Carbon dioxide hydrogenation to methanol catalyst, preparation method and application thereof

Abstract

The application relates to the field of catalyst preparation and discloses a preparation method of a carbon dioxide hydrogenation methanol catalyst, characterized in that the preparation method comprises the following steps: (1) mixing a first metal source, an organic ligand, an organic acid and a first solvent, and then performing a hydrothermal reaction to obtain product A; (2) mixing the product A, a second solvent, a second metal source and a third metal source to perform a reaction, and obtaining product B; (3) mixing the product B, a third solvent, a reducing agent and a fourth solvent to perform a reaction, and obtaining product C; and (4) mixing the product C, a Lewis acid compound and a fifth solvent, then mixing the obtained mixture with a hydrophobic modifier to perform a reaction, and obtaining the carbon dioxide hydrogenation methanol catalyst. The carbon dioxide hydrogenation methanol catalyst has high catalytic activity, the conversion rate of carbon dioxide is greater than 25%, the selectivity of methanol is greater than 95%, the carbon dioxide hydrogenation methanol can be efficiently catalyzed, the active center of the catalyst is a non-noble metal, the preparation cost is lower, and the industrial large-scale production can be realized.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, specifically to a catalyst for the hydrogenation of carbon dioxide to methanol, its preparation method, and its application. Background Technology

[0002] Methanol is a basic organic chemical raw material with a wide range of applications, including the synthesis of fibers, formaldehyde, plastics, pharmaceuticals, pesticides, dyes, and synthetic proteins. It can also be used as a liquid fuel in direct methanol fuel cells and improved diesel engines. Methanol has a simple molecular structure, and its production from carbon dioxide is relatively easy to achieve, making it one of the ideal products obtained from carbon dioxide reduction. Utilizing the catalytic hydrogenation of CO2 to produce methanol, a high-value-added product, is even more significant for carbon reduction and plays a crucial role in the development of clean energy and carbon reduction.

[0003] Catalysts are crucial for the hydrogenation of CO2 to methanol. The activity, stability, and cost of the catalyst largely determine the yield, purity, and economic viability of the CO2 hydrogenation process. Currently, common catalysts for CO2 hydrogenation to methanol are mainly Cu-based catalysts and noble / rare metal catalysts. Cu-based catalysts exhibit strong CO2 adsorption capacity during the reaction and can promptly activate H2 into atomic *H, allowing CO2 to react with surface atomic *H at relatively low temperatures and pressures to generate the intermediate formate, which is then hydrogenated to methanol via the Eley-Rideal mechanism. However, Cu-based catalysts have a limited number of basic sites, resulting in low single-pass CO2 conversion and methanol selectivity, representing significant drawbacks. Noble / rare metal catalysts possess high catalytic activity, but their high production costs prevent large-scale production. Furthermore, the limited reserves of noble and rare metals fundamentally restrict the industrialization of CO2 hydrogenation to methanol.

[0004] Patent application CN112588320A discloses a hydrophobic catalyst for the hydrogenation of carbon dioxide to methanol, its preparation method, and its application. The preparation method includes: uniformly dispersing an oxide support in anhydrous ethanol, adding a modifier to react, washing and vacuum drying the reaction product to obtain a modified hydrophobic support; impregnating an equal volume of a precursor salt solution of a co-catalyst into the modified hydrophobic support, drying, and then calcining to obtain the hydrophobic catalyst for the hydrogenation of carbon dioxide to methanol. However, the catalyst prepared by this method has a CO2 conversion rate of less than 10% and a methanol selectivity of less than 80%. Patent application CN102302934A discloses a novel co-modified catalyst for the catalytic hydrogenation of carbon dioxide to methanol and its preparation method. The catalyst prepared by this method has a CO2 conversion rate of less than 45% and a methanol selectivity of less than 45%. Patent CN113368861A discloses a catalyst for the hydrogenation of carbon dioxide to methanol, its preparation method, and its application. The catalyst prepared by this method has a CO2 conversion rate of less than 20% and a methanol selectivity of less than 50%. Patent application CN103721719A discloses a catalyst for the hydrogenation of carbon dioxide to methanol. However, the catalyst prepared by this method has a CO2 conversion rate of less than 30% and a methanol selectivity of less than 60%. Therefore, existing carbon dioxide hydrogenation catalysts for methanol production still face the dual challenges of low preparation cost and poor catalytic activity. There is an urgent need to find a carbon dioxide hydrogenation catalyst for methanol production that uses a non-precious metal as the active center and still possesses excellent catalytic activity. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high preparation cost and low conversion rate of carbon dioxide and methanol selectivity in existing technologies for carbon dioxide hydrogenation to methanol catalysts. This invention provides a carbon dioxide hydrogenation to methanol catalyst, its preparation method, and its application. This carbon dioxide hydrogenation to methanol catalyst has high catalytic activity, with a carbon dioxide conversion rate greater than 25% and a methanol selectivity greater than 95%, enabling highly efficient catalytic carbon dioxide hydrogenation to methanol. Furthermore, the active center of the catalyst is a non-precious metal, resulting in lower preparation cost and facilitating large-scale industrial production.

