Copper-based catalyst, preparation method therefor, and use thereof

Abstract

The present application discloses a copper-based catalyst, a preparation method therefor, and a use thereof. The preparation method for 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 auxiliary agent precursor to obtain a second mixed solution, and preparing an alkaline precipitant solution, wherein the alkaline precipitant solution comprises a silicon dioxide precursor; mixing the first mixed solution with the alkaline precipitant solution, and precipitating a zinc component and an aluminum component to obtain a first suspension; adding the second mixed solution and the alkaline precipitant solution to the first suspension, and precipitating a copper component and an auxiliary agent to obtain a second suspension; and sequentially carrying out aging treatment, drying treatment, and roasting treatment on the second suspension to obtain a copper-based catalyst.

Description

Copper-based catalyst and its preparation method and application

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202410306520.9 filed on March 18, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of catalyst technology, and in particular to a copper-based catalyst and a preparation method and application thereof. Background Art

[0004] Methanol, as an important basic chemical raw material, can be used to synthesize a variety of chemicals, including dimethyl ether, light olefins, aromatics, and acetic acid. It can also serve as an alternative fuel. China's methanol production primarily relies on coal-to-chemical processes, which have a high carbon intensity and are not conducive to carbon reduction. In the context of achieving carbon peak and carbon neutrality, the development of methanol production from carbon dioxide hydrogenation is of great significance.

[0005] Copper-based catalysts are often used in the reaction of carbon dioxide hydrogenation to produce methanol, and copper-based catalysts are often prepared by co-precipitation. Summary of the Invention

[0006] The main purpose of this application is to provide a copper-based catalyst and its preparation method and application, aiming to solve the technical problems of poor stability and low catalytic hydrogenation activity of copper-based catalysts in the prior art.

[0007] To achieve the above objectives, the present application provides a method for preparing a copper-based catalyst, which comprises the following steps:

[0008] Mixing a zinc element precursor and an aluminum element precursor to obtain a first mixed solution, mixing a copper element precursor and an auxiliary agent precursor to obtain a second mixed solution, and preparing an alkaline precipitant solution, wherein the alkaline precipitant solution contains a silicon dioxide precursor;

[0009] mixing the first mixed solution with an alkaline precipitant solution to precipitate zinc and aluminum components to obtain a first suspension;

[0010] adding the second mixed solution and the alkaline precipitant solution to the first suspension to precipitate the copper component and the auxiliary agent to obtain a second suspension;

[0011] The second suspension is subjected to aging treatment, drying treatment and calcination treatment in sequence to obtain a copper-based catalyst.

[0012] In one embodiment, in the copper-based catalyst, the ratio of the amount of aluminum to the sum of the amounts of zinc, aluminum, copper and promoter metals is 0.13-0.28.

[0013] In one embodiment, the copper-based catalyst includes copper oxide, aluminum oxide, zinc oxide, promoter oxide, and silicon dioxide.

[0014] In one embodiment, the mass proportion of the promoter oxide in the copper-based catalyst is 0.5-4%;

[0015] And / or, the mass proportion of silicon dioxide in the copper-based catalyst is 0.5-4%.

[0016] In one embodiment, the additive oxide includes at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide, and europium oxide.

[0017] In one embodiment, during the precipitation of the zinc component and the aluminum component, the pH value of the reaction system is controlled to be 8-10;

[0018] And / or, during the process of precipitating the copper component and the auxiliary agent, the pH value of the reaction system is controlled to be 8-10.

[0019] In one embodiment, the alkaline precipitant solution further comprises sodium carbonate and sodium hydroxide, and the molar ratio of the sodium carbonate to the sodium hydroxide is 0.5-1.5.

[0020] In one embodiment, the aging treatment temperature is 50-70° C., and the aging treatment time is 10-24 hours;

[0021] And / or, the temperature of the calcination treatment is 300-500° C., and the time of the aging treatment is 3-5 hours.

[0022] The present application also provides a copper-based catalyst, which is prepared using the copper-based catalyst preparation method described above.

[0023] The present application also provides a copper-based catalyst prepared by the method for preparing the copper-based catalyst as described above, or the use of the copper-based catalyst as described above in the hydrogenation of carbon dioxide to produce methanol.

