High-entropy metal oxide for carbon dioxide hydrogenation and method of making same

Abstract

The application belongs to the technical field of high-entropy oxide materials, and discloses a high-entropy metal oxide for carbon dioxide hydrogenation and a preparation method thereof.The high-entropy metal oxide comprises CeO2, CuO, ZnO, Ga2O3 and ZrO2, wherein the molar ratio of elements Ce, Cu, Zn, Ga and Zr is (4±0.1):(1±0.1):(1±0.1):(1±0.1):(1±0.1).The preparation method comprises the following steps: configuring a complexing agent, fuel and metal salt into a uniform mixed solution; evaporating excess water in the mixed solution until the mixed solution turns into a gelatinous substance; making the gelatinous substance perform a combustion reaction in an air atmosphere to obtain a combustion product; and performing calcination treatment on the combustion product in an air atmosphere, so that the high-entropy metal oxide for carbon dioxide hydrogenation is obtained after the calcination is completed.The high-entropy metal oxide has the characteristics of high specific surface area, porous structure and excellent thermal stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-entropy oxide materials, and particularly relates to a high-entropy metal oxide for carbon dioxide hydrogenation and a preparation method thereof. BACKGROUND

[0002] With the increasingly serious global warming problem, carbon dioxide emission reduction and resource utilization have become key issues. Carbon dioxide is not only a major greenhouse gas, but also is often discharged as waste gas in industrial production. Therefore, finding an effective way to convert carbon dioxide into useful chemicals has become an important way to achieve the carbon emission reduction target. Carbon dioxide hydrogenation to methanol (CO2+3H2→CH3OH+H2O) is an effective carbon recycling technology, and through this reaction, carbon dioxide can be converted into an important chemical raw material-methanol. As a basic chemical raw material, methanol is widely used in fuel, solvent, plastic and medicine fields, and the optimization of its production process not only helps to improve resource utilization efficiency, but also reduces carbon dioxide emissions. The catalyst for carbon dioxide hydrogenation to methanol plays a crucial role in the process. The performance of the catalyst directly affects the conversion rate and selectivity of the reaction, so developing an efficient and stable catalyst is the key to realizing industrial production.

[0003] Currently, CO2 hydrogenation to methanol catalysts can be roughly divided into the following categories: transition metal catalysts dominated by copper-based catalysts, noble metal catalysts, and composite metal oxide catalysts. Among them, copper-based catalysts are the most widely used, which is attributed to their high reaction activity and methanol space-time yield. However, the most widely studied Cu / ZnO / Al2O3 catalyst has poor water resistance, which leads to easy sintering of active sites, seriously affecting its catalytic activity and stability, and the activity begins to decline after a period of reaction (Patent Publication No. CN116020467A). Pt / In2O3 catalysts have anti-sintering, anti-poisoning ability and high stability, and are widely concerned, but due to their high cost, they are not suitable for all scales of production (Patent Publication No. CN118179498A). In recent years, composite metal oxide catalysts have shown excellent performance in CO2 hydrogenation to methanol. By adjusting the composition and proportion of metal atoms in the composite metal oxide, the surface oxygen vacancy concentration can be increased, and the reaction activity can be improved. For example, ZnZrO xThe molar ratio of Zn / (Zn+Zr) in the system is 13%, which has the best reactivity (Patent Publication No. CN116078370A), and the reactivity will decrease when the ratio exceeds the optimal ratio. Therefore, from a macroscopic point of view, the phase change of the composite metal oxide caused by the increase of the metal atom ratio is the key to the difficulty of improving the reaction performance. In addition, the active sites of the binary composite metal oxide are not rich enough, and CO2 and the reaction byproduct CO compete for adsorption, especially the adsorption of a large amount of CO2 makes it difficult for CO to adsorb and hydrogenate, ultimately leading to a high selectivity of the byproduct CO.

