A copper-based catalyst for carbon dioxide hydrogenation to synthesize methanol and a preparation method thereof

Abstract

A copper-based catalyst for the hydrogenation of carbon dioxide to methanol and its preparation method are disclosed, relating to the field of catalyst technology. The method includes: providing a support mixture solution comprising soluble iron and aluminum salts; providing a precipitant solution comprising sodium carbonate and sodium hydroxide; providing an active metal mixture solution comprising soluble copper, soluble zinc, and soluble metal auxiliary salts; mixing the support mixture solution and the precipitant solution to obtain a precipitate slurry; aging the precipitate slurry, followed by washing, drying, and calcination to obtain a support; mixing the support with the active metal mixture solution, and then drying and calcining the mixture. This catalyst can improve the activation capacity of CO2 and inhibit the sintering deactivation of Cu.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a copper-based catalyst for the synthesis of methanol from carbon dioxide and its preparation method. Background Technology

[0002] Carbon dioxide is not only a major greenhouse gas contributing to global warming, but it is also a cheap, clean, and abundant natural resource. To fully utilize this resource and promote the development of the chemical industry and a sustainable energy economy, biomass methanol technology utilizes renewable biomass resources to produce green methanol from syngas obtained through biomass gasification. It boasts advantages such as low carbon emissions throughout its entire lifecycle, relatively low production costs, and ease of obtaining EU green methanol certification, attracting widespread attention from the industry.

[0003] Highly efficient catalysts are crucial for the CO2 hydrogenation to methanol synthesis technology. Currently, the most widely used industrial methanol synthesis catalysts are Cu-Zn-Al systems. However, in the CO2 hydrogenation to methanol reaction, CO2 is stable and difficult to activate, resulting in low CO2 conversion rates with traditional catalysts. Furthermore, the H2O produced during the reaction can degrade the active component Cu in the catalyst. 0 The sintering deactivation of the catalyst is a concern. Therefore, how to improve the CO2 activation ability of the catalyst while suppressing the active component Cu is crucial. 0 The study of sintering deactivation is crucial for Cu-based catalysts. Summary of the Invention

[0004] This invention provides a copper-based catalyst for the synthesis of methanol from carbon dioxide and its preparation method. The catalyst can improve the activation ability of CO2 and inhibit the sintering deactivation of Cu.

[0005] This invention provides a method for preparing a copper-based catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising:

[0006] A carrier mixture solution is provided, comprising soluble iron salts and aluminum salts;

[0007] A precipitant solution is provided, which includes sodium carbonate and sodium hydroxide;

[0008] An active metal mixture solution is provided, comprising a soluble copper salt, a soluble zinc salt, and a soluble metal additive salt;

[0009] The carrier mixture solution is mixed with the precipitant solution to obtain a precipitated slurry;

[0010] The precipitated slurry is aged, then washed, dried and calcined in sequence to obtain the carrier;

[0011] The carrier is mixed with the active metal mixed solution, and the mixture is then dried and calcined.

[0012] The molar ratio of Cu, Zn, Fe, Al and metal additives is 20-50%: 10-30%: 10-25%: 10-25%: 0-10%.

[0013] Furthermore, the concentration of the carrier mixture solution is 0.1-2 mol / L.

[0014] Furthermore, the concentration of the precipitant solution is 0.1-2 mol / L.

[0015] Furthermore, the concentration of the active metal mixed solution is 0.1-2 mol / L.

[0016] Furthermore, in the carrier mixture solution, the molar ratio of Fe to Al is 0.4-2.5:1.

[0017] Furthermore, in the active metal mixed solution, the molar ratio of Cu to Zn is 0.66-5:1.

[0018] Furthermore, the molar ratio of sodium carbonate to sodium hydroxide is 1-3:1.

[0019] Furthermore, the metal additive includes one or more of Zr, Mg, La, Ce, Mn, and Ti.

[0020] Furthermore, when mixing the carrier mixture solution with the precipitant solution, the method includes:

[0021] Establish a liquid level in the reactor and control the temperature within the set temperature range;

[0022] Under continuous stirring, the carrier mixture and the precipitant solution are simultaneously added dropwise into the reaction vessel;

[0023] The pH of the system is maintained at a set value by adjusting the dropping rate of the precipitant solution.