[0024] The present application provides a copper-based catalyst and its preparation method and application. First, the co-precipitation is divided into 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, the zinc-aluminum hydrotalcite structure is formed before the copper and additives are precipitated, which is beneficial to improve the dispersibility of the subsequently precipitated copper, making the copper particle size more uniform, thereby suppressing the Oswald ripening effect. On the other hand, the zinc-aluminum hydrotalcite structure can play a confining role, inhibiting the migration and sintering of the copper component in the subsequent catalytic process. By inhibiting the migration of the copper component, the growth of the copper component in the catalytic process can be inhibited, thereby also inhibiting its ripening and sintering. Second, copper and additives are co-precipitated, and the inhibitory effect of the additive is used to inhibit the migration of copper, thereby inhibiting the sintering caused by the migration of copper. Third, the introduction of a silica precursor in an alkaline precipitant solution can achieve the purpose of introducing hydrophobic silica in situ during the coprecipitation process. On the one hand, the introduction of silica can improve the hydrophobicity of the copper-based catalyst and avoid the situation in which the catalyst is deactivated due to the presence of water. On the other hand, compared to other strategies for introducing silica, such as silane coupling agent modification strategies, physical mixing, etc., the in-situ introduction of silica will not cover the surface active sites of the copper-based catalyst, and the catalytic hydrogenation activity of the obtained copper-based catalyst is higher. Therefore, the technical defect that the copper-based catalyst has poor hydrothermal stability and low catalytic hydrogenation activity is overcome. The present application can prepare a copper-based catalyst with higher hydrothermal stability and higher catalytic hydrogenation activity by improving the preparation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0026] FIG1 is a schematic flow chart of an embodiment of a method for preparing a copper-based catalyst of the present application.

[0027] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. Modes for Carrying Out the Invention

[0028] To make the above-mentioned purposes, features, and advantages of the present application more clearly understood, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of them. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0029] However, the copper-based catalysts prepared by co-precipitation generally have larger copper particles and a wide range of particle size distribution. The uneven particle size is prone to Oswald ripening effect, which leads to sintering and deactivation of the catalyst. In addition, the reaction of carbon dioxide hydrogenation to methanol occurs under high temperature conditions, and the hydrothermal stability of copper-based catalysts is poor. On the one hand, copper-based catalysts are prone to sintering at reaction temperatures above 200°C, resulting in a reduction in active centers and deactivation of the catalyst. On the other hand, the process of carbon dioxide hydrogenation to methanol is accompanied by the generation of water, which will accelerate the sintering of copper. The embodiment of the present application provides a method for preparing a copper-based catalyst. Referring to Figure 1, the method for preparing the copper-based catalyst comprises the following steps:

[0030] Step S10: mixing a zinc element precursor and an aluminum element precursor to obtain a first mixed solution, mixing a copper element precursor and an auxiliary agent precursor to obtain a second mixed solution, and preparing an alkaline precipitant solution, wherein the alkaline precipitant solution contains a silicon dioxide precursor;

[0031] In this embodiment, the copper-based catalyst refers to a copper-zinc-aluminum system copper-based catalyst, which can catalyze the hydrogenation of carbon dioxide to produce methanol. The copper-zinc-aluminum system copper-based catalyst includes at least copper oxide, aluminum oxide, and zinc oxide. Among them, copper is the main active metal in the copper-based catalyst; zinc oxide can be used as a structural additive and an electronic additive to improve the dispersion of copper and increase the specific surface area; aluminum oxide can be used as a structural additive to increase the specific surface area and mechanical stability of the catalyst. However, the stability of the copper-based catalyst is poor, and it will gradually deactivate during the catalytic hydrogenation process, mainly including: first, deactivation caused by the migration of copper species; second, sintering and aging caused by uneven particle size of copper species; third, water-induced catalyst deactivation.

[0032] In one embodiment, the copper-based catalyst includes copper oxide, aluminum oxide, zinc oxide, a promoter, and silicon dioxide.

