Catalyst for methanol production by carbon dioxide hydrogenation and preparation method thereof

Abstract

The application discloses a catalyst for methanol synthesis by carbon dioxide hydrogenation and a preparation method thereof. The preparation method of the catalyst for methanol synthesis by carbon dioxide hydrogenation comprises the following steps: co-precipitating a copper metal salt, a zinc metal salt, an aluminum metal salt, a first additive and a precipitant, aging, washing and drying a co-precipitation product to obtain a catalyst precursor; introducing a second additive into the catalyst precursor, and calcining a product after the second additive is introduced to obtain the catalyst for methanol synthesis by carbon dioxide hydrogenation. The application solves the technical problem of low carbon dioxide hydrogenation activity, methanol selectivity and stability of the catalyst for methanol synthesis by carbon dioxide hydrogenation in the prior art.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and in particular to a catalyst for the hydrogenation of carbon dioxide to methanol and a method for preparing the same. Background Technology

[0002] Methanol, as an important basic chemical raw material, can be used to synthesize various chemicals such as dimethyl ether, light olefins, aromatics, and acetic acid, and can also serve as an alternative fuel. The increase in atmospheric carbon dioxide concentration is a major cause of global climate change. With the rapid development of modern industry, global carbon dioxide emissions are gradually increasing, and environmental pollution and frequent extreme weather events have attracted great attention from countries around the world, making carbon dioxide emission reduction an urgent priority. Currently reported catalysts for the hydrogenation of carbon dioxide to methanol mainly include copper-based catalysts, oxide catalysts, noble metal catalysts, and novel catalysts represented by MoS2 (molybdenum sulfide). Among them, copper-based catalysts have achieved industrial application; however, the activity of copper-based catalysts in carbon dioxide hydrogenation still falls far short of the thermodynamic equilibrium conversion rate, and the selectivity and stability of methanol remain low. Summary of the Invention

[0003] The main objective of this application is to provide a catalyst for the hydrogenation of carbon dioxide to methanol and a method for preparing the same, aiming to solve the technical problems of low carbon dioxide hydrogenation activity, methanol selectivity and stability of existing catalysts for the hydrogenation of carbon dioxide to methanol.

[0004] To achieve the above objectives, this application also provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, the method comprising the following steps:

[0005] Co-precipitation is performed using copper salt, zinc salt, aluminum salt, a first additive, and a precipitant. The co-precipitated product is then aged, washed, and dried to obtain the catalyst precursor.

[0006] A second additive is introduced onto the catalyst precursor, and the product after introducing the second additive is calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol.

[0007] Optionally, the first additive contains one or more of yttrium, molybdenum, niobium, gallium, indium, lanthanum, tungsten, magnesium, and cadmium.

[0008] Optionally, the second additive contains one or more of zirconium, gallium, indium, and lanthanum.

[0009] Optionally, the total amount of the first auxiliary agent and the second auxiliary agent in the catalyst accounts for 2% to 10% of the mass fraction.

[0010] The first auxiliary agent has a mass fraction of 1% to 6% in the catalyst;

[0011] The second auxiliary agent accounts for 1% to 6% of the mass fraction of the catalyst.

[0012] Optionally, the coprecipitation is either co-current coprecipitation or countercurrent coprecipitation.

[0013] Optionally, the pH of the co-precipitation is 6-11, the temperature is 40-90°C, and the aging time is 1-15 hours.

[0014] Optionally, the step of introducing a second promoter onto the catalyst precursor, and then calcining the product after introducing the second promoter to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes:

[0015] The second auxiliary agent is prepared into a second auxiliary agent solution, and the second auxiliary agent solution is added dropwise to the catalyst precursor for impregnation. The product after introducing the second auxiliary agent is dried and calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol.

[0016] Optionally, the step of introducing a second promoter onto the catalyst precursor, and then calcining the product after introducing the second promoter to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes:

[0017] The second auxiliary agent is prepared into a second auxiliary agent solution. The second auxiliary agent solution, the precipitant and the catalyst precursor are mixed. The product after introducing the second auxiliary agent is washed, dried and calcined to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0018] Optionally, the step of introducing a second promoter onto the catalyst precursor, and then calcining the product after introducing the second promoter to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes:

[0019] The second additive and the catalyst precursor are mixed and ball-milled. The product after introducing the second additive is calcined to obtain the catalyst.

[0020] Optionally, the roasting temperature is 300–500°C, and the roasting time is 2–6 hours.

[0021] Optionally, the precipitant is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, and potassium bicarbonate.

[0022] Optionally, the mass ratio of copper, zinc oxide, and aluminum oxide in the catalyst is (3-7):(1-4):(1-3).

[0023] This application also provides a catalyst for the hydrogenation of carbon dioxide to methanol, which is prepared by the method described above for preparing a catalyst for the hydrogenation of carbon dioxide to methanol.

