A catalyst for the hydrogenation of carbon dioxide to methanol

Abstract

This invention belongs to the field of chemical engineering technology, specifically the field of heterogeneous catalytic reaction technology, and is a catalyst for the hydrogenation of carbon dioxide to methanol. The catalyst comprises a metal component, an additive, a support, and rare earth elements; the metal component includes at least one of copper, gallium, alkali metals or alkaline earth metals, and zirconium or titanium oxides; wherein the additive is added at 2-10%, the support at 5-20%, the rare earth elements at 0.1-5%, and the balance is the metal component; of the metal component, the copper content is 30-70%, the gallium content is 1-10%, the alkali metal or alkaline earth metal content is 0.1-3%, and the Zr or Ti oxide content is 1-10%. The application of this catalyst aims to convert the greenhouse gas CO2 into valuable methanol, which not only helps reduce CO2 emissions but also provides a sustainable raw material source for the chemical industry.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering technology, specifically the field of heterogeneous catalytic reaction technology, and is a catalyst for the reaction of carbon dioxide hydrogenation to methanol. Background Technology

[0002] Methanol, as one of the most basic chemical raw materials, has a wide range of applications and is one of the most important products in C1 chemistry. Currently, the most commonly used catalysts for the catalytic hydrogenation of CO2 to methanol are copper-based catalysts, typically prepared by co-precipitation. However, catalysts prepared by co-precipitation generally have large particle sizes, poor dispersibility, and a wide particle size distribution, resulting in poor stability. Copper-based catalysts are prone to particle agglomeration or sintering, especially when the catalyst has low dispersibility and uneven particle size, leading to agglomeration of active components and reduced catalytic activity. Therefore, preparing a supported, highly dispersible copper-based catalyst to inhibit copper particle migration, agglomeration, and ripening growth to improve catalyst stability is a significant challenge.

[0003] Chinese patent CN 104841429 A discloses a catalyst for the hydrogenation of CO2 to methanol, which uses a multilayer supported method to prepare a copper-based catalyst, achieving high catalytic activity at a low loading rate. However, the preparation steps of this method are relatively cumbersome, and a large number of organic reagents are used in the preparation process, making it difficult to achieve large-scale production.

[0004] Chinese patent CN 104549362 A discloses a highly dispersed copper-based catalyst with high catalytic activity and stability. However, this catalyst has high production costs due to the addition of precious metals during its preparation.

[0005] Chinese patent CN 107185543 A discloses a copper-based catalyst for CO2 hydrogenation. This catalyst supports copper on a ZnO support with a specific morphology. Compared with the catalyst prepared by co-precipitation, the activity and methanol selectivity of the catalyst are significantly improved. However, the stability of this catalyst is relatively poor. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of relatively poor stability of existing carbon dioxide hydrogenation to methanol catalysts, and the fact that existing solutions increase costs and have limited effectiveness, and to provide a carbon dioxide hydrogenation to methanol reaction catalyst, as well as its preparation and application.

[0007] To achieve the above-mentioned objectives, the specific technical solution of the present invention is as follows:

[0008] A catalyst for the hydrogenation of carbon dioxide to methanol, the catalyst composition comprising: a metal component, an additive, a support, and rare earth elements; wherein the additive is added at an amount of 2-10%, the support at 5-20%, the rare earth elements at 0.1-5%, and the balance is the metal component, the total mass percentage being 100%.

[0009] Furthermore, the metal component includes at least one of copper, gallium, alkali metal and alkaline earth metal and at least one transition metal oxide of zirconium (Zr) and titanium (Ti); that is, the metal component includes at least one of copper, gallium, alkali metal and zirconium (Zr) or titanium (Ti); or includes at least one of copper, gallium, alkaline earth metal and zirconium (Zr) or titanium (Ti).

[0010] Furthermore, in the metal components, the copper content (by mass) is 30-70%, the gallium content is 1-10%, the alkali metal or alkaline earth metal content is 0.1-3%, and the Zr or Ti oxide content is 1-10%.

[0011] Furthermore, the additive is at least one of zinc (Zn), aluminum (Al), zirconium (Zr), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), tin (Sn) and their oxides; wherein the carrier is at least one of aluminum oxide (Al2O3), silicon dioxide, molecular sieve and porous material.

[0012] Furthermore, the rare earth elements are lanthanum, cerium, praseodymium, neodymium, yttrium, etc.

[0013] Furthermore, the rare earth element is preferably cerium (Ce), and its content is preferably between 0.5 wt% and 3 wt% to optimize catalytic performance.

