Copper-based catalysts, processes for their preparation and use

Abstract

The application discloses a copper-based catalyst and a preparation method and application thereof, relates to the technical field of catalysts, and discloses a preparation method of the copper-based catalyst, which comprises the following steps: mixing a zinc element precursor and an aluminum element precursor to obtain a first mixed solution, mixing a copper element precursor and an additive precursor to obtain a second mixed solution, and configuring an alkaline precipitator solution, wherein the alkaline precipitator solution contains a silicon dioxide precursor; the first mixed solution and the alkaline precipitator solution are mixed with each other, zinc components and aluminum components are precipitated, and a first suspension liquid is obtained; the second mixed solution and the alkaline precipitator solution are added into the first suspension liquid, copper components and additives are precipitated, and a second suspension liquid is obtained; and the second suspension liquid is subjected to aging treatment, drying treatment and calcination treatment in sequence, so that the copper-based catalyst is obtained. The application solves the technical problems of poor stability and low catalytic hydrogenation activity of the copper-based catalyst in the prior art.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and in particular to a copper-based catalyst, its preparation method, and its application. 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. China's methanol production mainly relies on the coal chemical route, which has a high carbon emission intensity and is detrimental to carbon reduction. In the context of "carbon peaking" and "carbon neutrality," developing methanol production via carbon dioxide hydrogenation is of great significance.

[0003] Copper-based catalysts are commonly used in the hydrogenation of carbon dioxide to methanol reaction, and these catalysts are often prepared via co-precipitation. However, copper-based catalysts prepared by co-precipitation generally have large copper particles with a wide particle size distribution. This inhomogeneity in particle size easily leads to the Oswald ripening effect, resulting in catalyst sintering and deactivation. Furthermore, the hydrogenation of carbon dioxide to methanol reaction occurs under high-temperature conditions, while copper-based catalysts have poor hydrothermal stability. On the one hand, copper-based catalysts are prone to sintering at reaction temperatures above 200°C, leading to a reduction in active sites and catalyst deactivation. On the other hand, the generation of water during the hydrogenation of carbon dioxide to methanol reaction accelerates copper sintering. Summary of the Invention

[0004] The main objective of this application is to provide a copper-based catalyst, its preparation method, and its application, aiming to solve the technical problems of poor stability and low catalytic hydrogenation activity of existing copper-based catalysts.

[0005] To achieve the above objectives, this application provides a method for preparing a copper-based catalyst, the method comprising the following steps:

[0006] A first mixed solution is obtained by mixing zinc and aluminum precursors, and a second mixed solution is obtained by mixing copper and auxiliary precursors. An alkaline precipitant solution is then prepared, wherein the alkaline precipitant solution contains a silica precursor.

[0007] The first mixed solution is mixed with an alkaline precipitant solution to precipitate zinc and aluminum components, thus obtaining a first suspension.

[0008] The second mixed solution and the alkaline precipitant solution are added to the first suspension to precipitate the copper component and the additive, thereby obtaining the second suspension.

[0009] The second suspension was subjected to aging, drying and calcination treatments in sequence to obtain a copper-based catalyst.

[0010] Optionally, in the copper-based catalyst, the ratio of the amount of aluminum to the sum of the amounts of zinc, aluminum, copper, and auxiliary metals is 0.13-0.28.

[0011] Optionally, the copper-based catalyst includes copper oxide, aluminum oxide, zinc oxide, auxiliary oxides, and silicon dioxide.

[0012] Optionally, the mass percentage of the promoter oxide in the copper-based catalyst is 0.5-4%;

[0013] And / or, the mass percentage of silicon dioxide in the copper-based catalyst is 0.5-4%.

[0014] Optionally, the auxiliary oxide includes at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide, and europium oxide.

[0015] Optionally, during the precipitation of zinc and aluminum components, the pH of the reaction system is controlled to be 8-10;

[0016] And / or, during the process of precipitating the copper components and additives, the pH of the reaction system is controlled to be 8-10.

[0017] Optionally, the alkaline precipitant solution further includes sodium carbonate and sodium hydroxide, wherein the molar ratio of sodium carbonate to sodium hydroxide is 0.5-1.5.

