Modified catalysts and their preparation methods and methods for producing methanol by CO2 hydrogenation

Abstract

This invention relates to the field of catalyst technology, and discloses a modified catalyst and its preparation method, as well as a method for producing methanol by CO2 hydrogenation, comprising: (1) mixing a hydrophobic modifier, mesoporous nanomaterials, and an additive in the presence of a solvent to obtain a homogeneous mixture; wherein the additive is a silane compound; based on the total mass of the hydrophobic modifier, mesoporous nanomaterials, and additive, the content of the hydrophobic modifier is 45-70 wt%, the content of the mesoporous nanomaterials is 20-35 wt%, and the content of the additive is 10-20 wt%; (2) aging the homogeneous mixture, followed by solid-liquid separation and drying to obtain a solid product; (3) mixing the solid product with a copper-based methanol catalyst, followed by optional molding. The modified catalyst prepared by this method has a high methanol yield and a low methanol yield decay after heat treatment.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a modified catalyst and its preparation method, and a method for producing methanol by CO2 hydrogenation. Background Technology

[0002] Given the current energy and environmental crisis and the urgency of carbon reduction targets, the resource utilization of carbon dioxide has attracted much attention. Converting carbon dioxide into high-value fuels and chemical products (such as methanol, formic acid, and gasoline) can effectively contribute to carbon reduction. Methanol, as an organic synthesis intermediate and liquid fuel, has a wide range of applications and shows great potential to replace fossil fuels. However, traditional coal-based methanol production is energy-intensive and heavily polluting. With advancements in renewable energy hydrogen production technology, efficient carbon dioxide hydrogenation to methanol processes have been developed, among which Cu-based catalysts are favored due to their low cost, high activity, and ease of preparation. However, high temperature and humidity environments easily lead to the deactivation of Cu catalysts. Therefore, exploring the effects of water on catalysts and hydrophobic modification techniques is of great significance for the research and application of Cu-based methanol synthesis catalysts. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of poor heat resistance and easy deactivation of copper-based methanol catalysts in the prior art, and to provide a modified catalyst, its preparation method and a method for producing methanol by CO2 hydrogenation. The modified catalyst prepared by this method has high stability and reactivity.

[0004] To achieve the above objectives, the present invention provides a method for preparing a modified catalyst, the method comprising: (1) In the presence of a solvent, a hydrophobic modifier, mesoporous nanomaterials and an additive are mixed to obtain a homogeneous mixture; the additive is a silane compound; Based on the total mass of the hydrophobic modifier, mesoporous nanomaterials, and additives, the content of the hydrophobic modifier is 45-70 wt%, the content of the mesoporous nanomaterials is 20-35 wt%, and the content of the additives is 10-20 wt%. (2) The homogeneous mixture is aged, then solid-liquid separation and drying are performed to obtain a solid product; (3) The solid product is mixed with a copper-based methanol catalyst and then optionally shaped.

[0005] The second aspect of the present invention provides a modified catalyst prepared by the above-described method for preparing the modified catalyst.

[0006] A third aspect of the present invention provides a method for producing methanol by hydrogenation of CO2, comprising: contacting a mixed gas containing CO2 and hydrogen with a catalyst under the reaction conditions for producing methanol by hydrogenation of CO2; The catalyst is the modified catalyst described in the second aspect.

[0007] The preparation method provided by this invention utilizes hydrophobic polymer materials, high-temperature resistant mesoporous nanomaterials, and a certain amount of additives to construct a hydrophobic encapsulation structure on the surface of a copper-based catalyst, thereby functionally modifying the catalyst and controlling the hydrophobic properties of the copper-based methanol catalyst surface under high-temperature conditions. The modified catalyst obtained has reduced adsorption of water molecules, thereby reducing the interference of water on the catalytic process, further suppressing water-related side reactions, enhancing catalyst stability, and improving reaction performance. The obtained modified catalyst has good thermal stability. Detailed Implementation

