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

Abstract

The application relates to the technical field of catalysts, and discloses a carbon dioxide hydrogenation methanol catalyst as well as a preparation method and application thereof. x Mo2C, x=0.01-1, and the active component is selected from one or more of Cu, Zn, Al, Zr, In, Ce and Ga. The catalyst of the application does not use noble metals, is low in price, simple in preparation method, and can be easily mass-produced by adjusting the carrier component and the loaded metal. The catalyst of the application can be used for carbon dioxide hydrogenation methanol, and can improve the carbon dioxide conversion rate and the methanol selectivity.

Description

Technical Field

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

[0002] Methanol is a basic organic chemical raw material with a wide range of applications. The methanol molecule has a simple structure, and the process of producing methanol from CO2 is relatively easy to implement. Producing methanol from CO2 can leverage existing C1 chemical systems to achieve green manufacturing of chemical products; therefore, methanol holds promise as an important direction for the resource utilization of CO2. CO2 is a nonpolar linear molecule, while CO is a linear polar molecule; CO2 is more kinetically and thermodynamically stable and more difficult to activate. The hydrogenation of CO2 requires a relatively high temperature to activate the CO2 molecule, but since the CO2 hydrogenation reaction is exothermic, increasing the temperature is detrimental to the reaction. Therefore, the rational design of catalysts to prepare highly active catalysts for the hydrogenation of CO2 to methanol is crucial.

[0003] Copper-based catalysts are widely used in industrial methanol synthesis due to their advantages such as low cost, high activity, excellent low-temperature performance, few side reactions, good methanol selectivity, and high crude methanol purity. Among these, Cu / ZnO2 / Al2O3 catalytic hydrogenation of syngas is currently the main method for industrial methanol synthesis. This method typically uses syngas (with CO and H2 as the main components) as feedstock, with a reaction pressure of 50-100 bar and a temperature of 200-300℃.

[0004] CN109794276A discloses a Cu-C3N4-M-ZnO catalyst for the hydrogenation of carbon dioxide to methanol, but the CO2 conversion rate is low (<6%).

[0005] CN103272607A discloses a copper-based catalyst for the hydrogenation of CO2 to methanol. The catalyst utilizes a polymer as a stabilizer and is prepared via a co-current co-precipitation method using a Cu / Zn / Al / Zr-based catalyst. The catalyst is tested at 250℃, 5.0 MPa, an H2 / CO2 volume ratio of 3 / 1, and a GHSV of 4000 h⁻¹. -1 Under the given reaction conditions, the catalyst exhibits good stability, but its CO2 conversion and methanol selectivity are relatively low. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low carbon dioxide conversion rate and poor methanol selectivity in the prior art of carbon dioxide hydrogenation to methanol, and to provide a catalyst for carbon dioxide hydrogenation to methanol, its preparation method and application. This catalyst can be used for carbon dioxide hydrogenation to methanol and can improve carbon dioxide conversion rate and methanol selectivity.

[0007] To achieve the above objectives, a first aspect of the present invention provides a catalyst for the hydrogenation of carbon dioxide to methanol, the catalyst comprising a support and an active component supported on the support, wherein the support is C@Cu. x Mo2C, x = 0.01-1, wherein the active component is selected from one or more of Cu, Zn, Al, Zr, In, Ce and Ga.

[0008] A second aspect of this invention provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising the following steps:

[0009] Activated carbon was dispersed in a solution containing Cu and Mo sources, stirred, and freeze-dried to obtain a precursor. Under a hydrogen atmosphere, the precursor was kept at 600-800°C for 1-5 hours, and after cooling, the support C@Cu was obtained. x Mo2C, where x = 0.01-1;

[0010] The support is passivated, then dispersed in a metal salt solution, and a precipitant is added to precipitate the material to obtain a precipitate. The precipitate is then calcined and reduced to obtain a catalyst.

[0011] A third aspect of the present invention provides a method for producing methanol by hydrogenation of carbon oxide, the method comprising: reacting carbon dioxide with hydrogen in the presence of a catalyst as described in any one of the first aspects or a catalyst prepared by any one of the preparation methods described in any one of the second aspects.

[0012] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0013] 1) The catalyst of the present invention does not use precious metals, is inexpensive and has a simple preparation method. The support components and loaded metals can be modified, making it easy to mass-produce.

