A catalyst for producing methanol by hydrogenation of carbon dioxide, and its preparation method and application

Abstract

The present invention relates to the field of catalyst technology, and discloses a carbon dioxide hydrogenation methanol catalyst and its preparation method and application. The preparation method comprises the following steps: a metal organic framework and a metal oxide nanopowder are prepared into a mixed powder, wherein the metal organic framework includes DUT-8(Cu) and Cu3(BTC)2 in a molar ratio of 1-5:1; the mixed powder is Joule heated in an inert atmosphere to obtain a carbon dioxide hydrogenation methanol catalyst. The present invention can utilize the fast and efficient heating characteristics of Joule heat and the interfacial phase thermal segregation during Joule heat heating to enable the Cu atomic active component to migrate rapidly on the surface of the metal oxide support, reduce unit cell agglomeration, and enhance the strong interaction between Cu atoms and the metal oxide support, thereby improving the catalytic activity, stability and reaction selectivity of the CO2 hydrogenation methanol catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and in particular to a catalyst for producing methanol by hydrogenating carbon dioxide, a preparation method thereof, and an application thereof. Background Art

[0002] Catalytic conversion of CO2 into fuels and high-value-added chemicals is a key approach to achieving carbon recycling and addressing climate change. Methanol, an important basic chemical feedstock and clean fuel, can be synthesized through the hydrogenation of CO or CO2. It has broad application prospects, including in the production of olefins (MTO), the synthesis of formaldehyde and acetic acid, and as a gasoline additive. However, the development of efficient catalysts remains a key technical challenge in the industrialization of CO2 hydrogenation to methanol.

[0003] There are many types of catalysts that can be used for CO2 hydrogenation to produce methanol, mainly including Cu-based catalysts (Cu bimetallic, Cu / metal oxide composite catalysts, etc.), precious metal catalysts (Ag, Pd, etc.), metal oxide catalysts and other new catalysts. Among them, Cu-based catalysts have higher catalytic activity for the CO2 hydrogenation reaction to produce methanol. Although there are many types, existing CO2 hydrogenation to methanol catalysts (including Cu / metal oxide composite catalysts) are generally prepared by co-precipitation method (i.e., co-precipitation of metal salt and another metal salt solution, followed by washing, drying, calcination and other steps to obtain the catalyst), impregnation method (i.e., impregnating the catalyst support in a metal salt solution, followed by washing, drying, calcination and other steps to obtain the catalyst) and hydrothermal method (i.e., under high temperature and high pressure hydrothermal conditions, allowing metal salt and another metal salt to react with water to generate corresponding hydroxides or oxides, followed by washing, drying, calcination and other steps to obtain the catalyst). These preparation methods make it difficult to precisely control the structure and distribution of active sites. The active component Cu is unevenly distributed on the surface of the metal oxide, and the interaction between the active component and the support is weak, resulting in low catalyst stability and selectivity, which limits the large-scale application of CO2 hydrogenation to methanol technology.

[0004] For example, patent CN115845914B uses an impregnation method to prepare a Cu-based catalyst for catalytic carbon dioxide hydrogenation to methanol. The highest achievable carbon dioxide conversion rate is only 24.82%, and the methanol selectivity is only 65.23%. Summary of the Invention

[0005] To address the technical issues of low catalytic activity, stability, and reaction selectivity in existing CO2 hydrogenation to methanol catalysts, the present invention provides a CO2 hydrogenation to methanol catalyst, its preparation method, and its application. The preparation method of the present invention enables the resulting CO2 hydrogenation to methanol catalyst to exhibit high catalytic activity and reaction selectivity, as well as high stability over long-term use.

[0006] The specific technical solutions of the present invention are:

[0007] In a first aspect, the present invention provides a method for preparing a catalyst for producing methanol by hydrogenating carbon dioxide, comprising the following steps:

[0008] S1: preparing a mixed powder of a metal organic framework (MOF) and metal oxide nanopowder; the metal organic framework comprises DUT-8(Cu) and Cu3(BTC)2 in a molar ratio of 1-5:1;

[0009] S2: The mixed powder is heated by Joule heat in an inert atmosphere to obtain a catalyst for hydrogenation of carbon dioxide to methanol.

