Indium-gallium-cerium composite metal oxide catalyst, preparation method thereof and application of catalyst in preparation of dimethyl carbonate by catalyzing methanol carbonylation

Abstract

The invention discloses a method for preparing dimethyl carbonate through direct carbonylation of methanol under catalysis of an indium gallium cerium composite oxide, and belongs to the technical field of catalysts. The preparation method of the catalyst comprises the following four steps: step 1, stirring and dissolving indium, gallium and cerium metal salts and citric acid in deionized water; 2, heating the catalyst precursor solution, and taking out the catalyst precursor solution after water is evaporated to form a viscous sol-like mixture; 3, placing the sol-like mixture in a drying oven for drying; and 4, transferring the dried solid into a muffle furnace, and calcining in an air atmosphere to obtain the indium-gallium-cerium composite metal oxide catalyst. The preparation method of the catalyst is simple, the catalyst is nanoparticles, the specific surface area is large, the number of active sites is large, and the catalyst has excellent catalytic performance when being applied to the reaction of preparing dimethyl carbonate through direct carbonylation of methanol and CO2.

Description

Technical Field

[0001] The present invention belongs to methanol and CO 2 The technical field of preparing dimethyl carbonate by direct carbonylation is particularly concerned with an indium gallium cerium composite metal oxide catalyst and a preparation method thereof, and application of the catalyst in preparing dimethyl carbonate by catalyzing the direct carbonylation of methanol. Background Art

[0002] Dimethyl carbonate (DMC) is an important chemical raw material and organic solvent, widely used in the fields of medicine, pesticides, solvents, lubricants and polymer materials. Traditional methods for preparing DMC mainly include phosgene method, ethylene carbonate method and direct oxidation method, but these methods have significant disadvantages. Phosgene method has poor safety due to the use of highly toxic phosgene, and will produce a large number of toxic by-products, causing serious pollution to the environment. Although the ethylene carbonate method reduces some toxicity problems, the cost of the raw material ethylene carbonate is high, and the by-products generated during the reaction are cumbersome to handle, which increases the difficulty and cost of production. The direct oxidation method relies on efficient catalysts, which are usually expensive and easy to deactivate. At the same time, the method requires high temperature and high pressure conditions, making the production process complicated and costly. Chinese patent CN114054043B discloses a catalyst for synthesizing dimethyl carbonate using a mixture of aluminum oxide, silicon dioxide and calcium oxide as a carrier, palladium as an active component, and copper, titanium and nickel metals as additives. The preparation process is cumbersome, and the reaction uses CO toxic gas, which brings great safety hazards.

[0003] The method of synthesizing DMC by direct carbonylation of methanol and carbon dioxide has significant advantages in environmental protection, economy and safety. First of all, by utilizing carbon dioxide, a greenhouse gas, this method not only effectively reduces its emissions, but also helps to alleviate the problem of global warming. Economically, methanol is cheap and widely available, and carbon dioxide can also be captured from industrial waste gas, with low raw material costs. At the same time, the direct synthesis method has a simple process flow, low equipment requirements, and is easy to achieve industrial production, thereby reducing the overall production cost. In terms of safety, methanol and carbon dioxide are relatively safe, easy to store and transport, reducing potential safety risks, and there is no need to use highly toxic and high-risk phosgene during the reaction process, and the operating environment is safer. With the continuous advancement of catalyst technology and reaction engineering, the efficiency of this method will be further improved, the production cost will be further reduced, and it has broad prospects for industrial application. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the problems of high raw material toxicity, complex process, environmental pollution, high cost and the like brought about by the traditional DMC synthesis method, thereby providing a green and environmentally friendly DMC synthesis route with readily available raw materials and simplified process, and thus providing an indium gallium cerium composite metal oxide catalyst with high conversion rate, difficulty in deactivation and good stability, a preparation method thereof and an application of the catalyst in catalyzing the carbonylation of methanol to prepare dimethyl carbonate.

[0005] The technical solution provided by the present invention is as follows:

[0006] A method for preparing an indium gallium cerium composite metal oxide catalyst comprises the following steps:

[0007] 1) Mixing and dissolving metal salts of indium, gallium and cerium with citric acid in deionized water, stirring to form a catalyst precursor solution; based on 1 mol of citric acid, the amounts of metal salts of indium, gallium and cerium are 0.05-0.2 mol, 0-0.2 mol and 0.6-0.9 mol respectively;

[0008] 2) adding nitric acid dropwise to the catalyst precursor solution of step 1) to adjust the pH to 1-2, heating and stirring, and taking out after the water evaporates to form a viscous sol-like mixture;

[0009] 3) Step 2) The sol-like mixture is dried and then transferred to a muffle furnace and calcined in an air atmosphere to obtain an InGaC composite metal oxide catalyst.

