A multi-metal oxide catalyst, a preparation method and application thereof

Abstract

The application discloses a multi-metal oxide catalyst and a preparation method and application thereof, and the composition of the catalyst comprises copper oxide, zinc oxide, zirconium oxide and indium oxide. In the catalyst, the mass fraction of the copper oxide is 5%-70%, the mass fraction of the zinc oxide is 5%-80%, the mass fraction of the zirconium oxide is 5%-50%, and the mass fraction of the indium oxide is 5%-60%. The application preferably adopts a multi-metal oxide system, the system has a synergistic effect among the metals, and the system can effectively improve the conversion rate of CO2 and the selectivity of methanol. By adjusting a reaction temperature and adding sodium citrate, the particle size of the catalyst is reduced, the formation of a metal interface is promoted, and the performance of the catalytic conversion of carbon dioxide is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a multi-metal oxide catalyst and a preparation method and application thereof. BACKGROUND

[0002] Efficient conversion and utilization of carbon dioxide has important strategic support significance for relieving energy crisis and achieving the goal of "carbon neutralization". Using green hydrogen from renewable energy and carbon dioxide to prepare methanol under relatively mild reaction conditions is an important way. The common CO2 hydrogenation catalysts at present mainly include Cu-based catalysts, In-based catalysts and oxide solid solution catalysts. Traditional metal oxide catalysts usually need a high reaction temperature (> 300℃) to catalyze CO2 hydrogenation to methanol, which is often accompanied by a serious reverse water gas shift reaction, resulting in a large amount of by-product carbon monoxide. The introduction of transition metal components into the metal oxide catalyst can promote the activation of H2 and thus reduce the reaction temperature, but at the same time it is easy to cause CO2 to be over-hydrogenated to methane, thereby reducing the selectivity of methanol. The mutual restriction of activity and selectivity in the metal / metal oxide catalytic hydrogenation system for preparing methanol seriously limits the improvement of low-temperature catalytic performance. Among the existing catalyst systems, Cu-based catalysts have good carbon dioxide catalytic conversion activity and are considered to be the most promising catalyst for industrial application, but they have the problem of easy sintering in the reaction atmosphere, which leads to catalyst deactivation, in addition, the selectivity of CO, alkane and other by-products is high. Therefore, it is urgent to develop a carbon dioxide hydrogenation catalyst for preparing methanol with high activity, high selectivity and high stability. SUMMARY

[0003] The application can effectively improve the low-temperature performance and stability of the catalyst by designing a multi-metal oxide solid solution.

[0004] The application aims to provide a multi-metal oxide catalyst, the composition of which comprises copper oxide, zinc oxide, zirconium oxide and indium oxide.

[0005] According to a specific embodiment of the application, the mass fraction of copper oxide in the catalyst is 5%-70%, the mass fraction of zinc oxide is 5%-80%, the mass fraction of zirconium oxide is 5%-50%, and the mass fraction of indium oxide is 5%-60%.

[0006] The second object of the application is to provide a preparation method of the above-mentioned catalyst, comprising the following steps:

[0007] S1, uniformly mixing copper salt, zinc salt, zirconium salt and indium salt in a solvent, adding sodium citrate to the mixture, and fully stirring to obtain a mixed solution A;

[0008] Before adding the base solution to adjust the pH, a proper amount of sodium citrate is added. Due to the special nature of sodium citrate, the addition of sodium citrate here improves the conversion rate of carbon dioxide and the selectivity of methanol. To solve the problem that the commonly used dispersants and stabilizers such as polyvinylpyrrolidone, polyethylene glycol, EDTA, etc. cannot well adjust the catalyst particle size to be more uniform, and more greatly improve the conversion rate of carbon dioxide and the selectivity of methanol, the acidic citric acid used in the prior art is used.

[0009] S2, keep the constant temperature T1, slowly add a base solution to the mixed solution A, adjust the pH of the solution to 7-10, preferably, adjust the pH of the solution to 8-9; keep the constant temperature T2, and make it fully react;

[0010] S3, after full reaction, centrifugation, washing, drying and calcination, the multi-metal oxide catalyst is obtained.

[0011] The centrifugation refers to centrifugal separation of the solid-liquid mixture after full reaction to obtain a solid product.

