (Mn:Ce:Cu=5:1:1), wherein (a) is an X-ray diffraction pattern, and (b) is a partial enlarged view of (a);

[0027] Figure 4 The energy dispersive spectroscopy (EDS) diagram of the elements in copper-doped manganese-cerium composite oxide (Mn:Ce:Cu=5:1:1); wherein (a) is the EDS diagram of the catalyst as a whole, and (b) is the EDS diagram of the Cu element;

[0028] Figure 5 This is a scanning electron microscope (SEM) image of copper-doped manganese-cerium composite oxide (Mn:Ce:Cu=5:1:1). DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific implementation schemes and drawings.

[0030] The invention provides a method for preparing a copper-doped manganese-cerium composite oxide catalyst which is low in cost, simple in operation, good in recyclability and environmentally friendly, and endows the catalyst with good toluene degradation performance. Specifically, the catalyst can maintain a toluene removal rate of 90% for 48 hours at 260° C., has good stability and recyclability, and is energy-saving and environmentally friendly.

[0031] The preparation method of the copper-doped manganese-cerium composite oxide catalyst for catalytic combustion of toluene comprises the following steps:

[0032] (1) Preparation of precursor: Add a certain amount of Mn into the ball mill 2+ Salt, Ce 3+ Salt, Cu 2+ Salt and stabilizer citric acid, of which Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is controlled at 5:0.2:0.5 to 5:2:1.5, citric acid and Mn 2+ The molar ratio of the salt is controlled at 5:1 to 1:1, and the ball milling is performed at a rate of 400 rpm to 600 rpm for 10 min to 30 min to obtain a uniformly distributed precursor. 2+ The salt is (CH3COO)2Mn or Mn(NO3)2, Ce 3+ The salt is Ce(NO3)3·6H2O or Ce(CH3COO)3·4H2O, Cu 2+ The salt is Cu(NO3)2·3H2O or Cu(CH3COO)2.

[0033] (2) Drying the precursor: Place the precursor obtained by ball milling in an oven at 30°C-80°C and dry it for 0.5h-1h.

[0034] (3) Calcination to prepare copper-doped manganese-cerium composite oxide: The precursor dried in step (2) is calcined in a muffle furnace at 360° C.-400° C. for 4 h-8 h to generate a solid powder, which is a catalyst for the catalytic combustion of toluene by the copper-doped manganese-cerium composite oxide.

[0035] The obtained copper-doped manganese-cerium composite oxide catalyst has good oxygen cycle performance and can degrade toluene. 90 As low as 260°C.

[0036] The activation energy of the obtained copper-doped manganese-cerium composite oxide catalyst is about 30 kJ / mol lower than that of the manganese-cerium composite oxide prepared by the present method.

[0037] If the ratio of the amount of Mn, Ce, and Cu in the present invention is exceeded, the prepared nanocatalyst T 90 The temperature is high, the activation energy is high, and the toluene degradation efficiency is low.

[0038] The following are specific embodiments.

[0039] Example 1

[0040] Synthesis of Mn5Ce 0.2 Cu 0.5 Nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 5:0.2:0.5, citric acid and Mn 2+ The salt molar ratio is 5:1).

[0041] The specific steps are as follows:

[0042] (1) Preparation of precursor: Add Mn and Nd in a ratio of 5:0.2:0.5 into a ball mill. 2+ Salt, Ce 3+ Salt and Cu 2 + Salt, citric acid and Mn 2+ The molar ratio of salt was 5:1, and the copper-doped manganese-cerium composite oxide precursor was obtained by ball milling at a rate of 400 rpm for 10 min. 2+ The salt is Mn(NO3)2, Ce 3+ The salt is Ce(CH3COO)3·4H2O, Cu 2+ The salt is Cu(NO3)2·3H2O.

[0043] (2) Drying the precursor: Place the ball-milled precursor in an oven at 30°C and dry for 0.5 h.

[0044] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 360° C. for 4 h to generate a solid powder, namely Mn5Ce 0.2 Cu 0.5 Nanocatalyst.