[0014] 2) The catalyst of this invention can be used to produce methanol by hydrogenation of carbon dioxide. It has the characteristics of high methanol selectivity, high CO2 conversion rate and excellent recycling performance. In the temperature range of 180-270℃, the methanol selectivity is above 90% and the single-pass conversion rate of carbon dioxide is above 17%. When the catalyst contains two active components, the single-pass conversion rate of carbon dioxide is above 19%. Attached Figure Description

[0015] Figure 1 This is a TEM image of the catalyst C1 sample prepared in Example 1;

[0016] Figure 2 This is a TEM-mapping elemental distribution diagram of the catalyst C1 sample prepared in Example 1. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] A first aspect of this invention provides a catalyst for the hydrogenation of carbon dioxide to methanol, the catalyst comprising a support and an active component supported on the support, wherein the support is C@Cu. x Mo2C, x = 0.01-1, wherein the active component is selected from one or more of Cu, Zn, Al, Zr, In, Ce and Ga.

[0019] Through extensive research, the inventors of this invention discovered that in the CO2 hydrogenation to methanol reaction, under the formic acid mechanism, water on the surface of the copper-based catalyst can inhibit further hydrogenation or decomposition of HCOO to methanol, reducing the methanol selectivity and yield in the product. Therefore, the addition of Mo to the catalyst to improve methanol selectivity was considered. However, since Mo does not bind tightly to C, Cu was added as an intermediate, which can simultaneously improve the dispersion of the active component Cu, thereby increasing the CO2 conversion rate and methanol selectivity. A Cu-modified Mo2C coating was then applied to an activated carbon support to form the composite material C@Cu. x Mo2C. The Mo2C coating exhibits good interfacial bonding with both Cu and C, forming an interconnected network structure.

[0020] The catalyst of this invention uses C@Cu x Using Mo2C as a carrier and one or more metals selected from Cu, Zn, Al, Zr, In, Ce, and Ga as active components, it can achieve good methanol selectivity and CO2 conversion rate when used for the hydrogenation of carbon dioxide to methanol.

[0021] In some embodiments of the present invention, the Mo content is 0.5-20 wt%, preferably 0.7-5 wt%, based on the total weight of the carrier.

[0022] In this invention, during the CO2 hydrogenation process, the CO2 molecule has a relatively stable structure and requires high energy to break the C=O bond. Since the CO bond is highly polar and easily breaks, increasing the CO content facilitates the hydrogenation reaction. The introduction of molybdenum carbide accelerates the conversion of carbon dioxide to carbon monoxide, and the surface-active components on the support can simultaneously catalyze the hydrogenation of CO2 and CO to methanol, thus improving the carbon dioxide conversion efficiency. Compared to single CO2 hydrogenation, the introduction of Mo2C increases the methanol yield and CO2 conversion rate; however, excessive Mo2C can lead to excess CO and decreased product selectivity.

[0023] In some embodiments of the present invention, the content of the support is 50-96.5 wt% and the content of the active component is 3.5-50 wt% based on the total weight of the catalyst.

[0024] In some preferred embodiments of the present invention, the content of the support is 60-95 wt% and the content of the active component is 5-40 wt% based on the total weight of the catalyst.

[0025] In some embodiments of the present invention, the carrier C@Cu x The specific surface area of ​​Mo2C is 100-1500 m². 2 / g, preferably 500-1000m 2 / g, the mass content of Mo does not exceed 10wt%, for example 9wt%, 8wt%, 7wt%, 6wt%, 5wt%, 4wt%, 3wt%, 2wt%, 1wt%, and any value within the range of any two values, preferably 6-9wt%.

[0026] A second aspect of this invention provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising the following steps:

[0027] Activated carbon was dispersed in a solution containing Cu and Mo sources, stirred, and freeze-dried to obtain a precursor. Under a hydrogen atmosphere, the precursor was kept at 600-800°C for 1-5 hours, and after cooling, the support C@Cu was obtained. x Mo2C, where x = 0.01-1;

[0028] The support is passivated, then dispersed in a metal salt solution, and a precipitant is added to precipitate the material to obtain a precipitate. The precipitate is then calcined and reduced to obtain a catalyst.

[0029] The catalyst of this invention is used for the hydrogenation of carbon dioxide to methanol. It has the characteristics of high methanol selectivity, high CO2 conversion rate, and excellent recycling performance. In the temperature range of 180-270℃, the methanol selectivity is above 90%, and the single-pass conversion rate of carbon dioxide is above 17%. When the catalyst contains two active components, the single-pass conversion rate of carbon dioxide is above 19%.

