Catalyst for preparing methanol through hydrogenation of carbon dioxide as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for preparation of methanol by hydrogenation of carbon dioxide and a preparation method and application thereof, a carrier of the catalyst for preparation of methanol by hydrogenation of carbon dioxide comprises a zirconia skeleton carrier of an octahedral cage structure, and active components are loaded on the surface and pore inner walls of the carrier, the zirconium oxide skeleton carrier with an octahedral cage structure can carry out space and electronic regulation and control on a loaded metal active center through a geometric confinement effect and an electronic effect, and the zirconium oxide skeleton carrier is high in reaction selectivity, high in activity and high in stability when being applied to a catalytic reaction for preparing methanol through carbon dioxide hydrogenation, and has an industrial application prospect.

Description

Technical Field

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

[0002] Methanol, as an important basic chemical raw material, has a wide range of downstream applications. Primary processing of methanol yields nearly 30 products, including formaldehyde, acetic acid, and methylamine, while further processing produces over 100 products, such as plastics, synthetic rubber, synthetic fibers, pharmaceuticals, and pesticides. It is widely used in the energy, chemical, materials, and pharmaceutical industries. In recent years, methanol has also been widely used as a clean energy source for vehicle fuel, methanol-to-fuel fuel cells (DMFC), and hydrogen storage. In my country, methanol synthesis is primarily coal-based, accounting for over 80% of the country's capacity, with natural gas accounting for 8% and coke oven gas for 12%. On the one hand, the inherent limitations of coal gasification plants—limited scale and large size—constrain the development of large-scale methanol production facilities. Furthermore, the significant increase in coal prices in recent years has had a substantial impact on coal-based methanol production, which previously had a certain cost advantage. On the other hand, my country's methanol industry emits 200 million tons of carbon annually, with coal-based methanol production accounting for 96.6%. This also results in the emission of large amounts of acidic gases and solid residues, causing significant environmental pollution. With the increasing global awareness of environmental protection, the adverse effects of traditional methanol production routes on the economy, environment and society urgently need to be addressed. Furthermore, with the introduction of the "dual carbon" policy in the past two years, the green and environmentally friendly carbon dioxide hydrogenation to methanol route has received widespread attention.

[0003] Carbon dioxide, a major component of greenhouse gases, is increasingly concentrated in the atmosphere due to its massive emissions, leading to environmental problems such as global warming, glacial melting, water acidification, and frequent extreme weather events. Therefore, reducing carbon dioxide emissions is urgent. As the simplest C1 resource, carbon dioxide has immense potential for use and economic benefits. Thus, the catalytic conversion of the greenhouse gas carbon dioxide into high-value-added methanol has significant research value and practical implications. It can not only reduce carbon dioxide emissions and mitigate the greenhouse effect, contributing to the achievement of national "dual carbon" goals, but also enable the recycling of carbon resources to supplement the methanol demand from industries such as chemicals, energy, and hydrogen energy, alleviating the shortage of fossil resources and the growing demand for methanol, thus contributing to sustainable economic and social development.

[0004] The reaction principle for producing methanol by hydrogenation of carbon dioxide (CO2) is as follows: Due to the high stability and low reactivity of carbon dioxide, the hydrogenation of carbon dioxide to methanol is subject to both kinetic and thermodynamic limitations. Therefore, one of the core technologies for carbon dioxide hydrogenation to methanol is the development of efficient and stable catalysts. Currently, catalysts exhibiting good performance in the carbon dioxide hydrogenation to methanol reaction mainly include copper-based catalysts, noble metal catalysts, oxide catalysts, and other novel catalysts. Among them, Cu-based catalysts are the most widely used industrially for carbon dioxide to methanol synthesis due to their high yield and reactivity at low temperatures and low cost. Although Cu-based catalysts have been industrially applied, their low water resistance and easy sintering significantly reduce their activity and stability. Therefore, finding suitable promoters, supports, and optimizing catalyst structures have become the current research focus for Cu-based methanol synthesis catalysts. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a catalyst for the hydrogenation of carbon dioxide to methanol, its preparation method and application. The catalyst supports include a zirconia framework support with an octahedral cage structure. The active component is loaded on the surface and inner wall of the pores of the support. The octahedral cage structure of the zirconia framework support can spatially and electronically regulate the supported metal active centers through geometric confinement effect and electronic effect. In the catalytic reaction of hydrogenation of carbon dioxide to methanol, the CO2 conversion rate can be above 13.3%, with a maximum of 24.3%, and the methanol selectivity can be above 74.4%, with a maximum of 95.7%. It also has the advantage of long service life and catalyst stability of more than 200 hours.

[0006] To achieve this objective, the present invention adopts the following technical solution: One objective of this invention is to provide a catalyst for the hydrogenation of carbon dioxide to methanol, the catalyst comprising a support and an active component; the support comprising a zirconium oxide framework support having an octahedral cage structure, and the active component being loaded on the surface and inner walls of the pores of the support.

[0007] It should be noted that the carbon dioxide hydrogenation to methanol catalyst described in this invention refers to the process before reduction treatment, at which point the active components and promoters still exist in ionic form. When applied to the catalytic reaction, a reducing gas is first passed through for reduction, and then a feed gas containing hydrogen and carbon dioxide is passed through to carry out the catalytic reaction of carbon dioxide hydrogenation to methanol.