[0008] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0009] The first aspect of this invention provides a method for preparing a modified catalyst, the method comprising: (1) In the presence of a solvent, a hydrophobic modifier, mesoporous nanomaterials and an additive are mixed to obtain a homogeneous mixture; the additive is a silane compound; Based on the total mass of the hydrophobic modifier, mesoporous nanomaterials, and additives, the content of the hydrophobic modifier is 45-70 wt%, the content of the mesoporous nanomaterials is 20-35 wt%, and the content of the additives is 10-20 wt%. (2) The homogeneous mixture is aged, then solid-liquid separation and drying are performed to obtain a solid product; (3) The solid product is mixed with a copper-based methanol catalyst and then optionally shaped.

[0010] According to the present invention, a hydrophobic encapsulation structure is constructed on the surface of a copper-based catalyst using hydrophobic polymer materials, high-temperature resistant mesoporous nanomaterials, and a certain amount of additives. This functionally modifies the catalyst, thereby controlling the hydrophobic properties of the copper-based methanol catalyst surface under high-temperature conditions. This reduces the adsorption of water molecules by the copper-based methanol catalyst, reduces the interference of water on the catalytic process, further suppresses water-related side reactions, and enhances the catalyst stability and improves the reaction performance. The resulting modified catalyst exhibits good thermal stability.

[0011] According to some preferred embodiments of the present invention, based on the total mass of the hydrophobic modifier, mesoporous nanomaterial, and additives, the content of the hydrophobic modifier is 55-65 wt%, the content of the mesoporous nanomaterial is 25-30 wt%, and the content of the additives is 10-15 wt%. In the above preferred embodiments, it is beneficial to construct abundant gas transport channels on the catalyst surface, improve the hydrophobic properties of the copper-based catalyst, and enhance the stability of the catalyst.

[0012] According to the present invention, preferably, the hydrophobic modifier is a hydrophobic polymer particle. The present invention has a wide range of choices for the types of hydrophobic polymer particles. Preferably, the hydrophobic polymer particles are selected from at least one of polytetrafluoroethylene, polyphenylene sulfide, polyvinylidene fluoride, and perfluoroethylene propylene, and more preferably polytetrafluoroethylene and / or perfluoroethylene propylene. The above-mentioned preferred hydrophobic polymer particles have good high and low temperature resistance and chemical corrosion resistance, and can further exert the synergistic effect with mesoporous nanomaterials and additives, further improving the heat resistance, mechanical properties and stability of the material in the new system, without significantly changing the internal spatial structure and good hydrophobic properties of the material, and can form a good synergistic effect with copper-based catalysts.

[0013] Preferably, the weight-average molecular weight of the hydrophobic polymer particles is 50,000-300,000.

[0014] Preferably, the average particle size of the hydrophobic polymer particles is 4-12 μm, more preferably 4-10 μm.

[0015] According to the present invention, preferably, the mesoporous nanomaterial is selected from at least one of silicon oxide, cerium oxide, boron nitride and bacilli tubes, and more preferably silicon oxide and / or cerium oxide.

[0016] Preferably, the average pore size of the mesoporous nanomaterial is 1-10 nm.

[0017] Preferably, the particle size of the mesoporous nanomaterial is 50-120 nm.

[0018] In this invention, the auxiliary agent is a silane compound used for surface modification of mesoporous materials to improve the high hydrothermal stability of the catalyst. This invention allows for a wide range of silane compounds; preferably, the auxiliary agent is selected from at least one of methyltrichlorosilane, octadecyltrichlorosilane, γ-mercaptopropylmethyldimethoxysilane, and polysiloxane.

[0019] According to the present invention, preferably, the solvent is selected from at least one of alcohol compounds, such as at least one of methanol, ethanol, and isopropanol, with ethanol being preferred.

[0020] According to some preferred embodiments of the invention, in step (1), the mixing temperature is 35-65℃, preferably 40-55℃, and the time is 1-3h, preferably 1-2h. Using the above preferred embodiments facilitates the thorough mixing of the hydrophobic modifier, mesoporous nanomaterials, and additives, forming a stable homogeneous system.