[0033] In the present embodiment, in addition to comprising copper oxide, aluminum oxide and zinc oxide, the copper-based catalyst may also include an auxiliary agent and silicon dioxide. The auxiliary agent refers to a substance that is inactive or has very little activity itself, but can change some properties of the catalyst, such as electronic structure, ionic valence, acidity and alkalinity, surface structure, grain size, etc., so that the activity, selectivity, anti-toxicity or stability of the catalyst are improved. The auxiliary agent can be at least one of a metal oxide or an inorganic non-metallic porous material. The silicon dioxide is formed by reacting a silicon dioxide precursor with a zinc element precursor, an aluminum element precursor, a copper element precursor and an auxiliary agent precursor. On the one hand, silicon dioxide has hydrophobicity, so the introduction of silicon dioxide can improve the hydrophobicity of the copper-based catalyst, avoids the situation that the catalyst deactivation is accelerated due to the presence of water, and on the other hand, compared to other strategies for introducing silicon dioxide, such as silane coupling agent modification strategy, physical mixing, etc., the in-situ introduction of silicon dioxide will not cover the copper-based catalyst surface active sites, and the catalytic hydrogenation activity of the copper-based catalyst obtained is higher.

[0034] In one embodiment, the auxiliary agent includes at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide, and europium oxide.

[0035] In this embodiment, the metal oxide has excellent mechanical properties and thermal conductivity. This not only improves copper dispersion, inhibits copper migration, ensures uniform copper particle size, and prevents aging and sintering, but also enhances the mechanical stability and thermal conductivity of the copper-based catalyst, reducing high-temperature sintering. The hydrophobic metal oxide further prevents accelerated catalyst deactivation due to the presence of water, enhances 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.

[0036] The zinc element precursor is used to prepare zinc oxide and can be a soluble salt of zinc, including at least one of zinc nitrate and zinc acetate. The aluminum element precursor is used to prepare aluminum oxide and can be a soluble salt of aluminum, including at least one of aluminum nitrate and aluminum acetate. The copper element precursor is used to prepare copper oxide and can be a soluble salt of copper, including at least one of copper nitrate and copper acetate. The auxiliary agent precursor is used to prepare auxiliary agents and 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 value, and the alkaline precipitant solution contains a silicon dioxide precursor. The silicon dioxide precursor is used to prepare silicon dioxide and can be an alkaline soluble silicate, including at least one of sodium silicate and potassium silicate.

[0037] In one embodiment, the alkaline precipitant solution further comprises sodium carbonate and sodium hydroxide, and the molar ratio of the sodium carbonate to the sodium hydroxide is 0.5-1.5.

[0038] In this embodiment, by compounding sodium carbonate and sodium hydroxide, a zinc-aluminum hydrotalcite structure can be formed when the zinc component and the aluminum component are precipitated, and the molar ratio of the sodium carbonate to the sodium hydroxide is 0.5-1.5, for example, 0.5, 0.8, 1.0, 1.2, 1.5, etc.

[0039] As an example, step S10 includes: weighing a zinc element precursor, an aluminum element precursor, a copper element precursor, an auxiliary agent precursor, a silicon dioxide precursor and a precipitant in a certain proportion. The zinc element precursor and the aluminum element precursor are dissolved, mixed evenly, and configured into a first mixed solution; the copper element precursor and the auxiliary agent precursor are dissolved, mixed evenly, and configured into a second mixed solution; the silicon dioxide precursor and the precipitant are dissolved, mixed evenly, and configured into a precipitant solution. It should be noted that the first mixed solution, the second mixed solution and the precipitant solution are configured separately, and the order of configuration is not limited. The amount of the zinc element precursor, the aluminum element precursor, the copper element precursor, the auxiliary agent precursor, the silicon dioxide precursor and the precipitant can be determined and adjusted in advance according to experimental test results or actual conditions, and this embodiment does not limit this.

[0040] In one embodiment, in the copper-based catalyst, the ratio of the amount of aluminum to the sum of the amounts of zinc, aluminum, copper and promoter metals is 0.13-0.28.

[0041] In this embodiment, the various raw materials for preparing 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 finally prepared copper-based catalyst is 0.13-0.28, for example, 0.13, 0.15, 0.2, 0.25, 0.28, etc. In this case, the stability and catalytic hydrogenation activity of the copper-based catalyst are better.

[0042] In one embodiment, the mass proportion of the additive in the copper-based catalyst is 0.5-4%;

[0043] And / or, the mass proportion of silicon dioxide in the copper-based catalyst is 0.5-4%.

[0044] In this embodiment, if the mass proportion of the auxiliary agent in the copper-based catalyst is too low, the improvement of the catalyst performance is not obvious. If the mass proportion of the auxiliary agent in the copper-based catalyst is too high, it may cover the active center, which in turn leads to a decrease in catalytic hydrogenation activity. Therefore, the mass proportion of the auxiliary agent in the copper-based catalyst is determined to be 0.5-4%, for example, 0.5%, 1%, 2%, 3%, 4%, etc.

