Bifunctional catalyst for preparing methanol through industrial carbon dioxide hydrogenation and preparation method of bifunctional catalyst

Abstract

The invention discloses a bifunctional catalyst for preparing methanol through industrial carbon dioxide hydrogenation and a preparation method of the bifunctional catalyst, and belongs to the technical field of methanol synthesis. The preparation method comprises the following steps: S1, providing a copper-based catalyst; s2, providing an MOFs material; the MOFs material is subjected to metallization, and ferrous chloride loaded on MOFs nodes is obtained; the ferrous chloride loaded on the MOFs nodes is reduced, and ferrous hydride loaded on the MOFs nodes is obtained; hydrolyzing the MOFs node-loaded ferrous hydride to obtain a MOFs node-loaded ferric hydroxide catalyst which is recorded as [MOFs-Fe (OH) x] catalyst (0 lt; x < = 2; and S3, mixing the copper-based catalyst with the [MOFs-Fe (OH) x] catalyst to obtain the bifunctional catalyst. According to the preparation method, the copper-based catalyst and the [MOFs-Fe (OH) x] catalyst are physically mixed to obtain the catalyst, the method is simple and easy to operate, the high CO2 conversion rate is kept, CH4 accumulation in the catalytic process of preparing methanol through industrial carbon dioxide hydrogenation is avoided, the selectivity of methanol is further improved, and energy consumption is reduced.

Description

Technical Field

[0001] This invention belongs to the field of methanol synthesis technology, specifically relating to a bifunctional catalyst for industrial-scale carbon dioxide hydrogenation to methanol and its preparation method. Background Technology

[0002] CO2, a greenhouse gas, causes significant harm to the natural environment. Utilizing CO2, a non-toxic and non-flammable raw material, to produce high-value-added products such as methanol aligns with the requirements of green chemistry and offers substantial environmental and economic benefits. Methanol, as a basic organic chemical raw material and fuel, has broad application prospects and can be used to prepare products such as low-carbon olefins, formic acid, methyl formate, and acetic acid. However, in the production of methanol from CO2 via hydrogenation, methane formation is a common side reaction. Methane formation leads to a decrease in methanol yield and reduces reaction selectivity.

[0003] Copper-based catalysts are widely used in the catalytic hydrogenation of CO2 to methanol due to their relatively high catalytic activity and low preparation cost. However, the presence of numerous side reactions in the CO2 catalytic hydrogenation to methanol reaction, mainly the reverse water-gas shift reaction and the CO2 methanation reaction, results in a methanol selectivity generally below 50%. Furthermore, the CH4 generated by the side reactions is difficult to separate, and in industrial production, a recycling process is often used, leading to CH4 accumulation and increased energy consumption.

[0004] Therefore, there is an urgent need in this field to develop an industrial bifunctional catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method. This bifunctional catalyst can reduce CH4 generation in the process of efficiently catalyzing the hydrogenation of carbon dioxide to methanol, thereby greatly improving the selectivity of methanol and reducing energy consumption. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a bifunctional catalyst for the industrial hydrogenation of carbon dioxide to methanol and its preparation method. This bifunctional catalyst, in the efficient catalytic hydrogenation of carbon dioxide to methanol process, can reduce CH4 formation, thereby significantly improving methanol selectivity and reducing energy consumption.

[0006] In a first aspect, embodiments of the present invention provide a method for preparing a bifunctional catalyst for industrial-scale carbon dioxide hydrogenation to methanol, the preparation method comprising the following steps: S1. Provides copper-based catalysts; S2. Provide MOFs material; metallize the MOFs material to obtain ferric chloride supported on MOFs nodes; reduce the ferric chloride supported on MOFs nodes to obtain ferrous hydride supported on MOFs nodes; hydrolyze the ferrous hydride supported on MOFs nodes to obtain ferric hydroxide catalyst supported on MOFs nodes, denoted as [MOFs-Fe(OH)x] catalyst, wherein 0 <x≤2; S3. The copper-based catalyst is mixed with the [MOFs-Fe(OH)x] catalyst to obtain a bifunctional catalyst.

[0007] The advantages and technical effects of the preparation method of this invention are as follows: The preparation method uses a physical mixture of copper-based catalyst and [MOFs-Fe(OH)x] catalyst. The method is simple and easy to operate, which maintains a high CO2 conversion rate and avoids the accumulation of CH4 in the industrial process of carbon dioxide hydrogenation to methanol catalysis. It further improves the selectivity of methanol and reduces energy consumption.