[0012] According to an embodiment of the present application, in step S1, the copper salt, zinc salt, zirconium salt and indium salt are selected from one or more of the corresponding nitrate, hydrochloride, sulfate and acetylacetone salt.

[0013] According to an embodiment of the present application, in step S1, the solvent is one or more of water, methanol and ethanol; preferably water.

[0014] According to an embodiment of the present application, in step S1, the mass ratio of sodium citrate to metal salt is 1:20-1:10; the mass of the metal salt is the mass sum of the copper salt, zinc salt, zirconium salt and indium salt.

[0015] According to an embodiment of the present application, in step S2, the base solution is one or more of sodium carbonate solution, potassium carbonate solution, ammonium carbonate solution, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the concentration of the base solution is 0.5-5.0 mol / L.

[0016] According to an embodiment of the present application, in step S1, the dropwise adding speed of the base solution is 1-5 drops per second.

[0017] According to an embodiment of the present application, in step S2, the temperature T1 is 20-80℃; the temperature T2 is 40-80℃, preferably 60℃, and the reaction time is 12-48 hours, preferably 24 hours.

[0018] According to one embodiment of the present application, in step S3, the calcination temperature is 200-400 DEG C, preferably 250 DEG C, the temperature rising rate is 2-5 DEG C per minute, and the time is 2-8 hours, preferably 2 hours.

[0019] According to one embodiment of the present application, in step S3, the calcination atmosphere is air.

[0020] Another object of the present application is to provide an application of the above-mentioned catalyst or the catalyst prepared by the above-mentioned preparation method in the carbon dioxide hydrogenation to methanol.

[0021] Advantages:

[0022] Compared with the prior art, the present application has the following advantages:

[0023] 1. The preferred multi-metal oxide system of the present application integrates CuO with excellent low-temperature performance, In2O3 with high-temperature performance, ZnO with long-term stability and ZrO2 together, and the components have a synergistic effect on each other, which can effectively improve the CO2 conversion rate and the methanol selectivity. By adjusting the reaction temperature and adding sodium citrate, the catalyst particle size is reduced and the metal interface formation is promoted, thereby improving the performance of the carbon dioxide catalytic conversion.

[0024] 2. The synthesis method of the present application is simple and environmentally friendly, and no organic solvent is needed. The composition and structure of the obtained catalyst are easy to control.

[0025] 3. The catalyst of the present application uses non-noble metal raw materials, and has the advantages of low price, simple preparation process, good repeatability and easy scale-up production.

[0026] 4. The catalyst of the present application has high carbon dioxide conversion rate and methanol selectivity at a relatively low reaction temperature (less than 300 DEG C).

[0027] The present application will be further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a transmission electron microscope (TEM) image of the multi-metal oxide catalyst prepared in Example 1.

[0029] Figure 2 FIG. 2 is an X-ray diffraction (XRD) pattern of the multi-metal oxide catalyst prepared in Example 1. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be further described below with reference to specific embodiments. The protection scope of the present application is not limited to the following embodiments, and these embodiments are listed only for exemplary purposes without limiting the present application in any way.

[0031] In the context of the present specification, unless explicitly stated otherwise, any matter or item not mentioned is directly applicable as known in the art without any change. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, whereby the resulting technical solution or technical idea is considered to be part of the original disclosure or original description of the present application and should not be considered as new content not disclosed or anticipated herein, unless the combination is considered to be obviously unreasonable by a person skilled in the art.

[0032] Carbon dioxide hydrogenation activity test

[0033] The catalyst prepared in the following examples and comparative examples was tested for carbon dioxide catalytic hydrogenation activity using a fixed bed microreactor, with a feed gas of H2, CO2 and Ar in a volume ratio of 72:24:4, and a space velocity of 12000 mL.g -1 ·min -1 The catalyst loading was 0.5 g, with 4.5 g of quartz sand, the reaction temperature was 200-300°C, and the reaction pressure was 3.0 MPa. A chromatograph equipped with a hydrogen flame ion detector and a thermal conductivity cell detector was used for sample analysis.

[0034] Example 1:

[0035] 15 g of copper nitrate, 10 g of zinc nitrate, 2.5 g of zirconium nitrate and 2.5 g of indium nitrate were mixed uniformly in 100 mL of water, then 3.0 g of sodium citrate was added, and after stirring, a mixture was obtained; a 0.5 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second at a constant temperature of 40°C, adjusting the solution pH to 8.0; after sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying, the temperature was raised to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was carried out for 2 hours, after which the temperature was cooled to room temperature to obtain a multi-metal oxide catalyst.