[0018] Optionally, the aging treatment temperature is 50-70℃, and the aging treatment time is 10-24h;

[0019] And / or, the calcination temperature is 300-500℃, and the aging time is 3-5h.

[0020] This application also provides a copper-based catalyst, which is prepared using the copper-based catalyst preparation method described above.

[0021] This application also provides copper-based catalysts prepared by the method described above, or the application of copper-based catalysts as described above in the hydrogenation of carbon dioxide to methanol.

[0022] This application provides a copper-based catalyst, its preparation method, and its application. The preparation method of the copper-based catalyst includes the following steps: mixing zinc and aluminum precursors to obtain a first mixed solution; mixing copper and auxiliary precursors to obtain a second mixed solution; and preparing an alkaline precipitant solution, wherein the alkaline precipitant solution contains a silica precursor; mixing the first mixed solution with the alkaline precipitant solution to precipitate zinc and aluminum components, obtaining a first suspension; adding the second mixed solution and the alkaline precipitant solution to the first suspension to precipitate copper and auxiliary components, obtaining a second suspension; and subjecting the second suspension to aging, drying, and calcination treatments sequentially to obtain the copper-based catalyst. First, the co-precipitation process is carried out in two steps. First, zinc and aluminum are precipitated to form a zinc-aluminum hydrotalcite structure, and then copper and additives are precipitated. On the one hand, forming the zinc-aluminum hydrotalcite structure before precipitating copper and additives improves the dispersibility of the subsequently precipitated copper, making the copper particle size more uniform and thus suppressing the Oswald ripening effect. On the other hand, the zinc-aluminum hydrotalcite structure can confine the copper component, inhibiting its migration and sintering during the subsequent catalytic process. Furthermore, by inhibiting copper component migration, its growth during catalysis can be suppressed, thereby also inhibiting ripening and sintering. Second, the co-precipitation of copper and additives utilizes the hindering effect of the additives to suppress copper migration, thereby inhibiting sintering caused by copper migration. Third, introducing a silica precursor into the alkaline precipitant solution allows for the in-situ introduction of hydrophobic silica during the co-precipitation process. On one hand, the introduction of silica improves the hydrophobicity of the copper-based catalyst, preventing accelerated catalyst deactivation due to the presence of water. On the other hand, compared to other silica introduction strategies, such as silane coupling agent modification or physical mixing, in-situ silica introduction does not cover the active sites on the copper-based catalyst surface, resulting in a copper-based catalyst with higher catalytic hydrogenation activity. Therefore, this overcomes the technical shortcomings of poor hydrothermal stability and low catalytic hydrogenation activity in copper-based catalysts. This invention, through improved preparation methods, can prepare copper-based catalysts with higher hydrothermal stability and higher catalytic hydrogenation activity. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic flowchart of an embodiment of the preparation method of the copper-based catalyst of the present invention.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] 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.

[0027] This application provides a method for preparing a copper-based catalyst, referring to... Figure 1 The preparation method of the copper-based catalyst includes the following steps:

[0028] Step S10: Mix zinc precursor and aluminum precursor to obtain a first mixed solution, mix copper precursor and auxiliary precursor to obtain a second mixed solution, and prepare an alkaline precipitant solution, wherein the alkaline precipitant solution contains a silica precursor.

[0029] In this embodiment, it should be noted that the copper-based catalyst refers to a copper-zinc-aluminum system copper-based catalyst that can catalyze the hydrogenation of carbon dioxide to methanol. The copper-zinc-aluminum system copper-based catalyst includes at least copper oxide, aluminum oxide, and zinc oxide. Copper is the main active metal in the copper-based catalyst; zinc oxide can act as a structural and electronic aid, improving copper dispersion and increasing specific surface area; aluminum oxide can act as a structural aid, improving the catalyst's specific surface area and mechanical stability. However, copper-based catalysts have poor stability and gradually deactivate during catalytic hydrogenation, mainly due to: first, deactivation caused by copper species migration; second, aging and sintering caused by uneven copper species particle size; and third, water-induced catalyst deactivation.

[0030] Optionally, the copper-based catalyst includes copper oxide, aluminum oxide, zinc oxide, additives, and silicon dioxide.