[0024] Furthermore, when mixing the support with the active metal mixed solution, the method includes:

[0025] The carrier is ground into powder.

[0026] At a set temperature, the active metal mixture solution and the carrier are mixed and stirred.

[0027] The present invention also provides a copper-based catalyst for the synthesis of methanol from carbon dioxide hydrogenation. The copper-based catalyst for the synthesis of methanol from carbon dioxide hydrogenation is prepared by the above-described method for preparing a copper-based catalyst for the synthesis of methanol from carbon dioxide hydrogenation. The catalyst includes a support and a loading. The support is Fe2O3 / Al2O3 with a porous structure, and the loading is CuO, ZnO, and a metal additive. The mass ratio of Cu, Zn, Fe, Al, and the metal additive is 20-50%:10-30%:10-25%:10-25%:0%-10%, wherein the metal additive is one or more of Mg, La, Ce, Mn, and Ti.

[0028] In summary, in this invention, a mixed support is first obtained by co-precipitation of a mixed solution of Fe and Al nitrates; then, active metals Cu and Zn, along with additives, are loaded onto the support via impregnation. This effectively forms a porous structure on the support and efficiently introduces the loading into it. By mixing and calcining a first mixed metal solution containing iron and aluminum with a precipitant solution containing sodium carbonate and sodium hydroxide, Fe2O3 can be introduced into the support. The resulting Al2O3 / Fe2O3 composite support improves the pore structure of the catalyst, increasing its specific surface area and expanding its pore size. This allows the catalyst to improve the dispersion of the active metals while accelerating the escape of water vapor and inhibiting Cu oxidation. 0 The sintering process increases the stability of the catalyst. Furthermore, during the reduction process, the reduction of Fe₂O₃ generates a large number of oxygen vacancies on the catalyst surface. These oxygen vacancies are beneficial for CO₂ adsorption and activation, thus improving the catalyst's CO₂ activation capacity. Moreover, a dynamic interaction exists between Cu and Fe₂O₃; Cu particles promote the reduction of Fe₂O₃ to Fe. 2+ The Fe formed 2+ The substance, in turn, promotes the reaction of H2 in Cu 0 Surface activation, and the activation and dissociation of H2 are the rate-determining steps in the synthesis of methanol from CO2, thus greatly improving the reaction efficiency of the catalyst and achieving a highly efficient methanol synthesis reaction.

[0029] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0030] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the present invention will be described in detail below with reference to preferred embodiments.

[0031] This invention provides a copper-based catalyst for the synthesis of methanol from carbon dioxide and its preparation method. The catalyst can improve the activation ability of CO2 and inhibit the sintering deactivation of Cu.

[0032] The method for preparing a copper-based catalyst for the hydrogenation of carbon dioxide to methanol provided by this invention includes the following steps:

[0033] A carrier mixture solution is provided, which includes soluble iron salts and aluminum salts.

[0034] In this embodiment, the soluble iron and aluminum salts in the carrier mixture solution can be ferric nitrate and aluminum nitrate. The concentration of the carrier mixture solution can be 0.1-2 mol / L (i.e., the total concentration of iron and aluminum salts in the solution), and more specifically, it can be 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 1.0 mol / L, 1.2 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, etc.

[0035] The molar ratio of Fe to Al is 0.4-2.5:1. Further, it can be 0.5:1, 0.8:1, 1:1, 1.5:1, 2:1, 2.2:1, etc.

[0036] The above solution can be obtained by dissolving soluble iron and aluminum salts in deionized water.

[0037] A precipitant solution is provided, which may be a mixed solution of sodium carbonate and sodium hydroxide.

[0038] In this embodiment, the concentration of the precipitant solution is 0.1-2 mol / L (i.e., the total concentration of sodium carbonate and sodium hydroxide). Further, it can be: 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 1.0 mol / L, 1.2 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, etc.

[0039] The molar ratio of sodium carbonate to sodium hydroxide can be 1-3:1.