[0008] The carbon dioxide hydrogenation to methanol catalyst of this invention focuses on improving the support. The support for loading the active component includes a zirconia framework support with an octahedral cage structure. Zirconia itself has advantages such as chemical stability, high temperature resistance, and porosity. By designing the zirconia framework support into an octahedral cage structure, spatial and electronic control of the loaded metal active centers can be further achieved through geometric confinement effect and electronic effect. This not only anchors the metal active centers in specific positions within the cage to form uniform active centers, but also restricts the type, orientation, and configuration of substrate molecules entering the cage and contacting the metal active centers by utilizing the size and shape of the octahedral cage. In the catalytic reaction of carbon dioxide hydrogenation to methanol, the CO2 conversion rate can reach above 13.3%, with a maximum of 24.3%, and the methanol selectivity can reach above 74.4%, with a maximum of 95.7%.

[0009] As a preferred embodiment of the present invention, the carbon dioxide hydrogenation to methanol catalyst further includes an auxiliary agent, which is also loaded on the surface and inner wall of the pores of the support.

[0010] As a preferred technical solution of the present invention, the additives include any one or a combination of at least two of the additives such as sodium, potassium, magnesium or manganese; specifically, in the carbon dioxide hydrogenation to methanol catalyst of the present invention, the additives such as sodium, potassium, magnesium or manganese exist in ionic form, but in the process of application to the catalytic reaction, the main reaction form of sodium additive is Na2O, the main reaction form of potassium additive is K2O, the main reaction form of magnesium additive is MgO, and the main reaction forms of manganese additive are Mn2O3, Mn3O4 and MnO2.

[0011] And / or, based on metal elements, the mass ratio of the additive to the active component is (0-0.5):1, for example 0:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1 or 0.5:1, preferably (0-0.2):1, but not limited to the listed values; other unlisted values ​​within the above range are also applicable. When the mass ratio of the additive to the active component is 0:1 based on metal elements, it refers to the case where the catalyst does not contain the additive.

[0012] As a preferred technical solution of the present invention, the active component includes any one or a combination of at least two of the active components such as copper, zinc, indium, aluminum, iron, gold, palladium, platinum, or cerium. Specifically, in the carbon dioxide hydrogenation to methanol catalyst of the present invention, the active component exists in ionic form, but in the process of catalytic reaction, the main reaction forms of the copper-based catalytic active component are CuO, Cu2O, and Cu; the main reaction forms of the zinc-based catalytic active component are Zn, ZnO, and Zn2O; the main reaction forms of the indium-based catalytic active component are In, In2O3, and InO; the main reaction form of the aluminum-based catalytic active component is Al2O3; the main reaction forms of the iron-based catalytic active component are Fe2O3 and Fe3O4; the main reaction forms of the gold-based catalytic active component are Au, Au2O, and Au2O3; the main reaction forms of the palladium-based catalytic active component are Pd, PdO, and PdO2; the main reaction forms of the platinum-based catalytic active component are Pt, PtO, and PtO2; and the main reaction forms of the cerium-based catalytic active component are Ce2O3 and CeO2.

[0013] And / or, based on metal elements, the proportion of the active component to the carrier mass is 0.5-50 wt%, such as 0.5 wt%, 1 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, or 50 wt%, but not limited to the listed values; other unlisted values ​​within the above range also apply.

[0014] And / or, the octahedral cage-like zirconia framework carrier is prepared by calcination and pyrolysis of the metal-organic framework material UiO-66.

[0015] It should be noted that UiO-66 is a zirconium-based metal-organic framework (MOF) developed by the University of Oslo (UiO) in Norway. It has a high specific surface area and tunable pore structure. The present invention utilizes the calcination and pyrolysis of the metal-organic framework material UiO-66 to prepare a zirconium oxide framework support. This not only preserves the octahedral cage structure and avoids structural collapse, but also provides more pores in the support, which helps to enhance the geometric confinement effect and electronic effect, and improve the spatial and electronic control of the loaded metal active centers.

[0016] And / or, the average particle size D50 of the carbon dioxide hydrogenation to methanol catalyst is 20-500 nm, such as 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] A second objective of this invention is to provide a method for preparing the carbon dioxide hydrogenation to methanol catalyst described in one objective, the method comprising the following steps: Prepare an impregnation solution of the active component precursor, add it dropwise onto a support comprising a zirconium oxide framework support with an octahedral cage structure, and dry it to obtain the carbon dioxide hydrogenation to methanol catalyst.

[0018] As a preferred technical solution of the present invention, the preparation method further includes: preparing an auxiliary precursor impregnation solution, adding it dropwise to a support, and drying it to obtain the carbon dioxide hydrogenation to methanol catalyst.

[0019] It should be noted that the active component precursor in the impregnation solution of the present invention includes any one or a combination of at least two of copper nitrate, zinc nitrate, indium nitrate, aluminum nitrate, iron nitrate, chloroauric acid, palladium nitrate, potassium tetrachloroplatinate, and cerium nitrate; the auxiliary agent precursor in the impregnation solution of the present invention includes any one or a combination of at least two of sodium carbonate or sodium bicarbonate, potassium carbonate or potassium bicarbonate, magnesium nitrate, and manganese nitrate.

[0020] It should be noted that if multiple catalytically active components need to be loaded, the above-mentioned steps can be repeated, or the active component precursors can be mixed together to obtain a composite active component precursor impregnation solution for impregnation. Similarly, if multiple additives need to be loaded, the above-mentioned steps can be repeated, or the additive precursors can be mixed together to obtain a composite additive precursor impregnation solution for impregnation. Moreover, in this invention, the catalytically active components are impregnated first, followed by the additives. On the one hand, this avoids the aggregation of the catalytically active components and additives during simultaneous impregnation and prevents the additives from occupying effective zirconium oxide active sites, hindering the interaction between the support and the metal active components, thereby affecting the catalytic reaction performance. On the other hand, it ensures that the active components and additives are uniformly distributed.