[0024] This application provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol. The method involves co-precipitating a copper salt, a zinc salt, an aluminum salt, a first promoter, and a precipitant. The co-precipitated product is then aged, washed, and dried to obtain the catalyst precursor. This method improves copper dispersion and enhances the metal-oxide interfacial interaction, thus improving the catalyst's hydrogenation activity. Furthermore, the promoter introduced during co-precipitation promotes the formation of oxygen vacancies and Cu atoms. + The generation of cuprous ions helps stabilize formate and methoxy groups, inhibiting their decomposition to produce CO (carbon monoxide), which improves methanol selectivity. Furthermore, the addition of promoters inhibits the sintering of active centers and improves the catalyst's heat resistance. Then, by introducing a second promoter onto the catalyst precursor, the product after introducing the second promoter is calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol. This process achieves partial coverage of Cu sites, reducing the number of active sites in the reverse water-gas shift reaction and improving methanol selectivity. Additionally, the oxide covering the Cu sites forms a highly active oxide-Cu interface, which can improve the catalyst's hydrogenation activity to some extent. Furthermore, the introduced hydrophobic promoters improve the catalyst's hydrophobicity, inhibiting the sintering of active centers caused by water. Thus, by introducing promoters twice, the technical shortcomings of copper-based catalysts—such as a significant gap between their carbon dioxide hydrogenation activity and thermodynamic equilibrium conversion rate, and relatively low methanol selectivity and stability—are overcome, while simultaneously improving the hydrogenation activity, selectivity, and stability of the catalyst for the hydrogenation of carbon dioxide to methanol. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic flowchart of an embodiment of the method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol in this application.

[0028] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This application provides a method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, referring to... Figure 1 The method for preparing the catalyst for the hydrogenation of carbon dioxide to methanol, as described above, includes the following steps:

[0031] Step S10: Co-precipitate copper salt, zinc salt, aluminum salt, first additive and precipitant. The co-precipitated product is aged, washed and dried to obtain catalyst precursor.

[0032] In this embodiment, adjusting the formulation of the copper-based catalyst, such as by introducing additives, can effectively improve the dispersibility of copper, thereby enhancing catalyst performance. Currently, there are methods for preparing alloy catalysts by grinding and dispersing the main and auxiliary components of the catalyst. This method is simple to operate, but the metal-oxide interaction of the catalyst prepared by this method is weak, resulting in low carbon dioxide hydrogenation performance. Another method involves preparing a Cu-Zn-Zr (copper-zinc-zirconium) suspension via countercurrent coprecipitation, simultaneously adding metal additives and complexing agents to the suspension and stirring until it forms a gel. The product is then dried, calcined, and reduced to obtain the catalyst. This method produces catalysts with high selectivity but low carbon dioxide conversion. There are also methods for preparing catalysts via stepwise coprecipitation, which produces catalysts with high carbon dioxide conversion but low selectivity. In other words, existing technologies struggle to simultaneously improve the carbon dioxide hydrogenation activity, methanol selectivity, and stability of catalysts for the hydrogenation of carbon dioxide to methanol.

[0033] It should be noted that the catalyst for the hydrogenation of carbon dioxide to methanol prepared in this embodiment is a copper-based catalyst, which refers to a catalyst with copper as the active center. In copper-based catalysts, the catalyst support, which supports and disperses the active center, plays a crucial role. The support can act as a dispersant and stabilizer for the active components, providing support for the surface and pore structure of the active components while better dispersing and stabilizing them. ZnO (zinc oxide) can be used as a support for copper-based catalysts because it can increase the specific surface area of ​​the catalyst and prevent the sintering of copper grains on the catalyst surface. Al2O3 (alumina) not only plays a supporting role in the catalyst but also better disperses the active components, inhibits the reduction of copper oxide, and improves the catalytic activity of the catalyst; therefore, it can also be used as a support for copper-based catalysts. Additives refer to components that can modify and alter the active components and the support, thereby affecting their role in the catalyst and further influencing its catalytic activity. These include rare earth element additives, transition metal element additives, alkaline earth metal element additives, and / or non-metal element additives.

[0034] The copper salt refers to a salt whose cation is copper ion, and can be copper nitrate, copper sulfate, copper acetate, etc.; the zinc salt refers to a salt whose cation is zinc ion, and can be zinc nitrate, zinc sulfate, zinc acetate, etc.; the aluminum salt refers to a salt whose cation is aluminum ion, and can be aluminum nitrate, aluminum sulfate, aluminum acetate, etc.; the first auxiliary agent refers to an agent that can promote Cu + Metal elemental promoters, such as salts of yttrium (Y), molybdenum (Mo), niobium (Nb), gallium (Ga), indium (In), lanthanum (La), tungsten (W), magnesium (Mg), and cadmium (Cd), can enhance methanol selectivity. Furthermore, the first promoter can improve the dispersion of metal active sites, increase oxygen vacancies and metal-oxide interfacial interactions, which is beneficial for improving the hydrogenation activity of the catalyst. In addition, it can act as a spacer to isolate copper. Moreover, the promoter can enhance the interaction between copper and the support, which is beneficial for inhibiting copper sintering. The precipitant refers to a reagent that can separate the product of the mixture of copper salt, zinc salt, aluminum salt, and the first promoter from the solution in the form of a precipitate without introducing impurities, including carbonates and bicarbonates.