[0004] High entropy metal oxides (HEMO) are single-phase structure stable solid solutions composed of five or more (near) equimolar ratio oxides, with a configurational entropy greater than or equal to 1.5R R is the ideal gas constant, x i is the molar fraction of cations). The common single crystal phase high entropy metal oxides formed at present include rock salt type, perovskite type, fluorite type, spinel type, etc. The unique properties of HEMO are likely to solve the problems existing in ordinary composite metal oxides. (1) The multi-element characteristics of high entropy metal oxides enable them to adjust the selectivity of catalytic reactions. By adjusting the ratio of different elements, the electronic structure of the catalyst can be optimized to improve the selectivity of methanol generation and reduce the occurrence of side reactions. (2) Due to the lattice distortion effect, a large number of oxygen vacancies can be generated on the surface of HEMO, promoting the activation of CO2 and H2. Moreover, experiments have reported that adding rare earth metal components to HEMO can further increase the concentration of surface oxygen vacancies. (3) Due to the hysteresis diffusion effect, HEMO has high chemical stability, thermodynamic stability and mechanical stability, and can maintain good catalytic performance for a long time under complex harsh conditions such as high temperature and high pressure.

[0005] However, the difficulty of preparing high-entropy metal oxide catalysts suitable for carbon dioxide hydrogenation to methanol mainly lies in the following aspects: (1) The complexity of material design, high-entropy metal oxide catalysts usually contain multiple metal elements, and the ratio, distribution and interaction between these elements have a significant impact on the performance of the catalyst. Designing such a catalyst requires precise control of components and structure to achieve optimal catalytic activity and stability; (2) The challenge of synthesis method, the synthesis of high-entropy metal oxide catalysts may require special high-temperature, high-pressure or atmosphere conditions, which may be difficult to control and may affect the microstructure and surface properties of the catalyst. In addition, uniformity and purity during the synthesis process are also challenges; (3) Optimization of catalytic performance, even if the high-entropy metal oxide catalyst is successfully synthesized, ensuring its high activity, high selectivity and high stability is also a complex engineering. This requires fine-tuning of the surface chemistry, acid sites, electronic structure, etc. of the catalyst. SUMMARY

[0006] In order to solve the problems in the prior art, the present application aims to provide a high-entropy metal oxide for carbon dioxide hydrogenation and a preparation method thereof.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] The high-entropy metal oxide for carbon dioxide hydrogenation comprises the following components: CeO2, CuO, ZnO, Ga2O3 and ZrO2, wherein the molar ratio of elements Ce, Cu, Zn, Ga and Zr is (3.9-4.1):(0.9-1.1):(0.9-1.1):(0.9-1.1):(0.9-1.1).

[0009] The preparation method of the high-entropy metal oxide for carbon dioxide hydrogenation comprises the following processes:

[0010] The complexing agent, fuel and metal salt containing elements Ce, Cu, Zn, Ga and Zr are configured into a uniform mixed solution;

[0011] The excess water in the mixed solution is evaporated until the mixed solution turns into a gel-like substance;

[0012] The gel-like substance is subjected to a combustion reaction in an air atmosphere to obtain a combustion product;

[0013] The combustion product is subjected to calcination treatment in an air atmosphere, and the high-entropy metal oxide for carbon dioxide hydrogenation is obtained after the calcination is completed.

[0014] Preferably, the metal salt comprises at least one kind of rare earth metal salt or transition metal salt corresponding to the respective elements.

[0015] Preferably, the metal salt comprises one or more of nitrate, hydrochloride and acetate corresponding to the respective elements.

[0016] Preferably, the fuel is a mixture of any one or more of glycine, urea and glucose.

[0017] When the metal salt is a nitrate corresponding to the respective elements, the ratio of the amount of substance of the fuel to the amount of substance of all the element nitrates is 0.9-1.1.

[0018] Preferably, the complexing agent comprises citric acid and / or polyvinylpyrrolidone, wherein the amount of substance of the complexing agent is n1, the sum of the amounts of substance of Ce, Cu, Zn, Ga and Zr is n2, and the ratio of n2:n1 is 0-0.5.

[0019] Preferably, when the excess water in the mixed solution is evaporated, the mixed solution is continuously stirred at 75-85 DEG C until the mixed solution is changed into a gel.

[0020] Preferably, when the gel-like substance is subjected to a combustion reaction in an air atmosphere, the heating temperature is 295-305 DEG C.

[0021] Preferably, when the combustion product is subjected to a calcination treatment in an air atmosphere, the calcination temperature is 395-405 DEG C, the holding time is 4.5-5.5 h, the calcination is ended after the material is completely reacted, and then the natural cooling is performed to obtain the high-entropy metal oxide for carbon dioxide hydrogenation.