[0021] It should be noted that, in the preparation method of the present invention, the loading of the active component precursor and the auxiliary agent precursor on the support can be completed by drying after impregnation, so that the active component and the auxiliary agent still exist in ionic form. Before being applied to the catalytic reaction, the active component and the auxiliary agent are reduced to a reduced phase with a lower valence state through reduction treatment. Moreover, the preparation method of the present invention does not perform calcination after impregnation, which can avoid damage to the structure and performance of the octahedral cage-like structure of the zirconia framework support.

[0022] As a preferred technical solution of the present invention, both the active component precursor impregnation solution and the auxiliary agent precursor impregnation solution adopt the equal volume impregnation method, and the drying process independently includes: first, air drying in a ventilated place for 12-48 hours, such as 12 hours, 18 hours, 24 hours, 30 hours, 36 hours, 42 hours or 48 hours, etc., and then vacuum drying at 80-120°C for 12-24 hours. The vacuum drying temperature is, for example, 80°C, 90°C, 100°C, 110°C or 120°C, etc., and the vacuum drying time is, for example, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0023] As a preferred embodiment of the present invention, the zirconia framework carrier with an octahedral cage structure is prepared by the following method: Prepare an N,N-dimethylformamide solution containing zirconium chloride, add 1,4-phthalic acid dropwise, and perform hydrothermal crystallization on the resulting homogeneous suspension. After washing and drying, obtain the metal-organic framework material UiO-66. The metal-organic framework material UiO-66 is then calcined and pyrolyzed to obtain a zirconium oxide framework carrier with an octahedral cage structure.

[0024] As a preferred technical solution of the present invention, the hydrothermal crystallization temperature is 120-180℃, such as 120℃, 130℃, 140℃, 150℃, 160℃, 170℃ or 180℃, etc., and the hydrothermal crystallization time is 12-48h, such as 12h, 18h, 24h, 30h, 36h, 42h or 48h, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0025] And / or, the washing includes: centrifugal washing with methanol until the pH of the washing solution is neutral, for example, the pH of the washing solution is 6.8-7.2.

[0026] And / or, the drying includes: vacuum drying at 60-110°C for 12-24 hours, where the vacuum drying temperature is, for example, 60°C, 70°C, 80°C, 90°C, 100°C, or 110°C, and the vacuum drying time is, for example, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, or 24 hours, but is not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0027] And / or, the calcination pyrolysis temperature is 400-800℃, such as 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃, etc., and the calcination pyrolysis time is 3-12h, such as 3h, 6h, 9h, 10h or 12h, etc., but not limited to the listed values, other unlisted values ​​within the above range are also applicable.

[0028] And / or, the reaction atmosphere of the calcination pyrolysis is any one or a combination of at least two of air, oxygen-enriched gas, nitrogen, or vacuum, wherein oxygen-enriched gas refers to a mixed gas with an oxygen volume fraction of 30-80%.

[0029] As a preferred embodiment of the present invention, the preparation method of the carbon dioxide hydrogenation to methanol catalyst of the present invention includes the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0030] At room temperature (20-25℃), a certain amount of zirconium chloride is added to 10-15 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride is completely dissolved. Then, an appropriate amount of 1,4-phthalic acid is slowly added dropwise. After the addition is complete, the mixture is stirred at room temperature for 6-24 hours to obtain a homogeneous precursor suspension. The precursor is transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120-180℃ for 12-48 hours. After hydrothermal crystallization, the mixture is cooled to room temperature. The crystallized product is washed with methanol and centrifuged until the pH of the washing solution is neutral, for example, the pH of the washing solution is 6.8-7.2. Then, it is vacuum dried at 60-110℃ for 12-24 hours to obtain the UiO-66 product.

[0031] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0032] In an air, oxygen-enriched, nitrogen, or vacuum atmosphere, the UiO-66 product is calcined and pyrolyzed at 400-800℃ for 3-12 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which is then ground into powder for later use.

[0033] The third step is loading the catalytically active components.

[0034] A ZrO2 support is loaded with any one or at least two of the catalytically active components selected from copper, zinc, indium, aluminum, iron, gold, palladium, platinum, or cerium using an equal-volume impregnation method. First, the required mass of the active component compound is calculated according to a specific ratio of catalytically active component to support, and an impregnation solution of the active component precursor is prepared. Then, the salt solution is added dropwise to the ZrO2 support powder at room temperature, with continuous stirring of the support powder until the metal salt solution completely and uniformly wets all of the support. After impregnation, the impregnated material is air-dried in a clean, ventilated area (at 20-25℃) for 12-48 hours, and then vacuum-dried at 80-120℃ for 12-24 hours to complete the loading of the catalytically active component. The material is then ground into powder.

[0035] Step 4: Additive loading.

[0036] The catalyst prepared in the third step is loaded with any one or at least two combinations of sodium, potassium, magnesium, or manganese as additives using an equal-volume impregnation method. First, the required mass of the metal additive salt is calculated according to a specific ratio of additive to active catalyst component, and an additive precursor impregnation solution is prepared. Then, the salt solution is added dropwise to the catalyst powder at room temperature, with continuous stirring until the salt solution completely and uniformly impregnates all catalyst components. After impregnation, the impregnated material is air-dried in a clean, ventilated area (at 20-25℃) for 12-48 hours, and then vacuum-dried at 80-120℃ for 12-24 hours to complete the additive loading, ultimately obtaining the carbon dioxide hydrogenation to methanol catalyst.