[0014] A method for preparing a catalyst for the hydrogenation of carbon dioxide to methanol includes the following steps:

[0015] a) Provide a soluble salt solution containing a copper salt, a gallium salt, and at least one selected from alkali metals and alkaline earth metals;

[0016] b) Mix the solution from step a) with a precursor containing an auxiliary agent (such as a transition metal oxide of zirconium or titanium) to form a composite solution;

[0017] c) Add a compound containing rare earth elements to the composite solution in step b), and stir until homogeneous to obtain a mixed solution.

[0018] d) Add the precursor of the auxiliary agent to the mixture from step c) according to the predetermined ratio, and stir thoroughly.

[0019] e) Immerse the carrier material in the mixture of step d), add a precipitant to allow the metal ions to precipitate and load the material, so that the components are evenly distributed on the carrier.

[0020] f) The loaded support is dried and / or calcined to fix the active components and form the final catalyst structure;

[0021] g) The product obtained in step f) is subjected to reduction treatment to activate the metal component.

[0022] Preferably, the gallium salt in step a) is selected from gallium nitrate, gallium sulfate, or gallium chloride.

[0023] Preferably, the precursor containing the auxiliaries in step b) includes zinc salts, aluminum salts, etc.; the zinc salt is selected from zinc nitrate, zinc sulfate, or zinc chloride; and the aluminum salt is selected from aluminum nitrate, aluminum sulfate, or aluminum chloride.

[0024] Preferably, the drying temperature range in step f) is 80℃ to 200℃ (specifically 80℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, etc.), the calcination temperature range is 300℃ to 600℃ (specifically 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, etc.), and the calcination time is 2-6 hours (specifically 2h, 3h, 4h, 5h, 6h, etc.); and the calcination atmosphere can be air, inert gas, or reducing gas.

[0025] Preferably, the precipitant in step e) is selected from sodium carbonate, potassium carbonate, sodium hydroxide, or potassium hydroxide.

[0026] Preferably, the reduction treatment in step g) is carried out in the presence of hydrogen or other reducing gases within a temperature range of 200°C to 400°C (specifically, 200°C, 250°C, 300°C, 350°C, 400°C, etc.) to ensure proper activation of the metal components.

[0027] Preferably, the reduction process in step g) takes 1-3 hours (specifically, 1h, 1.5h, 2h, 2.5h, 3h, etc.).

[0028] This invention also protects the use of the catalyst (copper-based catalyst) described above or the catalyst (copper-based catalyst) prepared by the above method in the hydrogenation of carbon dioxide to methanol.

[0029] Preferably, a method for producing methanol by hydrogenation of carbon dioxide using a copper-based catalyst includes the following steps:

[0030] (a) The copper-based catalyst is loaded into the reactor;

[0031] (b) Introduce a mixture of carbon dioxide and hydrogen into the reactor;

[0032] (c) The reaction is carried out at a reaction temperature of 200-300℃ and a reaction pressure of 1-10MPa to produce methanol.

[0033] Preferably, in step (b), the molar ratio of carbon dioxide to hydrogen is 1:3 to 1:5.

[0034] Preferably, in step (c), the reaction time is 1-5 hours.

[0035] Compared with the prior art, the positive effects of the present invention are reflected in:

[0036] (1) Adding gallium (Ga) to a copper-based catalyst can adjust the electronic structure of the copper surface, thereby changing its selectivity for different reaction pathways. For the production of methanol by CO2 hydrogenation, the selectivity for the target product methanol can be enhanced by optimizing the copper-gallium interface, and the formation of byproducts such as carbon monoxide (CO) or hydrocarbons can be reduced.

[0037] When operating under high temperature and high pressure conditions, traditional copper-based catalysts may sinter, leading to the loss of active sites. The presence of gallium helps stabilize copper particles, preventing them from excessively agglomerating, thereby maintaining the long-term activity and stability of the catalyst.

[0038] Gallium alters the chemical properties of the copper surface, making CO2 more accessible and converting it into intermediates, which can then be further converted into methanol. This helps improve CO2 adsorption capacity and activation efficiency, making the entire catalytic process more efficient.

[0039] The addition of appropriate amounts of gallium can influence the overall acid-base environment of the catalyst. A proper acid-base balance is crucial for the conversion of CO2 to methanol, as it relates to the efficient formation and desorption of intermediate products. By adjusting this property, the entire catalytic process can be made more efficient.

[0040] Gallium-containing copper-based catalysts exhibit better resistance to sulfur poisoning compared to pure copper-based catalysts. This is crucial for practical industrial applications, as trace amounts of sulfur compound contamination are unavoidable in real-world operating environments.

[0041] The presence of gallium can also improve the thermal stability of the catalyst, enabling it to maintain good catalytic performance over a wider operating temperature range, which is especially important for long-term continuous operation in industrial applications.