[0021] The present invention offers a wide range of options for the mixing method, as long as a homogeneous mixed solution can be formed. According to some preferred embodiments of the present invention, the mixing includes: premixing the hydrophobic modifier, mesoporous nanomaterials, additives, and solvent, and then feeding the mixture into a microchannel reactor for further mixing.

[0022] The remixing can be carried out using any conventional microchannel reactor in the art, and the present invention does not impose any particular limitation on the channel size and shape of the microchannel reactor.

[0023] According to some preferred embodiments of the present invention, the system pressure of the microchannel reactor is controlled to be 200-500 bar, preferably 300-400 bar.

[0024] According to the present invention, during the aging process described in step (3), the amorphous precipitate will form a crystalline product through structural rearrangement. This change process will have a significant impact on the subsequent formation of the catalyst structure, so that the catalyst can reach the optimal catalytic performance state.

[0025] According to some preferred embodiments of the present invention, the aging time is 24-48 hours, preferably 28-40 hours.

[0026] According to the present invention, the product obtained by aging is a solid-liquid mixture, and a solid product can be obtained by any conventional solid-liquid separation operation in the art, such as filtration, vacuum filtration, centrifugation, etc. The present invention does not have any particular limitation in this regard.

[0027] According to the present invention, step (3) further includes drying the product after solid-liquid separation to remove residual solvents, etc. Preferably, the drying temperature is 100-120°C and the drying time is 24-48 hours. The drying is preferably carried out in a vacuum drying oven.

[0028] According to some preferred embodiments of the present invention, the mass ratio of solid product to copper-based methanol catalyst is (10-25):(75-90), preferably (15-20):(80-85). Controlling the mass ratio of solid product to copper-based methanol catalyst within the above-mentioned preferred range is beneficial to further improve the catalytic performance, stability and service life of the catalyst.

[0029] The present invention does not have any particular limitation on the specific mixing method in step (3). Conventional solid-phase mixing methods in the art can be used, as long as the solid product and the copper-based methanol catalyst can be mixed evenly.

[0030] According to some preferred embodiments of the present invention, the mixture is ball-milled at least once in a ball mill, preferably 2-5 times, for example, 2 times, 3 times, 4 times, 5 times, etc.

[0031] Preferably, the ball mill rotation speed is 300-600 r / min, more preferably 400-550 r / min, the ball milling time is 20-60 min, more preferably 25-50 min, and the ball-to-material mass ratio is 1-10:1, more preferably 1-5:1.

[0032] The method for preparing the modified catalyst provided by this invention can be applied to any conventional copper-based methanol catalyst in the art. This invention does not have any particular limitation on the source of the copper-based methanol catalyst, which can be commercially available or prepared by any known method in the art.

[0033] According to some particularly preferred embodiments of the present invention, the copper-based methanol catalyst comprises alumina, zinc oxide, and Cu.

[0034] Preferably, based on the total mass of the copper-based methanol catalyst, the content of Cu element is 50-70 wt%, the content of zinc oxide is 20-30 wt%, and the content of aluminum oxide is 5-10 wt%.

[0035] Those skilled in the art can choose to mold the product after mixing in step (3) according to the needs of actual application, or they can directly use the mixed product as a composition in the CO2 hydrogenation to methanol reaction. The present invention does not have any particular limitation on this. The present invention also does not have any special requirements on the molding method. Any conventional molding method in the art can be used to form products with regular shapes such as sheets, strips, and spheres.

[0036] The second aspect of the present invention provides a modified catalyst prepared by the above-described method for preparing the modified catalyst.

[0037] A third aspect of the present invention provides a method for producing methanol by hydrogenation of CO2, comprising: contacting a mixed gas containing CO2 and hydrogen with a catalyst under the reaction conditions for producing methanol by hydrogenation of CO2; The catalyst is the modified catalyst described in the second aspect.