[0022] The application of the high-entropy metal oxide for carbon dioxide hydrogenation as described above is used as a catalyst for a carbon dioxide hydrogenation methanol synthesis reaction, and the conditions for the carbon dioxide hydrogenation methanol synthesis reaction using the catalyst include:

[0023] The molar ratio of H2 to CO2 is 2-4;

[0024] The mass space velocity of the reaction is 2000-20000 mL / g cat h;

[0025] The reaction temperature is 280-350 DEG C;

[0026] The reaction pressure is 3-5 MPa.

[0027] The application has the following beneficial effects:

[0028] The high-entropy metal oxide for carbon dioxide hydrogenation is a fluorite-type high-entropy metal oxide with cerium dioxide as a base, and the components include CeO2, CuO, ZnO, Ga2O3 and ZrO2, wherein the CeO2 is a base material, which provides a stable oxide structure and facilitates the generation of oxygen vacancies and the enhancement of the surface basicity of the rare earth metal component to strengthen the activation of CO2 and H2; the CuO can effectively promote the adsorption and activation of hydrogen and enhance the reaction activity of the catalyst; the ZnO has a support and electronic assistant effect, helps to adsorb H2, improves the dispersion of copper, and exposes a larger specific surface area; the Ga2O3 can dissociate H2 at high temperatures, and within a certain temperature range, the higher the temperature, the stronger the dissociation ability of H2; in the methanol synthesis reaction, Ga mainly acts as an assistant to improve the dispersion of the active components Cu and Zn and improve the hydrogenation capacity; and the ZrO2 is mainly responsible for the adsorption of CO2. The detection shows that the high-entropy metal oxide for carbon dioxide hydrogenation has a porous structure and a high specific surface area, and the thermal stability is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Ce1(CuZnGaZr) prepared for the present application example 1 and example 2 1 / 4 XRD pattern of Ce1(CuZnGaZr)O4 fluorite-type high-entropy metal oxide powder;

[0030] Figure 2 Ce1(CuZnGaZr) prepared for the present application example 1 1 / 4 SEM image of Ce1(CuZnGaZr)O4 fluorite-type high-entropy metal oxide powder;

[0031] Figure 3 Ce1(CuZnGaZr) prepared for the present application example 2 1 / 4 SEM image of Ce1(CuZnGaZr)O4 fluorite-type high-entropy metal oxide powder. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and beneficial technical effects of the present application clearer and more understandable, the present application will be further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described in the present specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0033] The present application is a process for preparing fluorite-type high-entropy metal oxide (i.e. high-entropy metal oxide for carbon dioxide hydrogenation of the present application) by controlling the ratio of complexing agent and fuel using the solution combustion method, and the preparation method comprises the following steps:

[0034] (1) mixing metal salts containing at least five metal elements, a complexing agent and fuel to obtain a uniform mixed solution;

[0035] (2) stirring the mixed solution of step (1) to ensure that the metal ions, complexing agent and fuel are fully mixed and uniform;

[0036] (3) placing the mixed solution after stirring of step (2) on a heating plate for stirring, and evaporating the excess water in the mixed solution at 80±5℃ until the mixed solution is converted into a gel-like substance to obtain a gel-like substance;

[0037] (4) continuing to increase the temperature to 300±5℃, so that the gel-like substance prepared in step (3) undergoes a combustion reaction in an air atmosphere, after the reaction is completed, the heating plate is turned off, and the combustion reaction product obtained is a fluffy black powder;

[0038] (5) transferring the black powder obtained by the combustion reaction to a muffle furnace for calcination treatment under an air atmosphere, and finally obtaining the high-entropy metal oxide for carbon dioxide hydrogenation of the present application.

[0039] The high-entropy metal oxide for carbon dioxide hydrogenation obtained by the above method of the application is fluorite-type high-entropy metal oxide with cerium dioxide as a base, and the components thereof include: CeO2, CuO, ZnO, Ga2O3 and ZrO2, wherein the element molar ratio is Ce:Cu:Zn:Ga:Zr=(4±0.1):(1±0.1):(1±0.1):(1±0.1):(1±0.1).