[0045] Example 2

[0046] Synthesis of Mn5Ce2Cu 1.5 Nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 5:2:1.5, citric acid and Mn 2+ The salt molar ratio is 4:1).

[0047] The specific steps are as follows:

[0048] (1) Preparation of precursor: Add Mn and Nd in a ratio of 5:2:1.5 into a ball mill. 2+ Salt, Ce 3+ Salt and Cu 2+ Salt, citric acid and Mn 2+ The molar ratio of salt was 4:1, and the copper-doped manganese-cerium composite oxide precursor was obtained by ball milling at a speed of 600 rpm for 30 min. 2+ The salt is (CH3COO)2Mn, Ce 3+ The salt is Ce(CH3COO)3·4H2O, Cu 2+ The salt is Cu(CH3COO)2.

[0049] (2) Drying the precursor: Place the ball-milled precursor in an oven at 80°C and dry for 1 h.

[0050] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 400° C. for 8 h to generate a solid powder, namely Mn5Ce2Cu 1.5 Nanocatalyst.

[0051] Example 3

[0052] Synthesis of Mn5Ce 0.7 Cu1 nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 5:0.7:1, citric acid and Mn 2+ The salt molar ratio is 2:1).

[0053] The specific steps are as follows:

[0054] (1) Preparation of precursor: Add Mn and Nd in a ratio of 5:0.7:1 into a ball mill. 2+ Salt, Ce 3+ Salt and Cu 2+ Salt, citric acid and Mn 2+ The molar ratio of salt was 2:1, and the copper-doped manganese-cerium composite oxide precursor was obtained at a rate of 500 rpm for 15 min. 2+ The salt is Mn(NO3)2, Ce 3+ The salt is Ce(CH3COO)3·4H2O, Cu 2+ The salt is Cu(CH3COO)2.

[0055] (2) Drying the precursor: Place the ball-milled precursor in an oven at 70°C and dry for 1 h.

[0056] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 380° C. for 6 h to generate a solid powder, namely Mn5Ce 0.7 Cu1 nanocatalyst.

[0057] Example 4

[0058] Synthesis of Mn5Ce 0.8 Cu1 nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 5:0.8:1, citric acid and Mn 2+ The salt molar ratio is 1:1).

[0059] The specific steps are as follows:

[0060] (1) Preparation of precursor: Add Mn and Nd in a ratio of 5:0.8:1 into a ball mill. 2+ Salt, Ce 3+ Salt and Cu 2+ Salt, citric acid and Mn 2+ The molar ratio of salt was 1:1, and the copper-doped manganese-cerium composite oxide precursor was obtained at a rate of 500 rpm for 15 min. 2+ The salt is (CH3COO)2Mn, Ce 3+ The salt is Ce(NO3)3·6H2O, Cu 2+ The salt is Cu(NO3)2·3H2O.

[0061] (2) Drying the precursor: Place the ball-milled precursor in an oven at 70°C and dry for 1 h.

[0062] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 380° C. for 6 h to generate a solid powder, namely Mn5Ce 0.8 Cu1 nanocatalyst.

[0063] Example 5

[0064] Synthesis of Mn5Ce 0.9 Cu1 nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 5:0.9:1, citric acid and Mn 2+ The salt molar ratio is 2:1).

[0065] The specific steps are as follows:

[0066] (1) Preparation of precursor: Add Mn and Nd in a ratio of 5:0.9:1 into a ball mill. 2+Salt, Ce 3+ Salt and Cu 2+ Salt, citric acid and Mn 2+ The molar ratio of salt was 2:1, and the copper-doped manganese-cerium composite oxide precursor was obtained at a rate of 500 rpm for 15 min. 2+ The salt is (CH3COO)2Mn, Ce 3+ The salt is Ce(NO3)3·6H2O, Cu 2+ The salt is Cu(NO3)2·3H2O.

[0067] (2) Drying the precursor: Place the ball-milled precursor in an oven at 70°C and dry for 1 h.

[0068] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 380° C. for 6 h to generate a solid powder, namely Mn5Ce 0.9 Cu1 nanocatalyst.