[0010] Joule heating is the process of converting electrical energy into thermal energy by utilizing the resistive heating effect generated when current passes through a conductor. The present invention uses Joule heating technology to transform a mixed powder of DUT-8(Cu), Cu3(BTC)2, and metal oxides into a catalyst for the hydrogenation of carbon dioxide to methanol. In this process, the rapid and efficient heating characteristics of Joule heat can be utilized to carbon-thermally reduce the central Cu atoms of the DUT-8(Cu) and Cu3(BTC)2 materials, and combine them with nano-metal oxides to cause interfacial phase thermal segregation, forming a local Cu-O x -Metal oxide active sites. Leveraging the single-metal center structure of DUT-8(Cu) and Cu3(BTC)2 and the rapid heating process generated by Joule heating, Cu can quickly migrate and disperse on the metal oxide surface, reducing unit cell agglomeration. This in turn gives the resulting CO2 hydrogenation to methanol catalyst high catalytic activity. Furthermore, phase thermal segregation stabilizes Cu atoms, enhancing the strong interaction between Cu atoms and the metal oxide support, thereby improving the catalyst's stability and reaction selectivity.

[0011] Moreover, compared with conventional co-precipitation, impregnation and hydrothermal methods, the present invention utilizes Joule heating technology and, by directly coupling a metal-organic framework and metal oxide nanopowders, can achieve a more uniform Cu distribution and a more stable bond between Cu and the metal oxide support. This has the advantage of easily regulating the Cu loading amount and the type and size of the metal oxide support.

[0012] Furthermore, the present invention utilizes a specific molar ratio of DUT-8(Cu) and Cu3(BTC)2 to produce a CO2 hydrogenation to methanol catalyst with enhanced catalytic activity. Specifically, the unique pore structures and surface chemical properties of the two MOF materials, DUT-8(Cu) and Cu3(BTC)2, allow for optimized H2 and CO2 adsorption, activation, and diffusion efficiencies through ratio optimization, while simultaneously enhancing methanol removal efficiency, thereby synergistically improving catalytic activity. The DUT-8(Cu) material has a smaller and narrower pore size range (0.3-1.5 nm), enabling precise control of the ratio of H2 and CO2 gaseous reactants, resulting in a more optimal H2 / CO2 ratio. However, this does not facilitate methanol removal. The Cu3(BTC)2 material, on the other hand, has a wider pore size distribution (0.23-7.9 nm) and possesses both micropore and mesopore functionality. The micropores allow for the entry of H2 and CO2 reaction products, while the mesopores facilitate the transfer and removal of methanol, thereby optimizing mass transfer in the CO2 hydrogenation to methanol reaction. In addition, more Cu atomic active sites can be exposed by regulating the coordination balance of BTC ligands, thereby accelerating the adsorption and activation of CO2 to generate formic acid intermediates (HCOO - By designing the molar ratio of the two (the molar ratio of DUT-8(Cu) to Cu3(BTC)2 is 1-5:1), pore size complementarity can be achieved, improving the efficiency of reactant supply and product separation, thereby achieving higher catalytic activity.

[0013] Preferably, in step S1, the molar ratio of DUT-8(Cu) to Cu3(BTC)2 is 1-3:1.

[0014] By controlling the ratio of the two metal organic frameworks within the above range, the catalyst can have both high catalytic activity and reaction selectivity.

[0015] Preferably, in step S1, the metal oxide nanopowder comprises ZnO nanopowder, ZrO2 nanopowder and In2O3 nanopowder in a molar ratio of 1-6:1-3:1.

[0016] The present invention uniformly mixes three metal oxide powders with DUT-8(Cu) and Cu3(BTC)2, and then performs heat treatment using rapid Joule heating technology. During this process, the central Cu atoms of the two MOF materials, DUT-8(Cu) and Cu3(BTC)2, undergo thermal segregation and migrate to the surface interface of the metal oxide powders while maintaining their pore structure characteristics, thereby constructing a Cu-Ox-M (M=Zn, Zr and In) multi-metal oxide interface. The Cu-ZnO interface formed by ZnO promotes electron transfer and oxygen vacancy generation, enhancing CO2 adsorption and activation, resulting in high methanol selectivity (>90%) and effective suppression of side reactions. However, it is susceptible to sintering and deactivation at high temperatures, and its active sites are easily deactivated by water poisoning. ZrO2, on the other hand, is weakly hydrophilic, reducing water poisoning of its active sites and exhibiting excellent high-temperature stability (>350°C), but its low-temperature catalytic activity is poor. In2O3, with its rich surface oxygen vacancies, directly promotes CO2 activation and maintains high methanol selectivity at low temperatures, but its oxygen vacancies are easily deactivated by poisoning. By combining the three in a specific molar ratio (1-6:1-3:1), the advantages of the catalytically active components can be complemented, improving the catalyst's catalytic activity, selectivity, high-temperature resistance, and stability against water poisoning for CO2 hydrogenation to methanol.