[0031] In this embodiment, the copper-based catalyst may include, in addition to copper oxide, aluminum oxide, and zinc oxide, an additive and silica. The additive is a substance that is inactive or has very low activity, but can alter some properties of the catalyst, such as electronic structure, ionic valence state, acidity / basicity, surface structure, and grain size, thereby improving the catalyst's activity, selectivity, anti-toxicity, or stability. The additive can be at least one of a metal oxide or an inorganic non-metallic porous material. The silica is formed by reacting a silica precursor with a zinc precursor, an aluminum precursor, a copper precursor, and an additive precursor, respectively. On one hand, silica is hydrophobic; therefore, its introduction can improve the hydrophobicity of the copper-based catalyst, preventing accelerated catalyst deactivation due to the presence of water. On the other hand, compared to other silica introduction strategies, such as silane coupling agent modification or physical mixing, in-situ silica introduction does not cover the active sites on the copper-based catalyst surface, resulting in a copper-based catalyst with higher catalytic hydrogenation activity.

[0032] Optionally, the additive includes at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide, and europium oxide.

[0033] In this embodiment, the metal oxide exhibits excellent mechanical properties and good thermal conductivity, which not only improves the dispersibility of copper, inhibits copper migration, ensures uniform copper particle size, and avoids aging and sintering, but also enhances the mechanical stability and thermal conductivity of the copper-based catalyst, reducing high-temperature sintering. The hydrophobic nature of the metal oxide further prevents accelerated catalyst deactivation due to the presence of water, strengthens the interaction between copper and zinc, and thus improves catalytic hydrogenation activity. Therefore, the additive is selected from at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide, and europium oxide.

[0034] The zinc precursor, used to prepare zinc oxide, can be a soluble salt of zinc, including at least one of zinc nitrate and zinc acetate. The aluminum precursor, used to prepare aluminum oxide, can be a soluble salt of aluminum, including at least one of aluminum nitrate and aluminum acetate. The copper precursor, used to prepare copper oxide, can be a soluble salt of copper, including at least one of copper nitrate and copper acetate. The auxiliary agent precursor, used to prepare the auxiliary agent, can be a soluble metal salt, including nitrates and acetates of metals such as magnesium, zirconium, calcium, strontium, and europium. The alkaline precipitant solution refers to a precipitant solution with an alkaline pH, and the alkaline precipitant solution contains a silica precursor. The silica precursor, used to prepare silica, can be an alkaline soluble silicate, including at least one of sodium silicate and potassium silicate.

[0035] Optionally, the alkaline precipitant solution further includes sodium carbonate and sodium hydroxide, wherein the molar ratio of sodium carbonate to sodium hydroxide is 0.5-1.5.

[0036] In this embodiment, by combining sodium carbonate and sodium hydroxide, a zinc-aluminum hydrotalcite structure can be formed when precipitating zinc and aluminum components. The molar ratio of sodium carbonate to sodium hydroxide is 0.5-1.5, for example, 0.5, 0.8, 1.0, 1.2, 1.5, etc.

[0037] As an example, step S10 includes: weighing zinc precursor, aluminum precursor, copper precursor, auxiliary agent precursor, silica precursor, and precipitant in a certain proportion. Dissolving the zinc and aluminum precursors and mixing them evenly to prepare a first mixed solution; dissolving the copper and auxiliary agent precursors and mixing them evenly to prepare a second mixed solution; and dissolving the silica precursor and precipitant and mixing them evenly to prepare a precipitant solution. It should be noted that the first mixed solution, the second mixed solution, and the precipitant solution are prepared independently, and the order of preparation is not limited. The amounts of zinc precursor, aluminum precursor, copper precursor, auxiliary agent precursor, silica precursor, and precipitant can be determined and adjusted in advance based on experimental test results or actual conditions; this embodiment does not impose any restrictions on this.

[0038] Optionally, in the copper-based catalyst, the ratio of the amount of aluminum to the sum of the amounts of zinc, aluminum, copper, and auxiliary metals is 0.13-0.28.

[0039] In this embodiment, the raw materials used to prepare the copper-based catalyst should ensure that the ratio of the amount of aluminum to the sum of the amounts of zinc, aluminum, copper, and auxiliary metals in the final copper-based catalyst is 0.13-0.28, for example, 0.13, 0.15, 0.2, 0.25, 0.28, etc. Under these conditions, the copper-based catalyst exhibits good stability and catalytic hydrogenation activity.