[0010] Furthermore, the metal salts of indium, gallium and cerium in step 1) are independently selected from chlorides, nitrates, sulfates or acetylacetonates of the respective metals; based on 1 mol of citric acid, the amounts of the metal salts of indium, gallium and cerium are 0.1-0.2 mol, 0.05-0.1 mol and 0.8-0.9 mol respectively; the ratio of the total molar amount of the indium metal salt and the gallium metal salt to the molar amount of citric acid is 0.2-0.25:1.

[0011] Furthermore, in step 1), metal salts of indium, gallium and cerium are dissolved in deionized water by stirring, and citric acid is added after stirring for 10-30 minutes, and stirring is continued until the citric acid is completely dissolved.

[0012] Furthermore, in step 2), the catalyst precursor solution is heated in an oil bath at a temperature of 60-150° C., preferably 70-90° C., and is heated while being stirred.

[0013] Furthermore, step 3) is calcined in stages in a muffle furnace, with the temperature of the first stage being 200-500°C, preferably 300-350°C, and calcining for 1-3h; in the second stage, the temperature is increased to 600-900°C, preferably 700-750°C, and calcining for 4-8h.

[0014] The present invention also discloses the application of the indium gallium cerium composite metal oxide catalyst, which is used for catalyzing the reaction of methanol and CO. 2 In the direct carbonylation reaction to prepare dimethyl carbonate, the application method is: add methanol and a catalyst into a high-pressure reactor, fill with 0.1-10MPa carbon dioxide, preferably 2-6MPa, and check the air tightness of the reactor; when ensuring good air tightness, increase the temperature to 50-200°C, preferably 90-180°C, at a heating rate of 1-10°C / min, react for 1-24h, preferably 2-15h, and then cool to obtain the product.

[0015] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0016] 1) The present invention uses an indium gallium cerium composite metal oxide catalyst to catalyze the reaction of methanol and CO 2 Direct carbonylation to prepare dimethyl carbonate has many significant advantages. First, the catalyst exhibits high selectivity and high catalytic activity during the reaction, which can effectively improve the product yield and reduce the generation of by-products. Chinese patent CN102423707B discloses an iron zirconium oxide catalyst for the catalytic reaction of methanol and CO 2 The direct carbonylation method is used to prepare dimethyl carbonate, with a methanol conversion rate of 0.8509% and a dimethyl carbonate selectivity of 87.12%. The catalytic activity of the catalyst of the present invention is significantly improved compared with that of Chinese patent CN102423707B.

[0017] 2) Indium gallium cerium composite metal oxide catalyst has excellent durability and stability, and can maintain efficient catalytic performance even after multiple cycles of use, reducing the cost of catalyst use. Furthermore, this method uses methanol and carbon dioxide as raw materials. The latter is an industrial by-product, and the former is widely available and economical, making the raw material supply stable and economically feasible. Most importantly, this process is green and environmentally friendly, overcoming the problems of high raw material toxicity, complex process, and environmental pollution brought about by the traditional DMC synthesis method, helping to reduce greenhouse gas emissions and meeting the requirements of green chemistry and sustainable development. Overall, the Indium gallium cerium composite metal oxide catalyst has excellent performance in methanol and CO 2 It shows great research value and application prospects in the application of direct carbonylation to prepare dimethyl carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 For methanol and CO 2 Direct carbonylation of dimethyl carbonate catalyst In 0.1 Ga 0.1 Ce 0.8 O x Transmission electron microscopy spectrum.