[0037] The third objective of this invention is to provide an application of a carbon dioxide hydrogenation to methanol catalyst, wherein the carbon dioxide hydrogenation to methanol catalyst described in the first objective, or the carbon dioxide hydrogenation to methanol catalyst prepared by the preparation method described in the second objective, is used in the catalytic reaction of carbon dioxide hydrogenation to methanol after reduction treatment.

[0038] As a preferred technical solution of the present invention, the reducing gas in the reduction treatment includes pure hydrogen or a mixture of hydrogen and nitrogen, and the flow rate of the reducing gas is 25-100 ml / min, such as 25 ml / min, 35 ml / min, 45 ml / min, 50 ml / min, 60 ml / min, 70 ml / min, 80 ml / min, 90 ml / min or 100 ml / min, etc., but is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0039] Preferably, when the reducing gas used in the reduction process is a mixture of hydrogen and nitrogen, the hydrogen content is 20-80 vol%, such as 20 vol%, 30 vol%, 40 vol%, 50 vol%, 60 vol%, 70 vol%, or 80 vol%, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0040] And / or, the heating rate of the reduction treatment is 1-5℃ / min, such as 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, etc., carried out under normal pressure, the reduction temperature is 150-250℃, such as 150℃, 160℃, 180℃, 200℃, 210℃, 230℃ or 250℃, etc., and the reduction time is 8-24h, such as 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, etc., but not limited to the listed values, other unlisted values ​​within the above range are also applicable.

[0041] And / or, the molar ratio of hydrogen to carbon dioxide in the feed gas of the catalytic reaction is (1-6):1, for example 1:1, 2:1, 3:1, 4:1, 5:1 or 6:1, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0042] And / or, the heating rate of the catalytic reaction is 1-5℃ / min, for example 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, etc.; the reaction temperature is 160-280℃, for example 160℃, 180℃, 200℃, 220℃, 240℃, 260℃ or 280℃, etc.; the reaction pressure is 3-10MPa, for example 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa or 10MPa, etc.; and the space velocity is 4000-20000h. -1 For example, 4000h -1 8000h -1 10000h -1 12000h -1 16000h -1 or 20000h -1 The reaction time is 12-72h, such as 12h, 18h, 24h, 30h, 36h, 42h, 48h, 54h, 60h, 66h or 72h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0043] As a preferred embodiment of the present invention, the application of the carbon dioxide hydrogenation to methanol catalyst of the present invention includes the following steps: The first step is to grind the carbon dioxide hydrogenation to methanol catalyst into powder and pack it into the isothermal section of the fixed-bed tubular reactor. The second step involves raising the temperature from room temperature to the reduction temperature at a rate of 1-5℃ / min under an inert gas atmosphere such as nitrogen or helium and normal pressure. Then, a reducing gas, either pure hydrogen or a mixture of hydrogen and nitrogen, is introduced, with the flow rate of the reducing gas controlled at 25-100 ml / min. The reduction process is carried out at 150-250℃ for 8-24 hours. In the third step, after the reduction is complete, the reducing gas is shut off and nitrogen or helium is introduced to replace the reducing gas in the reactor. The reactor temperature is raised to the reaction temperature at a heating rate of 1-5℃ / min. Nitrogen is then switched to the feed gas (a mixture of H2 / CO2 / N2), with a molar ratio of hydrogen to carbon dioxide of (1-6):1. The catalytic reaction of carbon dioxide hydrogenation to methanol is carried out, with the reaction temperature controlled at 160-280℃, the reaction pressure at 3-10MPa, and the space velocity at 4000-20000h. -1 The reaction time is 12-72 hours.

[0044] Compared with existing technical solutions, the present invention has at least the following beneficial effects: (1) The carbon dioxide hydrogenation to methanol catalyst of the present invention has improved the support. The support for the active components includes a zirconium oxide framework support with an octahedral cage structure. It can spatially and electronically regulate the active metal centers supported by the geometric confinement effect and electronic effect. When applied to the catalytic reaction of carbon dioxide hydrogenation to methanol, the CO2 conversion rate can be above 13.3%, and up to 24.3%. The methanol selectivity can be above 74.4%, and up to 95.7%. It also has the advantage of long service life and catalyst stability of more than 200h.

[0045] (2) The preparation method described in this invention is simple to operate, and the catalyst obtained has a rich pore structure and a large specific surface area, which can expose a large number of active reaction sites on the catalyst, reduce the mass transfer resistance between reactants and products on the catalyst surface and inside, improve the catalyst reaction shape selectivity, and can significantly improve the catalyst's CO2 conversion rate, methanol selectivity and service life. Moreover, the average pore volume of the prepared supported catalyst is 0.3-0.7 cm³. 3 / g, BET specific surface area is 1000-2000m² 2 / g, with an average pore size of 6-20Å.

[0046] (3) The carbon dioxide hydrogenation to methanol catalyst described in this invention is applied to the catalytic reaction of carbon dioxide hydrogenation to methanol, and is especially suitable for industries with high carbon emissions such as factories, vehicles, and ships that emit large amounts of carbon dioxide tail gas. It is beneficial to energy conservation, emission reduction and the production and development of downstream products. Attached Figure Description

[0047] Figure 1 This is the first SEM image of the carbon dioxide hydrogenation to methanol catalyst prepared in Example 4 of this invention.