[0040] The above-mentioned precipitant solution can be obtained by dissolving sodium carbonate and sodium hydroxide in deionized water.

[0041] An active metal mixture solution is provided, which may include soluble copper salt, soluble zinc salt and soluble metal auxiliary salt.

[0042] In this embodiment, the soluble copper salt and soluble zinc salt can be copper nitrate and zinc nitrate. The concentration of the active metal mixed solution can be 0.1-2 mol / L (that is, the total concentration of copper salt, zinc salt and auxiliary metal salt in the solution), and more specifically, it can be 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 1.0 mol / L, 1.2 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, etc.

[0043] Furthermore, in the active metal mixed solution, the molar ratio of Cu to Zn is 0.66-5:1. Further, it can be 0.7:1, 0.8:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, etc.

[0044] The carrier mixture solution is mixed with the precipitant solution to form a precipitate slurry.

[0045] In this step, a certain liquid level can be established in the reactor first, and the temperature can be controlled within the range of 20-90℃. Under continuous stirring, the carrier mixture solution and the precipitant solution are simultaneously added dropwise to the reactor. By adjusting the dropping rate of the precipitant solution, the pH of the system is adjusted to 6-9 to form a precipitate slurry.

[0046] The precipitated slurry is aged, then washed, dried and calcined in sequence to obtain the carrier.

[0047] In this embodiment, the aging temperature can be 1-6 hours to allow the mixture of carrier solution and precipitant to fully precipitate. During drying, the drying temperature is 50-120°C, and during calcination, the calcination temperature is 350-550°C, and the calcination time is 2-6 hours.

[0048] The support was mixed with an active metal mixed solution, and then the mixture was dried and calcined to obtain a copper-based catalyst for the synthesis of methanol by hydrogenation of carbon dioxide.

[0049] In this embodiment, the carrier can be ground thoroughly to form a powder, and then the active metal mixed solution and the carrier can be mixed and stirred at a temperature of 20-80°C to ensure thorough mixing.

[0050] After mixing, the mixture is dried at a temperature of 50-120°C and then calcined at a temperature of 350-550°C.

[0051] Furthermore, in the obtained catalyst, the molar ratio of Cu, Zn, Fe, Al and metal promoter is 20-50%:10-30%:10-25%:10-25%:0%-10%; the metal promoter includes one or more of Zr, Mg, La, Ce, Mn and Ti.

[0052] In this embodiment, a mixed support is first obtained by co-precipitation of a mixed solution of Fe and Al nitrates; then, active metals Cu and Zn, along with additives, are loaded onto the support by impregnation. This effectively forms a porous structure on the support and efficiently introduces the loading into it. After mixing and calcining a first mixed metal solution containing iron and aluminum with a precipitant solution containing sodium carbonate and sodium hydroxide, Fe2O3 is introduced into the support. The resulting Al2O3 / Fe2O3 composite support improves the pore structure of the catalyst, increasing its specific surface area and expanding its pore size. This allows the catalyst to improve the dispersion of the active metals while accelerating the escape of water vapor and inhibiting Cu oxidation. 0 The sintering process increases the stability of the catalyst. Furthermore, during the reduction process, the reduction of Fe₂O₃ generates a large number of oxygen vacancies on the catalyst surface. These oxygen vacancies are beneficial for CO₂ adsorption and activation, thus improving the catalyst's CO₂ activation capacity. Moreover, a dynamic interaction exists between Cu and Fe₂O₃; Cu particles promote the reduction of Fe₂O₃ to Fe. 2+ The Fe formed 2+ The substance, in turn, promotes the reaction of H2 in Cu 0 Surface activation, and the activation and dissociation of H2 are the rate-determining steps in the synthesis of methanol from CO2, thus greatly improving the reaction efficiency of the catalyst and achieving a highly efficient methanol synthesis reaction.

[0053] The preparation method described above will be further explained below with specific implementation methods.