[0035] As an example, the amounts of copper salt, zinc salt, aluminum salt, first additive, and precipitant can be determined in advance based on literature, experimental results, etc. The copper salt, zinc salt, aluminum salt, first additive, and precipitant are weighed according to the predetermined amounts. The copper salt, zinc salt, aluminum salt, and first additive are prepared into a first mixed solution, and the precipitant is prepared into an aqueous precipitant solution. The first mixed solution and the aqueous precipitant solution are added to a mixer for co-precipitation. The co-precipitated product is aged, washed, and dried to obtain the catalyst precursor. The specific concentrations of the first mixed solution and the aqueous precipitant solution can be determined based on literature, experimental results, etc. The specific conditions for the coprecipitation, aging, washing, and drying steps can be determined based on literature, experimental results, etc., and this embodiment does not impose any limitations on these conditions. The coprecipitation can be a forward coprecipitation, reverse coprecipitation, co-current coprecipitation, countercurrent coprecipitation, homogeneous precipitation, etc. The specific conditions for the coprecipitation, aging, washing, and drying steps can be determined based on literature, experimental results, etc., and this embodiment does not impose any limitations on these conditions. The catalyst precursor can be represented as CuO / ZnO / Al2O3-X1, where X1 refers to the oxide of the metal element in the first additive. For example, the catalyst precursor can be represented as CuO / ZnO / Al2O3-Y2O3, CuO / ZnO / Al2O3-Ga2O3, etc.

[0036] In one feasible embodiment, the concentration of the first mixed solution is 0.1–1 mol / L, for example, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, etc. Optionally, the first additive contains one or more of yttrium, molybdenum, niobium, gallium, indium, lanthanum, tungsten, magnesium, and cadmium.

[0037] In this embodiment, the first additive can be one or more of yttrium salts, molybdenum salts, niobium salts, gallium salts, indium salts, lanthanum salts, tungsten salts, magnesium salts, and cadmium salts. The introduction of alkaline additives or other additives during the co-precipitation process is beneficial for promoting Cu precipitation. + The generation of oxygen vacancies can stabilize intermediates such as formate and methoxy groups and inhibit their decomposition to produce CO, thereby improving methanol selectivity.

[0038] Optionally, the coprecipitation is either co-current coprecipitation or countercurrent coprecipitation.

[0039] In this embodiment, using co-current co-precipitation or counter-current co-precipitation methods can make the components in the catalyst more uniformly dispersed, reduce the particle size of the prepared catalyst, and improve the catalytic activity.

[0040] Optionally, the pH of the co-precipitation is 6-11, the temperature is 40-90°C, and the aging time is 1-15 hours.

[0041] In this embodiment, the pH of the coprecipitation is 6 to 11, such as 6, 8, 10, 11, etc.; the temperature is 40 to 90°C, such as 40°C, 60°C, 75°C, 90°C, etc.; and the aging time is 1 to 15 hours, such as 1h, 5h, 10h, 15h, etc.

[0042] Step S20: The second additive is introduced onto the catalyst precursor, and the product after introducing the second additive is calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol.

[0043] In this embodiment, it should be noted that the second additive refers to a metal element additive that can cover part of the Cu sites and inhibit the reverse water-gas shift reaction, such as salts of metals such as zirconium (Zr), gallium, indium, and lanthanum, which can improve methanol selectivity.

[0044] As an example, the amount of the second additive can be determined in advance based on literature, experimental results, etc. The second additive is weighed according to the predetermined amount, and mixed with the catalyst precursor to introduce the metal element in the second additive into the catalyst precursor. The metal element in the second additive introduced into the catalyst precursor can cover the copper sites with reverse water gas activity, inhibit the reverse water gas shift reaction, improve methanol selectivity, and then calcine the product after introducing the second additive to obtain the catalyst for the hydrogenation of carbon dioxide to methanol. The method of introducing the second additive into the catalyst precursor can be ball milling, impregnation, deposition, etc. The catalyst can be represented as CuO / ZnO / Al2O3-X2, where X2 refers to the oxide of the metal element in the first additive and the oxide of the metal element in the second additive. For example, the catalyst precursor can be represented as CuO / ZnO / Al2O3-Y2O3-ZrO2, CuO / ZnO / Al2O3-Ga2O3-La2O3, etc.