[0019] Figure 2Methanol and CO in Examples 1-6 2 Comparison of catalytic performance of catalysts for direct carbonylation to prepare dimethyl carbonate. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0021] Example 1: In 0.05 Ga 0.05 Ce 0.9 O x Preparation of catalysts and their application in methanol and CO 2 The direct carbonylation reaction for preparing dimethyl carbonate comprises the following steps:

[0022] Preparation of In using citric acid-assisted sol-gel method 0.05 Ga 0.05 Ce 0.9 O x Catalyst: weigh a certain amount of indium nitrate, gallium nitrate, and cerium nitrate, dissolve them in 40 mL of deionized water, stir and heat to fully mix and dissolve them, stir for 30 minutes, add 2.1 g of citric acid AC to the solution to form a catalyst precursor solution, and make the molar ratio of the precursor solution be AC: In(NO 3 ) 3 :Ga(NO 3 ) 3 :Ce(NO 3 ) 3 =1:0.05:0.05:0.9, where the concentration of citric acid AC in the solution is 0.274mmol / mL. Nitric acid is added dropwise to adjust the pH of the precursor solution to 1-2. The precursor solution is heated and stirred in an 80°C oil bath, and after the water evaporates to form a sol mixture, it is taken out and placed in a 110°C oven to dry overnight. The dried sample is placed in a muffle furnace with an air atmosphere at 350°C and calcined for 1h, and then the temperature is raised to 700°C and calcined for 5h to obtain In. 0.05 Ga 0.05 Ce 0.9 O x catalyst.

[0023] Using the In prepared in Example 1 0.05 Ga 0.05 Ce 0.9 O x The catalyst is used for catalytic reaction: add 10ml methanol and 0.5g catalyst into the autoclave, fill with 3MPa carbon dioxide, seal, and check the air tightness of the autoclave. When the air tightness is good, increase the temperature to 150℃ at a rate of 5℃ / min, react for 6h, and then cool to obtain the product. 0.05 Ga0.05 Ce 0.9 O x Catalysts for methanol and CO 2 The catalytic performance of direct carbonylation to prepare dimethyl carbonate was as follows: methanol conversion rate was 1.27%, dimethyl carbonate selectivity was nearly 100% ( Figure 2 ).

[0024] Example 2: In 0.1 Ga 0.1 Ce 0.8 O x Preparation of catalysts and their application in methanol and CO 2 The direct carbonylation reaction for preparing dimethyl carbonate comprises the following steps:

[0025] Preparation of In using citric acid-assisted sol-gel method 0.1 Ga 0.1 Ce 0.8 O x Catalyst: Weigh a certain mass of indium nitrate, gallium nitrate, and cerium nitrate, dissolve them in 40g of deionized water, stir and heat to fully mix and dissolve them, stir for 30min, add 2.1g of citric acid (AC) to the solution to form a catalyst precursor solution, and make the molar ratio of the precursor solution be AC: In(NO 3 ) 3 :Ga(NO 3 ) 3 :Ce(NO 3 ) 3 =1:0.1:0.1:0.8. Nitric acid was added dropwise to adjust the pH of the precursor solution to 1-2, wherein the concentration of citric acid AC in the solution was 0.274mmol / mL. The precursor solution was heated and stirred in an 80°C oil bath, and after the water evaporated to form a sol mixture, it was taken out and placed in a 110°C oven to dry overnight. The dried sample was placed in a muffle furnace in an air atmosphere at 350°C and calcined for 1h, and then the temperature was raised to 700°C and calcined for 5h to obtain In. 0.1 Ga 0.1 Ce 0.8 O x catalyst.

[0026] Using the In prepared in Example 2 0.1 Ga 0.1 Ce 0.8 O x The catalyst is used for catalytic reaction: add 10ml methanol and 0.5g catalyst into the autoclave, fill with 3MPa carbon dioxide, seal, and check the air tightness of the autoclave. When the air tightness is good, increase the temperature to 150℃ at a rate of 5℃ / min, react for 6h, and then cool to obtain the product. 0.1 Ga0.1 Ce 0.8 O x Catalysts for methanol and CO 2 The catalytic performance of direct carbonylation to prepare dimethyl carbonate was as follows: methanol conversion rate was 1.80%, dimethyl carbonate selectivity was nearly 100% ( Figure 2 ).

[0027] In prepared in Example 2 0.1 Ga 0.1 Ce 0.8 O x The transmission electron microscopy spectrum of the catalyst is shown in Figure 1 As shown, from Figure 1 It can be seen that 0.1 Ga 0.1 Ce 0.8 O x The catalyst is a nanoparticle with a large specific surface area, which can expose more active sites and greatly promote the improvement of catalytic performance.