[0045] If the mass proportion of the silica in the copper-based catalyst is too low, the improvement of the hydrophobicity of the catalyst is not obvious. If the mass proportion of the silica in the copper-based catalyst is too high, it may cover the active centers, which in turn leads to a decrease in catalytic hydrogenation activity. Therefore, the mass proportion of silica in the copper-based catalyst is determined to be 0.5-4%, for example, 0.5%, 1%, 2%, 3%, 4%, etc.

[0046] Step S20, mixing the first mixed solution with an alkaline precipitant solution to precipitate zinc and aluminum components to obtain a first suspension;

[0047] As an example, step S20 includes: taking a certain amount of pure water, synchronously and uniformly dropping the first mixed solution and the alkaline precipitant solution into the pure water, so that the zinc component and the aluminum component are co-precipitated to form a zinc-aluminum hydrotalcite structure, and after the first mixed solution is added, a first suspension is obtained.

[0048] In one embodiment, during the precipitation of the zinc component and the aluminum component, the pH value of the reaction system is controlled to be 8-10.

[0049] In this embodiment, the pH value of the reaction system can be simultaneously tested during the process of dropwise adding the first mixed solution and the alkaline precipitant solution, and the pH value of the reaction system can be controlled within the range of 8-10 by adjusting the dropwise addition speed of the alkaline precipitant solution.

[0050] Step S30, adding the second mixed solution and the alkaline precipitant solution to the first suspension to precipitate the copper component and the auxiliary agent to obtain a second suspension;

[0051] As an example, step S30 includes: after the first mixed solution is added, the second mixed solution and the alkaline precipitant solution can be further added to the first suspension at a uniform speed, so that the copper component and the auxiliary agent are co-precipitated, and the copper component and the auxiliary agent are dispersed and attached to the zinc-aluminum hydrotalcite together. After the second mixed solution is added, a second suspension is obtained.

[0052] In one embodiment, during the process of precipitating the copper component and the auxiliary agent, the pH value of the reaction system is controlled to be 8-10.

[0053] In this embodiment, the pH value of the reaction system can be simultaneously tested during the process of adding the second mixed solution and the alkaline precipitant solution, and the pH value of the reaction system can be controlled within the range of 8-10 by adjusting the dropping speed of the alkaline precipitant solution.

[0054] Step S40: performing aging treatment, drying treatment and calcination treatment on the second suspension in sequence to obtain a copper-based catalyst.

[0055] As an example, step S40 includes: after the zinc, aluminum, copper, and additives are precipitated stepwise, the second suspension is sequentially aged. After the aging, the precipitate can be washed, dried, and calcined to obtain the copper-based catalyst. The specific process parameters for the aging, drying, and calcining processes can be determined and adjusted based on actual needs and test results, and are not limited in this embodiment.

[0056] In one embodiment, the aging treatment temperature is 50-70° C., and the aging treatment time is 10-24 hours;

[0057] And / or, the temperature of the calcination treatment is 300-500° C., and the time of the aging treatment is 3-5 hours.

[0058] In this embodiment, the temperature of the aging treatment is 50-70°C, such as 50°C, 60°C, 70°C, etc., and the time of the aging treatment is 10-24h, such as 10h, 15h, 20h, 24h, etc.

[0059] The temperature of the calcination treatment is 300-500°C, such as 300°C, 350°C, 400°C, 450°C, 500°C, etc., and the time of the aging treatment is 3-5h, such as 3h, 4h, 5h, etc.