[0006] To achieve the above objectives, the present invention provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising:

[0007] (1) The first metal source, organic ligand, organic acid and first solvent are mixed and then subjected to a hydrothermal reaction to obtain product A;

[0008] (2) The product A, the second solvent, the second metal source and the third metal source are mixed and reacted to obtain product B;

[0009] (3) Mix the product B, the third solvent, the reducing agent and the fourth solvent and react them to obtain product C;

[0010] (4) The product C, Lewis acid compound and fifth solvent are mixed, and then the resulting mixture is mixed with hydrophobic modifier to react and obtain carbon dioxide hydrogenation to methanol catalyst.

[0011] The first metal source is selected from one or more of copper salts, zinc salts, aluminum salts, and iron salts;

[0012] The organic ligand contains a carboxyl group, and one or two of naphthyl and quinolinyl groups;

[0013] The hydrophobic modifier is selected from haloalkanes, C2-C 12 fatty alcohols and C2-C 12 At least one of the chain olefins;

[0014] The first metal, the second metal, and the third metal are different.

[0015] Preferably, the organic ligand is selected from one or more of 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3-quinolinedicarboxylic acid, and 2,2'-bisquinoline-4,4'-dicarboxylic acid.

[0016] Preferably, the first metal source, the second metal source, and the third metal source are different;

[0017] Preferably, the second metal source is selected from one of zirconium salt, zinc salt, cerium salt, aluminum salt, iron salt, nickel salt, copper salt, and lanthanum salt;

[0018] Preferably, the third metal source is selected from one of zirconium salt, zinc salt, cerium salt, aluminum salt, iron salt, nickel salt, copper salt, and lanthanum salt.

[0019] Preferably, the first solvent is selected from one or more of N,N-dimethylacetamide, dimethyl sulfoxide, butanone, N,N-dimethylformamide, chloroform and methyl acetate;

[0020] Preferably, the second solvent is selected from one or more of n-hexane, n-pentane, cyclopentane, n-heptane, petroleum ether, and benzene;

[0021] Preferably, the third solvent is selected from one or more of tetrahydrofuran, pyridine, N,N-dimethylacetamide, acetone, ethyl acetate, methyl acetate, acetic acid, dichloromethane, and chloroform.

[0022] Preferably, the fourth solvent is selected from one or more of tetrahydrofuran, benzene, chlorobenzene, ethyl acetate, acetone, toluene, xylene, isopropyl ether, methyl tert-butyl ether, dichloromethane, chloroform, and petroleum ether.

[0023] Preferably, the fifth solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, methanol, tetrahydrofuran, ethylene glycol, acetone and pyridine.

[0024] Preferably, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, octanoic acid, adipic acid, oxalic acid, malonic acid, succinic acid, maleic acid, tartaric acid, benzoic acid, phenylacetic acid, valeric acid, hexanoic acid, decanoic acid, stearic acid, methanesulfonic acid, and thioacetic acid.

[0025] Preferably, the conditions for the hydrothermal reaction include: a temperature of 100-150℃ and a time of 12-48h.

[0026] Preferably, the reducing agent is selected from one or more of sodium triethylborohydride, potassium triethylborohydride, sodium trimethoxyborohydride, sodium trisec-butylborohydride, lithium hydride, lithium aluminum hydride, sodium borohydride, potassium trisec-butylborohydride, and lithium tritert-butoxyaluminum hydride.

[0027] Preferably, in the haloalkane, the alkyl group is C2-C. 12 The alkyl group is a straight-chain alkyl group or a branched alkyl group, and the halogen is selected from one or two of F, Cl, Br and I;

[0028] Preferably, the haloalkane is selected from one or more of chlorobutane, chloroisooctane, chloropropane, chlorocyclopentane, chlorooctane, and chlorononane;

[0029] Preferably, the C2-C 12 The fatty alcohol is selected from one or more of propanol, n-butanol, n-pentanol, n-heptanol, and n-octanol;

[0030] Preferably, the C2-C 12 The olefins are selected from one or more of propylene, butene, pentene, heptenene, and octene.

[0031] Preferably, the Lewis acid compound is selected from one or more of ferric chloride, aluminum chloride, boron trifluoride, niobium pentachloride, and trifluoromethanesulfonate.

[0032] Preferably, the weight ratio of the first metal source to the organic ligand is 1:0.2-5;

[0033] Preferably, the weight ratio of the product A, the second metal source, and the third metal source is 1:0.3-3:0.3-3;

[0034] Preferably, the weight ratio of product B to the reducing agent is 1-8:1;

[0035] Preferably, the weight ratio of the product C, the Lewis acid compound, and the hydrophobic modifier is 1:0.2-1:1-4.

[0036] Preferably, in step (2), the reaction conditions include: a temperature of 15-100℃ and a time of 3-24h;

[0037] Preferably, in step (3), the reaction conditions include: a temperature of 10-80°C and a time of 0.5-12 h;

[0038] Preferably, in step (4), the reaction conditions include: a temperature of 5-90°C and a time of 0.2-12h.

[0039] A second aspect of the present invention provides a catalyst for the hydrogenation of carbon dioxide to methanol prepared by the above-described preparation method.

[0040] A third aspect of the present invention provides an application of the above-described carbon dioxide hydrogenation to methanol catalyst in the process of carbon dioxide hydrogenation to methanol.