[0054] Example 1 (Cu:Zn:Fe:Al molar ratio = 50:15:10:25)

[0055] 1) Dissolve 4.84g of ferric nitrate nonahydrate and 11.25g of aluminum nitrate nonahydrate in deionized water to prepare a carrier mixed solution with a concentration of 0.5mol / L. Dissolve 12.24g of sodium carbonate and 2.4g of sodium hydroxide in deionized water to prepare a precipitant solution with a concentration of 0.5mol / L.

[0056] 14.46g of copper nitrate trihydrate and 5.34g of zinc nitrate hexahydrate were dissolved in deionized water to prepare an active metal mixed solution with a concentration of 0.5mol / L.

[0057] 2) Establish a certain liquid level in the reactor, control the precipitation temperature at 70℃, and use a peristaltic pump to simultaneously add the carrier mixture solution and the precipitant solution to the reactor under continuous stirring. Adjust the dropping rate of the precipitant to make the pH of the system 7, and form a precipitate slurry.

[0058] 3) After the metal solution on the carrier has precipitated completely, it is aged at 70°C for 2 hours. Then, the slurry is filtered and washed, and dried at 100°C for 12 hours. After the sample is dried, it is calcined in a muffle furnace at 500°C for 2 hours to obtain the mixed carrier Fe2O3 / Al2O3.

[0059] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 hours. After stirring, it was placed in a 100℃ oven to dry for 8 hours, and then calcined in a muffle furnace at 350℃ for 4 hours to obtain the desired catalyst.

[0060] Example 2 (Cu:Zn:Fe:Al:Mg molar ratio = 50:15:10:15:10)

[0061] 1) Dissolve 4.84g of ferric nitrate nonahydrate and 6.75g of aluminum nitrate nonahydrate in deionized water to prepare a carrier mixed solution with a concentration of 0.5mol / L. Dissolve 12.24g of sodium carbonate and 2.4g of sodium hydroxide in deionized water to prepare a precipitant solution with a concentration of 0.5mol / L.

[0062] 14.46g of copper nitrate trihydrate, 5.34g of zinc nitrate hexahydrate and 3.07g of magnesium nitrate hexahydrate were dissolved in deionized water to prepare an active metal mixed solution with a concentration of 0.5mol / L.

[0063] 2) Establish a certain liquid level in the reactor, control the precipitation temperature at 70℃, and use a peristaltic pump to simultaneously add the carrier mixture solution and the precipitant solution to the reactor under continuous stirring. Adjust the dropping rate of the precipitant to make the pH of the system 7, and form a precipitate slurry.

[0064] 3) After the metal solution on the carrier has precipitated completely, it is aged at 70°C for 2 hours. Then, the slurry is filtered and washed, and dried at 100°C for 12 hours. After the sample is dried, it is calcined in a muffle furnace at 500°C for 2 hours to obtain the mixed carrier Fe2O3 / Al2O3.

[0065] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 hours. After stirring, it was placed in a 100℃ oven to dry for 8 hours, and then calcined in a muffle furnace at 350℃ for 4 hours to obtain the desired catalyst.

[0066] Example 3 (Cu:Zn:Fe:Al:Ce molar ratio = 45:15:10:20:10)

[0067] 1) Dissolve 9.69g of ferric nitrate nonahydrate and 18g of aluminum nitrate nonahydrate together in deionized water to prepare a carrier mixed solution with a concentration of 1mol / L. Dissolve 24.48g of sodium carbonate and 4.8g of sodium hydroxide together in deionized water to prepare a precipitant solution with a concentration of 1mol / L.

[0068] 25.97g of copper nitrate trihydrate, 10.68g of zinc nitrate hexahydrate and 10.4g of cerium nitrate hexahydrate were dissolved in deionized water to prepare an active metal mixed solution with a concentration of 1mol / L.

[0069] 2) Establish a certain liquid level in the reactor, control the precipitation temperature at 80℃, and use a peristaltic pump to simultaneously add the carrier mixture solution and the first precipitant solution to the reactor under continuous stirring. Adjust the dropping rate of the precipitant to make the pH of the system 7.5 to form a precipitate slurry.