[0036] Figure 1 is a transmission electron microscope image of the multi-metal oxide catalyst prepared in this example, and it can be seen that the sample has a small particle size and good crystallinity.

[0037] Figure 2 is an X-ray diffraction pattern of the multi-metal oxide catalyst prepared in this example, and it can be seen that the sample has good crystallinity and mainly exists in the form of a metal oxide.

[0038] The catalyst prepared in this example was tested for carbon dioxide hydrogenation activity, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 19.1%, the methanol selectivity was 90.6%, the carbon monoxide selectivity was 9.1%, and the methane selectivity was 0.3%.

[0039] Example 2:

[0040] 10 g of copper nitrate, 10 g of zinc nitrate, 5 g of zirconium nitrate and 5 g of indium nitrate were mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 1.0 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under the condition of constant temperature of 60°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity test, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 18.4%, the methanol selectivity was 85.4%, the carbon monoxide selectivity was 14.0%, and the methane selectivity was 0.6%.

[0041] Example 3:

[0042] 10 g of copper nitrate, 5 g of zinc nitrate, 10 g of zirconium nitrate and 5 g of indium nitrate were mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 1.0 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under the condition of constant temperature of 50°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity test, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 17.9%, the methanol selectivity was 86.3%, the carbon monoxide selectivity was 13.1%, and the methane selectivity was 0.6%.

[0043] Example 4:

[0044] A mixture of 10 g of copper nitrate, 5 g of zinc nitrate, 5 g of zirconium nitrate and 10 g of indium nitrate was mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 1.0 mol / L aqueous solution of sodium carbonate was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under the condition of a constant temperature of 60°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 16.8%, the methanol selectivity was 87.1%, the carbon monoxide selectivity was 11.9%, and the methane selectivity was 1.0%.

[0045] Example 5:

[0046] A mixture of 10 g of copper chloride, 5 g of zinc chloride, 10 g of zirconium nitrate and 5 g of indium nitrate was mixed uniformly in 100 mL of water, and then 1.5 g of sodium citrate was added. After stirring, a mixture was obtained. A 0.5 mol / L aqueous solution of sodium hydroxide was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under the condition of a constant temperature of 40°C, and the pH of the solution was adjusted to 9.0. After sufficient reaction at 80°C for 48 hours, centrifugation, washing and drying were performed, and the temperature was increased to 300°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 20.1%, the methanol selectivity was 88.2%, the carbon monoxide selectivity was 10.8%, and the methane selectivity was 1.0%.

[0047] Example 6:

[0048] A mixture of 10 g of copper nitrate, 10 g of zinc nitrate, 10 g of zirconium nitrate and 20 g of indium nitrate was mixed uniformly in 100 mL of water, and then 2.5 g of sodium citrate was added. After stirring, a mixture was obtained. A 0.5 mol / L aqueous solution of potassium hydroxide was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under the condition of a constant temperature of 60°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 300°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 4 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 18.7%, the methanol selectivity was 86.9%, the carbon monoxide selectivity was 12.4%, and the methane selectivity was 0.7%.

[0049] Example 7:

[0050] 10 g of copper nitrate, 5 g of zinc nitrate, 10 g of zirconium nitrate and 5 g of indium nitrate were mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 1.0 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under constant temperature conditions, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 13.2%, the methanol selectivity was 85.6%, the carbon monoxide selectivity was 13.7%, and the methane selectivity was 0.7%.

[0051] Example 8:

[0052] 5 g of copper nitrate, 8 g of zinc nitrate, 10 g of zirconium nitrate and 17 g of indium nitrate were mixed uniformly in 100 mL of water, and then 4.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 2.0 mol / L aqueous ammonia solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second under constant temperature conditions of 60°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 14.6%, the methanol selectivity was 81.7%, the carbon monoxide selectivity was 12.2%, and the methane selectivity was 2.1%.