[0048] Figure 2 This is the second SEM image of the carbon dioxide hydrogenation to methanol catalyst prepared in Example 4 of this invention. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows: The reagents used in the specific embodiments of the present invention are shown in Table 1.

[0051] Table 1 Example 1 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0052] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0053] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0054] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0055] The third step is loading the catalytically active components.

[0056] The catalytically active component copper was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1 g of the prepared ZrO2 support powder was weighed. Then, 0.0378 g of Cu(NO3)2·3H2O was weighed according to a 1 wt% mass ratio of copper to support to prepare an impregnation solution. This solution was then added dropwise to the 1 g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated the entire support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 1Cu-ZrO2 catalyst containing 1 wt% Cu, which was then ground into powder.

[0057] Step 4: Additive loading.

[0058] Sodium additive was loaded onto a 1Cu-ZrO2 catalyst containing 1wt% Cu using an equal-volume impregnation method. First, 0.0007g of NaHCO3 was weighed according to a 2wt% mass ratio of sodium additive to 0.01g of catalytically active component copper, and an impregnation solution was prepared. Then, the salt solution was added dropwise to the 1Cu-ZrO2 catalyst containing 1wt% Cu at room temperature, with continuous stirring of the catalyst powder until the salt solution completely and uniformly impregnated all catalyst components. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the sodium additive loading, yielding a carbon dioxide hydrogenation to methanol catalyst, denoted as 1Cu-2Na-ZrO2 catalyst. This catalyst, based on a 1wt% mass ratio of catalytically active component copper to support and a 2wt% mass ratio of sodium additive to catalytically active component copper, was ground into powder.

[0059] Example 2 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0060] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0061] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0062] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0063] The third step is loading the catalytically active components.

[0064] The catalytically active component copper was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1 g of the prepared ZrO2 support powder was weighed. Then, 0.1134 g of Cu(NO3)2·3H2O was weighed according to a 3 wt% mass ratio of copper to support to prepare an impregnation solution. This solution was then added dropwise to the 1 g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated the entire support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 3Cu-ZrO2 catalyst containing 3 wt% Cu, which was then ground into powder.

[0065] Example 3 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0066] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0067] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0068] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0069] The third step is loading the catalytically active components.

[0070] Copper loading of catalytic active component: The catalytic active component copper was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1g of the prepared ZrO2 support powder was weighed. Then, based on the metal element, 0.1134g of Cu(NO3)2·3H2O was weighed according to a 3wt% mass ratio of copper to support to prepare the active component precursor impregnation solution. This solution was then added dropwise to the 1g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated all the support. After impregnation, the impregnated material was air-dried in a clean, ventilated place for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the copper loading of the catalytic active component, obtaining a 3Cu-ZrO2 catalyst containing 3wt% Cu, which was then ground into powder.

[0071] Zinc loading of catalytic active component: The catalytic active component zinc was further loaded onto a 3Cu-ZrO2 catalyst containing 3wt% Cu using an equal-volume impregnation method. First, 0.0915 g of Zn(NO3)2·6H2O was weighed according to a 2wt% mass ratio of zinc to support, and an active component precursor impregnation solution was prepared. This solution was then added dropwise to the 3Cu-ZrO2 catalyst containing 3wt% Cu at room temperature, with continuous stirring of the catalyst powder until the salt solution completely and uniformly wetted all catalyst components. After impregnation, the impregnated material was air-dried in a clean, ventilated place for 24 hours, and then vacuum-dried at 110℃ for 12 hours. This zinc loading yielded a carbon dioxide hydrogenation to methanol catalyst, denoted as 3Cu2Zn-ZrO2 catalyst, where the mass ratios of copper and zinc to support are 3wt% and 2wt%, respectively, and the catalyst was ground into powder.

[0072] Example 4 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0073] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0074] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0075] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0076] The third step is loading the catalytically active components.

[0077] The catalytically active component copper was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1 g of the prepared ZrO2 support powder was weighed. Then, 0.1134 g of Cu(NO3)2·3H2O was weighed according to a 1 wt% mass ratio of copper to support to prepare an impregnation solution. This solution was then added dropwise to the 1 g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated the entire support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 3Cu-ZrO2 catalyst containing 3 wt% Cu, which was then ground into powder.

[0078] Step 4: Additive loading.

[0079] Sodium additive was loaded onto a 3Cu-ZrO2 catalyst containing 3wt% Cu using an equal-volume impregnation method. First, 0.0022g of NaHCO3 was weighed according to a 2wt% mass ratio of sodium additive to copper (0.03g) to prepare an impregnation solution. Then, the salt solution was added dropwise to a 1Cu-ZrO2 catalyst containing 1wt% Cu at room temperature, with continuous stirring of the catalyst powder until the salt solution completely and uniformly impregnated all catalyst components. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the sodium additive loading, yielding a carbon dioxide hydrogenation to methanol catalyst, denoted as 3Cu-2Na-ZrO2 catalyst. This catalyst, based on a 3wt% mass ratio of copper to support and a 2wt% mass ratio of sodium additive to copper, was ground into powder.

[0080] The carbon dioxide hydrogenation to methanol catalyst prepared in this embodiment Figure 1 and Figure 2 SEM images at different magnifications are shown. It can be seen that the carbon dioxide hydrogenation to methanol catalyst prepared in this embodiment has a cluster morphology, while the single catalyst particles exhibit an octahedral cage structure.