[0070] 3) After the metal solution on the support has precipitated completely, the sample is aged at 70°C for 2 hours. The slurry is then filtered, washed, and dried at 70°C for 12 hours. After drying, the sample is calcined in a muffle furnace at 500°C for 2 hours to obtain the mixed support Fe2O3 / Al2O3.

[0071] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 hours. After stirring, it was placed in an 80°C oven to dry for 8 hours, and then calcined in a muffle furnace at 350°C for 4 hours to prepare the desired catalyst.

[0072] Example 4 (Cu:Zn:Fe:Al:Mg:Ce molar ratio = 45:15:10:20:5:5)

[0073] 1) Dissolve 9.69g of ferric nitrate nonahydrate and 18g of aluminum nitrate nonahydrate in deionized water to prepare a carrier mixed solution with a concentration of 1mol / L. Dissolve 24.48g of sodium carbonate and 4.8g of sodium hydroxide in deionized water to prepare a precipitant solution with a concentration of 1mol / L.

[0074] 25.97g of copper nitrate trihydrate, 10.68g of zinc nitrate hexahydrate, 4.1g of magnesium nitrate hexahydrate and 5.2g of cerium nitrate hexahydrate were dissolved in deionized water to prepare an active metal mixed solution with a concentration of 1mol / L.

[0075] 2) Establish a certain liquid level in the reactor, control the precipitation temperature at 80℃, and use a peristaltic pump to simultaneously add the carrier mixture solution and the first precipitant solution to the reactor under continuous stirring. Adjust the dropping rate of the precipitant to make the pH of the system 7.5 to form a precipitate slurry.

[0076] 3) After the metal solution on the support has precipitated completely, the sample is aged at 70°C for 2 hours. The slurry is then filtered, washed, and dried at 70°C for 12 hours. After drying, the sample is calcined in a muffle furnace at 500°C for 2 hours to obtain the mixed support Fe2O3 / Al2O3.

[0077] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 hours. After stirring, it was placed in a 60°C oven to dry for 8 hours, and then calcined in a muffle furnace at 350°C for 4 hours to obtain the desired catalyst.

[0078] Example 5 (Cu:Zn:Fe:Al:La molar ratio = 45:20:15:10:10)

[0079] 1) Dissolve 29.07g of ferric nitrate nonahydrate and 18g of aluminum nitrate nonahydrate in deionized water to prepare a carrier mixed solution with a concentration of 1.5mol / L. Dissolve 48.96g of sodium carbonate and 9.6g of sodium hydroxide in deionized water to prepare a precipitant solution with a concentration of 1.5mol / L.

[0080] 52.05g of copper nitrate trihydrate, 28.5g of zinc nitrate hexahydrate and 20.78g of lanthanum nitrate hexahydrate were dissolved in deionized water to prepare an active metal mixed solution with a concentration of 1.5mol / L.

[0081] 2) Establish a certain liquid level in the reactor and control the precipitation temperature at 80℃. Under continuous stirring, use a peristaltic pump to simultaneously add the carrier mixture solution and the first precipitant solution to the reactor. Adjust the dropping rate of the precipitant to make the pH of the system equal to 8, and form a precipitate slurry.

[0082] 3) After the metal solution on the support has precipitated completely, the sample is aged at 80℃ for 2 hours. The slurry is then filtered, washed, and dried at 80℃ for 12 hours. After drying, the sample is calcined in a muffle furnace at 500℃ for 2 hours to obtain the mixed support Fe2O3 / Al2O3.

[0083] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 hours. After stirring, it was placed in an 80°C oven to dry for 8 hours, and then calcined in a muffle furnace at 350°C for 4 hours to prepare the desired catalyst.

[0084] Example 6 (Cu:Zn:Fe:Al:Mg:La:Ce molar ratio = 50:10:15:10:5:5:5)

[0085] 1) Dissolve 19.38g of ferric nitrate nonahydrate and 18g of aluminum nitrate nonahydrate in deionized water to prepare a carrier mixed solution with a concentration of 1.5mol / L. Dissolve 48.96g of sodium carbonate and 9.6g of sodium hydroxide in deionized water to prepare a precipitant solution with a concentration of 1.5mol / L.