[0041] The preparation method described in this invention uses metal-organic frameworks (MOFs) as a support. Further assembly techniques, such as post-synthetic modification of ligands and secondary building blocks, functionalization of structural units, and non-covalent loading, are employed to solidify sub-nanometer or even atomic-level catalytically active metals with CO2 hydrogenation activity within the MOF material, synthesizing a composite MOF material. This achieves highly dispersed loading of the active metal, allowing the active metal in the prepared CO2 hydrogenation to methanol catalyst to fully exert its catalytic performance and improving its atom utilization. In this invention, functionalized MOFs replace traditional metal oxide supports, introducing strong metal-support interactions between metal nanoparticles, organic chelate ligands, and metal-oxygen cluster nodes. This optimizes catalytic activity and selectivity, providing abundant interfaces and exhibiting high chemoselectivity; moreover, it maintains catalytic activity even during prolonged catalytic processes.

[0042] Furthermore, in the preparation method described in this invention, a hydrophobic modifier is used to further hydrophobize the ligands in the prepared composite metal-organic framework material, thereby improving the hydrophobic properties of the catalyst support surface, inhibiting water molecule adsorption, and further enhancing the stability of the prepared catalyst. The carbon dioxide hydrogenation to methanol catalyst prepared using the method described in this invention can achieve high carbon dioxide conversion and also exhibits high product selectivity. In the catalytic hydrogenation of carbon dioxide to methanol, its selectivity for methanol can reach over 95%, and the carbon dioxide conversion rate can reach over 25%. Moreover, the preparation method described in this invention does not use expensive precious metals, successfully preparing a low-cost carbon dioxide hydrogenation to methanol catalyst with excellent catalytic activity, possessing broad application prospects. Detailed Implementation

[0043] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0044] 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.

[0045] This invention provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising:

[0046] (1) The first metal source, organic ligand, organic acid and first solvent are mixed and then subjected to a hydrothermal reaction to obtain product A;

[0047] (2) The product A, the second solvent, the second metal source and the third metal source are mixed and reacted to obtain product B;

[0048] (3) Mix the product B, the third solvent, the reducing agent and the fourth solvent and react them to obtain product C;

[0049] (4) The product C, Lewis acid compound and fifth solvent are mixed, and then the resulting mixture is mixed with hydrophobic modifier to react and obtain carbon dioxide hydrogenation to methanol catalyst.

[0050] In the method described in this invention, in step (1), a first metal source, an organic ligand, and an organic acid are mixed and subjected to a hydrothermal reaction to prepare a metal-organic framework material product A, which serves as a catalyst support. By selecting specific metal sources and organic ligands for combination, specific metal-organic framework materials are prepared. The obtained metal-organic framework material is used as a support for the active component. Further modification and loading of the obtained metal-organic framework material yields a highly active catalyst for the hydrogenation of carbon dioxide to methanol.

[0051] In a specific embodiment, the first metal source is selected from one or more of copper salts, zinc salts, aluminum salts, and iron salts, wherein the copper salts, zinc salts, aluminum salts, and iron salts are all soluble metal salts. For example, the copper salt can be one or more of copper nitrate, copper chloride, copper sulfate, cuprous oxide, and cuprous chloride; the zinc salt can be one or more of zinc nitrate, zinc chloride, and zinc sulfate; the aluminum salt can be aluminum nitrate and / or aluminum chloride; and the iron salt can be ferric nitrate and / or ferric chloride.

[0052] In a specific embodiment, the organic ligand contains a carboxyl group, and one or two of a naphthyl and a quinolinyl group. Specifically, the organic ligand contains a carboxyl group and a naphthyl group, or the organic ligand contains a carboxyl group and a quinolinyl group, or the organic ligand contains a carboxyl group, a naphthyl group, and a quinolinyl group.

[0053] In a preferred embodiment, the organic ligand is selected from one or more of 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3-quinolinedicarboxylic acid, and 2,2'-bisquinoline-4,4'-dicarboxylic acid.

[0054] In a preferred embodiment, the organic acid is one or more of carboxylic acid compounds, sulfonic acid compounds, sulfinic acid compounds, and thiocarboxylic acid compounds. Preferably, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, octanoic acid, adipic acid, oxalic acid, malonic acid, succinic acid, maleic acid, tartaric acid, benzoic acid, phenylacetic acid, valeric acid, hexanoic acid, decanoic acid, stearic acid, methanesulfonic acid, and thioacetic acid.

[0055] In a preferred embodiment, the first solvent is selected from one or more of N,N-dimethylacetamide, dimethyl sulfoxide, butanone, N,N-dimethylformamide, chloroform, and methyl acetate.

[0056] In a preferred embodiment, the performance of the prepared metal-organic framework material and the activity of the prepared catalyst can be further improved by controlling the dosage relationship between the first metal source and the organic ligand. Specifically, the weight ratio of the first metal source to the organic ligand is 1:0.2-5, preferably 1:0.5-3. More specifically, the weight ratio of the first metal source to the organic ligand can be 1:0.2, 1:1, 1:1.5, 1:2, 1:3, 1:4, or 1:5.

[0057] In a preferred embodiment, the conditions for the hydrothermal reaction include: a temperature of 100-150°C and a time of 12-48 hours.

[0058] In a preferred embodiment, in step (2), the metal-organic framework material product A obtained in step (1) is used as a carrier, and then the active metal is further loaded and solidified in the framework of the metal-organic framework material product A to prevent the aggregation of the active metal from reducing the catalytic activity, thereby preparing a carbon dioxide to methanol catalyst with three metal active centers.