[0040] Optionally, the mass percentage of the promoter in the copper-based catalyst is 0.5-4%;

[0041] And / or, the mass percentage of silicon dioxide in the copper-based catalyst is 0.5-4%.

[0042] In this embodiment, if the mass percentage of the promoter in the copper-based catalyst is too low, the improvement on catalyst performance will not be significant. If the mass percentage of the promoter in the copper-based catalyst is too high, it may cover the active center, which may lead to a decrease in catalytic hydrogenation activity. Therefore, the mass percentage of the promoter in the copper-based catalyst is determined to be 0.5-4%, such as 0.5%, 1%, 2%, 3%, 4%, etc.

[0043] If the mass percentage of silica in the copper-based catalyst is too low, the improvement on the hydrophobicity of the catalyst will not be significant. If the mass percentage of silica in the copper-based catalyst is too high, it may cover the active sites, which may lead to a decrease in catalytic hydrogenation activity. Therefore, the mass percentage of silica in the copper-based catalyst is determined to be 0.5-4%, such as 0.5%, 1%, 2%, 3%, 4%, etc.

[0044] Step S20: Mix the first mixed solution with an alkaline precipitant solution to precipitate the zinc and aluminum components, and obtain the first suspension;

[0045] As an example, step S20 includes: taking a certain amount of pure water, and simultaneously and uniformly dripping the first mixed solution and the alkaline precipitant solution into the pure water so that the zinc component and the aluminum component co-precipitate to form a zinc-aluminum hydrotalcite structure. After the first mixed solution is completely added, a first suspension is obtained.

[0046] Optionally, during the precipitation of zinc and aluminum components, the pH of the reaction system is controlled to be 8-10.

[0047] In this embodiment, the pH value of the reaction system can be tested simultaneously during the addition of the first mixed solution and the alkaline precipitant solution. By adjusting the dropping rate of the alkaline precipitant solution, the pH value of the reaction system can be controlled within the range of 8-10.

[0048] Step S30: Add the second mixed solution and the alkaline precipitant solution to the first suspension to precipitate the copper component and the additive, thereby obtaining the second suspension;

[0049] As an example, step S20 includes: after the first mixed solution is added dropwise, the second mixed solution and the alkaline precipitant solution can be added dropwise to the first suspension simultaneously and at a uniform rate, so that the copper component and the additive co-precipitate, and the copper component and the additive are dispersed and attached to the zinc-aluminum hydrotalcite. After the second mixed solution is added dropwise, a second suspension is obtained.

[0050] Optionally, during the precipitation of the copper component and additives, the pH of the reaction system is controlled to be 8-10.

[0051] In this embodiment, the pH value of the reaction system can be tested simultaneously during the addition of the second mixed solution and the alkaline precipitant solution. By adjusting the dropping rate of the alkaline precipitant solution, the pH value of the reaction system can be controlled within the range of 8-10.

[0052] In step S40, the second suspension is subjected to aging, drying and calcination treatments in sequence to obtain a copper-based catalyst.

[0053] As an example, step S40 includes: after the stepwise precipitation of zinc, aluminum, copper, and additives, the second suspension is sequentially aged; after aging, the precipitate is washed; and the washed precipitate is dried and calcined to obtain the copper-based catalyst. The specific process parameters for aging, drying, and calcination can be determined and adjusted according to actual needs and test results, and this embodiment does not impose any limitations on them.

[0054] Optionally, the aging treatment temperature is 50-70℃, and the aging treatment time is 10-24h;

[0055] And / or, the calcination temperature is 300-500℃, and the aging time is 3-5h.

[0056] In this embodiment, the aging treatment temperature is 50-70℃, such as 50℃, 60℃, 70℃, etc., and the aging treatment time is 10-24h, such as 10h, 15h, 20h, 24h, etc.

[0057] The calcination temperature is 300-500℃, for example 300℃, 350℃, 400℃, 450℃, 500℃, etc., and the aging time is 3-5h, for example 3h, 4h, 5h, etc.