[0030] In some embodiments of the present invention, the activated carbon has an average particle size of 500 nm-10 μm and a specific surface area of ​​200-1800 m². 2 / g, pore volume is 0.2-0.7cm³ 3 / g.

[0031] In some embodiments of the present invention, the activated carbon is selected from one or more of wood-based activated carbon, fruit shell activated carbon, coal-based activated carbon, recycled carbon, and petroleum-based activated carbon.

[0032] In some embodiments of the present invention, the activated carbon has one or more of the following morphologies: fiber, sphere, and sheet.

[0033] In some embodiments of the present invention, the Cu source is selected from one or more of copper nitrate, copper sulfate, copper chloride, and copper oxide.

[0034] In some embodiments of the present invention, the Mo source is selected from ammonium heptamolybdate ((NH4)6Mo7O) 24 One or more of molybdenum chloride and sodium molybdate.

[0035] In some embodiments of the present invention, the molar ratio of the Cu source, Mo source and activated carbon is 0.2-2.5:0.1-1.2:6.5-9.7, preferably 1-2:0.5-1:6-9.

[0036] In some embodiments of the present invention, the metal salt solution is selected from a soluble salt of at least one metal selected from Cu, Zn, Al, Zr, In, Ce and Ga.

[0037] In this invention, the soluble salt is preferably a nitrate.

[0038] In this invention, the soluble salts used are preferably nitrates corresponding to metals such as Cu, Zn, Al, Zr, In, Ce, and Ga.

[0039] In some embodiments of the present invention, the mass ratio of the carrier to the metal salt in the metal salt solution is 0.5-5:1.

[0040] In some embodiments of the present invention, the concentration of the metal salt in the metal salt solution is 0.01-2 mol / L.

[0041] In some embodiments of the present invention, the precipitant is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide.

[0042] In some embodiments of the present invention, the concentration of the precipitant is 0.05-0.5 mol / L, and the pH of the precipitate is 6.5-7.5.

[0043] In some embodiments of the present invention, the passivation treatment is performed at a temperature of 20-30°C for 1-3 hours.

[0044] In some embodiments of the present invention, the passivation gas is a mixture of oxygen and an inert gas, wherein the volume content of oxygen in the mixture is 0.05-1%, for example, 1% O2 / N2.

[0045] In this invention, the inert gas is selected from one or more of nitrogen, argon and helium.

[0046] In some embodiments of the present invention, the calcination is carried out under a nitrogen atmosphere at a temperature of 300-500°C for a time of 0.33-0.66 h.

[0047] In some embodiments of the present invention, the reduction is carried out in an H2 atmosphere, the temperature of the reduction is 200-250°C, and the time is 2-5 hours.

[0048] A third aspect of the present invention provides a method for producing methanol by hydrogenation of carbon oxide, the method comprising: reacting carbon dioxide with hydrogen in the presence of a catalyst as described in any one of the first aspects or a catalyst prepared by any one of the preparation methods described in any one of the second aspects.

[0049] In this invention, during the CO2 hydrogenation process, the CO2 molecule has a relatively stable structure and requires high energy to break the C=O bond. Since the CO bond is highly polar and easily breaks, increasing the CO content facilitates the hydrogenation reaction. The introduction of molybdenum carbide accelerates the conversion of CO2 to CO, and the active components on the support surface can simultaneously catalyze the hydrogenation of CO2 and CO to methanol, thus improving the carbon dioxide conversion efficiency. This catalyst can promote the conversion of some CO2 to CO and methanol, and then CO and CO2 are further hydrogenated on the metal active component to produce methanol, thereby improving the carbon dioxide conversion rate and methanol selectivity.

[0050] In some embodiments of the present invention, the volume ratio of carbon dioxide to hydrogen is 1:1 to 1:10, and the space velocity is 2000 to 20000 h⁻¹. -1 .

[0051] In some embodiments of the present invention, the reaction temperature is 180-280°C and the pressure is 3-8 MPa.

[0052] The following examples illustrate the function and effect of the method of the present invention, but the following examples do not constitute a limitation on the present invention.

[0053] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0054] C@Cu x The component content of the Mo2C support was determined using a DIONX ICS-900 inductively coupled plasma atomic emission spectrometer.

[0055] Example 1

[0056] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.0184g) and (NH4)6Mo7O. 24 The solution of (1.732 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 700 °C for 3 hours under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.081 Mo2C support, wherein C@Cu 0.081 The component content of the Mo2C support was determined using a DIONX ICS-900 inductively coupled plasma atomic emission spectrometer.