[0059] In the method described in this invention, the first metal, the second metal, and the third metal are different. Specifically, the first metal source, the second metal source, and the third metal source contain different types of metals. For example, when the metal in the first metal source is copper, the metals in the second metal source and the third metal source cannot be copper. When the metal in the first metal source is copper and the metal in the second metal source is zirconium, the metal in the third metal source cannot be either copper or zirconium.

[0060] In a preferred embodiment, the second metal source is selected from one of zirconium salt, zinc salt, cerium salt, aluminum salt, iron salt, nickel salt, copper salt, and lanthanum salt, and the third metal source is selected from one of zirconium salt, zinc salt, cerium salt, aluminum salt, iron salt, nickel salt, copper salt, and lanthanum salt. Specifically, the zirconium salt can be one or more of zirconium nitrate, zirconium chloride, zirconium fluoride, and zirconium oxychloride octahydrate; the zinc salt can be one or more of zinc nitrate, zinc chloride, and zinc sulfate; the cerium salt can be cerium nitrate and / or cerium chloride; the aluminum salt can be aluminum nitrate and / or aluminum chloride; the iron salt can be ferric nitrate and / or ferric chloride; the nickel salt can be nickel nitrate and / or nickel chloride hexahydrate; the copper salt can be one or more of copper nitrate, copper chloride, copper sulfate, cuprous oxide, and cuprous chloride; and the lanthanum salt can be lanthanum nitrate and / or lanthanum chloride.

[0061] In a preferred embodiment, the second solvent is selected from one or more of n-hexane, n-pentane, cyclopentane, n-heptane, petroleum ether, and benzene.

[0062] In a preferred embodiment, the weight ratio of the product A, the second metal source, and the third metal source is 1:0.3-3:0.3-3, preferably 1:0.3-3:0.5-2.5.

[0063] In a preferred embodiment, in step (2), the reaction conditions include a temperature of 15-100°C and a time of 3-24 hours.

[0064] In the method described in this invention, in step (3), the product B obtained in step (2) is mixed with a reducing agent to react and reduce the metal elements in the metal-organic framework material, the metal elements in the second metal source and the metal elements in the third metal source, thereby reducing the metal elements to prepare metal nanoparticles. The obtained metal nanoparticles have a small particle size and high activity. The sub-nanometer or even atomic-level metal active components are solidified inside the structure of the metal-organic framework material, which ensures the dispersion of the active components in the prepared catalyst, avoids the agglomeration between nanoparticles leading to a decrease in catalytic activity, and can further increase the loading of active components in the catalyst. Furthermore, the large specific surface area of ​​the metal-organic framework material can further increase the specific surface area of ​​the prepared carbon dioxide hydrogenation to methanol catalyst, increase adsorption sites, and achieve the effect of optimizing catalyst activity and selectivity, thus preparing a carbon dioxide hydrogenation to methanol catalyst with excellent activity.

[0065] In a specific implementation, step (3) includes: dissolving product B obtained in step (2) in a third solvent to obtain solution I, dissolving the reducing agent in a fourth solvent to obtain solution II, then mixing solution I and solution II evenly to react, then performing solid-liquid separation, and washing and drying the obtained solid product to obtain product C.

[0066] In a preferred embodiment, the third solvent is selected from one or more of tetrahydrofuran, pyridine, N,N-dimethylacetamide, acetone, ethyl acetate, methyl acetate, acetic acid, dichloromethane, and chloroform.

[0067] In a preferred embodiment, the fourth solvent is selected from one or more of tetrahydrofuran, benzene, chlorobenzene, ethyl acetate, acetone, toluene, xylene, isopropyl ether, methyl tert-butyl ether, dichloromethane, chloroform, and petroleum ether.

[0068] In a preferred embodiment, the reducing agent is selected from one or more of sodium triethylborohydride, potassium triethylborohydride, sodium trimethoxyborohydride, sodium trisec-butylborohydride, lithium hydride, lithium aluminum hydride, sodium borohydride, potassium trisec-butylborohydride, and lithium tritert-butoxyaluminum hydride, more preferably one or more of potassium triethylborohydride, sodium trisec-butylborohydride, sodium borohydride, and lithium aluminum hydride.

[0069] In a preferred embodiment, the weight ratio of product B to the reducing agent is 1-8:1, preferably 2-7:1. Specifically, the weight ratio of product B to the reducing agent can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, or 8:1.

[0070] In a preferred embodiment, in step (3), the reaction conditions include a temperature of 10-80°C and a time of 0.5-12h.

[0071] In the method described in this invention, the product C obtained in step (3) is reacted with a hydrophobic modifier, and alkyl long-chain groups are further introduced on the composite metal-organic framework material to modify the hydrophobicity of the prepared catalyst, thereby improving the hydrophobic performance of the prepared catalyst. This can inhibit the adsorption of water molecules, enhance the long-term stability of the prepared catalyst, and maintain the stability of catalytic activity.

[0072] In a specific embodiment, the hydrophobic modifier is selected from haloalkanes, C2-C... 12 fatty alcohols and C2-C 12 At least one of the chain olefins.

[0073] In a preferred embodiment, the alkyl group in the haloalkane is C2-C. 12 The alkyl group is a straight-chain alkyl group or a branched alkyl group, and the halogen is selected from one or two of F, Cl, Br and I. More preferably, the haloalkane is selected from one or more of chlorobutane, chloroisooctane, chloropropane, chlorocyclopentane, chlorooctane and chlorononane.