[0058] In this embodiment, the preparation method of the copper-based catalyst includes the following steps: mixing zinc and aluminum precursors to obtain a first mixed solution, mixing copper and auxiliary precursors to obtain a second mixed solution, and preparing an alkaline precipitant solution, wherein the alkaline precipitant solution contains a silica precursor; mixing the first mixed solution with the alkaline precipitant solution to precipitate zinc and aluminum components to obtain a first suspension; adding the second mixed solution and the alkaline precipitant solution to the first suspension to precipitate copper and auxiliary components to obtain a second suspension; and subjecting the second suspension to aging, drying, and calcination treatments in sequence to obtain the copper-based catalyst. First, the co-precipitation process is divided into two steps. First, zinc and aluminum are precipitated to form a zinc-aluminum hydrotalcite structure. Then, copper and additives are precipitated. On the one hand, forming the zinc-aluminum hydrotalcite structure before precipitating copper and additives improves the dispersibility of the subsequently precipitated copper, resulting in more uniform copper particle size and thus suppressing the Oswald ripening effect. On the other hand, the zinc-aluminum hydrotalcite structure can confine the copper component, inhibiting its migration and sintering during subsequent catalytic processes. Furthermore, by inhibiting copper migration, copper growth during catalysis can be suppressed, thereby also inhibiting sintering. Second, the co-precipitation of copper and additives utilizes the hindering effect of the additives to suppress copper migration, thereby inhibiting sintering caused by copper migration. Third, introducing a silica precursor into the alkaline precipitant solution allows for the in-situ introduction of hydrophobic silica during the co-precipitation process. On one hand, the introduction of silica improves the hydrophobicity of the copper-based catalyst, preventing accelerated catalyst deactivation due to the presence of water. On the other hand, compared to other silica introduction strategies, such as silane coupling agent modification or physical mixing, in-situ silica introduction does not cover the active sites on the copper-based catalyst surface, resulting in a copper-based catalyst with higher catalytic hydrogenation activity. Therefore, this overcomes the technical shortcomings of low hydrothermal stability and low catalytic hydrogenation activity in copper-based catalysts. This invention, through improved preparation methods, can prepare copper-based catalysts with higher hydrothermal stability and higher catalytic hydrogenation activity.

[0059] Furthermore, the present invention also provides a copper-based catalyst, which is prepared by the copper-based catalyst preparation method described above.

[0060] The copper-based catalyst provided by this invention is prepared using the copper-based catalyst preparation method described above, solving the technical problems of poor stability and low catalytic hydrogenation activity of existing copper-based catalysts. Compared with the prior art, the beneficial effects of the copper-based catalyst provided by the embodiments of this invention are the same as those of the copper-based catalyst preparation method provided in the above embodiments, and other technical features of this copper-based catalyst are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0061] Furthermore, the present invention also provides the application of the copper-based catalyst prepared by the method described above, or the copper-based catalyst described above, in the hydrogenation of carbon dioxide to methanol.

[0062] The copper-based catalyst prepared by the method described above, or the application of the copper-based catalyst described above in the hydrogenation of carbon dioxide to methanol, provided by this invention, solves the technical problems of poor stability and low catalytic hydrogenation activity of existing copper-based catalysts. Compared with the prior art, the beneficial effects of the copper-based catalyst provided by the embodiments of this invention in the hydrogenation of carbon dioxide to methanol are the same as the beneficial effects of the copper-based catalyst preparation method provided in the above embodiments, and other technical features of the copper-based catalyst in 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.

[0063] The present invention will now be described in detail with reference to specific embodiments and comparative examples. It is to be understood that the following description is merely exemplary and not intended to limit the specific scope of the invention.

[0064] Example 1

[0065] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 4:3:2. ZrO₂ promoter and SiO₂ accounted for 1 wt.% and 0.5 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0066] Weigh 9.16g of zinc nitrate hexahydrate and 12.88g of aluminum nitrate nonahydrate, add 223mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 13.30g of copper nitrate trihydrate and 0.38g of zirconium nitrate and dissolve in 188mL of deionized water to obtain the second mixed solution.

[0067] Weigh 26.5g of anhydrous sodium carbonate, 10g of sodium hydroxide and 0.27g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0068] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The solution was kept at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH of the suspension at 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat1 catalyst sample.