[0086] 57.83g of copper nitrate trihydrate, 14.3g of zinc nitrate hexahydrate, 6.15g of magnesium nitrate hexahydrate, 10.39g of lanthanum nitrate hexahydrate and 7.8g of cerium nitrate hexahydrate were dissolved in deionized water to prepare an active metal mixed solution with a concentration of 1.5mol / L.

[0087] 2) Establish a certain liquid level in the reactor, control the precipitation temperature at 70℃, and use a peristaltic pump to simultaneously add the carrier mixture solution and the first precipitant solution to the reactor under continuous stirring. Adjust the dropping rate of the precipitant to make the pH of the system 7.5 to form a precipitate slurry.

[0088] 3) After the metal solution on the support has precipitated completely, the sample is aged at 70°C for 2 hours. The slurry is then filtered, washed, and dried at 70°C for 12 hours. After drying, the sample is calcined in a muffle furnace at 500°C for 2 hours to obtain the mixed support Fe2O3 / Al2O3.

[0089] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 h. After stirring, it was placed in a 70 ℃ oven to dry for 8 h, and then calcined in a muffle furnace at 350 ℃ for 4 h to prepare the desired catalyst.

[0090] Comparative Example 1 (Cu:Zn:Al molar ratio = 50:15:35)

[0091] 1) Dissolve 23.62g of aluminum nitrate nonahydrate in deionized water to prepare a carrier mixed solution with a concentration of 0.5mol / L. Dissolve 12.24g of sodium carbonate and 2.4g of sodium hydroxide together in deionized water to prepare a precipitant solution with a concentration of 0.5mol / L.

[0092] Dissolve 14.46g of copper nitrate trihydrate and 5.34g of zinc nitrate hexahydrate in deionized water to prepare an active metal mixed solution with a concentration of 0.5mol / L;

[0093] 2) Establish a certain liquid level in the reactor, control the precipitation temperature at 70℃, and use a peristaltic pump to simultaneously add the carrier mixture solution and the precipitant solution to the reactor under continuous stirring. Adjust the dropping rate of the precipitant to make the pH of the system 7, and form a precipitate slurry.

[0094] 3) After the metal solution on the carrier has precipitated completely, it is aged at 70°C for 2 hours. Then, the slurry is filtered and washed, and dried at 100°C for 12 hours. After the sample is dried, it is calcined in a muffle furnace at 500°C for 2 hours to obtain the mixed carrier.

[0095] 4) The prepared support Fe2O3 / Al2O3 was thoroughly ground and then stirred together with the active metal mixed solution at room temperature for 12 hours. After stirring, it was placed in a 100℃ oven to dry for 8 hours, and then calcined in a muffle furnace at 350℃ for 4 hours to obtain the desired catalyst.

[0096] Comparative Example 2 (Cu:Zn:Fe:Al molar ratio = 50:15:10:25)

[0097] 1) Dissolve 4.84g of ferric nitrate nonahydrate and 11.25g of aluminum nitrate nonahydrate together in deionized water to prepare a carrier metal solution with a concentration of 0.5mol / L. Dissolve 12.24g of sodium carbonate and 2.4g of sodium hydroxide together in deionized water to prepare a precipitant solution with a concentration of 0.5mol / L.

[0098] Dissolve 14.46g of copper nitrate trihydrate and 5.34g of zinc nitrate hexahydrate in deionized water to prepare an active metal mixed solution with a concentration of 0.5mol / L;

[0099] 2) Establish a certain liquid level in the reactor and control the precipitation temperature at 70℃. Under continuous stirring, use a metering pump to simultaneously add the carrier mixture solution and a portion of the precipitant solution to the reactor. Adjust the dropping rate of the precipitant to make the pH of the system 7, and form a precipitate slurry.

[0100] 3) After the carrier metal solution has precipitated completely, age it at 70°C for 2 hours. After stirring the slurry evenly, add the active metal mixed solution and another part of the precipitant solution to the carrier precipitation slurry in a co-current dripping manner using a peristaltic pump at 70°C. Control the dripping rate of the precipitant to maintain the pH of the system at around 7.