[0069] Example 6

[0070] Synthesis of Mn5Ce1Cu1 nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 5:1:1, citric acid and Mn 2+ The salt molar ratio is 2:1).

[0071] The specific steps are as follows:

[0072] (1) Preparation of precursor: Add Mn and Nd in a ratio of 5:1:1 into a ball mill. 2+ Salt, Ce 3+ Salt and Cu 2+ Salt, citric acid and Mn 2+ The molar ratio of salt was 2:1, and the copper-doped manganese-cerium composite oxide precursor was obtained at a rate of 500 rpm for 15 min. 2+ The salt is (CH3COO)2Mn, Ce 3+ The salt is Ce(NO3)3·6H2O, Cu 2+ The salt is Cu(NO3)2·3H2O.

[0073] (2) Drying the precursor: Place the ball-milled precursor in an oven at 70°C and dry for 1 h.

[0074] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 380° C. for 6 h to generate a solid powder, which is the Mn5Ce1Cu1 nanocatalyst.

[0075] Example 7

[0076] Synthesis of Mn6Ce1Cu 1.5 Nanocatalyst (Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is 6:1:1.5, citric acid and Mn 2+ The salt molar ratio is 1:1).

[0077] The specific steps are as follows:

[0078] (1) Preparation of precursor: Add Mn and Nd in a mass ratio of 6:1:1.5 into a ball mill. 2+ Salt, Ce 3+ Salt and Cu 2+ Salt, citric acid and Mn 2+ The molar ratio of salt was 1:1, and the copper-doped manganese-cerium composite oxide precursor was obtained at a rate of 500 rpm for 15 min. 2+ The salt is (CH3COO)2Mn, Ce 3+ The salt is Ce(NO3)3·6H2O, Cu 2+ The salt is Cu(NO3)2·3H2O.

[0079] (2) Drying the precursor: Place the ball-milled precursor in an oven at 70°C and dry for 1 h.

[0080] (3) Calcination of copper-doped manganese-cerium composite oxide: The precursor in step (2) was calcined in a muffle furnace at 380° C. for 6 h to generate a solid powder, namely Mn6Ce1Cu 1.5 Nanocatalyst.

[0081] The following is a comparative example.

[0082] Comparative Example 1

[0083] Synthesis of Mn5Ce1 nanocatalyst (Mn 2+ Salt and Ce 3+ The molar ratio of salt is 5:1, no Cu is added 2+ Salt, citric acid and Mn 2+ The salt molar ratio is 2:1).

[0084] The specific steps are as follows:

[0085] (1) Preparation of precursor: Add Mn and Nd in a mass ratio of 5:1 into a ball mill. 2+ Salt and Ce 3+ Salt, citric acid and Mn 2+ The molar ratio of salt was 2:1, and the manganese-cerium composite oxide precursor was obtained by ball milling at a rate of 500 rpm for 15 min. 2+The salt is (CH3COO)2Mn, Ce 3+ The salt is Ce(NO3)3·6H2O.

[0086] (2) Drying the precursor: Place the ball-milled precursor in an oven at 70°C and dry for 1 h.

[0087] (3) Calcination of manganese-cerium composite oxide: The precursor in step (2) is calcined in a muffle furnace at 380° C. for 6 h to generate a solid powder, which is the Mn5Ce1 nanocatalyst.

[0088] Figure 1 The efficiency diagram of the catalytic combustion of toluene by the copper-doped manganese-cerium composite oxide prepared by this method. The degradation conditions are: 1000ppm toluene, 20% O2, and a space velocity of 60000mL·g -1 ·h -1 , 40-60 mesh catalyst 0.1g. Figure 1 It can be seen that the copper-doped manganese-cerium composite oxide prepared by this method has good catalytic activity for toluene. The activation energy of the copper-doped manganese-cerium composite oxide (Example 6) is as low as 96.6 kJ / mol, which is about 30 kJ / mol lower than that of the manganese-cerium composite oxide (Comparative Example 1). Under the same test conditions, T 90 It can be as low as 260℃, which is lower than the T reported in existing studies. 90 .