[0053] In addition, a comparative experiment was designed to prove that the synergistic effect of multi-metals plays an important role in improving the carbon dioxide hydrogenation activity and methanol selectivity, and the specific scheme is as follows:

[0054] Comparative Example 1:

[0055] A mixture of 5 g of copper nitrate, 10 g of zinc nitrate, and 10 g of indium nitrate was mixed uniformly in 100 mL of water, and then 2.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 2.0 mol / L aqueous ammonia solution was prepared, and the solution was slowly added to the above mixture at a rate of 2 drops per second under constant temperature conditions at 40°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing, and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this comparative example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 4.5%, the methanol selectivity was 45.6%, the carbon monoxide selectivity was 45.3%, and the methane selectivity was 9.1%.

[0056] Comparative Example 2

[0057] A mixture of 10 g of zinc nitrate and 10 g of indium nitrate was mixed uniformly in 100 mL of water, and then 2.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 2.0 mol / L aqueous ammonia solution was prepared, and the solution was slowly added to the above mixture at a rate of 2 drops per second under constant temperature conditions at 40°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing, and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this comparative example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 4.5%, the methanol selectivity was 45.6%, the carbon monoxide selectivity was 45.3%, and the methane selectivity was 9.1%.

[0058] Comparative Example 3

[0059] A mixture of 15 g of copper nitrate, 10 g of zinc nitrate, and 5 g of zirconium nitrate was mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 0.5 mol / L aqueous sodium carbonate solution was prepared, and the solution was slowly added to the above mixture at a rate of 2 drops per second under constant temperature conditions at 50°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing, and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this comparative example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 8.2%, the methanol selectivity was 51.3%, the carbon monoxide selectivity was 41.3%, and the methane selectivity was 7.4%.

[0060] Comparative Example 4

[0061] A mixture of 15 g of copper nitrate, 10 g of zinc nitrate and 5 g of indium nitrate was mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 0.5 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second at a constant temperature of 40°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this comparative example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 7.3%, the methanol selectivity was 58.6%, the carbon monoxide selectivity was 40.3%, and the methane selectivity was 1.1%.

[0062] Comparative Example 5

[0063] A mixture of 10 g of zinc nitrate, 5 g of zirconium nitrate and 5 g of indium nitrate was mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 0.5 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second at a constant temperature of 50°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this comparative example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 8.0%, the methanol selectivity was 60.0%, the carbon monoxide selectivity was 36.1%, and the methane selectivity was 3.9%.

[0064] Comparative Example 6

[0065] A mixture of 15 g of copper nitrate, 10 g of zirconium nitrate and 5 g of indium nitrate was mixed uniformly in 100 mL of water, and then 3.0 g of sodium citrate was added. After stirring, a mixture was obtained. A 0.5 mol / L aqueous sodium carbonate solution was prepared, and was slowly added to the above mixture at a rate of 2 drops per second at a constant temperature of 30°C, and the pH of the solution was adjusted to 8.0. After sufficient reaction at 60°C for 24 hours, centrifugation, washing and drying were performed, and the temperature was increased to 250°C at a rate of 2°C per minute in an air atmosphere, and calcination was performed for 2 hours. After cooling to room temperature, a multi-metal oxide catalyst was obtained. The catalyst prepared in this comparative example was subjected to carbon dioxide hydrogenation activity testing, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion rate was 6.2%, the methanol selectivity was 57.2%, the carbon monoxide selectivity was 39.4%, and the methane selectivity was 3.4%.

[0066] Comparative Example 7

[0067] The other conditions were the same as in Example 1, but sodium citrate was not added. The catalyst prepared in this comparative example was subjected to a carbon dioxide hydrogenation activity test, and the results are shown in Table 1. At a reaction temperature of 240°C, the carbon dioxide conversion was 2.1%, the methanol selectivity was 35.6%, the carbon monoxide selectivity was 42.7%, and the methane selectivity was 21.7%.

[0068] Comparative Example 8

[0069] The other conditions were the same as in Example 1, but sodium citrate was replaced with polyvinylpyrrolidone. As shown in Table 1, in Comparative Example 8, at a reaction temperature of 240°C, the carbon dioxide conversion was 6.1%, the methanol selectivity was 51.3%, the carbon monoxide selectivity was 38.7%, and the methane selectivity was 10.0%.