[0057] The obtained C@Cu 0.081 The Mo2C support was placed in 1% O2 / N2 and passivated at 30°C for 2 hours.

[0058] 5g of the passivated support was weighed and fully dispersed in 200ml of Cu(NO3)2 (0.75g), Al(NO3)39H2O (0.52g) and Zn(NO3)26H2O (0.68g) solution. The mixture was stirred thoroughly for 3 hours, and then sodium carbonate (0.1mol / L) was slowly added dropwise until the pH of the solution was 7. After centrifugation, washing, and drying, the solution was placed in a tube furnace and calcined at 300℃ for 0.60 hours under a nitrogen atmosphere to obtain catalyst C1.

[0059] 0.2 g of catalyst C1 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 200 °C for 5 h under normal pressure and pure H2 at a flow rate of 30 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) of 3:1, and the reaction was conducted at 5 MPa and 250 °C. The catalyst evaluation results are shown in Table 1.

[0060] like Figure 1 The image shown is a TEM image of the catalyst C1 sample. Figure 2 The image shows the TEM-mapping elemental distribution of catalyst C1 sample. From... Figure 1 and Figure 2 It can be seen that the catalyst C1 sample contains elements O, Al, Mo, Cu and Zn, and Cu, Zn and Al elements are distributed on the matrix composed of Mo / Cu.

[0061] Example 2

[0062] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.368g) and (NH4)6Mo7O. 24 The solution of (1.732 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 750 °C for 2 hours under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.34 Mo2C carrier;

[0063] The obtained C@Cu 0.34 Mo2C support was passivated in 1% O2 / N2 at 20°C for 3 hours;

[0064] 5g of the passivated support was weighed and fully dispersed in 200ml of Cu(NO3)2 (0.62g), In(NO3)36H2O (0.88g) and Ga(NO3)36H2O (1.14g) solution. The mixture was stirred thoroughly for 3 hours, and then sodium bicarbonate (0.1mol / L) was slowly added dropwise until the pH of the solution was 7. After centrifugation, washing, and drying, the solution was placed in a tube furnace and calcined at 500℃ for 0.33 hours under a nitrogen atmosphere to obtain catalyst C2.

[0065] 0.2 g of catalyst C2 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 250 °C for 2 h under normal pressure and pure H2 at a flow rate of 30 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) = 10:1, and the reaction was conducted at 3 MPa and 210 °C. The catalyst evaluation results are shown in Table 1.

[0066] Example 3

[0067] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.092g) and (NH4)6Mo7O. 24 The solution (0.866 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 600 °C for 5 hours under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.12 Mo2C carrier;

[0068] The obtained C@Cu 0.12 Mo2C support was passivated in 1% O2 / N2 at 30°C for 1 hour;

[0069] 5g of the passivated support was weighed and fully dispersed in 200ml of Cu(NO3)2 (0.21g), Zr(NO3)4 (0.13g) and In(NO3)3 (0.16g) solution. The mixture was stirred for 3 hours, and then potassium carbonate (0.1mol / L) was slowly added dropwise until the pH of the solution was 7. After centrifugation, washing and drying, the solution was placed in a tube furnace and calcined at 400℃ for 0.50 hours under a nitrogen atmosphere to obtain catalyst C3.

[0070] 0.2 g of catalyst C3 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 220 °C for 4 h in pure H2 at atmospheric pressure and a flow rate of 20 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) of 1:1, and the reaction was conducted at 8 MPa and 180 °C. The catalyst evaluation results are shown in Table 1.

[0071] Example 4

[0072] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.276g) and (NH4)6Mo7O. 24 The solution (0.866 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 800 °C for 1 hour under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.51 Mo2C carrier;

[0073] The obtained C@Cu 0.51 Mo2C support was passivated in 1% O2 / N2 at 30°C for 2 hours;

[0074] 5g of the passivated support was weighed and fully dispersed in 200ml of In(NO3)3 (1.12g) and Ce(NO3)4 (0.93g) solution, stirred thoroughly for 3 hours, and then potassium bicarbonate (0.1mol / L) was slowly added dropwise until the solution pH=7. After centrifugation, washing and drying, the solution was placed in a tube furnace and calcined at 350℃ for 0.40 hours under a nitrogen atmosphere to obtain catalyst C4.

[0075] 0.2 g of catalyst C4 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 230 °C for 3 h under normal pressure and pure H2 at a flow rate of 30 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) = 6:1, and the reaction was conducted at 6 MPa and 240 °C. The catalyst evaluation results are shown in Table 1.