[0040] In the above scheme of the application, the metal salt includes rare earth metal salt or transition metal salt, and the metal salt can be one or several of nitrate, hydrochloride and acetate;

[0041] The complexing agent includes citric acid and / or polyvinylpyrrolidone, and is preferably citric acid (CA). The complexing agent is a compound capable of promoting the dissolution of the precursor and stabilizing the reaction process, and its functions include: a. promoting dissolution, the complexing agent can form a complex with metal ions (M n+ ), thereby enhancing the solubility of the metal ions (M n+ ) in the solution and helping to form a uniform solution. b. controlling the reaction rate, the complexing agent can adjust the rate and temperature of the reaction, so that the reaction process is more controllable, and the reaction speed is avoided to be too fast or too slow. c. affecting the properties of the catalyst, the selection of the complexing agent can affect the structure, morphology and crystal structure of the final catalyst, and adjust the properties of the catalyst. The amount of citric acid is beneficial to the complexation of metal ions, but the increase of the amount of citric acid will increase the amount of oxidizing agent required for the reaction. In the above preparation method of the application, preferably, n(CA):n(M n+ )=0-0.5.

[0042] The fuel is any one or a combination of several of glycine, urea and glucose, and is preferably glycine. The fuel releases a large amount of heat energy in the combustion process, provides the heat required for the reaction, promotes the decomposition of the precursor and the progress of the reaction. The combustion of the fuel also produces gases such as carbon dioxide and water vapor, which help to form a uniform reaction environment and promote the dispersion of the precursor. The ratio of the amount of fuel to the amount of nitrate will affect the properties of the prepared catalyst. The chemical reactions involved are as follows:

[0043]

[0044] M is a metal element; and ν is the valence of the metal cation; is the amount-of-substance ratio of the fuel to the oxidant, respectively corresponding to lean combustion, rich combustion and stoichiometric combustion conditions. Generally, Preferably, 1-1.1.

[0045] The combustion reaction heating temperature in the above step (4) is 300±5 DEG C, the preliminary combustion reaction is usually carried out at a higher temperature, high-temperature and high-speed flame is generated, and the combustion reaction is violent, the heat released in the process can effectively convert the precursor into a metal oxide, and the powder generated in the combustion process is usually fine and suitable for further processing;

[0046] The calcination temperature in the above step (5) is 400±5 DEG C, the temperature rising rate is 3 DEG C / min, the calcination is ended after the product is completely reacted, and then natural cooling is carried out. Through experiments, under the experimental conditions of the present application, when the calcination time is 5 hours, the material can be completely reacted, and then the heat preservation is ended, the specific calcination heat preservation time is related to the use amount of raw materials, and the person skilled in the art can determine it according to the actual situation, and the present application does not make specific limitation. Calcination is helpful to promote the crystallization of the material, remove impurities, improve the structural stability and improve the performance, and the calcination duration in step (5) is 4.5-5.5h.

[0047] In the above scheme of the present application, due to the measurement error of weighing and heating equipment itself, the data after the above ''±'' are reasonable errors of corresponding parameters, and it can be predicted that the technical scheme of the present application is feasible within the above reasonable error range.

[0048] In the above step (1), the metal nitrate can be accurately weighed according to the stoichiometric ratio first, then dissolved in a certain amount of distilled water, and stirred uniformly at room temperature to obtain a mixed solution of five kinds of metal cations.

[0049] The use of the high-entropy metal oxide for carbon dioxide hydrogenation: the carbon dioxide hydrogenation to methanol reaction is a reaction with a decrease in the number of molecules, and the efficient activation of CO2 requires high temperature to overcome the kinetic barrier, therefore, in order to improve the methanol yield, the reaction needs to be carried out at high temperature and high pressure, and the specific conditions are as follows:

[0050] The molar ratio of H2 to CO2 is 2-4;

[0051] The mass space velocity of the reaction is 2000-20000 mL / g cat h;

[0052] The reaction temperature is 280-350 DEG C;

[0053] The reaction is carried out in a fixed bed reactor, the inner diameter of the reaction tube is 8 mm, and the length is 300 mm;

[0054] The reaction pressure is 3-5 MPa.