[0008] Optionally, the copper-based catalyst is one or more of CuZn catalyst, CuZnAl catalyst and CuZnZr catalyst.

[0009] Optionally, the MOF material is one or more of the MOF materials containing [AlO3(OH)] structural units and the MOF materials containing [AlO4(OH)2] structural units.

[0010] Optionally, the MOF material containing [AlO3(OH)] structural units is DUT-5.

[0011] Optionally, the MOF material containing [AlO4(OH)2] structural units is MIL-53.

[0012] Optionally, the MOFs material is metallized to obtain ferric chloride loaded on MOF nodes, specifically including the following steps: dissolving DUT-5 in tetrahydrofuran to obtain a DUT-5 solution; dissolving n-butyllithium in cyclohexane to obtain an n-butyllithium solution; mixing the DUT-5 solution and the n-butyllithium solution and performing a deprotonation reaction to obtain a deprotonated solid product; dissolving ferric chloride hexahydrate in tetrahydrofuran to obtain a ferric chloride hexahydrate solution; mixing the deprotonated solid product and the ferric chloride hexahydrate solution and performing a salt metathesis reaction to generate the ferric chloride loaded on MOF nodes.

[0013] Optionally, the content of the [MOFs-Fe(OH)x] catalyst is 1-10% based on the total mass of the catalyst mixture as 100%.

[0014] Secondly, embodiments of the present invention provide a bifunctional catalyst for industrial-scale carbon dioxide hydrogenation to methanol, wherein the bifunctional catalyst is prepared using the preparation method described in the first aspect.

[0015] The advantages and technical effects of the bifunctional catalyst of this invention are as follows: The bifunctional catalyst of this invention includes a copper-based catalyst and a [MOFs-Fe(OH)x] catalyst. The copper-based catalyst mainly catalyzes the hydrogenation of carbon dioxide to methanol, while the μ2-OH structure in the [MOFs-Fe(OH)x] catalyst can activate the CH bond of methane and oxidize it to methanol. Therefore, the bifunctional catalyst of this invention can be used for industrial hydrogenation of carbon dioxide to methanol, which can improve the selectivity of methanol and reduce energy consumption by reducing the generation of CH4.

[0016] Thirdly, embodiments of the present invention provide the application of the bifunctional catalyst in the industrial hydrogenation of carbon dioxide to methanol, wherein the bifunctional catalyst is placed in a reducing atmosphere for reduction, the reducing atmosphere being a mixture of H2 and CO2, to obtain a reduced bifunctional catalyst; and then the reduced bifunctional catalyst is applied to the industrial hydrogenation of carbon dioxide to methanol.

[0017] Optionally, the H2 content is 3-70% based on the total volume of the reducing atmosphere being 100%.

[0018] Optionally, the reduction holding temperature is 150~300℃, and the reduction holding time is 0.5~3 h. Detailed Implementation The technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion. In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0022] In a first aspect, embodiments of the present invention provide a method for preparing a bifunctional catalyst for industrial-scale carbon dioxide hydrogenation to methanol, the preparation method comprising the following steps: S1. Provides copper-based catalysts; S2. Provide MOFs material; metallize the MOFs material to obtain ferric chloride supported on MOFs nodes; reduce the ferric chloride supported on MOFs nodes to obtain ferrous hydride supported on MOFs nodes; hydrolyze the ferrous hydride supported on MOFs nodes to obtain ferric hydroxide catalyst supported on MOFs nodes, and denote the ferric hydroxide catalyst supported on MOFs nodes as [MOFs-Fe(OH)x] catalyst, wherein 0 <x≤2; S3. The copper-based catalyst is mixed with the [MOFs-Fe(OH)x] catalyst to obtain a bifunctional catalyst.

[0023] The preparation method of this invention uses a physical mixture of a copper-based catalyst and a [MOFs-Fe(OH)x] catalyst for industrial carbon dioxide hydrogenation to methanol. This method can improve CO2 conversion rate and reduce methanol selectivity and energy consumption by reducing CH4 generation.

[0024] Optionally, the copper-based catalyst may be one or more of CuZn catalysts, CuZnAl catalysts, and CuZnZr catalysts, including but not limited to CuZn catalysts, CuZnAl catalysts, and CuZnZr catalysts. The copper-based catalysts listed above exhibit high CO2 conversion rates.

[0025] Optionally, the MOFs material may include, but is not limited to, one or more of MOFs materials containing [AlO3(OH)] structural units and MOFs materials containing [AlO4(OH)2] structural units. Fe(OH)x is the key component in reducing methane formation, while the MOFs material may act as a dispersing active center and prevent sintering.