[0060] In this embodiment, the preparation method of the copper-based catalyst includes 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 auxiliary agent precursor 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 and the alkaline precipitant solution to precipitate the zinc component and the aluminum component to obtain a first suspension; adding the second mixed solution and the alkaline precipitant solution to the first suspension to precipitate the copper component and the auxiliary agent to obtain a second suspension; and performing aging treatment, drying treatment and calcination treatment on the second suspension in sequence to obtain a copper-based catalyst. First, the co-precipitation is carried out in two steps: first, zinc and aluminum are precipitated to form a zinc-aluminum hydrotalcite structure, followed by the precipitation of copper and additives. Forming the zinc-aluminum hydrotalcite structure before the copper and additives precipitate improves the dispersion of the subsequently precipitated copper, making the copper particle size more uniform and thus suppressing the Oswald ripening effect. Furthermore, the zinc-aluminum hydrotalcite structure acts as a confinement site, inhibiting the migration and sintering of the copper component during the subsequent catalytic process. This inhibition of copper migration also inhibits the growth of the copper component during the catalytic process, thereby also preventing sintering. Second, the copper and additive are co-precipitated, utilizing the inhibitory effect of the additive to inhibit copper migration, thereby suppressing sintering caused by copper migration. Third, by introducing a silica precursor into an alkaline precipitant solution, it is possible to achieve the purpose of introducing hydrophobic silica in situ during the coprecipitation process. On the one hand, the introduction of silica can improve the hydrophobicity of the copper-based catalyst and avoid the situation in which the catalyst is deactivated due to the presence of water. On the other hand, compared to other strategies for introducing silica, such as silane coupling agent modification strategies, physical mixing, etc., silica is introduced in situ without covering the surface active sites of the copper-based catalyst, and the catalytic hydrogenation activity of the obtained copper-based catalyst is higher. Therefore, the technical defect that the copper-based catalyst has low hydrothermal stability and low catalytic hydrogenation activity is overcome. The present application can prepare a copper-based catalyst with higher hydrothermal stability and higher catalytic hydrogenation activity by improving the preparation method.

[0061] The present application also provides a copper-based catalyst, which is prepared using the copper-based catalyst preparation method described above.

[0062] The copper-based catalyst provided in this application is prepared using the method for preparing the copper-based catalyst described above, which solves the technical problems of poor stability and low catalytic hydrogenation activity of the copper-based catalysts in the prior art. Compared with the prior art, the beneficial effects of the copper-based catalysts provided in the embodiments of this application are the same as the beneficial effects of the method for preparing the copper-based catalysts provided in the above embodiments, and the other technical features of the copper-based catalysts are the same as those disclosed in the above embodiments, which are not described in detail here.

[0063] The present application also provides a copper-based catalyst prepared by the preparation method of the copper-based catalyst as described above, or the use of the copper-based catalyst as described above in the hydrogenation of carbon dioxide to produce methanol.

[0064] The copper-based catalyst prepared by the method for preparing the copper-based catalyst as described above provided in the present application or the application of the copper-based catalyst as described above in the hydrogenation of carbon dioxide to produce methanol solves the technical problems of poor stability and low catalytic hydrogenation activity of the copper-based catalysts in the prior art. Compared with the prior art, the beneficial effects of the application of the copper-based catalyst provided in the embodiments of the present application in the hydrogenation of carbon dioxide to produce methanol are the same as the beneficial effects of the method for preparing the copper-based catalyst provided in the above embodiments, and the other technical features of the application of the copper-based catalyst in the hydrogenation of carbon dioxide to produce methanol are the same as the features disclosed in the above embodiment methods, which are not described in detail here.

[0065] The present application is described in detail below with reference to specific embodiments and comparative examples. The following description is merely illustrative and does not constitute a specific limitation on the present application.

[0066] Example 1

[0067] 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. The ZrO2 promoter and SiO2 in the copper-based catalyst accounted for 1 wt.% and 0.5 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0068] Weigh 9.16 g of zinc nitrate hexahydrate and 12.88 g of aluminum nitrate nonahydrate, add 223 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 13.30 g of copper nitrate trihydrate and 0.38 g of zirconium nitrate and dissolve in 188 mL of deionized water to obtain a second mixed solution.

[0069] Weigh 26.5 g of anhydrous sodium carbonate, 10 g of sodium hydroxide, and 0.27 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0070] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 300°C for 4 hours to obtain sample Cat1 catalyst.

[0071] Example 2

[0072] 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. The MgO additive and SiO2 in the copper-based catalyst accounted for 1 wt.% and 1 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0073] Weigh 9.11 g of zinc nitrate hexahydrate and 12.81 g of aluminum nitrate nonahydrate, add 223 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 13.23 g of copper nitrate trihydrate and 0.51 g of magnesium nitrate and dissolve in 188 mL of deionized water to obtain a second mixed solution.

[0074] Weigh 29.44 g of anhydrous sodium carbonate, 8.8 g of sodium hydroxide, and 0.54 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0075] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 9. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 9. After the addition was complete, the suspension was aged at 50°C for 24 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 500°C for 3 hours to obtain the sample Cat2 catalyst.