[0045] Optionally, the mass ratio of copper, zinc oxide, and aluminum oxide in the catalyst is (3-7):(1-4):(1-3).

[0046] In this embodiment, the mass ratio of copper, zinc oxide, and aluminum oxide in the catalyst is (3-7):(1-4):(1-3), for example, 3:1:1, 5:4:2, 6:3:1, 7:4:3, etc. Based on the mass ratio of copper, zinc oxide, and aluminum oxide in the final catalyst to be prepared, the amount of copper salt, zinc salt, and aluminum salt to be added can be calculated.

[0047] Optionally, the second additive contains one or more of zirconium, gallium, indium, and lanthanum.

[0048] In this embodiment, the second additive can be one or more of zirconium salt, gallium salt, indium salt, and lanthanum salt. The second additive introduced in the second step covers Cu sites with anti-water gas shift reaction, which can suppress the anti-water gas shift reaction and improve methanol selectivity. Although it covers Cu active sites, it also introduces a highly active oxide-Cu interface, which can improve hydrogenation activity to a certain extent. Furthermore, the second additive introduced in the second step has a certain degree of hydrophobicity, which can improve the hydrophobicity of the catalyst and suppress the sintering of the active center of the catalyst due to water.

[0049] Optionally, the total amount of the first auxiliary agent and the second auxiliary agent in the catalyst accounts for 2% to 10% of the mass fraction.

[0050] The first auxiliary agent has a mass fraction of 1% to 6% in the catalyst;

[0051] The second auxiliary agent accounts for 1% to 6% of the mass fraction of the catalyst.

[0052] In this embodiment, the total mass fraction of the first auxiliary agent and the second auxiliary agent in the catalyst is 1% to 6%, for example, 1%, 3%, 5%, 6%, etc.; the mass fraction of the first auxiliary agent in the catalyst is 1% to 6%, for example, 1%, 3%, 5%, 6%, etc.; and the mass fraction of the second auxiliary agent in the catalyst is 2% to 10%, for example, 2%, 5%, 8%, 10%, etc.

[0053] Optionally, the step of introducing a second promoter onto the catalyst precursor, and then calcining the product after introducing the second promoter to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes:

[0054] The second auxiliary agent is prepared into a second auxiliary agent solution, and the second auxiliary agent solution is added dropwise to the catalyst precursor for impregnation. The product after introducing the second auxiliary agent is dried and calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol.

[0055] As an example, the amount of the second additive can be determined in advance based on literature, experimental results, etc. The second additive is weighed according to the predetermined amount, and the second additive is prepared into a second additive solution. The second additive solution is added dropwise to the catalyst precursor. After all the addition is completed, the catalyst precursor is immersed in the second additive solution to introduce the metal element in the second additive into the catalyst precursor, covering part of the Cu active site. The product after introducing the second additive is dried and calcined to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0056] Optionally, the step of introducing a second promoter onto the catalyst precursor, and then calcining the product after introducing the second promoter to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes:

[0057] The second auxiliary agent is prepared into a second auxiliary agent solution. The second auxiliary agent solution, the precipitant and the catalyst precursor are mixed. The product after introducing the second auxiliary agent is washed, dried and calcined to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

[0058] As an example, the amounts of the second additive and the precipitant can be determined in advance based on literature, experimental results, etc. The second additive and the precipitant are weighed according to the predetermined amounts. The second additive is prepared into a second additive solution, and the precipitant is prepared into a precipitant solution. The second additive solution and the precipitant solution are added simultaneously to a mixer containing a catalyst precursor for mixing, so as to introduce the metal element in the second additive onto the catalyst precursor, covering part of the Cu active sites. The product after introducing the second additive is washed, dried, and calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol.

[0059] Optionally, the step of introducing a second promoter onto the catalyst precursor, and then calcining the product after introducing the second promoter to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes:

[0060] The second additive and the catalyst precursor are mixed and ball-milled. The product after introducing the second additive is calcined to obtain the catalyst.

[0061] As an example, the amount of the second additive can be determined in advance based on literature, experimental results, etc. After the second additive is mixed evenly with the catalyst precursor, it is added to a ball mill for ball milling to introduce the metal element in the second additive into the catalyst precursor, covering part of the Cu active sites. The product after introducing the second additive is calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol.

[0062] Optionally, the roasting temperature is 300–500°C, and the roasting time is 2–6 hours.

[0063] In this embodiment, the roasting temperature is 300-500℃, such as 300℃, 350℃, 400℃, 450℃, 500℃, etc., and the roasting time is 2-6 hours, such as 2h, 3h, 4h, 5h, 6h, etc.

[0064] Optionally, the precipitant is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, and potassium bicarbonate.