[0026] Optionally, the MOF material containing [AlO3(OH)] structural units is DUT-5.

[0027] Optionally, the MOF material containing [AlO4(OH)2] structural units is MIL-53.

[0028] Optionally, the MOFs material is metallized to obtain ferric chloride loaded on MOF nodes, specifically including the following steps: dissolving DUT-5 in tetrahydrofuran to obtain a DUT-5 solution; dissolving n-butyllithium in cyclohexane to obtain an n-butyllithium solution; mixing the DUT-5 solution and the n-butyllithium solution and performing a deprotonation reaction to obtain a deprotonated solid product; dissolving ferric chloride hexahydrate in tetrahydrofuran to obtain a ferric chloride hexahydrate solution; mixing the deprotonated solid product and the ferric chloride hexahydrate solution and performing a salt metathesis reaction to generate the ferric chloride loaded on MOF nodes.

[0029] Optionally, based on the total mass of the catalyst mixture, the content of the [MOFs-Fe(OH)x] catalyst is 1-10%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. This is beneficial for improving CO2 conversion while reducing CH4 formation, and for improving the overall performance of the bifunctional catalyst.

[0030] Secondly, embodiments of the present invention provide a bifunctional catalyst for industrial-scale carbon dioxide hydrogenation to methanol, wherein the bifunctional catalyst is prepared using the preparation method described in the first aspect.

[0031] The bifunctional catalyst of this invention includes a copper-based catalyst and a [MOFs-Fe(OH)x] catalyst. The copper-based catalyst mainly catalyzes the hydrogenation of carbon dioxide to methanol, with a high CO2 conversion rate and CH4 as a byproduct. The μ2-OH structure in the [MOFs-Fe(OH)x] catalyst can activate the CH bond of methane, oxidizing it to methanol. Therefore, the bifunctional catalyst of this invention can be used for industrial carbon dioxide hydrogenation to methanol, which can improve methanol selectivity and reduce energy consumption by reducing CH4 formation.

[0032] Thirdly, embodiments of the present invention provide the application of the bifunctional catalyst in the industrial hydrogenation of carbon dioxide to methanol, wherein the bifunctional catalyst is placed in a reducing atmosphere for reduction, the reducing atmosphere being a mixture of H2 and CO2, to obtain a reduced bifunctional catalyst; and then the reduced bifunctional catalyst is applied to the industrial hydrogenation of carbon dioxide to methanol.

[0033] The bifunctional catalyst prepared by the first method does not yet have catalytic activity. It needs to be reduced before it can be used for industrial-scale carbon dioxide hydrogenation to methanol production to activate its catalytic activity.

[0034] Optionally, the H2 content is 3-70% based on the total volume of the reducing atmosphere as 100%, for example, 3%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc.

[0035] Optionally, the reduction holding temperature is 150~300℃, such as 150℃, 180℃, 200℃, 220℃, 250℃, 280℃, 300℃, etc., and the reduction holding time is 0.5~3 h, such as 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, etc. The present invention will now be described in detail with reference to the embodiments.

[0036] Example 1 S1. Synthesis of CuZnAl catalyst: In the presence of alumina sol, a nitrate solution (Cu and Zn molar ratio of 2:1) was co-precipitated with a potassium carbonate solution at pH 6.5 and temperature of 68℃. The resulting precipitate was aged at 68℃ for 2 hours, filtered, washed with pure water, dried, and calcined in air at 350℃ for 6 hours to obtain the CuZnAl catalyst.

[0037] Synthesis of S2. [MOFs-Fe(OH)2] catalyst: (1) Synthesis of DUT-5: Weigh 10.0 g of 4,4'-biphenyl dicarboxylic acid and dissolve it in 300 mL of dimethylformamide (DMF) to obtain a biphenyl dicarboxylic acid solution; weigh 6.5 g of aluminum chloride hexahydrate (AlCl3·6H2O) and dissolve it in 300 mL of dimethylformamide (DMF) to obtain an aluminum chloride hexahydrate solution; after mixing the biphenyl dicarboxylic acid solution and aluminum chloride hexahydrate solution, transfer them to a polytetrafluoroethylene-lined stainless steel autoclave, carry out a solvothermal reaction at 120℃ for 48 h, cool, centrifuge, wash with dimethylformamide (DMF), dry under vacuum at 60℃ for 6 h, collect the white crystalline solid, and record it as DUT-5.