[0074] In a preferred embodiment, the C2-C 12 Fatty alcohols are selected from one or more of propanol, n-butanol, n-pentanol, n-heptanol, and n-octanol.

[0075] In a preferred embodiment, the C2-C 12 The olefins are selected from one or more of propylene, butene, pentene, heptenene, and octene.

[0076] In a preferred embodiment, the fifth solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, methanol, tetrahydrofuran, ethylene glycol, acetone, and pyridine.

[0077] In a specific embodiment, the Lewis acid compound is used as a catalyst for the alkylation reaction. Lewis acid catalysts, due to their electron-deficient central atoms, can form active electrophilic particles, thereby promoting the alkylation reaction. The Lewis acid compound is selected from one or more of ferric chloride, aluminum chloride, boron trifluoride, niobium pentachloride, and trifluoromethanesulfonate.

[0078] In a preferred embodiment, the weight ratio of the product C, the Lewis acid compound, and the hydrophobic modifier is 1:0.2-1:1-4, preferably 1:0.2-0.8:1-3.

[0079] In a preferred embodiment, in step (4), the reaction conditions include a temperature of 5-90°C and a time of 0.2-12h.

[0080] This invention also provides a carbon dioxide hydrogenation to methanol catalyst prepared by the above-described method. The catalyst uses a metal-organic framework (MOF) as a support, and then nanoscale or even atomic-level active metals are immobilized within the MOF. It is rich in multiple active metals and various heterocrystalline interfaces, enhancing the catalytic activity of the catalyst and thus improving the conversion rate of carbon dioxide and the selectivity of methanol. Further modification of the hydrophobicity of the MOF further improves the long-term stability of the prepared catalyst. Moreover, the active metal elements in this invention are all non-precious metals, further controlling the raw material cost of the catalyst and facilitating large-scale production. Therefore, the non-precious metal carbon dioxide hydrogenation to methanol catalyst successfully prepared by the method described in this invention has great application potential.

[0081] The present invention further provides an application of a catalyst for the hydrogenation of carbon dioxide to methanol.

[0082] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0083] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0084] Example 1

[0085] (1) Mix 5g of the first metal source (copper chloride), 5g of the organic ligand (1,4,5,8-naphthalenetetracarboxylic acid), and 1mL of the organic acid (acetic acid). Then add the mixture to 50mL of the first solvent (N,N-dimethylacetamide) and mix thoroughly. Place the mixture in a hydrothermal reactor for hydrothermal reaction at 150℃ for 24h. After the reaction, separate the solid and liquid phases to obtain a solid product. Wash the solid product three times with pyridine solution and dry it at 100℃ to obtain product A.

[0086] (2) 2g of the second metal source (zinc nitrate) was dissolved in water to prepare an aqueous solution of zinc nitrate, and 3g of the third metal source (zirconium chloride) was dissolved in water to prepare an aqueous solution of zirconium chloride. Then, 5g of product A was dissolved in 50mL of the second solvent (n-hexane) and ultrasonically dispersed for 1h. Then, the aqueous solutions of zinc nitrate and zirconium chloride were added dropwise and stirred thoroughly to carry out the reaction. The reaction temperature was 30℃ and the reaction time was 12h. After the reaction was completed, the solid product was separated by standing and then dried at 100℃ to obtain product B.

[0087] (3) Dissolve 5g of product B in a third solvent (tetrahydrofuran) to obtain solution I, and dissolve 1g of reducing agent (triethylborohydride potassium) in a fourth solvent (tetrahydrofuran) to obtain solution II. Mix solution I and solution II by stirring and reacting at a reaction temperature of 20°C for 2 hours. Separate the solid and liquid components to obtain a solid product. Then wash the obtained solid product with tetrahydrofuran and dry it at 80°C to obtain product C.

[0088] (4) Dissolve 2g of product C and 1g of Lewis acid compound (anhydrous aluminum trichloride) in 50mL of fifth solvent (N,N-dimethylformamide), then add 2g of hydrophobic modifier (chlorobutane) and stir at 20℃ for 0.5h. Centrifuge to separate the solid product, wash the obtained solid product with acetone and dry it under vacuum at 100℃ for 30min to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0089] The catalytic performance of the prepared carbon dioxide hydrogenation to methanol catalyst was evaluated using a "hydrogenation fixed-bed continuous flow reactor-GC combined system". A suitable amount of 20-40 mesh quartz sand was packed into a stainless steel reaction tube, positioned at the bottom of the isothermal zone. 1g of catalyst product was added to the isothermal zone, and the tube was further filled with quartz sand. The top was then secured with glass wool. The reaction tube was then placed in a heating furnace and connected to the gas path. H2 and N2 were introduced, with an H2 volume concentration of 10%. The reduction reaction was carried out at 280℃ for 150 min. The temperature was then adjusted to the reaction temperature of 220℃, and the mixture of reaction gases (CO2, H2, and N2) was switched to a concentration of 30% CO2, 65% H2, and 5% N2. The reaction pressure was then adjusted to 5 MPa. After 60 min of reaction, the product gas was sampled and analyzed using a stable gas chromatograph. The CO2 conversion rate of the catalyst was calculated by the N2-internal standard method, and the selectivity and yield of methanol were calculated by the C-based internal normalization method. The test data are shown in Table 1.