[0028] In addition, for the catalytic reaction in Example 2, a repeated application experiment of the catalyst was carried out. After the catalytic reaction was carried out at 150°C for 6 hours, it was cooled to room temperature, the catalyst was centrifuged and washed with methanol, and then put into the next catalytic experiment (considering that there is a certain loss in the catalyst recovery process, 0.01g of fresh catalyst was added each time the catalyst was applied). According to the above experimental process, the methanol and CO 2 The direct carbonylation reaction results are shown in Table 1.

[0029] Table 1

[0030]

[0031]

[0032] It can be seen from Table 1 that the InGaC composite metal oxide catalyst of the present invention has excellent durability and stability, and can maintain efficient catalytic performance even after multiple cycles of use.

[0033] Example 3: In 0.2 Ga 0.2 Ce 0.6 O x Preparation of catalysts and their application in methanol and CO 2 The direct carbonylation reaction for preparing dimethyl carbonate comprises the following steps:

[0034] Preparation of In using citric acid-assisted sol-gel method 0.2 Ga 0.2 Ce 0.6 O xCatalyst: Weigh a certain mass of indium nitrate, gallium nitrate, and cerium nitrate, dissolve them in 40 mL of deionized water, stir and heat to mix and dissolve them thoroughly, stir for 30 min, add 2.1 g of citric acid (AC) to the solution to form a catalyst precursor solution, and make the molar ratio of the precursor solution be AC: In(NO 3 ) 3 :Ga(NO 3 ) 3 :Ce(NO 3 ) 3 =1:0.2:0.2:0.6. Nitric acid was added dropwise to adjust the pH of the precursor solution to 1-2, wherein the concentration of citric acid AC in the solution was 0.274mmol / mL. The precursor solution was heated and stirred in an 80°C oil bath, and after the water evaporated to form a sol mixture, it was taken out and placed in a 110°C oven to dry overnight. The dried sample was placed in a muffle furnace in an air atmosphere at 350°C and calcined for 1h, and then the temperature was raised to 700°C and calcined for 5h to obtain In. 0.2 Ga 0.2 Ce 0.6 O x catalyst.

[0035] Using the In prepared in Example 3 0.2 Ga 0.2 Ce 0.6 O x The catalyst is used for catalytic reaction: add 10ml methanol and 0.5g catalyst into the autoclave, fill with 3MPa carbon dioxide, seal, and check the air tightness of the autoclave. When the air tightness is good, increase the temperature to 150℃ at a rate of 5℃ / min, react for 6h, and then cool to obtain the product. 0.2 Ga 0.2 Ce 0.6 O x Catalysts for methanol and CO 2 The catalytic performance of direct carbonylation to prepare dimethyl carbonate was as follows: methanol conversion rate was 0.96%, dimethyl carbonate selectivity was nearly 100% ( Figure 2 ).

[0036] By comparing the experimental results of Example 3 and Example 2, it can be seen that the amount of Ce salt used in the preparation of the catalyst has a great influence on the catalytic performance.

[0037] Example 4: Ga 0.2 Ce 0.8 O x Preparation of catalysts and their application in methanol and CO 2 The direct carbonylation reaction for preparing dimethyl carbonate comprises the following steps:

[0038] Preparation of Ga by citric acid-assisted sol-gel method0.2 Ce 0.8 O x Catalyst: Weigh a certain mass of gallium nitrate and cerium nitrate, dissolve them in 40 mL of deionized water, stir and heat to fully mix and dissolve them, stir for 30 min, add 2.1 g of citric acid (AC) to the solution to form a catalyst precursor solution, and make the molar ratio of the precursor solution be AC:Ga(NO 3 ) 3 :Ce(NO 3 ) 3 =1:0.2:0.8. Nitric acid was added dropwise to adjust the pH of the precursor solution to 1-2, wherein the concentration of citric acid AC in the solution was 0.274mmol / mL. The precursor solution was heated and stirred in an 80°C oil bath, and after the water evaporated to form a sol mixture, it was taken out and placed in a 110°C oven to dry overnight. The dried sample was placed in a muffle furnace in an air atmosphere at 350°C and calcined for 1h, and then the temperature was raised to 700°C and calcined for 5h to obtain Ga. 0.2 Ce 0.8 O x catalyst.