[0069] Example 2

[0070] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al2O3 in the copper-based catalyst was 4:3:2, and the MgO promoter and SiO2 accounted for 1 wt.% and 1 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0071] Weigh 9.11g of zinc nitrate hexahydrate and 12.81g of aluminum nitrate nonahydrate, add 223mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 13.23g of copper nitrate trihydrate and 0.51g of magnesium nitrate and dissolve in 188mL of deionized water to obtain the second mixed solution.

[0072] Weigh 29.44g of anhydrous sodium carbonate, 8.8g of sodium hydroxide and 0.54g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0073] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 9. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 9. After the addition was complete, the suspension was aged at 50°C for 24 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 500°C for 3 hours to obtain the Cat2 catalyst sample.

[0074] Example 3

[0075] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 4:3:2, and the MgO promoter and SiO₂ accounted for 2 wt.% and 4 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0076] Weigh 8.74g of zinc nitrate hexahydrate and 12.28g of aluminum nitrate nonahydrate, add 213mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 12.69g of copper nitrate trihydrate and 1.02g of magnesium nitrate and dissolve in 187mL of deionized water to obtain the second mixed solution.

[0077] Weigh 29.44g of anhydrous sodium carbonate, 8.8g of sodium hydroxide and 2.16g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0078] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The solution was kept at room temperature, maintaining the pH of the suspension at 10. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH of the suspension at 10. After the addition was complete, the suspension was aged at 70°C for 12 hours. The aged slurry was then washed, dried, and calcined in a muffle furnace at 500°C for 4 hours to obtain the Cat3 catalyst sample.

[0079] Example 4

[0080] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:2. MgO promoter and SiO₂ accounted for 1 wt.% and 4 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0081] Weigh 7.95g of zinc nitrate hexahydrate and 11.18g of aluminum nitrate nonahydrate, add 194mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 14.43g of copper nitrate trihydrate and 0.51g of magnesium nitrate and dissolve in 205mL of deionized water to obtain the second mixed solution.

[0082] Weigh 31.8g of anhydrous sodium carbonate, 8g of sodium hydroxide and 2.16g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0083] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 9.5. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 9.5. After the addition was complete, the suspension was aged at 70°C for 12 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 500°C for 4 hours to obtain the Cat4 catalyst sample.

[0084] Example 5

[0085] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:2, and the SrO₂ promoter and SiO₂ accounted for 1 wt.% and 2 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0086] Weigh 8.12g of zinc nitrate hexahydrate and 11.41g of aluminum nitrate nonahydrate, add 164mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 14.74g of copper nitrate trihydrate and 0.16g of strontium nitrate and dissolve in 229mL of deionized water to obtain the second mixed solution.

[0087] Weigh 31.8g of anhydrous sodium carbonate, 8g of sodium hydroxide and 1.08g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0088] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 8. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat5 catalyst sample.

[0089] Example 6

[0090] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 2:1:1, and the MgO promoter and SiO₂ accounted for 1 wt.% and 5 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0091] Weigh 6.56g of zinc nitrate hexahydrate and 13.82g of aluminum nitrate nonahydrate, add 201mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 14.28g of copper nitrate trihydrate and 1.02g of magnesium nitrate and dissolve in 209mL of deionized water to obtain the second mixed solution.

[0092] Weigh 22.71g of anhydrous sodium carbonate, 11.43g of sodium hydroxide and 1.08g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0093] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 8. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 8. After the addition was complete, the suspension was aged at 60°C for 20 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat6 catalyst sample.

[0094] Example 7

[0095] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:1, and the MgO promoter and SiO₂ accounted for 1 wt.% and 1 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0096] Weigh 9.11g of zinc nitrate hexahydrate and 6.41g of aluminum nitrate nonahydrate, add 165mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 16.54g of copper nitrate trihydrate and 0.51g of magnesium nitrate and dissolve in 234mL of deionized water to obtain the second mixed solution.

[0097] Weigh 29.44g of anhydrous sodium carbonate, 8.8g of sodium hydroxide and 0.54g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0098] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 8. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 8. After the addition was complete, the suspension was aged at 60°C for 20 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat7 catalyst sample.