[0038] In this invention, the selection range for the reaction conditions of CO2 hydrogenation to methanol is relatively wide, and conventional reaction conditions in the art can be adopted. Preferably, the reaction conditions for CO2 hydrogenation to methanol include: a reaction temperature of 200-280℃, preferably 220-260℃; a reaction pressure of 2-7 MPa, preferably 4-6 MPa; and a gas space velocity of 6000-15000 h⁻¹. -1 Preferably 8000-12000 h -1 .

[0039] According to the present invention, preferably, the content of CO2 in the mixed gas is 16-30 vol%, and the content of hydrogen is 60-78 vol%.

[0040] According to the present invention, the mixed gas may also contain inactive gases such as nitrogen, and the present invention does not have any particular limitation in this regard.

[0041] The present invention will be described in detail below through embodiments.

[0042] In the Cu / ZnO / Al2O3 catalyst used in the following examples, the content of Cu is 68wt%, the content of ZnO is 23wt%, and the content of Al2O3 is 9wt%.

[0043] Example 1 Polytetrafluoroethylene (PTFE) (weight average molecular weight 150,000, average particle size 10 μm), silica (average pore size 5.2 nm, particle size 80 nm), and methyltrichlorosilane were weighed and mixed, with the hydrophobic polymer accounting for 55% of the mixture, the mesoporous nanomaterials accounting for 30%, and the additives accounting for 15%. The mixture was added to anhydrous ethanol and stirred at 50 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 300 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 32 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0044] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 15:85. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated three times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0045] Example 2 Polytetrafluoroethylene (PTFE) (weight average molecular weight 150,000, average particle size 5 μm), silica (average pore size 3.4 nm, particle size 60 nm), and methyltrichlorosilane were weighed and mixed, with the hydrophobic polymer accounting for 65% of the mixture, the mesoporous nanomaterial accounting for 25%, and the additives accounting for 10%. The mixture was added to anhydrous ethanol and stirred at 50 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 400 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 40 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0046] Solid product B and self-made Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 15:85. The solid mixture was ground in a ball mill at 500 r / min for 30 min, and the process was repeated 3 times. The ground powder was pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0047] Example 3 Poly(fluoroethylene propylene) (FEP) with a weight-average molecular weight of 180,000 and an average particle size of 10 μm, cerium oxide (average pore size of 7.4 nm and particle size of 100 nm), and octadecyltrichlorosilane were weighed and mixed. The hydrophobic polymer material accounted for 55% of the mixture, the mesoporous nanomaterial accounted for 30%, and the additives accounted for 15%. The mixture was added to anhydrous ethanol and stirred at 50 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed in a high-pressure microchannel reactor at a controlled pressure of 350 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 32 h, separated by centrifugation, and then dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0048] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 15:85. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated three times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0049] Example 4 Polytetrafluoroethylene (PTFE) (weight average molecular weight 150,000, average particle size 5 μm), silica (average pore size 12.6 nm, particle size 140 nm), and methyltrichlorosilane were weighed and mixed, with the hydrophobic polymer accounting for 45% of the mixture, the mesoporous nanomaterial accounting for 35%, and the additives accounting for 20%. The mixture was added to anhydrous ethanol and stirred at 55 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 350 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 40 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0050] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 20:80. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated three times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0051] Example 5 Polyvinylidene fluoride (PVDF) (weight average molecular weight 100,000, average particle size 10 μm), boron nitride (average pore size 4.2 nm, particle size 80 nm), and polysiloxane were weighed and mixed, with the hydrophobic polymer accounting for 65% of the mixture, the mesoporous nanomaterial accounting for 25%, and the additives accounting for 10%. The mixture was added to anhydrous ethanol and stirred at 50 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 350 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 32 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0052] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 15:85. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated three times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0053] Example 6 Polyphenylene sulfide (PPS) (weight average molecular weight 130,000, average particle size 10 μm), buckytubes (average pore size 5.5 nm, particle size 80 nm), and polysiloxane were weighed and mixed, with the hydrophobic polymer accounting for 55% of the mixture, the mesoporous nanomaterials accounting for 25%, and the additives accounting for 20%. The mixture was added to anhydrous ethanol and stirred at 50 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 400 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 32 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0054] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 10:90. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated three times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0055] Example 7 Polytetrafluoroethylene (PTFE) (weight average molecular weight 150,000, average particle size 15 μm), buckytubes (average pore size 8.2 nm, particle size 120 nm), and methyltrichlorosilane were weighed and mixed, with the hydrophobic polymer material accounting for 60% of the mixture, the mesoporous nanomaterial accounting for 20%, and the additives accounting for 20%. The mixture was added to anhydrous ethanol and stirred at 35 °C for 1 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 300 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 24 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 100 °C for 12 h to obtain powdered solid product B.