[0090] Example 2

[0091] (1) Mix 5g of the first metal source (aluminum chloride), 5g of the organic ligand (1,4-naphthalenedicarboxylic acid), and 1mL of the organic acid (formic acid). Then add the mixture to 50mL of the first solvent (dimethyl sulfoxide) and mix thoroughly. Place the mixture in a hydrothermal reactor for hydrothermal reaction at 120℃ for 12h. After the reaction, separate the solid and liquid phases to obtain a solid product. Wash the solid product three times with tetrahydrofuran solution and dry it at 80℃ to obtain product A.

[0092] (2) Dissolve 3g of the second metal source (zinc nitrate) in water to prepare an aqueous solution of zinc nitrate, and dissolve 2g of the third metal source (cerium nitrate) in water to prepare an aqueous solution of cerium nitrate. Then, dissolve 3g of product A in 30mL of the second solvent (n-pentane), and disperse it by ultrasonication for 1h. Then, add the aqueous solutions of zinc nitrate and cerium nitrate dropwise, and stir thoroughly to carry out the reaction. The reaction temperature is 50℃ and the reaction time is 6h. After the reaction is completed, let it stand to separate and obtain a solid product. Then, dry it at 100℃ to obtain product B.

[0093] (3) Dissolve 4g of product B in a third solvent (pyridine) to obtain solution I, and dissolve 1g of reducing agent (sodium trisec-butylborohydride) in a fourth solvent (toluene) to obtain solution II. Mix solution I and solution II by stirring and reacting at a reaction temperature of 30°C for 2.5h. Separate the solid and liquid to obtain a solid product. Then wash the obtained solid product with tetrahydrofuran and dry it at 90°C to obtain product C.

[0094] (4) Dissolve 2g of product C and 1g of Lewis acid compound (boron trifluoride) in 50mL of fifth solvent (dimethyl sulfoxide), then add 3g of hydrophobic modifier (nonane chloride) and stir at 30℃ for 1h. Centrifuge to separate the solid product, wash the obtained solid product with acetone and dry it under vacuum at 80℃ for 60min to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0095] The catalytic performance of the carbon dioxide hydrogenation to methanol catalyst was evaluated using a combined hydrogenation fixed-bed continuous flow reactor-GC system. A suitable amount of 20-40 mesh quartz sand was packed into a stainless steel reaction tube, positioned at the bottom of the isothermal zone. 1g of catalyst product was added to the isothermal zone, and the tube was further filled with quartz sand. The top was then secured with glass wool. The reaction tube was then placed in a heating furnace and connected to the gas path. H2 and N2 were introduced, with an H2 volume concentration of 10%. The reduction reaction was then carried out at 300℃ for 150 min. The temperature was then adjusted to the reaction temperature of 240℃, and the mixture of reaction gases (CO2, H2, and N2) was switched to a concentration of 30% CO2, 65% H2, and 5% N2. The reaction pressure was then adjusted to 3 MPa. After 60 min of reaction, the resulting product gas was sampled and analyzed using a stable gas chromatograph. The CO2 conversion rate of the catalyst was calculated using the N2-internal standard method, while the selectivity and yield of methanol were calculated using the C-based internal normalization method. Test data are shown in Table 1.

[0096] Example 3

[0097] (1) 4g of the first metal source (copper chloride), 3g of the organic ligand (2,6-naphthalenedicarboxylic acid), and 3mL of the organic acid (propionic acid) were mixed, and then added to 70mL of the first solvent (N,N-dimethylacetamide) and mixed evenly. The mixture was then placed in a hydrothermal reactor for hydrothermal reaction at 130℃ for 12h. After the reaction, the solid product was separated into solid and liquid components. After washing three times with pyridine solution, the solid product was dried at 90℃ to obtain product A.

[0098] (2) Dissolve 3g of the second metal source (aluminum nitrate) in water to prepare an aqueous solution of aluminum nitrate, and dissolve 3g of the third metal source (lanthanum chloride) in water to prepare an aqueous solution of lanthanum chloride. Then, dissolve 3g of product A in 30mL of the second solvent (cyclopentane), and disperse it by ultrasonication for 1h. Then, add the aqueous solution of aluminum nitrate and the aqueous solution of lanthanum chloride dropwise, and stir thoroughly to carry out the reaction. The reaction temperature is 70℃ and the reaction time is 10h. After the reaction is completed, let it stand to separate and obtain a solid product. Then, dry it at 100℃ to obtain product B.

[0099] (3) Dissolve 3g of product B in a third solvent (N,N-dimethylacetamide) to obtain solution I, and dissolve 1g of reducing agent (sodium borohydride) in a fourth solvent (toluene) to obtain solution II. Mix solution I and solution II by stirring and reacting at a reaction temperature of 40℃ for 3h. Separate the solid and liquid to obtain a solid product. Then wash the obtained solid product with tetrahydrofuran and dry it at 110℃ to obtain product C.