[0099] Example 8

[0100] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:1. CaO promoter and SiO₂ accounted for 0.5 wt.% and 3 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0101] Weigh 8.97g of zinc nitrate hexahydrate and 6.31g of aluminum nitrate nonahydrate, add 163mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 16.28g of copper nitrate trihydrate and 0.07g of calcium nitrate and dissolve in 224mL of deionized water to obtain the second mixed solution.

[0102] Weigh 22.71g of anhydrous sodium carbonate, 11.43g of sodium hydroxide and 0.54g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0103] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 9. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 9. After the addition was complete, the suspension was aged at 60°C for 20 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 400°C for 4 hours to obtain the Cat8 catalyst sample.

[0104] Example 9

[0105] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:1. ZrO₂ promoter and SiO₂ accounted for 1 wt.% and 2 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0106] Weigh 9.02g of zinc nitrate hexahydrate and 6.34g of aluminum nitrate nonahydrate, add 164mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 16.37g of copper nitrate trihydrate and 0.38g of zirconium nitrate and dissolve in 188mL of deionized water to obtain the second mixed solution.

[0107] Weigh 26.5g of anhydrous sodium carbonate, 10g of sodium hydroxide and 0.11g of sodium silicate, add 400ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0108] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 8. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 300°C for 5 hours to obtain the Cat9 catalyst sample.

[0109] Comparative Example 1

[0110] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 4:3:2, without the addition of any additives or SiO₂. The specific preparation method is as follows:

[0111] Weigh 9.3g of zinc nitrate hexahydrate and 13.07g of aluminum nitrate nonahydrate, add 227mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 13.50g of copper nitrate trihydrate and dissolve in 185mL of deionized water to obtain the second mixed solution.

[0112] Weigh 26.5g of anhydrous sodium carbonate and 10g of sodium hydroxide, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0113] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 9. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 9. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 400°C for 4 hours to obtain the Cat10 catalyst sample.

[0114] Comparative Example 2

[0115] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:1. MgO was added as a promoter at 1 wt.% of the total catalyst mass, but SiO₂ was not added. The specific preparation method is as follows:

[0116] Weigh 9.21g of zinc nitrate hexahydrate and 6.47g of aluminum nitrate nonahydrate, add 167mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 16.71g of copper nitrate trihydrate and 0.51g of magnesium nitrate and dissolve in 236mL of deionized water to obtain the second mixed solution.

[0117] Weigh 26.5g of anhydrous sodium carbonate and 10g of sodium hydroxide, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0118] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The solution was kept at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH of the suspension at 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 400°C for 4 hours to obtain the Cat11 catalyst sample.

[0119] Comparative Example 3

[0120] A copper-based catalyst was prepared using a two-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 5:3:2. 1 wt.% SiO₂ was added to the total catalyst mass, and no additives were added. The specific preparation method is as follows:

[0121] Weigh 8.2g of zinc nitrate hexahydrate and 11.53g of aluminum nitrate nonahydrate, add 200mL of deionized water, stir and dissolve in a 500mL beaker to obtain the first mixed solution; weigh 14.88g of copper nitrate trihydrate and dissolve in 205mL of deionized water to obtain the second mixed solution.

[0122] Weigh 26.5g of anhydrous sodium carbonate, 10g of sodium hydroxide and 1.08g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0123] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The suspension was kept at room temperature, maintaining a pH of 9. After the first mixed solution was completely added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining a pH of 9. After the addition was complete, the suspension was aged at 50°C for 20 hours. The aged slurry was washed, dried, and then calcined in a muffle furnace at 500°C for 4 hours to obtain the Cat12 catalyst sample.

[0124] Comparative Example 4

[0125] A copper-based catalyst was prepared using a one-step co-precipitation method. The mass ratio of Cu:ZnO:Al₂O₃ in the copper-based catalyst was 4:3:2. ZrO₂ promoter and SiO₂ accounted for 1 wt.% and 0.5 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0126] Weigh out 9.16g of zinc nitrate hexahydrate, 12.88g of aluminum nitrate nonahydrate, 13.30g of copper nitrate trihydrate, and 0.38g of zirconium nitrate, and dissolve them in 411mL of deionized water to obtain a mixed solution;

[0127] Weigh 26.5g of anhydrous sodium carbonate, 10g of sodium hydroxide and 0.27g of sodium silicate, add 500ml of deionized water, stir to dissolve, and form a 1mol / L alkaline precipitant solution.