[0055] In the following examples of the present application, the metal nitrate is weighed according to the chemical formula Ce1(CuZnGaZr) 1 / 4O4 was accurately weighed according to the stoichiometric ratio, dissolved in a certain amount of distilled water, and stirred uniformly at room temperature to obtain a mixed solution of five metal cations.

[0056] Example 1

[0057] In this embodiment, a high-entropy metal oxide for carbon dioxide hydrogenation is prepared by a solution combustion method, and the chemical formula is Ce1(CuZnGaZr) 1 / 4 O4.

[0058] The preparation method of the high-entropy metal oxide for carbon dioxide hydrogenation in this embodiment includes the following steps:

[0059] (1) The corresponding metal nitrate was accurately weighed according to the stoichiometric ratio of the molecular formula, specifically 4.343 g of Ce(NO3)3·6H2O, 0.610 g of Cu(NO3)2·3H2O, 0.751 g of Zn(NO3)2·6H2O, 0.639 g of Ga(NO3)3, and 1.073 g of Zr(NO3)4·5H2O, and then all the nitrate was dissolved in 300 mL of distilled water and stirred uniformly at room temperature to obtain a mixed solution containing five metal cations;

[0060] (2) Then, according to the ratio of n(CA) : n(M n+ ) = 0, i.e. no citric acid was added; 2.398 g of glycine was added according to the ratio of , and stirred uniformly to mix the metal ions and fuel in the solution uniformly;

[0061] (3) The above mixed solution was placed on a heating plate for stirring, and the excess water in the mixed solution was evaporated at 80±5℃, and it was baked to a gel;

[0062] (4) Continue to increase the temperature to 300±5℃, and make the mixed solution undergo combustion reaction in air atmosphere, and after the reaction is completed, turn off the heating plate to obtain a fluffy black powder;

[0063] (5) The obtained powder was transferred to a muffle furnace for calcination, the calcination temperature was 400±5℃, the heating rate was 3℃ / min, and the holding time was 5h, after the calcination was completed, the natural cooling was carried out, and finally the high-entropy metal oxide sample was obtained.

[0064] As can be seen from Figure 1 , the diffraction peak intensity of the sample synthesized by glycine as fuel without adding citric acid is higher, and the peak shape is sharp, which indicates that the crystallinity of the powder is higher. As can be seen from Figure 2 , the powders prepared by the solution combustion method are all porous network structures, which is mainly due to the instantaneous release of a large amount of gas during the combustion of nitrate and fuel, which is beneficial to increase the specific surface area of the material and thus improve the reaction activity.

[0065] Experiments were conducted using a fixed-bed reactor under specific conditions, including temperature, pressure, space velocity, and CO2 / H2 feed ratio, to produce methanol via high-entropy metal oxide catalysis of CO2 hydrogenation. Gas chromatography was used to analyze product distribution. The activity and selectivity of the high-entropy metal oxide catalytic CO2 hydrogenation to methanol reaction under different reaction conditions were investigated. Catalyst performance was evaluated based on indicators such as CO2 conversion, methanol selectivity, yield, and catalyst stability, as detailed below:

[0066] The performance evaluation of the high-entropy metal oxide catalyst was conducted in a continuous flow fixed-bed reactor. 0.2 g of catalyst diluted with quartz sand (60-80 mesh) was loaded into a stainless steel tubular reactor. Before catalytic measurements, the fresh catalyst was reduced for 3 hours at atmospheric pressure (300±5℃) in a 10 vol% H2 / N2 gas stream. The reactor was then cooled to 200±5℃, and a reaction gas (CO2:H2 = 1:3, molar ratio) was introduced, increasing the pressure to 3.0 MPa and the temperature to 300±5℃. All pipelines and valves downstream of the reactor were heated to 150±5℃ to prevent product condensation. Four hours after the reaction began, the effluent was analyzed online using gas chromatography to calculate the carbon dioxide conversion and methanol selectivity. Under these conditions, the CO2 conversion reached 10.7%, and the methanol selectivity reached 72%, with stability exceeding 30 hours. The catalyst showed superior selectivity and thermal stability compared to Cu / ZnO / Al2O3. Specific results are shown in Table 1.