[0100] (4) Dissolve 3g of product C and 1g of Lewis acid compound (ferric chloride) in 50mL of fifth solvent (acetonitrile), then add 3g of hydrophobic modifier (chloro-octane) and stir at 40℃ for 2h. Centrifuge to separate the solid product, wash the obtained solid product with acetone and dry it under vacuum at 100℃ for 120min to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0101] The catalytic performance of the carbon dioxide hydrogenation catalyst for methanol production was evaluated using a combined hydrogenation fixed-bed continuous flow reactor-GC system. A suitable amount of 20-40 mesh quartz sand was packed into a stainless steel reaction tube, positioned at the bottom of the isothermal zone. 1g of catalyst product was added to the isothermal zone, and the tube was further filled with quartz sand. The top was then secured with glass wool. The reaction tube was then placed in a heating furnace and connected to the gas path. H2 and N2 were introduced, with an H2 volume concentration of 10%. The reduction reaction was then carried out at 270℃ for 120 min. The temperature was then adjusted to the reaction temperature of 240℃, and the mixture of reaction gases (CO2, H2, and N2) was switched to a concentration of 30% CO2, 65% H2, and 5% N2. The reaction pressure was then adjusted to 4 MPa. After 60 min of reaction, the resulting product gas was sampled and analyzed using a stable gas chromatograph. The CO2 conversion rate of the catalyst was calculated using the N2-internal standard method, while the selectivity and yield of methanol were calculated using the C-based internal normalization method. Test data are shown in Table 1.

[0102] Example 4

[0103] (1) 6g of the first metal source (zinc nitrate), 3g of the organic ligand (2,3-quinolinedicarboxylic acid), and 5mL of the organic acid (oxalic acid) were mixed, and then added to 100mL of the first solvent (butanone) and mixed evenly. The mixture was then placed in a hydrothermal reactor for hydrothermal reaction at 110℃ for 48h. After the reaction, solid-liquid separation was performed to obtain a solid product, which was washed three times with acetone solution and dried at 110℃ to obtain product A.

[0104] (2) Dissolve 3g of the second metal source (copper nitrate) in water to prepare a copper nitrate aqueous solution, and dissolve 3g of the third metal source (magnesium chloride) in water to prepare a magnesium chloride aqueous solution. Then, dissolve 4g of product A in 50mL of the second solvent (cyclopentane), and disperse it by ultrasonication for 2h. Then, add the copper nitrate aqueous solution and magnesium chloride aqueous solution dropwise, and stir thoroughly to carry out the reaction. The reaction temperature is 85℃ and the reaction time is 12h. After the reaction is completed, let it stand to separate and obtain a solid product. Then, dry it at 110℃ to obtain product B.

[0105] (3) Dissolve 3g of product B in a third solvent (acetone) to obtain solution I, and dissolve 0.5g of reducing agent (lithium aluminum hydride) in a fourth solvent (toluene) to obtain solution II. Mix solution I and solution II by stirring and reacting at a reaction temperature of 45℃ for 2.5h. Separate the solid and liquid to obtain a solid product. Then wash the obtained solid product with N,N-dimethylacetamide and dry it at 100℃ to obtain product C.

[0106] (4) Dissolve 3g of product C and 2g of Lewis acid compound (boron trifluoride) in 50mL of fifth solvent (N,N-dimethylformamide), then add 5g of hydrophobic modifier (chloroisooctane) and stir at 50℃ for 2h. Centrifuge to separate the solid product, wash the obtained solid product with acetone and dry it under vacuum at 100℃ for 120min to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0107] The catalytic performance of the carbon dioxide hydrogenation to methanol catalyst was evaluated using a combined hydrogenation fixed-bed continuous flow reactor-GC system. A suitable amount of 20-40 mesh quartz sand was packed into a stainless steel reaction tube, positioned at the bottom of the isothermal zone. 1g of catalyst product was added to the isothermal zone, and the tube was further filled with quartz sand. The top was then secured with glass wool. The reaction tube was then placed in a heating furnace and connected to the gas path. H2 and N2 were introduced, with an H2 volume concentration of 10%. The reduction reaction was then carried out at 290℃ for 150 min. The temperature was then adjusted to the reaction temperature of 260℃, and the mixture of reaction gases (CO2, H2, and N2) was introduced, with CO2 volume concentrations of 30%, H2 volume concentrations of 65%, and N2 volume concentrations of 5%. The reaction pressure was adjusted to 3 MPa. After 60 min of reaction, the resulting product gas was sampled and analyzed using a stable gas chromatograph. The CO2 conversion rate was calculated using the N2-internal standard method, and the selectivity and yield of methanol were calculated using the C-based internal normalization method. The test data is shown in Table 1.

[0108] Comparative Example 1

[0109] The method of Example 1 was implemented, except that step (4) was not performed, and the product C obtained was the carbon dioxide hydrogenation to methanol catalyst finally prepared.

[0110] Comparative Example 2

[0111] The method of Example 1 was implemented, except that in step (2), the third metal source (zirconium chloride) was replaced with an equal weight of the second metal source (zinc nitrate) for preparation.

[0112] Comparative Example 3

[0113] The method of Example 1 was implemented, except that in step (1), the first metal source (copper chloride) was replaced with an equal weight of zirconium chloride.

[0114] Comparative Example 4

[0115] A comparative experiment was conducted using a commercially available copper-based catalyst product (MegaMax 800DCARB from Klein, Germany).