[0039] Using the Ga prepared in Example 4 0.2 Ce 0.8 O x The catalyst is used for catalytic reaction: add 10ml methanol and 0.5g catalyst into the autoclave, fill with 3MPa carbon dioxide, seal, and check the air tightness of the autoclave. When the air tightness is good, increase the temperature to 150℃ at a rate of 5℃ / min, react for 6h, and then cool to obtain the product. 0.2 Ce 0.8 O x Catalysts for methanol and CO 2 The catalytic performance of direct carbonylation to prepare dimethyl carbonate was as follows: methanol conversion rate was 1.1%, dimethyl carbonate selectivity was nearly 100% ( Figure 2 ).

[0040] Example 5: In 0.2 Ce 0.8 O x Preparation of catalysts and their application in methanol and CO 2 The direct carbonylation reaction for preparing dimethyl carbonate comprises the following steps:

[0041] Preparation of In using citric acid-assisted sol-gel method 0.2 Ce 0.8 O xCatalyst: Weigh a certain mass of gallium nitrate and cerium nitrate, dissolve them in 40 mL of deionized water, stir and heat to mix and dissolve them thoroughly, stir for 30 min, add 2.1 g of citric acid (AC) to the solution to form a catalyst precursor solution, and make the molar ratio of the precursor solution be AC: In(NO 3 ) 3 :Ce(NO 3 ) 3 =1:0.2:0.8. Nitric acid was added dropwise to adjust the pH of the precursor solution to 1-2, wherein the concentration of citric acid AC in the solution was 0.274mmol / mL. The precursor solution was heated and stirred in an 80°C oil bath, and after the water evaporated to form a sol mixture, it was taken out and placed in a 110°C oven to dry overnight. The dried sample was placed in a muffle furnace in an air atmosphere at 350°C and calcined for 1h, and then the temperature was raised to 700°C and calcined for 5h to obtain In. 0.2 Ce 0.8 O x catalyst.

[0042] Using the In prepared in Example 5 0.2 Ce 0.8 O x The catalyst is used for catalytic reaction: add 10ml methanol and 0.5g catalyst into the autoclave, fill with 3MPa carbon dioxide, seal, and check the air tightness of the autoclave. When the air tightness is good, increase the temperature to 150℃ at a rate of 5℃ / min, react for 6h, and then cool to obtain the product. 0.2 Ce 0.8 O x Catalysts for methanol and CO 2 The catalytic performance of direct carbonylation to prepare dimethyl carbonate was as follows: methanol conversion rate was 1.7%, dimethyl carbonate selectivity was nearly 100% ( Figure 2 ).

[0043] Example 6: Ni 0.2 Ce 0.8 O x Preparation of catalysts and their application in methanol and CO 2 The direct carbonylation reaction for preparing dimethyl carbonate comprises the following steps:

[0044] Preparation of Ni using citric acid-assisted sol-gel method 0.2 Ce 0.8 O x Catalyst: weigh a certain mass of nickel nitrate and cerium nitrate, dissolve them in 40 mL of deionized water, stir and heat to fully mix and dissolve them, stir for 30 min, add 2.1 g of citric acid (AC) to the solution to form a catalyst precursor solution, and make the molar ratio of the precursor solution be AC: Ni(NO 3 )3 :Ce(NO 3 ) 3 =1:0.2:0.8. Nitric acid was added dropwise to adjust the pH of the precursor solution to 1-2, wherein the concentration of citric acid AC in the solution was 0.274mmol / mL. The precursor solution was heated and stirred in an 80°C oil bath, and after the water evaporated to form a sol mixture, it was taken out and placed in a 110°C oven to dry overnight. The dried sample was placed in a muffle furnace in an air atmosphere at 350°C and calcined for 1h, and then the temperature was raised to 700°C and calcined for 5h to obtain Ni 0.2 Ce 0.8 O x catalyst.

[0045] Using the Ni prepared in Example 6 0.2 Ce 0.8 O x The catalyst is used for catalytic reaction: add 10ml methanol and 0.5g catalyst into the autoclave, fill with 3MPa carbon dioxide, seal, and check the air tightness of the autoclave. When the air tightness is good, increase the temperature to 150℃ at a rate of 5℃ / min, react for 6h, and then cool to obtain the product. Ni 0.2 Ce 0.8 O x Catalysts for methanol and CO 2 The catalytic performance of direct carbonylation to prepare dimethyl carbonate was as follows: methanol conversion rate was 0.18%, dimethyl carbonate selectivity was nearly 100% ( Figure 2 ).