[0067] Example 2

[0068] The method for preparing high-entropy metal oxides for carbon dioxide hydrogenation in this embodiment includes the following steps:

[0069] (1) The second fluorite-type high-entropy oxide catalyst of the present invention was prepared by solution combustion method, and its chemical formula is Ce1(CuZnGaZr). 1 / 4 O4. Accurately weigh the corresponding metal nitrates according to the stoichiometric ratio of the molecular formula, specifically 4.343g of Ce(NO3)3·6H2O, 0.610g of Cu(NO3)2·3H2O, 0.751g of Zn(NO3)2·6H2O, 0.639g of Ga(NO3)3 and 1.073g of Zr(NO3)4·5H2O. Then dissolve all the nitrates in 300mL of distilled water and stir evenly at room temperature to obtain a mixed solution containing five metal cations.

[0070] (2) Then according to n(CA): n(M) n+ Add 2.101g of citric acid at a ratio of 0.5; according to 2.398g of glycine is added in proportion, and stirred to make the metal ions and fuel in the solution mixed uniformly;

[0071] (3) The mixed solution is placed on a heating plate for stirring, and the excess water in the mixed solution is evaporated at 80±5 DEG C, and is baked to a gel;

[0072] (4) The temperature is continuously increased to 300±5 DEG C, and the mixed solution is combusted in an air atmosphere, and after the reaction is completed, the heating plate is turned off, and a fluffy black powder is obtained;

[0073] (5) The obtained powder is transferred to a muffle furnace for calcination, the calcination temperature is 400±5 DEG C, the temperature rising rate is 3 DEG C / min, the holding time is 5h, after the calcination is completed, the natural cooling is carried out, and finally the high-entropy metal oxide sample is obtained.

[0074] From Figure 1 It can be seen that the characteristic peaks of the powders obtained in Example 1 and Example 2 are completely consistent, indicating that after the addition of citric acid, the crystal structure of the powder does not change. However, the characteristic diffraction peak intensity of the XRD pattern of the sample added with citric acid is slightly weak, and the peak width is widened, and according to the Scherrer formula, the grain size of the sample is smaller, and the specific surface area is increased, which is more conducive to improving the reaction activity. This result can also be followed Figure 2 、 Figure 3 The SEM images of the samples are mutually verified.

[0075] The catalyst performance evaluation steps are the same as those in Example 1, and are shown in Table 1.

[0076] Table 1

[0077]

[0078] Reaction conditions: n(H2):n(CO2)=3:1, 3MPa, 300±5 DEG C, 8000mL.g -1 ·h -1

[0079] It can be seen that the high-entropy metal oxide catalyst prepared by adding an appropriate amount of citric acid performs more excellent, the conversion rate of carbon dioxide and the product methanol yield are increased, and there is no deactivation phenomenon after 30h of reaction.

[0080] In summary, the present application has the following beneficial technical effects:

[0081] The present application uses a solution combustion method to prepare a high-entropy metal oxide catalyst suitable for carbon dioxide hydrogenation to methanol. Its advancement is reflected in the following aspects:

[0082] (1) High-entropy metal oxides have high thermal stability, which enables them to maintain good catalytic activity at high temperatures. For the CO2 hydrogenation reaction, which needs to be carried out at high temperatures, no deactivation phenomenon occurs after 30h of continuous reaction;

[0083] (2) Compared with the commercial catalyst Cu / ZnO / Al2O3, the high-entropy metal oxide used for the carbon dioxide hydrogenation to methanol has significantly improved selectivity and yield of product methanol.

[0084] (3) The solution combustion method for preparing high-entropy metal oxides has the advantages of simple operation, low cost, and high product uniformity, and the raw materials used are mostly transition metal salts.

[0085] (4) The most widely used catalyst for the carbon dioxide hydrogenation to methanol in industry is the copper-based catalyst (such as Cu / ZnO / Al2O3), which has high reaction activity, but poor water resistance, easy sintering of active sites, and poor stability. The high-entropy metal oxide catalyst prepared by the present application has high specific surface area, porous structure, and excellent thermal stability, and can be applied to the carbon dioxide hydrogenation to methanol reaction.

[0086] In summary, the catalyst prepared by the present application exhibits high-efficiency and stable catalytic performance, has low preparation cost, and the preparation method has good universality, and shows good application prospect in the field of carbon dioxide resource utilization.