[0065] In this embodiment, a catalyst precursor is obtained by co-precipitating copper salt, zinc salt, aluminum salt, a first promoter, and a precipitant. The co-precipitated product is then aged, washed, and dried. This process improves copper dispersion and enhances the metal-oxide interfacial interaction, which is beneficial for improving the hydrogenation activity of the catalyst. Furthermore, some of the promoters introduced during the co-precipitation process can promote the formation of oxygen vacancies and Cu. + The generation of [a specific additive] is beneficial for stabilizing formate and methoxy groups, inhibiting their decomposition to produce CO, and improving methanol selectivity. Furthermore, the addition of an additive inhibits the sintering of active centers and improves the catalyst's heat resistance. Subsequently, by introducing a second additive onto the catalyst precursor, the product after introducing the second additive is calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol. This process achieves partial coverage of Cu sites, reducing the number of active sites in the reverse water-gas shift reaction and improving methanol selectivity. Additionally, the oxide covering the Cu sites forms a highly active oxide-Cu interface, which can improve the catalyst's hydrogenation activity to some extent. Moreover, the introduced hydrophobic additive can improve the catalyst's hydrophobicity, inhibiting the sintering of active centers caused by water. Thus, by introducing additives twice, the technical shortcomings of copper-based catalysts—such as a significant gap between their carbon dioxide hydrogenation activity and thermodynamic equilibrium conversion rate, and relatively low methanol selectivity and stability—are overcome, while simultaneously improving the hydrogenation activity, selectivity, and stability of the catalyst for the hydrogenation of carbon dioxide to methanol.

[0066] Furthermore, the present invention also provides a catalyst for the hydrogenation of carbon dioxide to methanol, wherein the catalyst for the hydrogenation of carbon dioxide to methanol is prepared by the preparation method of the catalyst for the hydrogenation of carbon dioxide to methanol as described above.

[0067] The catalyst for the hydrogenation of carbon dioxide to methanol provided by this invention solves the technical problems of low carbon dioxide hydrogenation activity, methanol selectivity, and stability of existing catalysts for the hydrogenation of carbon dioxide to methanol. Compared with the prior art, the beneficial effects of the catalyst for the hydrogenation of carbon dioxide to methanol provided in this invention are the same as the beneficial effects of the preparation method of the catalyst for the hydrogenation of carbon dioxide to methanol provided in the above embodiments, and other technical features of this catalyst for the hydrogenation of carbon dioxide to methanol are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0068] Furthermore, to better understand this application, the preparation method of the catalyst for the hydrogenation of carbon dioxide to methanol provided in this application is described in detail below with reference to embodiments. All embodiments of this invention use commercially available raw materials.

[0069] Example 1

[0070] A catalyst with a Cu:ZnO:Al2O3 mass ratio of 6:3:1 was prepared by co-current co-precipitation, wherein Y2O3 and ZrO2 promoters accounted for 3 wt.% and 2 wt.% of the total catalyst mass, respectively. The specific method is as follows: 32.46 g of copper nitrate trihydrate, 14.91 g of zinc nitrate hexahydrate, 5.24 g of aluminum nitrate nonahydrate, and 0.76 g of yttrium nitrate hexahydrate were weighed and added to 205 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to obtain a 1 mol / L precipitant solution, denoted as solution B.

[0071] Solutions A and B were simultaneously added dropwise to a three-necked flask containing 100 mL of deionized water. The suspension in the three-necked flask was aged for 2 h under a water bath at 70 °C while maintaining a pH of 7. The aged slurry was washed and dried to obtain the catalyst precursor, labeled as p-Cat1.

[0072] 0.74 g of zirconium nitrate hexahydrate was dissolved in 10 mL of deionized water. After complete dissolution, the zirconium nitrate solution was added dropwise to p-Cat1. After impregnation for 12 hours, the sample was dried at 120 °C for 10 hours and then calcined in a muffle furnace at 350 °C for 4 hours to obtain the sample Cat1 catalyst.

[0073] Example 2

[0074] A catalyst with a Cu:ZnO:Al2O3 mass ratio of 6:3:1 was prepared by co-current co-precipitation, wherein Y2O3 and ZrO2 promoters accounted for 3 wt.% and 2 wt.% of the total catalyst mass, respectively. The specific method is as follows: 21.64 g of copper nitrate trihydrate, 9.94 g of zinc nitrate hexahydrate, 3.49 g of aluminum nitrate nonahydrate, and 0.51 g of yttrium nitrate hexahydrate were weighed and added to 274 mL of deionized water. The solution was stirred and dissolved in a 500 mL beaker to prepare a 0.5 mol / L metal precursor solution, denoted as solution A. 16.8 g of anhydrous sodium bicarbonate was weighed and added to 400 mL of deionized water. The solution was stirred and dissolved to form a 0.5 mol / L precipitant solution, denoted as solution B.