[0038] (2) DUT-5 was metallized in a glove box to synthesize DUT-5-FeCl2: Take 5.0 g of DUT-5 and dissolve it in 300 mL of tetrahydrofuran (THF) to obtain a DUT-5 solution; weigh n-butyllithium (n-BuLi) and dissolve it in 23.5 mL of cyclohexane to obtain an n-butyllithium solution with a concentration of 1.65 mol / L. Mix the above DUT-5 solution and n-butyllithium solution, stir magnetically at room temperature for 1.5 h, centrifuge, and wash with tetrahydrofuran (THF) to obtain a deprotonated solid product. 9.0 g of ferric chloride hexahydrate (FeCl3·6H2O) was dissolved in 300 mL of tetrahydrofuran (THF) to obtain a ferric chloride hexahydrate solution. The ferric chloride hexahydrate solution was poured into the above deprotonated solid product, and the mixture was magnetically stirred overnight at room temperature. After centrifugation, the product was washed with tetrahydrofuran (THF) and dried under vacuum at 60 °C for 4 h to obtain a yellowish-brown solid, namely ferric chloride loaded at the DUT-5 node, denoted as (DUT-5-FeCl2).

[0039] (3) Inside the glove box, DUT-5-FeCl2 was reduced to obtain DUT-5-FeH2: Take 5.0 g of DUT-5-FeCl2 and add 300 mL of tetrahydrofuran (THF) to obtain a DUT-5-FeCl2 solution; take triethyl sodium borohydride (NaEt3BH) and dissolve it in toluene solution to obtain a NaEt3BH solution with a concentration of 1 mol / L; slowly add 30 mL of NaEt3BH solution to the DUT-5-FeCl2 solution, let it stand for 1 h, centrifuge, wash with tetrahydrofuran (THF), and dry under vacuum at 60 ℃ for 4 h to obtain a black solid, namely ferrous hydride loaded on the DUT-5 node, denoted as DUT-5-FeH2.

[0040] (4) Hydrolyze DUT-5-FeH2 to obtain DUT-5-Fe(OH)2 catalyst: 5.0 g of DUT-5-FeH2 was placed in a beaker, 100 mL of deionized water was added, the mixture was stirred at room temperature for 10 min, centrifuged, washed with water, and dried under vacuum at 60 °C for 6 h to obtain iron(OH)2 supported on the DUT-5 node, denoted as DUT-5-Fe(OH)2 catalyst.

[0041] S3. The CuZnAl catalyst obtained in step S1 is physically mixed with the [DUT-5-Fe(OH)2] catalyst obtained in step S2 to obtain a bifunctional catalyst. The content of [DUT-5-Fe(OH)2] catalyst is 2% based on the total mass of the bifunctional catalyst as 100%.

[0042] Example 2 The preparation method of this embodiment is the same as that of Example 1, except that the content of [DUT-5-Fe(OH)2] catalyst is 4% based on the total mass of the bifunctional catalyst being 100%.

[0043] Example 3 The preparation method of this embodiment is the same as that of Example 1, except that the content of [DUT-5-Fe(OH)2] catalyst is 6% based on the total mass of the bifunctional catalyst being 100%.

[0044] Example 4 The preparation method of this embodiment is the same as that of Example 1, except that the content of [DUT-5-Fe(OH)2] catalyst is 8% based on the total mass of the bifunctional catalyst being 100%.

[0045] Example 5 The preparation method of this embodiment is the same as that of Example 1, except that the content of [DUT-5-Fe(OH)2] catalyst is 10% based on the total mass of the bifunctional catalyst being 100%.

[0046] Comparative Example 1 A commercial CuZnAl catalyst.

[0047] Comparative Example 2 Synthesis of CuZnAl catalyst: Same as step S1 in Example 1.

[0048] Comparative Example 3 Synthesis of [MOFs-Fe(OH)2] catalyst: Same as step S2 in Example 1.

[0049] Activity evaluation results The activity of the catalysts prepared in each example and comparative example was tested: Five g of the catalysts prepared in each of the examples and comparative examples were placed in a single-tube reactor for the hydrogenation of carbon dioxide to methanol. The single-tube reactor was filled with a reducing atmosphere, which was a mixture of H2 and CO2. The total volume of the reducing atmosphere was 100%, the H2 content was 5%, and the space velocity (GHSV) of the reducing atmosphere was 6000 h⁻¹. -1 The heating rate of the single-tube reaction apparatus was 1℃ / min. The catalysts prepared in each example and comparative example were reduced at 240℃ for 2h under a reducing atmosphere to obtain the reduced catalysts.