[0017] Preferably, in step S1, the molar ratio of the metal organic framework to the metal oxide nanopowder is 0.02-0.1:1.

[0018] Preferably, in step S2, the specific process of the Joule heat heating includes: heating to 800-1200°C at a rate of 100-1000°C / s, and then maintaining the temperature at 800-1200°C for 4-10 h.

[0019] Preferably, in step S2, the inert atmosphere is nitrogen; during the Joule heat heating process, the nitrogen flow rate is 200-400 SCCM.

[0020] Preferably, the specific process of step S1 includes: ultrasonically dispersing the metal organic framework and metal oxide nanopowder into a dispersion medium, stirring until the dispersion medium is completely volatilized to obtain a mixed powder; the molar volume ratio of the metal organic framework and the dispersion medium is 0.02-0.1 mol: 50-60 mL.

[0021] Furthermore, the dispersion medium includes at least one of deionized water, methanol, acetone and isopropanol.

[0022] In a second aspect, the present invention provides a catalyst prepared by the preparation method.

[0023] In a third aspect, the present invention provides use of the catalyst in the reaction of producing methanol by hydrogenation of carbon dioxide.

[0024] Preferably, during the carbon dioxide hydrogenation reaction to produce methanol, the temperature is 190-270°C, the pressure is 2-5 MPa, the molar ratio of hydrogen to carbon dioxide is 2-3:1, and the total space velocity of hydrogen and carbon dioxide is 4000-20000 mL / g cat / h.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention adopts Joule heat heating technology to transform the mixed powder of DUT-8(Cu), Cu3(BTC)2 and metal oxide into a CO2 hydrogenation to methanol catalyst. The invention can utilize the fast and efficient heating characteristics of Joule heat and the thermal segregation of the interface phase during the Joule heat heating process to enable the active components of Cu atoms to migrate rapidly on the surface of the metal oxide support, reduce the agglomeration of crystal cells, and enhance the strong interaction between Cu atoms and the metal oxide support, thereby improving the catalytic activity, stability and reaction selectivity of the CO2 hydrogenation to methanol catalyst.

[0027] (2) The present invention uses a compound of DUT-8(Cu) and Cu3(BTC)2 with a molar ratio of 1-5:1 as the copper source and carbon source in the catalyst preparation process, which can better regulate the adsorption activation ability and diffusion efficiency of H2 and CO2, while enhancing the removal efficiency of methanol products, thereby synergistically improving the catalytic activity.

[0028] (3) The present invention uses a compound of ZnO, ZrO2 and In2O3 to form a metal oxide support, which can make the CO2 hydrogenation to methanol catalyst have high catalytic activity, selectivity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a transmission electron microscope (TEM) image of the catalyst prepared in Example 1.

[0030] Figure 2 This is a high magnification TEM image of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the embodiments.

[0032] First, the present invention relates to a method for preparing a catalyst for producing methanol by hydrogenation of carbon dioxide, comprising the following steps:

[0033] S1: preparing a mixed powder of a metal organic framework and metal oxide nanopowder; the metal organic framework comprises DUT-8(Cu) and Cu3(BTC)2 in a molar ratio of 1-5:1;

[0034] S2: The mixed powder is heated by Joule heat in an inert atmosphere to obtain a catalyst for hydrogenation of carbon dioxide to methanol.

[0035] In some specific embodiments, in step S1, the molar ratio of DUT-8(Cu) to Cu3(BTC)2 is 1-3:1.

[0036] In some specific embodiments, in step S1, the metal oxide nanopowder includes ZnO nanopowder, ZrO2 nanopowder and In2O3 nanopowder in a molar ratio of 1-6:1-3:1.

[0037] In some specific embodiments, in step S1, the molar ratio of the metal organic framework to the metal oxide nanopowder is 0.02-0.1:1.

[0038] In some specific embodiments, the specific process of step S1 includes: ultrasonically dispersing the metal organic framework and the metal oxide nanopowder into a dispersion medium, stirring until the dispersion medium is completely volatilized to obtain a mixed powder; the molar volume ratio of the metal organic framework, the metal oxide nanopowder and the dispersion medium is 0.02-0.1 mol: 1 mol: 50-60 mL; and the dispersion medium includes at least one of deionized water, methanol, acetone and isopropanol.