[0076] Example 3

[0077] 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. The MgO additive and SiO2 in the copper-based catalyst accounted for 2 wt.% and 4 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0078] Weigh 8.74 g of zinc nitrate hexahydrate and 12.28 g of aluminum nitrate nonahydrate, add 213 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 12.69 g of copper nitrate trihydrate and 1.02 g of magnesium nitrate and dissolve in 187 mL of deionized water to obtain a second mixed solution.

[0079] Weigh 29.44 g of anhydrous sodium carbonate, 8.8 g of sodium hydroxide, and 2.16 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0080] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 10. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 10. After the addition was complete, the suspension was aged at 70°C for 12 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 500°C for 4 hours to obtain the Cat3 catalyst sample.

[0081] Example 4

[0082] 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. The MgO additive and SiO2 in the copper-based catalyst accounted for 1 wt.% and 4 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0083] Weigh 7.95 g of zinc nitrate hexahydrate and 11.18 g of aluminum nitrate nonahydrate, add 194 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 14.43 g of copper nitrate trihydrate and 0.51 g of magnesium nitrate and dissolve in 205 mL of deionized water to obtain a second mixed solution.

[0084] Weigh 31.8 g of anhydrous sodium carbonate, 8 g of sodium hydroxide, and 2.16 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0085] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 9.5. After the first mixed solution was 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 calcined in a muffle furnace at 500°C for 4 hours to obtain the Cat4 catalyst sample.

[0086] Example 5

[0087] 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. The SrO2 promoter and SiO2 in the copper-based catalyst accounted for 1 wt.% and 2 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0088] Weigh 8.12 g of zinc nitrate hexahydrate and 11.41 g of aluminum nitrate nonahydrate, add 164 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 14.74 g of copper nitrate trihydrate and 0.16 g of strontium nitrate and dissolve in 229 mL of deionized water to obtain a second mixed solution.

[0089] Weigh 31.8 g of anhydrous sodium carbonate, 8 g of sodium hydroxide, and 1.08 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0090] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat5 catalyst sample.

[0091] Example 6

[0092] 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. The MgO additive and SiO2 in the copper-based catalyst accounted for 1 wt.% and 5 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0093] Weigh 6.56 g of zinc nitrate hexahydrate and 13.82 g of aluminum nitrate nonahydrate, add 201 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 14.28 g of copper nitrate trihydrate and 1.02 g of magnesium nitrate and dissolve in 209 mL of deionized water to obtain a second mixed solution.

[0094] Weigh 22.71 g of anhydrous sodium carbonate, 11.43 g of sodium hydroxide, and 1.08 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0095] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 8. After the addition was complete, the suspension was aged at 60°C for 20 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat6 catalyst sample.

[0096] Example 7

[0097] 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. The MgO additive and SiO2 in the copper-based catalyst accounted for 1 wt.% and 1 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0098] Weigh 9.11 g of zinc nitrate hexahydrate and 6.41 g of aluminum nitrate nonahydrate, add 165 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 16.54 g of copper nitrate trihydrate and 0.51 g of magnesium nitrate and dissolve in 234 mL of deionized water to obtain a second mixed solution.

[0099] Weigh 29.44 g of anhydrous sodium carbonate, 8.8 g of sodium hydroxide, and 0.54 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0100] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 8. After the addition was complete, the suspension was aged at 60°C for 20 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat7 catalyst sample.

[0101] Example 8

[0102] 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. The CaO additive and SiO2 in the copper-based catalyst accounted for 0.5 wt.% and 3 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0103] Weigh 8.97 g of zinc nitrate hexahydrate and 6.31 g of aluminum nitrate nonahydrate, add 163 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 16.28 g of copper nitrate trihydrate and 0.07 g of calcium nitrate and dissolve in 224 mL of deionized water to obtain a second mixed solution.

[0104] Weigh 22.71 g of anhydrous sodium carbonate, 11.43 g of sodium hydroxide, and 0.54 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0105] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 9. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 9. After the addition was complete, the suspension was aged at 60°C for 20 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 400°C for 4 hours to obtain the Cat8 catalyst sample.