[0047] In Examples 1-6, methanol and CO 2 Comparison of catalytic performance of catalysts for direct carbonylation to prepare dimethyl carbonate Figure 2 ,from Figure 2 All catalyst test performances show that In 0.1 Ga 0.1 Ce 0.8 O x The catalyst showed excellent catalytic activity. This is mainly attributed to the CeO 2 can provide abundant oxygen vacancies, which is essential for promoting CO 2 The activation and reaction of CeO 2 It also has good oxygen reduction properties, which can enhance the stability and catalytic activity of the catalyst. 2 O 3 and Ga 2 O 3 The combination provides multiple active sites in the catalyst. 2 O 3 It can effectively adsorb and activate carbon dioxide, and Ga 2 O 3It has good adsorption and activation ability for methanol. 2 O 3 and Ga 2 O 3 The combination of Ga plays a synergistic role in the reaction mechanism, making it easier for methanol and carbon dioxide to react to form dimethyl carbonate. 2 O 3 The addition of CeO will speed up the reaction and generate dimethyl carbonate more quickly. 2 The presence of In also makes the catalyst have good anti-poisoning ability, especially the by-product water generated during the reaction will not easily deactivate the catalyst. 0.1 Ga 0.1 Ce 0.8 O x The catalyst has good stability and efficient catalytic performance. Obviously, the above embodiments are only examples for clear explanation, and are not limitations on the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the invention.

[0048] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A method for preparing an indium gallium cerium composite metal oxide catalyst, characterized in that: The following steps are involved: 1) Mix and dissolve metal salts of indium, gallium and cerium with citric acid in deionized water and stir to form a catalyst precursor solution; Based on 1 mol of citric acid, the amounts of metal salts of indium, gallium and cerium are 0.05-0.2 mol, 0-0.2 mol and 0.6-0.9 mol respectively; 2) adding nitric acid to the catalyst precursor solution of step 1) to adjust the pH to 1-2, heating and stirring, and taking out after the water evaporates to form a viscous sol-like mixture; 3) Step 2) The sol-like mixture is dried and then transferred to a muffle furnace and calcined in an air atmosphere to obtain an InGaC composite metal oxide catalyst.

2. The method for preparing an indium gallium cerium composite metal oxide catalyst according to claim 1, characterized in that: In step 1), the metal salts of indium, gallium and cerium are independently selected from chlorides, nitrates, sulfates or acetylacetonates of the metals; based on 1 mol of citric acid, the amounts of the metal salts of indium, gallium and cerium are 0.1-0.2 mol, 0.05-0.1 mol and 0.8-0.9 mol respectively; the ratio of the total molar amount of the indium metal salt and the gallium metal salt to the molar amount of citric acid is 0.2-0.25:

1.

3. The method for preparing an indium gallium cerium composite metal oxide catalyst according to claim 1, characterized in that: In step 1), the metal salts of indium, gallium and cerium are dissolved in deionized water by stirring, and citric acid is added after stirring for 10-30 minutes, and stirring is continued until the citric acid is completely dissolved.

4. The method for preparing an indium gallium cerium composite metal oxide catalyst according to claim 1, characterized in that: In step 2), the catalyst precursor solution is heated in an oil bath at a temperature of 60-150°C, preferably 70-90°C, while being stirred.

5. The method for preparing an indium gallium cerium composite metal oxide catalyst according to claim 1, characterized in that: Step 3) calcining in a muffle furnace in stages, the temperature of the first stage is 200-500°C, preferably 300-350°C, and calcining for 1-3 h; in the second stage, the temperature is increased to 600-900°C, preferably 700-750°C, and calcining for 4-8 h.

6. An Indium Gallium Ce composite metal oxide catalyst prepared by the method according to any one of claims 1 to 5.

7. Use of an indium gallium cerium composite metal oxide catalyst as claimed in any one of claims 1 to 6, characterized in that The catalyst is used in the reaction of catalyzing direct carbonylation of methanol and CO2 to prepare dimethyl carbonate.

8. The use according to claim 7, characterized in that Add methanol and catalyst into the autoclave, fill with 0.1-10 MPa carbon dioxide, preferably 2-6 MPa, and check the air tightness of the autoclave; when ensuring good air tightness, increase the temperature to 50-200 °C, preferably 90-180 °C, at a heating rate of 1-10 °C / min, react for 1-24 h, preferably 2-15 h, and then cool to obtain the product.

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