[0039] In some specific embodiments, in step S2, the specific process of the Joule heat heating includes: heating to 800-1200°C at a rate of 100-1000°C / s, and then maintaining the temperature at 800-1200°C for 4-10 h.

[0040] In some specific embodiments, in step S2, the inert atmosphere is nitrogen; during the Joule heating process, the nitrogen flow rate is 200-400 SCCM.

[0041] Second, the present invention relates to a catalyst prepared by the preparation method.

[0042] Third, the present invention relates to the application of the catalyst in the reaction of producing methanol by hydrogenation of carbon dioxide.

[0043] In some specific embodiments, during the carbon dioxide hydrogenation reaction to produce methanol, the temperature is 190-270°C, the pressure is 2-5 MPa, the molar ratio of hydrogen to carbon dioxide is 2-3:1, and the total space velocity of hydrogen and carbon dioxide is 4000-20000 mL / g cat / h.

[0044] The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0045] Examples 1-3 and Comparative Examples 1-3: Effect of Metal-Organic Framework Composition on Catalyst Performance

[0046] In Examples 1 to 3 and Comparative Examples 1 to 3, the steps for preparing the CO2 hydrogenation to methanol catalyst are as follows:

[0047] Take a certain amount (specific amounts are shown in Table 1) of DUT-8(Cu) and Cu3(BTC)2, and take 0.33 mol of ZnO nanopowder, 0.33 mol of ZrO2 nanopowder and 0.33 mol of In2O3 nanopowder, ultrasonically disperse them in 50 mL of deionized water, and then fully stir them at room temperature until the deionized water evaporates completely to obtain a mixed powder. The obtained mixed powder is placed in a Joule heat tube furnace and heated by Joule heat under nitrogen protection at a flow rate of 200 SCCM. The heating rate is controlled to be 800℃ / s, heated to 1000℃, and then kept at 1000℃ for 6 hours to obtain a CO2 hydrogenation to methanol catalyst. TEM image of the catalyst prepared in Example 1 is shown in FIG. Figure 1 and Figure 2 .

[0048] The CO2 hydrogenation to methanol catalysts prepared according to the methods of Examples 1 to 3 and Comparative Examples 1 to 3 were loaded into fixed beds, and H2 and CO2 were continuously introduced into the reactor at a molar ratio of 3:1. The temperature was 240°C, the pressure was 3 MPa, and the total space velocity of CO2 and H2 was 15000 mL / g. cat Methanol was produced by hydrogenation of CO2 at a rate of 100 ppm / h. The product was analyzed and detected by gas chromatography. The methanol selectivity, CO2 conversion rate, and methanol space-time yield measured using different catalysts are shown in Table 1.

[0049] Table 1 Effect of metal organic framework composition on catalyst performance

[0050]

[0051] Analysis of the test results in Table 1 shows that for the metal organic framework used in the present invention, compared with using DUT-8(Cu) or Cu3(BTC)2 alone (Comparative Example 1, Comparative Example 3), when the two are used in combination (Example 1-Example 3), the CO2 conversion rate and methanol space-time yield are higher, indicating that a synergistic effect can be produced between the two to improve the catalytic activity; and, the ratio between DUT-8(Cu) and Cu3(BTC)2 affects the catalytic activity and selectivity. The CO2 conversion rate and methanol space-time yield of Example 1 and Example 2 are higher than those of Comparative Example 2, and the methanol selectivity of Example 1 and Example 2 is higher than that of Example 3.

[0052] Analysis shows that the reason for the above phenomenon is that the two MOF materials, DUT-8(Cu) and Cu3(BTC)2, can optimize the adsorption, activation and diffusion efficiency of H2 and CO2 by optimizing the ratio, while enhancing the removal efficiency of methanol products, thereby synergistically improving the catalytic activity. The pore size of the DUT-8(Cu) material is smaller and narrower (0.3-1.5 nm), which can precisely control the ratio of H2 and CO2 gas reactants, resulting in a better H2 / CO2 ratio, but is not conducive to the removal of methanol products. The pore size distribution of the Cu3(BTC)2 material is wider (0.23-7.9 nm) and has both micropore and mesopore functions. The micropores can allow H2 and CO2 reaction products to enter, while the mesopores are conducive to the transfer and removal of methanol products, thereby optimizing the mass transfer process in the catalytic reaction of CO2 hydrogenation to methanol. In addition, by regulating the coordination balance of the BTC ligand, more Cu atomic active sites can be exposed, thereby accelerating the adsorption and activation of CO2 to form formic acid intermediates (HCOO - ). By designing a specific molar ratio between DUT-8(Cu) and Cu3(BTC)2, pore size complementarity can be achieved, improving the efficiency of reactant supply and product separation, thereby enabling the catalyst to have both high catalytic activity and reaction selectivity.