[0081] Example 5 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0082] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0083] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0084] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0085] The third step is loading the catalytically active components.

[0086] The catalytically active component copper was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1 g of the prepared ZrO2 support powder was weighed. Then, 0.3781 g of Cu(NO3)2·3H2O was weighed according to a copper-to-support mass ratio of 10 wt% to the metal element, and an impregnation solution was prepared. This solution was then added dropwise to the 1 g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated the entire support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 10Cu-ZrO2 catalyst containing 10 wt% Cu, which was then ground into powder.

[0087] Step 4: Additive loading.

[0088] Sodium additive was loaded onto a 10Cu-ZrO2 catalyst containing 10wt% Cu using an equal-volume impregnation method. First, 0.0073g of NaHCO3 was weighed according to a 2wt% mass ratio of sodium additive to 0.1g of catalytically active component copper, and an impregnation solution was prepared. Then, the salt solution was added dropwise to the 10Cu-ZrO2 catalyst containing 10wt% Cu at room temperature, with continuous stirring of the catalyst powder until the salt solution completely and uniformly impregnated all catalyst components. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the sodium additive loading, yielding a carbon dioxide hydrogenation to methanol catalyst, denoted as 10Cu-2Na-ZrO2 catalyst. This catalyst, based on a 10wt% mass ratio of catalytically active component copper to support and a 2wt% mass ratio of sodium additive to catalytically active component copper, was ground into powder.

[0089] Example 6 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0090] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0091] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0092] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0093] The third step is loading the catalytically active components.

[0094] The catalytically active component copper was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1 g of the prepared ZrO2 support powder was weighed. Then, 0.7562 g of Cu(NO3)2·3H2O was weighed according to a 1 wt% mass ratio of copper to support to prepare an impregnation solution. This solution was then added dropwise to the 1 g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly wetted all the support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 20Cu-ZrO2 catalyst containing 20 wt% Cu, which was then ground into powder.

[0095] Step 4: Additive loading.

[0096] Sodium additive was loaded onto a 20Cu-ZrO2 catalyst containing 20wt% Cu using an equal-volume impregnation method. First, 0.0146g of NaHCO3 was weighed according to a 2wt% mass ratio of sodium additive to copper (0.2g) to prepare an impregnation solution. Then, the salt solution was added dropwise to the 20Cu-ZrO2 catalyst containing 20wt% Cu at room temperature, with continuous stirring of the catalyst powder until the salt solution completely and uniformly impregnated all catalyst components. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the sodium additive loading, yielding a carbon dioxide hydrogenation to methanol catalyst, denoted as 20Cu-2Na-ZrO2 catalyst. This catalyst is characterized by a 20wt% mass ratio of copper to support and a 2wt% mass ratio of sodium additive to copper, and is ground into powder.

[0097] Example 7 This embodiment provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the preparation method comprising the following steps: The first step is to prepare the metal-organic framework material UiO-66.

[0098] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0099] The second step involves pyrolyzing the UiO-66 product to prepare a zirconia framework carrier with an octahedral cage structure.

[0100] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0101] The third step is loading the catalytically active components.

[0102] The catalytically active component zinc was loaded onto a ZrO2 support using an equal-volume impregnation method. First, 1 g of the prepared ZrO2 support powder was weighed. Then, 0.1373 g of Zn(NO3)2·6H2O was weighed according to a 3 wt% mass ratio of zinc to support, and an impregnation solution was prepared. This solution was then added dropwise to the 1 g ZrO2 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated the entire support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 3Zn-ZrO2 catalyst containing 3 wt% Zn, which was then ground into powder.

[0103] Comparative Example 1 This comparative example provides a zirconia framework carrier with an octahedral cage structure prepared by pyrolysis of UiO-66 product, that is, by following the first and second steps in Example 1, a zirconia framework carrier with an octahedral cage structure is obtained.

[0104] Comparative Example 2 This comparative example provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising the following steps: Step i: Prepare metal-organic framework material UiO-66.

[0105] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0106] Step ii: Loading of catalytically active components.

[0107] The catalytically active component copper was loaded onto a UiO-66 support using an equal-volume impregnation method. First, 1 g of the prepared UiO-66 support powder was weighed. Then, 0.1134 g of Cu(NO3)2·3H2O was weighed according to a 3wt% mass ratio of copper to support to prepare an impregnation solution. This solution was then added dropwise to the 1 g UiO-66 support powder at room temperature, with continuous stirring until the metal salt solution completely and uniformly impregnated the entire support. After impregnation, the impregnated material was air-dried in a clean, ventilated area for 24 hours, and then vacuum-dried at 110℃ for 12 hours to complete the loading of the catalytically active component, obtaining a 3Cu-UiO-66 catalyst containing 3wt% Cu, which was then ground into powder.

[0108] Comparative Example 3 This comparative example provides a method for preparing a catalyst, the method comprising the following steps: Step 1: Prepare metal-organic framework material UiO-66.

[0109] At room temperature, 0.106 g of zirconium chloride was added to 10 ml of N,N-dimethylformamide (DMF) and stirred continuously until the zirconium chloride was completely dissolved. Then, 0.068 g of 1,4-phthalic acid was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature for 12 hours to obtain a homogeneous precursor suspension. The precursor was transferred to a 25 ml Teflon hydrothermal crystallization vessel and hydrothermally crystallized at 120 °C for 24 hours. After hydrothermal crystallization, the mixture was cooled to room temperature. The crystallized product was washed with methanol and centrifuged until the pH of the washing solution was in the range of 6.8-7.2. Then, it was vacuum dried at 60 °C for 24 hours to obtain the UiO-66 product.