[0076] Example 5

[0077] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.46g) and (NH4)6Mo7O. 24 The solution (0.866 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 700 °C for 4 hours under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.9 Mo2C carrier;

[0078] The obtained C@Cu 0.9 Mo2C support was passivated in 1% O2 / N2 at 25°C for 3 hours;

[0079] 5 g of the passivated support was weighed and fully dispersed in 200 ml of Cu(NO3)2 (0.67 g) and Zr(NO3)4 (0.82 g) solution. The mixture was stirred thoroughly for 3 hours, and then sodium hydroxide (0.1 mol / L) was slowly added dropwise until the pH of the solution reached 7. After centrifugation, washing, and drying, the solution was placed in a tube furnace and calcined at 300 °C for 0.66 hours under a nitrogen atmosphere to obtain catalyst C5.

[0080] 0.2 g of catalyst C5 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 240 °C for 2 h under normal pressure and pure H2 at a flow rate of 30 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) = 8:1, and the reaction was conducted at 5 MPa and 270 °C. The catalyst evaluation results are shown in Table 1.

[0081] Example 6

[0082] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.0092g) and (NH4)6Mo7O. 24 The solution (0.866 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 600 °C for 5 hours under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.015 Mo2C carrier;

[0083] The obtained C@Cu 0.015 Mo2C support was passivated in 1% O2 / N2 at 30°C for 1 hour;

[0084] Weigh 5g of the passivated support and disperse it fully in 200ml of Zr(NO3)4 (0.5g) solution. Stir well for 3 hours, then slowly add potassium carbonate (0.1mol / L) until the solution pH = 7. After centrifugation, washing and drying, place it in a tube furnace and calcine at 400℃ for 0.50 hours under nitrogen atmosphere to obtain catalyst C6.

[0085] 0.2 g of catalyst C6 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 220 °C for 4 h in pure H2 at atmospheric pressure and a flow rate of 20 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) of 1:1, and the reaction was conducted at 8 MPa and 180 °C. The catalyst evaluation results are shown in Table 1.

[0086] Comparative Example 1

[0087] Weigh 10g of activated carbon and disperse it thoroughly in 200ml of Cu(NO3)2 (0.0092g) and (NH4)6Mo7O. 24 The solution (0.866 g) was stirred thoroughly for 3 hours, and then the precursor was obtained by freeze-drying. The precursor was placed in a tube furnace and held at 600 °C for 5 hours under a hydrogen atmosphere. After cooling, C@Cu was obtained. 0.014 Mo2C carrier;

[0088] The obtained C@Cu 0.014 The Mo2C support was passivated in 1% O2 / N2 at 30°C for 1 h to obtain catalyst D1.

[0089] 0.2 g of catalyst D1 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 220 °C for 4 h in pure H2 at atmospheric pressure and a flow rate of 20 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) of 1:1, and the reaction was conducted at 8 MPa and 180 °C. The catalyst evaluation results are shown in Table 1.

[0090] Comparative Example 2

[0091] Weigh out 0.21 g of Cu(NO3)2, 0.13 g of Zr(NO3)4, and 0.16 g of In(NO3)3 and disperse them thoroughly in 200 ml of solution. Stir thoroughly for 3 hours, then slowly add potassium carbonate (0.1 mol / L) dropwise until the solution pH = 7. After centrifugation, washing, and drying, place the solution in a tube furnace and calcine at 400 °C for 0.50 hours under a nitrogen atmosphere to obtain catalyst D2.

[0092] 0.2 g of catalyst D2 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 220 °C for 4 h in pure H2 at atmospheric pressure and a flow rate of 20 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) of 1:1, and the reaction was conducted at 8 MPa and 180 °C. The catalyst evaluation results are shown in Table 1.

[0093] Comparative Example 3

[0094] Weigh 5g of alumina support and disperse it thoroughly in 200ml of Cu(NO3)2 (0.21g), Zr(NO3)4 (0.13g) and In(NO3)3 (0.16g) solution. Stir thoroughly for 3 hours, then slowly add potassium carbonate (0.1mol / L) dropwise until the solution pH = 7. After centrifugation, washing and drying, place it in a tube furnace and calcine at 400℃ for 0.50 hours under nitrogen atmosphere to obtain catalyst D3.