[0053] Example 4 and Comparative Examples 4-6: Effect of Metal Oxide Composition on Catalyst Performance

[0054] In Example 4 and Comparative Examples 4 to 6, the steps for preparing the CO2 hydrogenation to methanol catalyst are as follows:

[0055] 0.03 mol of DUT-8(Cu) and 0.01 mol of Cu₃(BTC)₂ were ultrasonically dispersed in 50 mL of deionized water, along with a certain amount of ZnO nanopowder, ZrO₂ nanopowder, and In₂O₃ nanopowder (see Table 2 for specific amounts). The mixture was then stirred thoroughly at room temperature until the deionized water evaporated completely, yielding a mixed powder. The resulting mixed powder was then placed in a Joule-heated tube furnace and heated at a controlled heating rate of 800°C / s to 1000°C under a nitrogen atmosphere at a flow rate of 200 sccm. The mixture was then maintained at 1000°C for 6 h to yield a CO₂ hydrogenation to methanol catalyst.

[0056] The CO2 hydrogenation to methanol catalysts prepared according to the methods of Example 4 and Comparative Examples 4 to 6 were loaded into fixed beds, and H2 and CO2 with a molar ratio of 3:1 were continuously introduced into the reactor at a temperature of 240°C, a pressure of 3 MPa, and a total space velocity of CO2 and H2 of 15000 mL / g. cat CO₂ hydrogenation to methanol was carried out at a rate of 100 ppm / h. The product was analyzed by gas chromatography at the 1st and 6th hour of reaction. The measured methanol selectivity, CO₂ conversion, and methanol space-time yield for different catalysts are shown in Table 3.

[0057] Table 2 Composition of metal oxides in various examples and comparative examples

[0058]

[0059] Table 3 Effect of metal oxide composition on catalyst performance

[0060]

[0061] By analyzing the test results in Table 3, it can be seen that: for the metal oxides used in the present invention, compared with using ZnO, ZrO2 or In2O3 alone (Comparative Examples 4 to Comparative Examples 6), when the three are used in combination (Example 2, Example 4), the catalyst has higher catalytic activity, selectivity and stability; Comparative Examples 4 and Comparative Examples 6 use ZnO and In2O3 alone, respectively, and the stability of the catalyst is poor. After a period of use, the CO2 conversion rate and the methanol space-time yield decrease significantly; Comparative Example 5 uses ZrO2 alone, and the catalytic activity is low, and the CO2 conversion rate and methanol space-time yield are low.

[0062] Analysis shows that the reason for the above phenomenon is that the Cu-ZnO interface formed by ZnO can promote electron transfer and oxygen vacancy generation, enhance CO2 adsorption activation, and has the advantages of high methanol selectivity (>90%) and can effectively inhibit the occurrence of side reactions, but it is easy to sinter and deactivate at high temperatures, and the active sites are easily deactivated by water poisoning; ZrO2 has weak hydrophilicity, which can reduce the poisoning of water on the active sites, and has good high temperature stability (>350°C), but its low temperature catalytic activity is poor; In2O3 surface is rich in oxygen vacancies, which can directly promote CO2 activation and still maintain high methanol selectivity at low temperatures, but its oxygen vacancies are easily poisoned and deactivated. By using the three in a specific ratio in the present invention, the advantages of the catalytic active components can be complemented, and the selectivity of the catalyst for synthesizing methanol, its high temperature resistance and its stability against water poisoning can be improved.

[0063] Comparative Example 7: Effect of Preparation Method on Catalyst Performance

[0064] In Comparative Example 7, the steps for preparing a CO2 hydrogenation to methanol catalyst are as follows: 0.03 mol DUT-8(Cu) and 0.01 mol Cu3(BTC)2, as well as 0.33 mol ZnO nanopowder, 0.33 mol ZrO2 nanopowder, and 0.33 mol In2O3 nanopowder, are ultrasonically dispersed in 50 mL of deionized water, and then stirred thoroughly at room temperature until the deionized water is completely evaporated to obtain a mixed powder. The obtained mixed powder is placed in a tube furnace and, under a nitrogen protection at a flow rate of 200 SCCM, programmed heating is performed at a heating rate of 5°C / min to 1000°C, and then maintained at 1000°C for 6 hours to obtain a CO2 hydrogenation to methanol catalyst.