[0070] Comparative Example 9

[0071] The other conditions were the same as in Example 1, but sodium citrate was replaced with citric acid. As shown in Table 1, in Comparative Example 9, at a reaction temperature of 240°C, the carbon dioxide conversion was 5.5%, the methanol selectivity was 48.8%, the carbon monoxide selectivity was 39.2%, and the methane selectivity was 12.0%.

[0072] Comparative Example 10

[0073] The other conditions were the same as in Example 1, but sodium citrate was replaced with EDTA. As shown in Table 1, in Comparative Example 10, at a reaction temperature of 240°C, the carbon dioxide conversion was 3.9%, the methanol selectivity was 60.1%, the carbon monoxide selectivity was 35.9%, and the methane selectivity was 4.0%.

[0074] Comparative Example 11

[0075] The other conditions were the same as in Example 1, but sodium citrate was replaced with polyethylene glycol. As shown in Table 1, in Comparative Example 10, at a reaction temperature of 240°C, the carbon dioxide conversion was 4.6%, the methanol selectivity was 60.0%, the carbon monoxide selectivity was 28.0%, and the methane selectivity was 12.0%.

[0076] Table 1 is the results of carbon dioxide hydrogenation activity tests of the multi-metal oxide catalysts.

[0077] Table 1

[0078]

[0079] As can be seen from the comparison of Examples 1-8 and Comparative Examples 1-11, there is a synergistic effect between the four metal oxides, which can effectively improve the CO2 conversion and the methanol selectivity.

Claims

1. A method for preparing a multi-metal oxide catalyst, characterized by, The method comprises the following steps: S1, mixing copper salt, zinc salt, zirconium salt and indium salt in a solvent, then adding sodium citrate to the mixture and stirring to obtain a mixed solution A; S2, adding an alkali solution to the mixed solution A to adjust the pH of the solution to 7-10, and allowing the solution to react sufficiently; S3, after sufficient reaction, centrifuging, washing, drying and calcining to obtain the multi-metal oxide catalyst; In the catalyst, the mass fraction of copper oxide is 5%-70%, the mass fraction of zinc oxide is 5%-80%, the mass fraction of zirconium oxide is 5%-50%, and the mass fraction of indium oxide is 5%-60%.

2. The production method according to claim 1, characterized by, In step S1, the copper salt, zinc salt, zirconium salt and indium salt are selected from one or more of their corresponding nitrate, hydrochloride, sulfate and acetylacetone salt.

3. The preparation method according to claim 1, characterized in that, In step S1, the solvent is one or more of water, methanol and ethanol.

4. The method of claim 1, wherein, In step S1, the mass ratio of sodium citrate to metal salt is 1:20-1:10, and the mass of the metal salt is the sum of the masses of the copper salt, zinc salt, zirconium salt and indium salt.

5. The preparation method according to claim 1, characterized in that, In step S2, the alkali solution added to the mixed solution A is adjusted to a pH of 8-9.

6. The method of claim 1, wherein, In step S2, the alkali solution is one or more of sodium carbonate solution, potassium carbonate solution, ammonium carbonate solution, sodium hydroxide solution, potassium hydroxide solution and ammonia water, and the concentration of the alkali solution is 0.5-5.0 mol / L.

7. The preparation method according to claim 1, characterized in that, The step S2 specifically comprises the following steps: at temperature T1, adding an alkali solution to the mixed solution A to adjust the pH of the solution to 7-10; and allowing the solution to react sufficiently at temperature T2. In step S2, temperature T1 is 20-80℃, temperature T2 is 40-80℃, and the reaction time is 12-48 hours.

8. The preparation method according to claim 7, characterized in that, In step S2, temperature T2 is 60℃, and the reaction time is 24 hours.

9. The preparation method according to claim 7, characterized in that, In step S2, the alkali solution is added to the mixed solution A to adjust the pH of the solution to 8-9, temperature T2 is 60℃, and the reaction time is 24 hours.

10. The method of claim 1, wherein, In step S3, the calcination temperature is 200-400℃, and the calcination time is 2-8 hours.

11. The method of claim 10, wherein, In step S3, the calcination temperature is 250℃, and the calcination time is 2 hours.

12. A multi-metal oxide catalyst characterized in that, Prepared by the preparation method of any one of claims 1-11.

13. The catalyst of claim 12 or prepared by the preparation method of any one of claims 1-11 for use in the hydrogenation of carbon dioxide to produce methanol.

Images