[0116] The catalytic performance of commercially available copper-based catalysts for methanol production was evaluated using a combined hydrogenation fixed-bed continuous flow reactor-GC system. A suitable amount of 20-40 mesh quartz sand was packed into a stainless steel reaction tube, positioned at the bottom of the isothermal zone. 1g of catalyst product was added to the isothermal zone, and the tube was further filled with quartz sand. The top was then secured with glass wool. The reaction tube was then placed in a heating furnace and connected to the gas path. H2 and N2 were introduced, with an H2 volume concentration of 10%. The reduction reaction was then carried out at 280℃ for 150 min. The temperature was then adjusted to the reaction temperature of 220℃, and the mixture of reaction gases (CO2, H2, and N2) was switched on, with CO2 volume concentrations of 30%, H2 volume concentrations of 65%, and N2 volume concentrations of 5%. The reaction pressure was then adjusted to 5 MPa. After 60 min of reaction, the resulting product gas was sampled and analyzed using a stable gas chromatograph. The CO2 conversion rate of the catalyst was calculated using the N2-internal standard method, while the selectivity and yield of methanol were calculated using the C-based internal normalization method. Test data are shown in Table 1.

[0117] Table 1

[0118] Example number <![CDATA[CO2 conversion rate (%)]]> Methanol selectivity (%) Example 1 29 98 Example 2 26 97 Example 3 28 98 Example 4 26 96 Comparative Example 1 21 44 Comparative Example 2 18 57 Comparative Example 3 23 61 Comparative Example 4 27 52

[0119] As can be seen from the results in Table 1, the carbon dioxide hydrogenation to methanol catalyst prepared by the method described in this invention has higher methanol selectivity and CO2 conversion rate, with a methanol selectivity greater than 95% and a CO2 conversion rate greater than 25%. Furthermore, the carbon dioxide hydrogenation to methanol catalyst described in this invention has low preparation cost, facilitating large-scale production in the future.

[0120] 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 catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, The preparation method includes: (1) The first metal source, organic ligand, organic acid and first solvent are mixed and then subjected to a hydrothermal reaction to obtain product A; (2) The product A, the second solvent, the second metal source and the third metal source are mixed and reacted to obtain product B; (3) The product B, the third solvent, the reducing agent and the fourth solvent are mixed and reacted to obtain product C; (4) The product C, Lewis acid compound and fifth solvent are mixed, and then the resulting mixture is mixed with hydrophobic modifier to react and obtain carbon dioxide hydrogenation to methanol catalyst; The first metal source is selected from one or more of copper salts, zinc salts, aluminum salts, and iron salts; The organic ligand is selected from one or more of 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3-quinolinedicarboxylic acid and 2,2'-bisquinoline-4,4'-dicarboxylic acid, and the weight ratio of the first metal source to the organic ligand is 1:0.2-5. The second metal source is selected from one of zirconium salt, zinc salt, cerium salt, aluminum salt, iron salt, nickel salt, copper salt, and lanthanum salt; The third metal source is selected from one of zirconium salt, zinc salt, cerium salt, aluminum salt, iron salt, nickel salt, copper salt, and lanthanum salt; The hydrophobic modifier is selected from one or more of chloroisooctane, chloron-octane, and chlorononane; The first metal, the second metal, and the third metal are different; The weight ratio of the product A, the second metal source, and the third metal source is 1:0.3-3:0.3-3; The weight ratio of the product C, the Lewis acid compound, and the hydrophobic modifier is 1:0.2-1:1-4. In step (4), the reaction conditions include a temperature of 5-90℃ and a time of 0.2-12h.

2. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The first solvent is selected from one or more of N,N-dimethylacetamide, dimethyl sulfoxide, butanone, N,N-dimethylformamide, chloroform and methyl acetate.

3. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The second solvent is selected from one or more of n-hexane, n-pentane, cyclopentane, n-heptane, petroleum ether, and benzene.

4. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The third solvent is selected from one or more of tetrahydrofuran, pyridine, N,N-dimethylacetamide, acetone, ethyl acetate, methyl acetate, acetic acid, dichloromethane, and chloroform.

5. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The fourth solvent is selected from one or more of tetrahydrofuran, benzene, chlorobenzene, ethyl acetate, acetone, toluene, xylene, isopropyl ether, methyl tert-butyl ether, dichloromethane, chloroform, and petroleum ether.

6. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The fifth solvent is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, methanol, tetrahydrofuran, ethylene glycol, acetone, and pyridine.

7. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The organic acid is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, octanoic acid, adipic acid, oxalic acid, malonic acid, succinic acid, maleic acid, tartaric acid, benzoic acid, phenylacetic acid, valeric acid, hexanoic acid, decanoic acid, stearic acid, methanesulfonic acid, and thioacetic acid.

8. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The conditions for the hydrothermal reaction include: a temperature of 100-150℃ and a time of 12-48h.

9. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The reducing agent is selected from one or more of sodium triethylborohydride, potassium triethylborohydride, sodium trimethoxyborohydride, sodium trisec-butylborohydride, and sodium borohydride.

10. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The Lewis acid compound is selected from one or more of ferric chloride, aluminum chloride, boron trifluoride, and niobium pentachloride.

11. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The weight ratio of product B to the reducing agent is 1-8:

1.

12. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, In step (2), the reaction conditions include a temperature of 15-100℃ and a time of 3-24h.

13. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 1 or 12, characterized in that, In step (3), the reaction conditions include a temperature of 10-80℃ and a time of 0.5-12h.

14. The carbon dioxide hydrogenation to methanol catalyst prepared by the method according to any one of claims 1-13.

15. The application of the carbon dioxide hydrogenation to methanol catalyst according to claim 14 in the carbon dioxide hydrogenation to methanol process.