[0065] The CO2 hydrogenation to methanol catalyst prepared according to the method of Comparative Example 7 was loaded into a fixed bed, and H2 and CO2 with a molar ratio of 3:1 were continuously introduced into the reactor. The temperature was 240 ° C, the pressure was 3 MPa, and the total space velocity of CO2 and H2 was 15000 mL / g. cat CO₂ hydrogenation to methanol was carried out at a reaction rate of 100 ppm / h. The product was analyzed by gas chromatography at the 1st and 6th hour of the reaction. The measured methanol selectivity, CO₂ conversion, and methanol space-time yield for different catalysts are shown in Table 4.

[0066] Table 4 Effect of preparation method on catalyst performance

[0067]

[0068] By analyzing the test results in Table 4, it can be seen that compared with Comparative Example 7, the methanol selectivity, CO2 conversion rate and methanol space-time yield of Example 2 are higher, and the decrease in CO2 conversion rate and methanol space-time yield after a period of use is smaller.

[0069] Analysis of the reasons for the above phenomenon is that it is difficult to accurately control the structure and distribution of active sites in Comparative Example 7, the active component Cu is unevenly distributed on the surface of the metal oxide, and the interaction between the active component and the support is weak, resulting in low catalyst stability and selectivity; Example 7 uses Joule heat heating technology to convert a mixed powder of DUT-8 (Cu), Cu3 (BTC) 2 and metal oxide into a carbon dioxide hydrogenation methanol catalyst. In this process, the rapid and efficient heating characteristics of Joule heat can be utilized to carbon thermally reduce the central Cu atoms of DUT-8 (Cu) and Cu3 (BTC) 2 materials, and combine with nano-metal oxides to cause interfacial phase thermal segregation, forming a local Cu-O x -metal oxide active sites. In this process, with the help of the single metal center structure of DUT-8(Cu) and Cu3(BTC)2 and the rapid heating process generated by Joule heat heating, Cu can quickly migrate and disperse on the metal oxide surface, reducing unit cell agglomeration, thereby making the prepared CO2 hydrogenation to methanol catalyst have higher catalytic activity. At the same time, phase thermal segregation can stabilize the Cu atoms and enhance the strong interaction between the Cu atoms and the metal oxide support, thereby improving the stability and reaction selectivity of the catalyst.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a catalyst for producing methanol by hydrogenation of carbon dioxide, characterized in that: The following steps are involved: S1: preparing a mixed powder of a metal organic framework and metal oxide nanopowders; the metal organic framework comprises DUT-8(Cu) and Cu3(BTC)2 in a molar ratio of 1-5:1; the metal oxide nanopowders comprise ZnO nanopowder, ZrO2 nanopowder and In2O3 nanopowder in a molar ratio of 1-6:1-3:1; S2: Heating the mixed powder by Joule heat in an inert atmosphere to obtain a catalyst for hydrogenating carbon dioxide to methanol. The specific process of the Joule heat heating includes: heating the mixture to 800-1200°C at a rate of 100-1000°C / s, and then maintaining the temperature at 800-1200°C for 4-10 hours.

2. The preparation method according to claim 1, characterized in that In step S1, the molar ratio of the metal organic framework to the metal oxide nanopowder is 0.02-0.1:

1.

3. The preparation method according to claim 1, wherein In step S2, the inert atmosphere is nitrogen; during the Joule heat heating process, the nitrogen flow rate is 200-400 SCCM.

4. The preparation method according to claim 1, characterized in that The specific process of step S1 includes: ultrasonically dispersing the metal organic framework and the metal oxide nanopowder into a dispersion medium, and stirring until the dispersion medium is completely volatilized to obtain a mixed powder.

5. The preparation method according to claim 4, wherein The molar volume ratio of the metal organic framework to the dispersion medium is 0.02-0.1 mol:50-60 mL.

6. The preparation method according to claim 4, characterized in that The dispersion medium includes at least one of deionized water, methanol, acetone and isopropyl alcohol.

7. A catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the catalyst according to claim 7 in the reaction of producing methanol by hydrogenation of carbon dioxide.

9. The use according to claim 8, characterized in that During the carbon dioxide hydrogenation to methanol reaction, the temperature is 190-270°C, the pressure is 2-5 MPa, the molar ratio of hydrogen to carbon dioxide is 2-3:1, and the total space velocity of hydrogen and carbon dioxide is 4000-20000 mL / g. cat / h.

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