[0128] The mixed solution and alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water. The pH of the suspension in the three-necked flask was maintained at 8 at room temperature. After the addition was completed, the suspension was aged at 60 °C for 16 h. The aged slurry was washed, dried, and then calcined in a muffle furnace at 300 °C for 4 h to obtain the sample Cat13 catalyst.

[0129] The above-described embodiments and comparative catalysts were applied to the carbon dioxide hydrogenation to methanol reaction, and their reaction performance was tested under the following conditions: reaction temperature 250°C, reaction pressure 5 MPa, and reaction space velocity 10000 mL·h. -1 ·g cat-1 The H2 to CO2 flow rate ratio was 3:1. The test results are shown in Table 1.

[0130] Table 1 Test Results

[0131]

[0132] Referring to Table 1, a comparison of Cat. 10 and Cat. 1-9 shows that additives and silica can effectively improve the CO2 conversion, methanol selectivity, and methanol space-time yield of copper-based catalysts, and effectively slow down the deactivation rate of copper-based catalysts. A comparison of Cat. 11 and Cat. 1-9 shows that silica can effectively improve the CO2 conversion, methanol selectivity, and methanol space-time yield of copper-based catalysts, and effectively slow down the deactivation rate of copper-based catalysts. A comparison of Cat. 12 and Cat. 1-9 shows that additives can effectively improve the CO2 conversion, methanol selectivity, and methanol space-time yield of copper-based catalysts, and effectively slow down the deactivation rate of copper-based catalysts. A comparison of Cat. 13 and Cat. 1-9 shows that stepwise precipitation can effectively improve the CO2 conversion, methanol selectivity, and methanol space-time yield of copper-based catalysts, and effectively slow down the deactivation rate of copper-based catalysts.

[0133] 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 description of this application, or direct or indirect applications in other related technical fields, are similarly included within the patent scope of this application.

Claims

1. Use of a copper-based catalyst in the hydrogenation of carbon dioxide to methanol, characterized in that, The preparation method of the copper-based catalyst comprises the following steps: mixing a zinc element precursor and an aluminum element precursor to obtain a first mixed solution, mixing a copper element precursor and an additive precursor to obtain a second mixed solution, and configuring an alkaline precipitator solution, wherein the alkaline precipitator solution contains a silicon dioxide precursor, sodium carbonate and sodium hydroxide; mixing the first mixed solution and the alkaline precipitator solution, controlling the pH value of the reaction system to be 8-10, precipitating zinc components and aluminum components, forming a zinc-aluminum hydrotalcite structure, and obtaining a first suspension; adding the second mixed solution and the alkaline precipitator solution to the first suspension, controlling the pH value of the reaction system to be 8-10, precipitating copper components and additives, and obtaining a second suspension, wherein the additives include at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide and europium oxide; aging treatment, drying treatment and calcination treatment are sequentially performed on the second suspension to obtain a copper-based catalyst, wherein the ratio of the amount of substance of aluminum to the sum of the amounts of substance of zinc, aluminum, copper and additives in the copper-based catalyst is 0.13-0.28, the mass percentage of additives in the copper-based catalyst is 0.5-4%, and the mass percentage of silicon dioxide in the copper-based catalyst is 0.5-4%.

2. Use of a copper-based catalyst according to claim 1 for the hydrogenation of carbon dioxide to methanol, characterized in that, The copper-based catalyst comprises copper oxide, aluminum oxide, zinc oxide, additives and silicon dioxide.

3. Use of a copper-based catalyst according to claim 1 for the hydrogenation of carbon dioxide to methanol, characterized in that, The molar ratio of sodium carbonate to sodium hydroxide is 0.5-1.

5.

4. Use of a copper-based catalyst according to any one of claims 1 to 3 for the hydrogenation of carbon dioxide to methanol, characterized in that, The temperature of the aging treatment is 50-70℃, and the time of the aging treatment is 10-24h; And / or, the temperature of the calcination treatment is 300-500℃, and the time of the calcination treatment is 3-5h.

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