[0056] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 10:90. The solid mixture was then ground in a ball mill at 300 r / min for 30 min, and the process was repeated three times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0057] Comparative Example 1 Polytetrafluoroethylene (PTFE) (weight average molecular weight 100,000, average particle size 10 μm) and silica (average pore size 14.5 nm, particle size 80 nm) were weighed and mixed, with the hydrophobic polymer accounting for 70% of the mixture and the mesoporous nanomaterial accounting for 30%. The mixture was added to anhydrous ethanol and stirred at room temperature for 1 h to obtain mixture A. Mixture A was thoroughly mixed using a high-pressure microchannel reactor at a controlled pressure of 350 bar to obtain a stable homogeneous system. The homogeneous system was aged at room temperature for 12 h, and after solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 ℃ for 12 h to obtain powdered solid product B.

[0058] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 5:95. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated 3 times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0059] Comparative Example 2 Silica (average pore size 14.5 nm, particle size 80 nm) and methyltrichlorosilane were weighed and mixed, with the mesoporous nanomaterials accounting for 80% of the mixture and the additives accounting for 20%. The mixture was added to anhydrous ethanol and stirred at 50 °C for 2 h to obtain mixture A. Mixture A was thoroughly mixed by ultrasonication (20 kHz) and aged at room temperature for 12 h. After solid-liquid separation by centrifugation, it was dried in a vacuum drying oven at 120 °C for 12 h to obtain powdered solid product B.

[0060] Solid product B and Cu / ZnO / Al2O3 catalyst powder were weighed and mixed in a mass ratio of 5:95. The solid mixture was then ground in a ball mill at 500 r / min for 30 min, and the process was repeated 3 times. The ground powder was then pressed into tablets in a tableting machine, and then crushed and sieved (20-40 mesh) to obtain the final catalyst product.

[0061] Test case (1) Activity test conditions: In the catalytic CO2 hydrogenation to methanol reaction in a fixed bed reactor, the changes in catalyst activity and the rate of activity degradation after heat resistance were investigated.

[0062] The catalyst loading is 4 mL, and the mixed gas composition is: CO2 23 vol%, H2 69 vol%, balance N2, with a volumetric space velocity of 10000 h⁻¹. -1 The methanol synthesis catalytic reaction was carried out under the conditions of a reaction pressure of 5.0 MPa and a reaction temperature of 240 °C.

[0063] (2) Heat resistance test: After the catalyst was subjected to atmospheric pressure and 400℃ heat treatment for 6 h, it was tested according to the above experimental conditions, and the methanol yield decay rate was calculated. The results are shown in Table 1.

[0064] In the table below, Methanol yield (g / (mL-Cat·h)) = .

[0065] Where T represents the reaction time. This indicates the percentage of methanol by mass in the collected liquid after a reaction time T (obtained by chromatographic measurement). Vm represents the total mass of liquid collected after reaction time T, and Vm represents the catalyst loading volume.

[0066] Methanol yield reduction after heat resistance (%) = ((methanol yield before heat resistance - methanol yield after heat resistance) / methanol yield) × 100%.