[0089] Figure 2 The stability diagram of Mn5Ce1Cu1 catalyst at 260℃. Figure 2 It can be seen that the Mn5Ce1Cu1 catalyst can maintain a toluene degradation rate of 90% for 48 hours at 260°C, indicating that the catalyst has good stability.

[0090] Figure 3 (a) is the XRD pattern of Mn5Ce1 and Mn5Ce1Cu1. Figure 3 It can be seen from (a) and (b) that in Mn5Ce1, 18.0°, 32.5° and 36.0° are the main characteristic peaks of Mn3O4, and 28.7°, 47.9° and 68.8° are the main characteristic peaks of CeO2; in Mn5Ce1Cu1, 18.8°, 33.2° and 36.8° are the main characteristic peaks of Mn3O4, and 29.7° and 48.7° are the main characteristic peaks of CeO2. No characteristic peaks related to CuO were found. However, the peak positions of Mn3O4 and CeO2 in Mn5Ce1Cu1 shifted to higher angles compared with those in Mn5Ce1, and EDS scanning detected that Cu ions were uniformly distributed in the catalyst (see Figure 2). Figure 4 (a) and (b)), so Cu exists in the catalyst in the form of doping.

[0091] Figure 5 This is a SEM image of the Mn5Ce1Cu1 nanocatalyst. As can be seen from the image, the catalyst is composed of nanoparticles with a diameter of about 20nm.

[0092] The ball milling-calcination method adopted by the present invention is used to prepare the copper-doped manganese-cerium composite oxide catalyst. Compared with the existing preparation method, the present invention does not need to prepare a solution, repeatedly precipitate, control the pH value of the reaction, ultrasound and stirring, and the operation is simpler and more convenient; the drying temperature is lower and the time is shorter, which reduces the preparation time and energy consumption, has low reagent cost, good safety performance, and is green and environmentally friendly; and the catalytic combustion of toluene is good. The copper-doped manganese-cerium composite oxide catalyst synthesized by the present invention has good toluene degradation performance, high toluene degradation rate, low activation energy, strong oxygen circulation capacity, high stability, simple and safe operation, energy saving and environmental protection.

[0093] It should be noted that the above implementation does not limit the present invention in any form, and any technical solutions obtained by using equivalent or replacement or equivalent changes fall within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide, characterized in that: The following steps are involved: Mn was removed by dry ball milling 2+ Salt, Ce 3+ Salt, Cu 2+ After ball milling with salt and citric acid, drying and calcination, a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide is obtained; Mn 2+ Salt, Ce 3+ Salt and Cu 2+ The molar ratio of salt is controlled at 5:0.2:0.5 ~ 5:2:1.

5.

2. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 1, characterized in that: Citric acid and Mn 2+ The molar ratio of salt is controlled between 1:1 and 5:

1.

3. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 1, characterized in that: Mn 2+ Salt, Ce 3+ Salt, Cu 2+ Salt and citric acid are dry ball milled at a drying temperature of 30 ℃-80 ℃ for 0.5 h-1 h.

4. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 3, characterized in that: The rotation speed of dry ball milling is 400 rpm-600 rpm, and the time is 10 min-30 min.

5. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 1, characterized in that: The calcination temperature is 360 ℃-400 ℃, and the time is 4 h-8 h.

6. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 1, characterized in that: Mn 2+ The salt is (CH3COO)2Mn or Mn(NO3)2.

7. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 1, characterized in that: Ce 3+ The salt is Ce(NO3)3∙6H2O or Ce(CH3COO)3∙4H2O.

8. The method for preparing a catalyst for catalytic combustion of toluene by copper-doped manganese-cerium composite oxide according to claim 1, characterized in that: Cu 2+ The salt is Cu(NO3)2∙3H2O or Cu(CH3COO)2.

9. A catalyst for catalytic combustion of toluene using a copper-doped manganese-cerium composite oxide prepared by the method according to any one of claims 1 to 8.

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