[0110] Step 2: Pyrolysis of UiO-66 product to prepare zirconia framework carrier with octahedral cage structure.

[0111] In an air atmosphere, the UiO-66 product was calcined and pyrolyzed at 700℃ for 4 hours to obtain a ZrO2 support with a UiO-66 framework structure, namely a zirconium oxide framework support with an octahedral cage structure, which was then ground into powder for later use.

[0112] Step 3, additive loading.

[0113] Sodium additive was directly loaded onto a ZrO2 support using an equal-volume impregnation method. First, 0.0022 g of NaHCO3 was weighed and an impregnation solution for the additive precursor was prepared. Then, the salt solution was added dropwise to the ZrO2 support at room temperature, with continuous stirring of the catalyst powder until the salt solution completely and uniformly impregnated all the catalyst. After impregnation, the impregnated material was air-dried in a clean, ventilated place for 24 hours, and then vacuum-dried at 110°C for 12 hours to complete the sodium loading and obtain the catalyst, designated as the 2Na-ZrO2 catalyst. That is, compared to Example 4, the catalyst in this comparative example did not involve the loading of the active component copper.

[0114] Comparative Example 4 This comparative example provides a UiO-66 product, namely, a UiO-66 product with an octahedral cage structure obtained by following the first step in Example 1.

[0115] Comparative Example 5 This comparative example provides a method for preparing a catalyst. Compared with Example 4, the only difference is that instead of pyrolyzing the UiO-66 product to prepare an octahedral cage-like zirconium framework support, commercially available ZrO2-c is directly ground into powder as a support. The resulting catalyst is denoted as 3Cu-2Na-ZrO2-c catalyst.

[0116] The catalysts prepared in the above examples and comparative examples were subjected to application testing. The application testing method included: loading the catalysts to be tested into the isothermal section of a fixed-bed tubular reactor, and then, under a nitrogen atmosphere and atmospheric pressure, raising the temperature from room temperature to 180°C at a rate of 2°C / min. Then, a 20 vol% hydrogen / nitrogen reducing gas was introduced at a rate of 25 ml / min to reduce the catalyst. After 12 hours of reduction treatment, the reducing gas was turned off and nitrogen was introduced to replace the reducing gas in the reactor. The reactor temperature was raised to 240°C at a rate of 2°C / min. The nitrogen gas was then switched to a mixture of feed gas H2 / CO2 / N2 (H2:CO2 = 3:1) to carry out the catalytic reaction of carbon dioxide hydrogenation to methanol. The reaction pressure was controlled at 5 MPa and the space velocity at 12000 h⁻¹. -1 The reaction time was 24 hours. The relevant results of the application tests are summarized in Table 2.

[0117] Table 2 Note: In Table 2, CO2 conv. represents the conversion rate of CO2, MeOH sel. represents the selectivity of methanol product, CO sel. represents the selectivity of CO product, CH4 sel. represents the selectivity of methane product, and other sel. represents the selectivity of products other than methanol, CO and methane.

[0118] As can be seen from Table 2: (1) Comparing Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 4, the CO2 conversion rate and methanol selectivity of the metal-organic framework material UiO-66 (pure UiO-66) in Comparative Example 4 are extremely low. However, Comparative Example 1 prepares an octahedral cage-like zirconium framework support (pure ZrO2 support) after pyrolysis of UiO-66, which improves the CO2 conversion rate and methanol selectivity. In Comparative Example 2, the direct loading of the catalytically active component Cu on UiO-66 has little effect on improving the catalytic performance, indicating that UiO-66 has almost no catalytic performance for methanol synthesis. Zr, which exists in the form of ZrO2 support after pyrolysis, has certain catalytic activity for methanol synthesis. Further comparing Example 2 with Comparative Example 1 and Example 4 with Comparative Example 3, using the octahedral cage-like zirconium framework support as the support and further loading the catalytically active component Cu, the CO2 conversion rate and methanol selectivity are greatly improved, and the selectivity of by-products CO and methane is reduced, indicating that Cu has strong catalytic activity for CO2 hydrogenation to methanol.

[0119] (2) Comparing Examples 2, 3 and 7, although Examples 2 and 7 are loaded with the same mass of Cu and Zn respectively, the CO2 conversion rate and methanol selectivity of the Cu-loaded catalyst are significantly higher, while the CO and methane selectivity are significantly lower. Furthermore, Example 3 adds active metal Zn to the Cu-loaded catalyst, which can further improve the CO2 conversion rate and methanol selectivity. This shows that although the catalytic performance of Cu is better than that of Zn, the dual catalytic active components of Cu and Zn can optimize the product distribution to a certain extent.

[0120] (3) Comparing Example 2 and Example 4, after adding Na to the Cu supported catalyst for modification, the CO2 conversion rate and methanol selectivity were improved, and the by-product selectivity was reduced, indicating that Na modification can improve the catalyst reaction performance.

[0121] (4) Comparing Examples 1, 4, 5 and 6, as the Cu loading increases, the CO2 conversion rate and methanol selectivity first increase and then decrease, while the selectivity of by-products shows the opposite trend, indicating that the Cu loading cannot be too low or too high, and there is an optimal loading.