[0106] Example 9

[0107] 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. The ZrO2 promoter and SiO2 in the copper-based catalyst accounted for 1 wt.% and 2 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0108] Weigh 9.02 g of zinc nitrate hexahydrate and 6.34 g of aluminum nitrate nonahydrate, add 164 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 16.37 g of copper nitrate trihydrate and 0.38 g of zirconium nitrate and dissolve in 188 mL of deionized water to obtain a second mixed solution.

[0109] Weigh 26.5 g of anhydrous sodium carbonate, 10 g of sodium hydroxide, and 0.11 g of sodium silicate, add 400 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0110] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 300°C for 5 hours to obtain the Cat9 catalyst sample.

[0111] Comparative Example 1

[0112] 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 no additives or SiO2 were added. The specific preparation method is as follows:

[0113] Weigh 9.3 g of zinc nitrate hexahydrate and 13.07 g of aluminum nitrate nonahydrate, add 227 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 13.50 g of copper nitrate trihydrate and dissolve it in 185 mL of deionized water to obtain a second mixed solution.

[0114] Weigh 26.5 g of anhydrous sodium carbonate and 10 g of sodium hydroxide, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0115] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 9. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 9. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 400°C for 4 hours to obtain the Cat10 catalyst sample.

[0116] Comparative Example 2

[0117] 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 mass of the catalyst, and no SiO2 was added. The specific preparation method is as follows:

[0118] Weigh 9.21 g of zinc nitrate hexahydrate and 6.47 g of aluminum nitrate nonahydrate, add 167 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 16.71 g of copper nitrate trihydrate and 0.51 g of magnesium nitrate and dissolve in 236 mL of deionized water to obtain a second mixed solution.

[0119] Weigh 26.5 g of anhydrous sodium carbonate and 10 g of sodium hydroxide, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0120] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 8. After the addition was complete, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 400°C for 4 hours to obtain the Cat11 catalyst sample.

[0121] Comparative Example 3

[0122] 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. SiO2 was added at 1 wt.% of the total mass of the catalyst, and no additives were added. The specific preparation method is as follows:

[0123] Weigh 8.2 g of zinc nitrate hexahydrate and 11.53 g of aluminum nitrate nonahydrate, add 200 mL of deionized water, and stir to dissolve in a 500 mL beaker to obtain a first mixed solution. Weigh 14.88 g of copper nitrate trihydrate and dissolve it in 205 mL of deionized water to obtain a second mixed solution.

[0124] Weigh 26.5 g of anhydrous sodium carbonate, 10 g of sodium hydroxide, and 1.08 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0125] First, the first mixed solution and the alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 9. After the first mixed solution was added, the second mixed solution and the alkaline precipitant solution were added dropwise to the suspension, maintaining the pH at 9. After the addition was complete, the suspension was aged at 50°C for 20 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 500°C for 4 hours to obtain the Cat12 catalyst sample.

[0126] Comparative Example 4

[0127] 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. The ZrO2 promoter and SiO2 in the copper-based catalyst accounted for 1 wt.% and 0.5 wt.% of the total catalyst mass, respectively. The specific preparation method is as follows:

[0128] Weigh 9.16 g of zinc nitrate hexahydrate, 12.88 g of aluminum nitrate nonahydrate, 13.30 g of copper nitrate trihydrate, and 0.38 g of zirconium nitrate and dissolve them in 411 mL of deionized water to obtain a mixed solution.

[0129] Weigh 26.5 g of anhydrous sodium carbonate, 10 g of sodium hydroxide, and 0.27 g of sodium silicate, add 500 ml of deionized water, and stir to dissolve to form a 1 mol / L alkaline precipitant solution.

[0130] The mixed solution and alkaline precipitant solution were simultaneously added dropwise to a three-necked flask containing 100 ml of deionized water at room temperature, maintaining the pH of the suspension in the flask at 8. After the addition, the suspension was aged at 60°C for 16 hours. The aged slurry was washed, dried, and calcined in a muffle furnace at 300°C for 4 hours to obtain the Cat13 catalyst sample.

[0131] The above-described example and comparative catalysts were used in the carbon dioxide hydrogenation to methanol reaction to test their performance. The test conditions were: reaction temperature of 250°C, reaction pressure of 5 MPa, reaction space velocity of 10,000 mL∙h⁻¹∙gcat⁻¹, and a H₂:CO₂ flow ratio of 3:1. The test results are shown in Table 1.