[0075] Solutions A and B were simultaneously added dropwise to a three-necked flask. The suspension in the three-necked flask was kept at pH 8 under a water bath at 70°C and aged for 4 hours. The aged slurry was then washed, dried, and used for later use to obtain sample p-Cat2.

[0076] 0.74 g of zirconium nitrate hexahydrate was dissolved in 10 mL of deionized water. After complete dissolution, the zirconium nitrate solution was added dropwise to p-Cat2. After impregnation for 12 hours, the mixture was dried at 120 °C for 10 hours and then calcined in a muffle furnace at 300 °C for 4 hours to obtain the Cat2 catalyst.

[0077] Example 3

[0078] A Cu:ZnO:Al2O3 catalyst with a mass ratio of 5:4:2 was prepared by countercurrent coprecipitation, wherein MgO and CeO2 promoters accounted for 5 wt.% and 3 wt.% of the total catalyst mass, respectively. The specific method is as follows: 23.82 g of copper nitrate trihydrate, 17.50 g of zinc nitrate hexahydrate, 9.22 g of aluminum nitrate nonahydrate, and 4.8 g of magnesium nitrate hexahydrate were weighed and added to 207 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0079] Solution B was first poured into a three-necked flask, and then solution A was gradually added dropwise. The pH of the suspension was controlled at 8 under an 80°C water bath. The mixture was stirred continuously and aged for 4 hours. After aging, the slurry was washed and dried, and the sample was labeled as p-Cat.3.

[0080] 1.14 g of cerium nitrate hexahydrate was dissolved in 10 mL of deionized water. After complete dissolution, zirconium nitrate solution was added dropwise to p-Cat.3. After impregnation for 12 hours, the mixture was dried at 120 °C for 10 hours and then calcined in a muffle furnace at 300 °C for 4 hours to obtain the Cat.3 catalyst.

[0081] Example 4

[0082] A catalyst was prepared using Cu:ZnO:Al2O3 in a mass ratio of 7:4:3, with CdO and In2O3 promoters accounting for 6 wt.% and 4 wt.% of the total catalyst mass, respectively. The specific method is as follows: 25.63 g of copper nitrate trihydrate, 13.45 g of zinc nitrate hexahydrate, 7.09 g of aluminum nitrate nonahydrate, and 2.17 g of cadmium nitrate tetrahydrate were weighed and added to 363 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 0.5 mol / L metal precursor solution, denoted as solution A. 16.8 g of anhydrous sodium bicarbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 0.5 mol / L precipitant solution, denoted as solution B.

[0083] Solution B was first poured into a three-necked flask, and then solution A was gradually added dropwise. The pH of the suspension was controlled at 8 under an 80°C water bath. The suspension was stirred continuously and aged for 4 hours. After washing and drying, the sample was labeled as p-Cat.4.

[0084] Dissolve 0.69g of indium nitrate hexahydrate in 10mL of deionized water, and denote this as solution C; add 2.08g of anhydrous sodium carbonate to 20mL of deionized water, stir to dissolve, and form a precipitant solution, which is denoteed as solution D.

[0085] Solution C and solution D were simultaneously added dropwise to a three-necked flask containing p-Cat.4, the pH was adjusted to 7, and after precipitation was complete, the product was dried and calcined in a muffle furnace at 300°C for 6 hours to obtain the Cat.4 catalyst.

[0086] Example 5

[0087] A catalyst was prepared using Cu:ZnO:Al2O3 in a mass ratio of 5:4:2, with MgO and CeO2 promoters accounting for 5 wt.% and 3 wt.% of the total catalyst mass, respectively. The specific method is as follows: 23.82 g of copper nitrate trihydrate, 17.50 g of zinc nitrate hexahydrate, 9.22 g of aluminum nitrate nonahydrate, and 4.8 g of magnesium nitrate hexahydrate were weighed and added to 207 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0088] Solutions A and B were simultaneously added dropwise to a three-necked flask. The pH of the suspension in the three-necked flask was maintained at 8 under an 80°C water bath, and the mixture was continuously stirred and aged for 4 hours. The aged slurry was then washed, dried, and used for later use, and labeled as p-Cat.5.

[0089] Dissolve 1.14g of cerium nitrate hexahydrate in 10mL of deionized water, and denote this as solution C; add 2.08g of anhydrous sodium bicarbonate to 20mL of deionized water, stir to dissolve, and form a precipitant solution, which is denoteed as solution D.

[0090] Solution C and solution D were simultaneously added dropwise to a three-necked flask containing p-Cat.4, the pH was adjusted to 8, and after precipitation was complete, the product was dried and calcined in a muffle furnace at 350°C for 4 hours to obtain the Cat.5 catalyst.