[0122] (5) Comparing Example 4 and Comparative Example 5, compared with ordinary ZrO2 support, the ZrO2 support catalyst prepared by pyrolysis of metal-organic framework material UiO-66 has higher CO2 conversion rate and methanol selectivity, and CO selectivity and methane selectivity are reduced. This indicates that the ZrO2 support prepared by pyrolysis of UiO-66 is beneficial to improving the CO2 activation performance of the catalyst and can suppress the side reactions reverse water-gas shift and methanation reaction to a certain extent.

[0123] (6) Based on the above evaluation results of the catalytic reaction, the carbon dioxide hydrogenation to methanol catalyst developed in this invention, when applied to the catalytic reaction of carbon dioxide hydrogenation to methanol, can achieve a CO2 conversion rate of more than 13.3%, up to a maximum of 24.3%, and a methanol selectivity of more than 74.4%, up to a maximum of 95.7%. The selectivity of by-products CO and methane can be optimally controlled within 3%.

[0124] In summary, the ZrO2 support in the carbon dioxide hydrogenation to methanol catalyst developed in this invention is prepared by the pyrolysis of the metal-organic framework material UiO-66. UiO-66 possesses a unique octahedral cage-like structure with abundant pores, a large surface area, suitable pore size, and large pore volume. Therefore, compared to common catalysts, it has more active sites and higher mass transfer efficiency, thereby improving reaction activity and product shape selectivity. Consequently, the ZrO2 support structure prepared in this invention is superior to that of traditional ZrO2 supports, and the catalyst prepared based on this support exhibits superior performance compared to traditional methanol synthesis catalysts.

[0125] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0126] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0127] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0128] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, The carbon dioxide hydrogenation to methanol catalyst includes a support and an active component; the support includes a zirconium oxide framework support with an octahedral cage structure, and the active component is loaded on the surface and inner wall of the pores of the support.

2. The catalyst for carbon dioxide hydrogenation to methanol according to claim 1, characterized in that, The carbon dioxide hydrogenation to methanol catalyst also includes an auxiliary agent, which is also loaded on the surface and pore walls of the support.

3. The catalyst for carbon dioxide hydrogenation to methanol according to claim 2, characterized in that, The adjuvant includes any one or a combination of at least two of sodium, potassium, magnesium or manganese; And / or, based on metal elements, the mass ratio of the auxiliary to the active component is (0-0.5):

1.

4. The catalyst for carbon dioxide hydrogenation to methanol according to claim 1 or 2, characterized in that, The active component includes any one or a combination of at least two of copper, zinc, indium, aluminum, iron, gold, palladium, platinum or cerium; And / or, based on metal elements, the active component accounts for 0.5-50 wt% of the carrier mass; And / or, the octahedral cage-like zirconia framework carrier is prepared by calcination and pyrolysis of metal-organic framework material UiO-66; And / or, the average particle size D50 of the carbon dioxide hydrogenation to methanol catalyst is 20-500 nm.

5. A method for preparing the catalyst for the hydrogenation of carbon dioxide to methanol according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: Prepare an impregnation solution of the active component precursor, add it dropwise onto a support comprising a zirconium oxide framework support with an octahedral cage structure, and dry it to obtain the carbon dioxide hydrogenation to methanol catalyst.

6. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 5, characterized in that, The preparation method further includes: preparing an auxiliary precursor impregnation solution, adding it dropwise onto a support, and drying it to obtain the carbon dioxide hydrogenation to methanol catalyst.

7. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 5 or 6, characterized in that, The octahedral cage-like zirconia framework carrier was prepared using the following method: Prepare an N,N-dimethylformamide solution containing zirconium chloride, add 1,4-phthalic acid dropwise, and perform hydrothermal crystallization on the resulting homogeneous suspension. After washing and drying, obtain the metal-organic framework material UiO-66. The metal-organic framework material UiO-66 is then calcined and pyrolyzed to obtain a zirconium oxide framework carrier with an octahedral cage structure.

8. The method for preparing the catalyst for carbon dioxide hydrogenation to methanol according to claim 7, characterized in that, The hydrothermal crystallization temperature is 120-180℃, and the hydrothermal crystallization time is 12-48h; And / or, the washing includes: centrifugal washing with methanol until the pH of the washing solution is neutral; And / or, the drying includes: vacuum drying at 60-110°C for 12-24 hours; And / or, the calcination pyrolysis temperature is 400-800℃, and the calcination pyrolysis time is 3-12h; And / or, the reaction atmosphere of the calcination pyrolysis is any one or a combination of at least two of air, oxygen-enriched gas, nitrogen, or vacuum.

9. An application of a catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, Prepare a carbon dioxide hydrogenation to methanol catalyst according to any one of claims 1-4, or a carbon dioxide hydrogenation to methanol catalyst prepared by any one of claims 5-8, and use it in the catalytic reaction of carbon dioxide hydrogenation to methanol after reduction treatment.

10. The application of the carbon dioxide hydrogenation to methanol catalyst according to claim 9, characterized in that, The reducing gas used in the reduction process includes pure hydrogen or a mixture of hydrogen and nitrogen, and the flow rate of the reducing gas is 25-100 ml / min. And / or, the reduction treatment is carried out at a heating rate of 1-5℃ / min under normal pressure, at a reduction temperature of 150-250℃, and for a reduction time of 8-24h; And / or, the molar ratio of hydrogen to carbon dioxide in the feed gas of the catalytic reaction is (1-6):1; And / or, the catalytic reaction has a heating rate of 1-5 °C / min, a reaction temperature of 160-280 °C, a reaction pressure of 3-10 MPa, and a space velocity of 4000-20000 h⁻¹. -1 The reaction time is 12-72 hours.

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