[0101] 4) After the second active metal mixed solution has been added dropwise, stop adding the precipitant solution, stop stirring, and maintain aging at the precipitation temperature for 4 hours. Then, filter and wash the aged catalyst precursor slurry, and dry it at 100°C for 8 hours. After the sample is dried, calcine it in a muffle furnace at 350°C for 4 hours to finally obtain reference catalyst 2.

[0102] Table 1. Performance of catalysts for carbon dioxide hydrogenation to methanol under different preparation process conditions

[0103] Reaction conditions: 230 ℃, GHSV = 10000 ml.gcat -1 . h -1 5MPa, H2:CO2:N2=23:69:8

[0104]

[0105] As can be seen from the table above, compared with reference catalysts 1-2, catalysts 1-6 show significant improvements in carbon dioxide conversion rate, methanol selectivity, and methanol space-time yield. However, their decay rate after 50 hours of reaction is noticeably reduced.

[0106] This invention also provides a copper-based catalyst for the hydrogenation of carbon dioxide to methanol, prepared according to the above-described method for preparing a copper-based catalyst for the hydrogenation of carbon dioxide to methanol. The catalyst comprises a support and a loading. The support is Fe₂O₃ / Al₂O₃ with a porous structure, and the loading consists of CuO, ZnO, and a metal additive. The mass ratio of Cu, Zn, Fe, Al, and the metal additive is 20-50%:10-30%:10-25%:10-25%:0%-10%. The metal additive is one or more of Mg, La, Ce, Mn, and Ti.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a copper-based catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that: The method includes: A carrier mixture solution is provided, which is a soluble iron salt and aluminum salt; A precipitant solution is provided, which includes sodium carbonate and sodium hydroxide; An active metal mixture solution is provided, comprising a soluble copper salt, a soluble zinc salt, and a soluble metal additive salt; The carrier mixture solution is mixed with the precipitant solution to obtain a precipitated slurry; The precipitated slurry is aged, then washed, dried and calcined in sequence to obtain a carrier; The carrier is mixed with the active metal mixed solution to obtain a mixture, and the mixture is then dried and calcined. The molar ratio of Cu, Zn, Fe, Al and metal additives is 20-50%: 10-30%: 10-25%: 10-25%: 0-10%.

2. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: It includes at least one of the following: the concentration of the carrier mixed solution is 0.1-2 mol / L, the concentration of the precipitant solution is 0.1-2 mol / L, and the concentration of the active metal mixed solution is 0.1-2 mol / L.

3. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: In the carrier mixture solution, the molar ratio of Fe to Al is 0.4-2.5:

1.

4. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: In the active metal mixed solution, the molar ratio of Cu to Zn is 0.66-5:

1.

5. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: The molar ratio of sodium carbonate to sodium hydroxide is 1-3:

1.

6. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: The metal additives include one or more of Zr, Mg, La, Ce, Mn, and Ti.

7. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: The method includes the following steps when mixing the carrier mixture with the precipitant solution: Establish a liquid level in the reactor and control the temperature within the set temperature range; Under continuous stirring, the carrier mixture and the precipitant solution are simultaneously added dropwise into the reaction vessel; The pH of the system is maintained at a set value by adjusting the dropping rate of the precipitant solution.

8. The method for preparing the copper-based catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: The method includes the following steps when mixing the carrier with the active metal mixed solution: The carrier is ground into powder. At a set temperature, the active metal mixture solution and the carrier are mixed and stirred.

9. A copper-based catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that: The copper-based catalyst for the synthesis of methanol by hydrogenation of carbon dioxide is prepared by the method for preparing the copper-based catalyst for the synthesis of methanol by hydrogenation of carbon dioxide according to any one of claims 1 to 8. The catalyst includes a support and a loading, wherein the support is Fe2O3 / Al2O3 with a porous structure, and the loading is CuO, ZnO and a metal additive. The mass ratio of Cu, Zn, Fe, Al and the metal additive is 20-50%:10-30%:10-25%:10-25%:0%-10% by mass, wherein the metal additive is one or more of Mg, La, Ce, Mn and Ti.

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