[0091] Example 6

[0092] A catalyst was prepared using Cu:ZnO:Al2O3 in a mass ratio of 5:3:3, with Ga2O3 and La2O3 promoters accounting for 4 wt.% and 6 wt.% of the total catalyst mass, respectively. The specific method is as follows: 23.30 g of copper nitrate trihydrate, 12.84 g of zinc nitrate hexahydrate, 13.54 g of aluminum nitrate nonahydrate, and 1.20 g of lanthanum nitrate hexahydrate were weighed and added to 202 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0093] Solutions A and B were simultaneously added dropwise to a three-necked flask, maintaining the pH of the suspension in the flask at 7, and aging at 80°C with continuous stirring for 2 hours. The aged slurry was then washed, dried, and used for later use, and labeled as p-Cat.6.

[0094] 0.82 g of gallium nitrate hydrate and 15 g of p-Cat.6 were mixed and ball-milled at a speed of 100 r / min and a ball-to-material ratio of 7:1 for 1 hour. The product was dried and then calcined in a muffle furnace at 400 °C for 3 hours to obtain the Cat.6 catalyst.

[0095] Example 7

[0096] A catalyst was prepared using Cu:ZnO:Al2O3 in a mass ratio of 7:4:2, with Ga2O3 and La2O3 promoters accounting for 4 wt.% and 6 wt.% of the total catalyst mass, respectively. The specific method is as follows: 27.60 g of copper nitrate trihydrate, 14.49 g of zinc nitrate hexahydrate, 7.64 g of aluminum nitrate nonahydrate, and 1.20 g of lanthanum nitrate hexahydrate were weighed and added to 192 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0097] Solution B was first poured into a three-necked flask, and then solution A was gradually added dropwise. The pH of the suspension was controlled at 8. After aging, washing and drying, the solution was ready for use. The sample was labeled as p-Cat.7.

[0098] 0.82 g of gallium nitrate hydrate and 15 g of p-Cat.7 were mixed and ball-milled for 2 hours at a speed of 150 r / min and a ball-to-material ratio of 5:1. The product was dried and then calcined in a muffle furnace at 450 °C for 2 hours to obtain the Cat.7 catalyst.

[0099] Example 8

[0100] A catalyst was prepared using Cu:ZnO:Al2O3 in a mass ratio of 3:1:1, with Ga2O3 and La2O3 promoters accounting for 1 wt.% and 1 wt.% of the total catalyst mass, respectively. The specific method is as follows: 30.44 g of copper nitrate trihydrate, 9.32 g of zinc nitrate hexahydrate, 9.83 g of aluminum nitrate nonahydrate, and 0.20 g of lanthanum nitrate hexahydrate were weighed and added to 186 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0101] Solutions A and B were simultaneously added dropwise to a three-necked flask, and the pH of the suspension in the three-necked flask was maintained at 7. The mixture was then stirred and aged at 80°C for 15 hours. The aged slurry was washed, dried, and then used for later use, and labeled as p-Cat.8.

[0102] 0.20 g of gallium nitrate hydrate and 15 g of p-Cat.7 were mixed and ball-milled for 1 hour at a speed of X r / min and a ball-to-material ratio of 3:1. The product was dried and then calcined in a muffle furnace at 500 °C for 2 hours to obtain the Cat.8 catalyst.

[0103] Comparative Example 1

[0104] The catalyst was prepared by mass ratio of Cu:ZnO:Al2O3 of 6:3:1, and the specific method is as follows: 34.17g of copper nitrate trihydrate, 15.69g of zinc nitrate hexahydrate and 5.51g of aluminum nitrate nonahydrate were weighed and added to 211mL of deionized water. The mixture was stirred and dissolved in a 500mL beaker to prepare a 1mol / L metal precursor solution, which is denoted as solution A. 41.6g of anhydrous sodium carbonate was weighed and added to 400mL of deionized water. The mixture was stirred and dissolved to form a 1mol / L precipitant solution, which is denoted as solution B.

[0105] Solutions A and B were simultaneously added dropwise to a three-necked flask, and the pH of the suspension in the three-necked flask was maintained at 7. The mixture was then continuously stirred and aged at 70°C for 2 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 350°C for 4 hours to obtain the Cat.9 catalyst.

[0106] Comparative Example 2

[0107] A catalyst was prepared using Cu:ZnO:Al2O3 in a mass ratio of 6:3:1, with Y2O3 promoter accounting for 3 wt.% of the total catalyst mass. The specific method is as follows: 32.46 g of copper nitrate trihydrate, 14.91 g of zinc nitrate hexahydrate, 5.24 g of aluminum nitrate nonahydrate, and 0.76 g of yttrium nitrate hexahydrate were weighed and added to 205 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0108] Solutions A and B were simultaneously added dropwise to a three-necked flask. The pH of the suspension in the three-necked flask was maintained at 7 under a water bath at 70°C, and the mixture was continuously stirred and aged for 2 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 350°C for 4 hours to obtain the catalyst, which was labeled Cat.10.