[0095] 0.2 g of catalyst D3 (20-40 mesh) was weighed and placed into a reaction tube with an inner diameter of 8 mm. Reduction was carried out at 220 °C for 4 h in pure H2 at atmospheric pressure and a flow rate of 20 mL / min. Afterwards, the feed gas was switched to a ratio of n(H2):n(CO2) of 1:1, and the reaction was conducted at 8 MPa and 180 °C. The catalyst evaluation results are shown in Table 1.

[0096] Table 1 Catalyst Evaluation Results

[0097]

[0098] As shown in Table 1, the catalysts prepared in Examples 1-6 of this invention exhibit high methanol selectivity (above 90%, even reaching 97.56%) and high CO2 conversion rate (above 17% single-pass conversion rate). The catalysts prepared in Examples 1-5, containing two active components, achieve a single-pass carbon dioxide conversion rate above 19%. Compared to the catalysts prepared in Comparative Examples 1-3, the catalysts prepared in these examples demonstrate significantly better catalytic performance.

[0099] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, The catalyst comprises a support and an active component supported on the support, wherein the support is C@Cu. x Mo2C, x=0.01-1, wherein the active component is selected from one or more of Cu, Zn, Al, Zr, In, Ce and Ga; The Mo content is 0.7-5 wt% based on the total weight of the carrier. The content of the support is 50-96.5 wt% and the content of the active component is 3.5-50 wt% based on the total weight of the catalyst.

2. The catalyst according to claim 1, wherein, Based on the total weight of the catalyst, the content of the support is 60-95 wt%, and the content of the active component is 5-40 wt%.

3. The catalyst according to claim 1 or 2, wherein, The carrier C@Cu x The specific surface area of ​​Mo2C is 100-1500 m². 2 / g.

4. The catalyst according to claim 3, wherein, The carrier C@Cu x The specific surface area of ​​Mo2C is 500-1000 m². 2 / g.

5. A method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, The preparation method includes the following steps: Activated carbon was dispersed in a solution containing Cu and Mo sources, stirred, and freeze-dried to obtain a precursor. Under a hydrogen atmosphere, the precursor was kept at 600-800°C for 1-5 hours, and after cooling, the support C@Cu was obtained. x Mo2C, where x = 0.01 - 1; The support is passivated, then dispersed in a metal salt solution, and a precipitant is added to precipitate the material to obtain a precipitate. The precipitate is then calcined and reduced to obtain a catalyst. The molar ratio of Cu source, Mo source and activated carbon is 0.2-2.5:0.1-1.2:6.5-9.7; The metal salt in the metal salt solution is selected from a soluble salt of at least one metal selected from Cu, Zn, Al, Zr, In, Ce and Ga; The passivation treatment is performed at a temperature of 20-30℃ for 1-3 hours. The calcination is carried out under a nitrogen atmosphere at a temperature of 300-500℃ for a time of 0.33-0.66h. The reduction is carried out in an H2 atmosphere at a temperature of 200-250°C for 2-5 hours.

6. The preparation method according to claim 5, wherein, The activated carbon has an average particle size of 500 nm-10 μm and a specific surface area of ​​200-1800 m². 2 / g, pore volume is 0.2-0.7cm³ 3 / g; And / or, the activated carbon is selected from one or more of wood-based activated carbon, fruit shell activated carbon, coal-based activated carbon, recycled carbon and petroleum-based activated carbon; And / or, the Cu source is selected from one or more of copper nitrate, copper sulfate, copper chloride, and copper oxide; And / or, the Mo source is selected from one or more of ammonium heptamolybdate, molybdenum chloride, and sodium molybdate; And / or, the mass ratio of the carrier to the metal salt in the metal salt solution is 0.5-5:1; And / or, the precipitant is one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, and potassium hydroxide.

7. The preparation method according to claim 6, wherein, The concentration of the precipitant is 0.05-0.5 mol / L, and the pH of the precipitate is 6.5-7.

5.

8. The preparation method according to claim 5 or 6, wherein, The passivation gas is a mixture of oxygen and inert gas, wherein the volume content of oxygen in the mixture is 0.05-1%.

9. A method for producing methanol by hydrogenation of carbon oxide, characterized in that, The method comprises reacting carbon dioxide with hydrogen in the presence of a catalyst according to any one of claims 1-4 or a catalyst prepared by any one of claims 5-8.

10. The method according to claim 9, wherein, The volume ratio of carbon dioxide to hydrogen is 1:1 to 1:10, and the space velocity is 2000-20000 h⁻¹. -1 ; And / or, the reaction is carried out at a temperature of 180-280°C and a pressure of 3-8 MPa.

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