[0087] The technical solution provided by the present application demonstrates its unique principles and application potential through the above-mentioned embodiments. However, the present application is not limited to the described embodiments, but covers any specific method, material preparation, and conclusion that meets the technical essence. Any reasonable modification to the existing embodiments, or equivalent modification based on the principles of the present application, should not exceed the protection scope of the present application.

[0088] Therefore, the present application welcomes academic exploration and technical practice from all aspects, aiming to promote the scientific and technological progress and innovative development in related fields. Any interested individual or organization can further conduct in-depth research and application development based on the technical solution of the present application, and contribute to the progress of science and technology.

Claims

1. A high-entropy metal oxide for the hydrogenation of carbon dioxide, characterized in that, The components include CeO2, CuO, ZnO, Ga2O3 and ZrO2, wherein the molar ratio of elements Ce, Cu, Zn, Ga and Zr is (3.9-4.1):(0.9-1.1):(0.9-1.1):(0.9-1.1):(0.9-1.1). The preparation method of the high-entropy metal oxide for carbon dioxide hydrogenation comprises the following steps: The complexing agent, fuel and metal salt containing elements Ce, Cu, Zn, Ga and Zr are configured into a uniform mixed solution; The excess water in the mixed solution is evaporated until the mixed solution turns into a gelatinous substance; The gelatinous substance is subjected to a combustion reaction in an air atmosphere to obtain a combustion product; The combustion product is subjected to calcination treatment in an air atmosphere, and the high-entropy metal oxide for carbon dioxide hydrogenation is obtained after the calcination is completed.

2. The method of claim 1 for the preparation of high entropy metal oxides for carbon dioxide hydrogenation, characterized by, The preparation method of the high-entropy metal oxide for carbon dioxide hydrogenation comprises the following steps: The complexing agent, fuel and metal salt containing elements Ce, Cu, Zn, Ga and Zr are configured into a uniform mixed solution; the fuel is any one or a mixture of several of glycine, urea and glucose; the complexing agent includes citric acid and / or polyvinylpyrrolidone, wherein the amount of substance of the complexing agent is n1, the sum of the amounts of substance of Ce, Cu, Zn, Ga and Zr is n2, and the ratio of n2 to n1 is 0-0.5; The mixed solution is continuously stirred at 75-85°C, and the excess water in the mixed solution is evaporated until the mixed solution turns into a gelatinous substance; The gelatinous substance is heated to 295-305°C, and the gelatinous substance is subjected to a combustion reaction in an air atmosphere to obtain a combustion product; The combustion product is subjected to calcination treatment in an air atmosphere; wherein the calcination temperature is 395-405°C, the calcination is completed after the material is completely reacted, and then natural cooling is performed to obtain the high-entropy metal oxide for carbon dioxide hydrogenation.

3. The method for preparing high-entropy metal oxides for carbon dioxide hydrogenation according to claim 2, characterized in that, The metal salt includes at least one corresponding rare earth metal salt or transition metal salt of the corresponding element.

4. The method of claim 2, wherein the high-entropy metal oxide for carbon dioxide hydrogenation is prepared by the steps of: preparing a solution of metal salts; mixing the solution of metal salts with a base; and precipitating the high-entropy metal oxide. The metal salt includes one or several of nitrate, hydrochloride and acetate of the corresponding element.

5. The method of claim 4, wherein the high entropy metal oxide for carbon dioxide hydrogenation is prepared by the steps of: a) providing a metal oxide; b) mixing the metal oxide with a metal salt; c) heating the mixture to form a high entropy metal oxide; and d) washing the high entropy metal oxide with water. When the metal salt is the nitrate of the corresponding element, the ratio of the amount of substance of the fuel to the amount of substance of all element nitrates is 0.9-1.

1.

6. Use of the high-entropy metal oxide for carbon dioxide hydrogenation according to claim 1, characterized in that, The high-entropy metal oxide for carbon dioxide hydrogenation is used as a catalyst for the reaction of carbon dioxide hydrogenation to methanol, and the conditions for the reaction of carbon dioxide hydrogenation to methanol using the catalyst include: The molar ratio of H2 to CO2 is 2-4; The mass space velocity of the reaction is 2000-20000 mL / (g cat h); The reaction temperature is 280-350°C; The reaction pressure is 3-5 MPa.

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