[0109] Comparative Example 3

[0110] A catalyst was prepared by mixing Cu, ZnO, and Al2O3 in a mass ratio of 6:3:1, with ZrO2 promoter accounting for 2 wt.% of the total catalyst mass. The specific method is as follows: 32.46 g of copper nitrate trihydrate, 14.91 g of zinc nitrate hexahydrate, and 5.24 g of aluminum nitrate nonahydrate were weighed and added to 205 mL of deionized water. The mixture was stirred and dissolved in a 500 mL beaker to prepare a 1 mol / L metal precursor solution, denoted as solution A. 41.6 g of anhydrous sodium carbonate was weighed and added to 400 mL of deionized water. The mixture was stirred and dissolved to form a 1 mol / L precipitant solution, denoted as solution B.

[0111] Solutions A and B were added dropwise to a three-necked flask at the same time. The pH of the suspension in the three-necked flask was maintained at 7, and the mixture was continuously stirred and aged at 70°C for 2 hours. The aged slurry was washed, dried, and then used for later use, and labeled as p-Cat.11.

[0112] Dissolve 0.74 g of zirconium nitrate hexahydrate in 10 mL of deionized water and add it dropwise onto CuO / ZnO / Al2O3. After drying, calcine in a muffle furnace at 350 °C for 4 hours to obtain the Cat.10 catalyst.

[0113] Furthermore, the catalysts prepared in Examples 1-7 and Comparative Examples 1-3 were used to test the performance of the carbon dioxide hydrogenation to methanol reaction. The reaction performance test conditions were: reaction temperature 250℃, reaction pressure 5MPa, and reaction space velocity 10000mL·h. -1 ·g cat -1 The H2 to CO2 flow rate ratio was 3:1. The test results are shown in Table 1.

[0114] Table 1

[0115]

[0116] As shown in Table 1, compared with Comparative Example 1 (sample name Cat.9) without the introduction of the additive and Comparative Example 2 (sample name Cat.10) and Comparative Example 3 (sample name Cat.11) with the introduction of the additive once, the present application adopts the method of introducing the additive twice, which can simultaneously improve the carbon dioxide hydrogenation activity, methanol selectivity and stability of the catalyst for the production of methanol by carbon dioxide hydrogenation.

[0117] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. A method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, The preparation method of the catalyst for the hydrogenation of carbon dioxide to methanol includes the following steps: Co-precipitation is performed using copper salt, zinc salt, aluminum salt, a first additive, and a precipitant. The co-precipitated product is then aged, washed, and dried to obtain a catalyst precursor. The first additive is one or more of yttrium, lanthanum, magnesium, and cadmium. A second auxiliary agent is introduced onto the catalyst precursor, and the product after introducing the second auxiliary agent is calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol. The second auxiliary agent is one or more of zirconium, gallium, and indium, and the total mass fraction of the first auxiliary agent and the second auxiliary agent in the catalyst is 2% to 10%. The step of introducing a second additive onto the catalyst precursor, and then calcining the product after introducing the second additive to obtain a catalyst for the hydrogenation of carbon dioxide to methanol, includes: The second auxiliary agent is prepared into a solution, and the solution is added dropwise to the catalyst precursor for impregnation. The product after introducing the second auxiliary agent is dried and calcined to obtain a catalyst for the hydrogenation of carbon dioxide to methanol; or... The second auxiliary agent is prepared into a second auxiliary agent solution. The second auxiliary agent solution, the precipitant and the catalyst precursor are mixed. The product after introducing the second auxiliary agent is washed, dried and calcined to obtain the catalyst for the hydrogenation of carbon dioxide to methanol.

2. The method for preparing the catalyst for the hydrogenation of carbon dioxide to methanol as described in claim 1, characterized in that, The first auxiliary agent accounts for 1% to 6% of the mass fraction of the catalyst; The second auxiliary agent accounts for 1% to 6% of the mass fraction of the catalyst.

3. The method for preparing the catalyst for the hydrogenation of carbon dioxide to methanol as described in claim 1, characterized in that, The coprecipitation is either co-current coprecipitation or counter-current coprecipitation.

4. The method for preparing the catalyst for the hydrogenation of carbon dioxide to methanol as described in claim 1, characterized in that, The co-precipitation occurs at a pH of 6-11, a temperature of 40-90°C, and an aging time of 1-15 hours.

5. The 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 roasting temperature is 300~500℃, and the roasting time is 2~6 hours.

6. The 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 precipitant is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, and potassium bicarbonate.

7. The 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 mass ratio of copper, zinc oxide and aluminum oxide in the catalyst is (3~7):(1~4):(1~3).

8. A catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that, The catalyst for the hydrogenation of carbon dioxide to methanol is prepared by the method described in any one of claims 1-7.

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