[0050] After obtaining the reduced catalyst, the reducing atmosphere in the single-tube reactor was switched to a reactant gas, which was a mixture of H2 and CO2. The total volume of the reactant gas was 100%, the H2 content was 5%, and the gas space velocity (GHSV) was 6000 h⁻¹. -1 The evaluation temperature was 230℃, the evaluation pressure was 6MPa, and the evaluation time was 10h. Finally, the tail gas and liquid products were detected and analyzed by an Agilent Technologies 7980B gas chromatograph (GC), and the CO2 conversion rate, the selectivity of the product CH3OH, and the selectivity of the byproduct CH4 were calculated. The results are shown in Table 1.

[0051] Table 1. Activity evaluation data of catalysts prepared in each example and comparative example

[0052] As shown in Table 1, the selectivity of the byproduct CH4 decreased significantly after mixing the CuZnAl catalyst with the [MOFs-Fe(OH)2] catalyst. We utilized oxygen from CO2 to consume the byproduct CH4. After the CuZnAl catalyst and the [MOFs-Fe(OH)2] catalyst were physically mixed evenly, the bifunctional catalyst exhibited the best activity evaluation performance when the [MOFs-Fe(OH)2] catalyst accounted for 6% of the total mass of the bifunctional catalyst. At this point, the CO2 conversion rate reached 24.3%, the selectivity of CH3OH reached 64.9%, and the selectivity of the byproduct CH4 was 0.09%.

[0053] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0054] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a bifunctional catalyst for industrial-scale carbon dioxide hydrogenation to methanol, characterized in that, The preparation method includes the following steps: S1. Provides copper-based catalysts; S2. Provide MOFs material; metallize the MOFs material to obtain ferric chloride supported on MOFs nodes; reduce the ferric chloride supported on MOFs nodes to obtain ferrous hydride supported on MOFs nodes; hydrolyze the ferrous hydride supported on MOFs nodes to obtain ferric hydroxide catalyst supported on MOFs nodes, denoted as [MOFs-Fe(OH)x] catalyst, wherein 0 <x≤2; S3. The copper-based catalyst is mixed with the [MOFs-Fe(OH)x] catalyst to obtain a bifunctional catalyst.

2. The preparation method according to claim 1, characterized in that, The copper-based catalyst is one or more of CuZn catalyst, CuZnAl catalyst and CuZnZr catalyst.

3. The preparation method according to claim 1, characterized in that, The MOFs material is one or more of the following: MOFs material containing [AlO3(OH)] structural units and MOFs material containing [AlO4(OH)2] structural units.

4. The preparation method according to claim 3, characterized in that, The MOF material containing [AlO3(OH)] structural units is DUT-5; and / or, the MOF material containing [AlO4(OH)2] structural units is MIL-53.

5. The preparation method according to claim 3, characterized in that, The MOFs material is metallized to obtain ferric chloride loaded on MOF nodes, specifically including the following steps: dissolving DUT-5 in tetrahydrofuran to obtain a DUT-5 solution; dissolving n-butyllithium in cyclohexane to obtain an n-butyllithium solution; mixing the DUT-5 solution and the n-butyllithium solution and performing a deprotonation reaction to obtain a deprotonated solid product; dissolving ferric chloride hexahydrate in tetrahydrofuran to obtain a ferric chloride hexahydrate solution; mixing the deprotonated solid product and the ferric chloride hexahydrate solution and performing a salt metathesis reaction to generate the ferric chloride loaded on MOF nodes.

6. The preparation method according to claim 1, characterized in that, Based on the total mass of the bifunctional catalyst being 100%, the content of the [MOFs-Fe(OH)x] catalyst is 1~10%.

7. A bifunctional catalyst for the industrial hydrogenation of carbon dioxide to methanol, characterized in that, The bifunctional catalyst is prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the bifunctional catalyst according to claim 7 in the industrial hydrogenation of carbon dioxide to methanol, characterized in that, The bifunctional catalyst was reduced in a reducing atmosphere, which was a mixture of H2 and CO2, to obtain a reduced bifunctional catalyst. The reduced bifunctional catalyst was then applied to the industrial production of methanol by carbon dioxide hydrogenation.

9. The application according to claim 8, characterized in that, With the total volume of the reducing atmosphere being 100%, the content of H2 is 3-70%.

10. The application according to claim 8, characterized in that, The reduction holding temperature is 150~300℃, and the reduction holding time is 0.5~3 h.

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