[0067] Table 1

[0068] As can be seen from the results in Table 1, the modified catalyst prepared in the embodiments of the present invention has a high methanol yield and a low methanol yield decay rate after heat resistance.

[0069] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a modified catalyst, characterized in that, The preparation method includes: (1) In the presence of a solvent, a hydrophobic modifier, mesoporous nanomaterials and an additive are mixed to obtain a homogeneous mixture; the additive is a silane compound; Based on the total mass of the hydrophobic modifier, mesoporous nanomaterials, and additives, the content of the hydrophobic modifier is 45-70 wt%, the content of the mesoporous nanomaterials is 20-35 wt%, and the content of the additives is 10-20 wt%. (2) The homogeneous mixture is aged, then subjected to solid-liquid separation and drying to obtain a solid product; (3) The solid product is mixed with a copper-based methanol catalyst and then optionally shaped.

2. The preparation method according to claim 1, wherein, Based on the total mass of the hydrophobic modifier, mesoporous nanomaterials and additives, the content of the hydrophobic modifier is 55-65 wt%, the content of the mesoporous nanomaterials is 25-30 wt%, and the content of the additives is 10-15 wt%.

3. The preparation method according to claim 1 or 2, wherein, The hydrophobic modifier is a hydrophobic polymer compound, preferably at least one of polytetrafluoroethylene, polyphenylene sulfide, polyvinylidene fluoride, and perfluoroethylene propylene. Preferably, the mesoporous nanomaterial is selected from at least one of silicon oxide, cerium oxide, boron nitride, and bacilli tubes; Preferably, the auxiliary agent is selected from at least one of methyltrichlorosilane, octadecyltrichlorosilane, γ-mercaptopropylmethyldimethoxysilane, and polysiloxane; Preferably, the solvent is selected from at least one of alcohol compounds, and more preferably ethanol.

4. The preparation method according to any one of claims 1-3, wherein, In step (1), the mixing temperature is 35-65℃, preferably 40-55℃, and the time is 1-3h, preferably 1-2h; Preferably, the mixing includes: premixing the hydrophobic modifier, mesoporous nanomaterials, additives and solvent, and then feeding them into a microchannel reactor for remixing; Preferably, the system pressure of the microchannel reactor is controlled at 200-500 bar, and more preferably 300-400 bar.

5. The preparation method according to any one of claims 1-4, wherein, The aging time is 24-48 hours, preferably 28-40 hours; Preferably, the drying temperature is 100-120℃ and the drying time is 24-48h.

6. The preparation method according to any one of claims 1-5, wherein, The mass ratio of solid product to copper-based methanol catalyst is (10-25):(75-90), preferably (15-20):(80-85). Preferably, the mixture is ball-milled at least once, preferably 2-5 times; Preferably, the ball milling speed is 300-600 r / min, more preferably 400-550 r / min, and the ball milling time is 20-60 min, more preferably 25-50 min.

7. The preparation method according to any one of claims 1-6, wherein, The copper-based methanol catalyst comprises aluminum oxide, zinc oxide, and Cu element; Preferably, based on the total mass of the copper-based methanol catalyst, the content of Cu element is 50-70 wt%, the content of zinc oxide is 20-30 wt%, and the content of aluminum oxide is 5-10 wt%.

8. The modified catalyst prepared by the method of any one of claims 1-7.

9. A method for producing methanol by CO2 hydrogenation, comprising: Under the conditions of CO2 hydrogenation to methanol reaction, a mixture of gas containing CO2 and hydrogen is brought into contact with a catalyst. The catalyst is the modified catalyst according to claim 8.

10. The method according to claim 9, wherein, The reaction conditions for CO2 hydrogenation to methanol include: a reaction temperature of 200-280℃, preferably 220-260℃; a reaction pressure of 2-7 MPa, preferably 4-6 MPa; and a mixed gas volume hourly space velocity of 6000-15000 h⁻¹. -1 Preferably 8000-12000 h -1 ; Preferably, the mixture contains 16-30 vol% CO2 and 60-78 vol% hydrogen.

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