[0132] Table 1 Test results

[0133] Sample name CO2 conversion (%) Methanol selectivity (%) Methanol space-time yield (gMeOH∙gcat-1∙h-1) Deactivation rate (% / h) Cat.124.156.50.4860.083 Cat.221.4530.4050.078 Cat.320.651.90.3820.046 Cat.422.156.40.4450.045 Cat.523.659.10.4980.072 Cat.621.95 4.30.4250.062Cat.724.662.10.5460.059Cat.822.5530.4260.089Cat.924.160.20.5180.075Cat.1018 .248.50.3150.129Cat.1123.958.80.5020.081Cat.1221.652.80.4070.076Cat.1320.550.80.3720.091

[0134] Referring to Table 1, a comparison of Cat.10 and Cat.1-9 shows that the additive and silica can effectively improve the CO2 conversion rate, methanol selectivity, and methanol space-time yield of the copper-based catalyst, and effectively slow down the deactivation rate of the copper-based catalyst. A comparison of Cat.11 and Cat.1-9 shows that silica can effectively improve the CO2 conversion rate, methanol selectivity, and methanol space-time yield of the copper-based catalyst, and effectively slow down the deactivation rate of the copper-based catalyst. A comparison of Cat.12 and Cat.1-9 shows that the additive can effectively improve the CO2 conversion rate, methanol selectivity, and methanol space-time yield of the copper-based catalyst, and effectively slow down the deactivation rate of the copper-based catalyst. A comparison of Cat.13 and Cat.1-9 shows that step-by-step precipitation can effectively improve the CO2 conversion rate, methanol selectivity, and methanol space-time yield of the copper-based catalyst, and effectively slow down the deactivation rate of the copper-based catalyst.

[0135] The above are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structures or equivalent process transformations made using the description of this application, or directly or indirectly applied in other related technical fields, are also included in the patent scope of the present application.

Claims

1. A method for preparing a copper-based catalyst, wherein: 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 auxiliary agent precursor to obtain a second mixed solution, and preparing an alkaline precipitant solution, wherein the alkaline precipitant solution contains a silicon dioxide precursor; mixing the first mixed solution with an 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 the copper component and the auxiliary agent to obtain a second suspension; The second suspension is subjected to aging treatment, drying treatment and calcination treatment in sequence to obtain a copper-based catalyst.

2. The method for preparing a copper-based catalyst according to claim 1, wherein In the copper-based catalyst, the ratio of the amount of aluminum to the sum of the amounts of zinc, aluminum, copper and promoter metal is 0.13-0.

28.

3. The method for preparing a copper-based catalyst according to claim 1, wherein The copper-based catalyst comprises copper oxide, aluminum oxide, zinc oxide, an auxiliary agent and silicon dioxide.

4. The method for preparing a copper-based catalyst according to claim 3, wherein The mass proportion of the additive in the copper-based catalyst is 0.5-4%; And / or, the mass proportion of silicon dioxide in the copper-based catalyst is 0.5-4%.

5. The method for preparing a copper-based catalyst according to claim 3, wherein The auxiliary agent includes at least one of magnesium oxide, zirconium oxide, calcium oxide, strontium oxide and europium oxide.

6. The method for preparing a copper-based catalyst according to claim 1, wherein During the precipitation of the zinc component and the aluminum component, the pH value of the reaction system is controlled to be 8-10; And / or, during the process of precipitating the copper component and the auxiliary agent, the pH value of the reaction system is controlled to be 8-10.

7. The method for preparing a copper-based catalyst according to claim 1, wherein The alkaline precipitant solution further comprises sodium carbonate and sodium hydroxide, and the molar ratio of the sodium carbonate to the sodium hydroxide is 0.5-1.

5.

8. The method for preparing a copper-based catalyst according to any one of claims 1 to 7, wherein The aging treatment temperature is 50-70°C, and the aging treatment time is 10-24h; And / or, the temperature of the calcination treatment is 300-500° C., and the time of the aging treatment is 3-5 hours.

9. A copper-based catalyst, wherein The copper-based catalyst is prepared by the method for preparing the copper-based catalyst according to any one of claims 1 to 8.

10. Use of the copper-based catalyst prepared by the method for preparing the copper-based catalyst according to any one of claims 1 to 8 or the copper-based catalyst according to claim 9 in the hydrogenation of carbon dioxide to methanol.

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