[0042] Gallium, as a dopant element, helps to uniformly disperse metal nanoparticles and prevent them from agglomerating at high temperatures, thereby maintaining a high specific surface area and more active sites, which is crucial for improving catalytic efficiency.

[0043] The addition of gallium causes a change in the electron density on the catalyst surface. This change can affect the adsorption behavior of reactant molecules and the energy barriers of the reaction pathway, ultimately improving catalytic activity and selectivity.

[0044] Gallium, as an effective additive, has shown great potential in improving copper-based catalysts for CO2-to-methanol production. However, the specific effects depend on factors such as gallium content, distribution, and interactions with other components, thus requiring optimized design based on specific circumstances.

[0045] (2) By selecting specific proportions of metal components (such as Cu and Ga), additives, support materials, rare earth elements (especially cerium Ce) and alkali metals or alkaline earth metals, the selectivity and activity of the catalyst for the hydrogenation reaction of carbon dioxide can be effectively improved.

[0046] (3) Rare earth elements, especially cerium, help to optimize the catalytic performance of this catalyst because rare earth elements can adjust the surface properties of the catalyst and enhance the interaction between the metal and the support, thereby improving the stability and activity of the catalyst.

[0047] (4) In the preparation method, we use the impregnation method combined with precipitation loading technology, which enables each component to be evenly distributed on the carrier, simplifying the preparation process and ensuring good dispersion and contact efficiency.

[0048] (5) Using common salts as precursors (such as nitrates, sulfates or chlorides) and choosing low-cost precipitants (such as sodium carbonate, sodium hydroxide, etc.) reduces the production cost of the catalyst and increases the possibility of industrial production.

[0049] (6) The application of this catalyst is intended to convert greenhouse gas CO2 into valuable chemical methanol, which not only helps reduce CO2 emissions, but also provides a sustainable source of raw materials for the chemical industry.

[0050] (7) When this catalyst is applied to the process of preparing methanol by hydrogenation of carbon dioxide, the carbon dioxide conversion rate is high and the methanol selectivity is high. Detailed Implementation

[0051] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0052] Any feature disclosed in this specification (including the claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0053] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0054] In this application, unless otherwise specified, % refers to the percentage content by mass. All raw materials mentioned are commercially available products; any unspecified process steps or apparatus are prior art.

[0055] Example 1

[0056] A catalyst for the hydrogenation of carbon dioxide to methanol reaction, comprising, by mass percentage, 8% additives, 15% support and 2% rare earth elements, with the balance being metal components (of which copper content is 60%, gallium content is 7%, alkali metal sodium content is 1%, and zirconium (Zr) content is 7%).

[0057] Furthermore, the additive is zinc; the carrier is silicon dioxide; and the rare earth element is cerium.

[0058] The specific preparation method is as follows:

[0059] a) Weigh out copper sulfate, gallium sulfate and sodium sulfate in proportion, and add water to prepare a mixed solution;

[0060] b) Mix the solution from step a) with zirconium carbonate to form a composite solution;

[0061] c) Add a compound containing the rare earth element cerium (such as CeO2) to the composite solution in step b), and stir until homogeneous to obtain a mixed solution;

[0062] d) Add the precursor of the additive (zinc powder) to the mixture from step c) in a predetermined ratio and mix thoroughly;

[0063] e) The carrier material silica is immersed in the mixture of step d), and sodium carbonate is added as a precipitant to precipitate the metal ions for loading treatment, so that the components are evenly distributed on the carrier.

[0064] f) The loaded support is dried and calcined to fix the active components and form the final catalyst structure; thus obtaining the (copper-based) catalyst.

[0065] The drying temperature range is 80℃, the calcination temperature range is 450℃, the calcination time is 4 hours, and the calcination atmosphere is air.

[0066] g) The product (catalyst) obtained in step f) is subjected to reduction treatment (reduction atmosphere is hydrogen, reduction temperature is 350℃, reduction time is 2 hours) to activate the metal component and obtain activated catalyst 1#.

[0067] Example 2:

[0068] A catalyst for the hydrogenation of carbon dioxide to methanol reaction, comprising, by mass percentage, 5% additives, 15% support and 2.5% rare earth elements, with the balance being metal components (of which copper content is 65%, gallium content is 6.5%, alkali metal sodium content is 1.5% and zirconium (Zr) content is 4.5%).

[0069] Furthermore, the additive is chromium; the carrier is aluminum oxide; and the rare earth element is cerium.

[0070] The specific preparation method is as follows:

[0071] a) Weigh out copper sulfate, gallium sulfate and sodium sulfate in proportion, and add water to prepare a mixed solution;

[0072] b) Mix the solution from step a) with zirconium carbonate to form a composite solution;

[0073] c) Add a compound containing the rare earth element cerium (such as CeO2) to the composite solution in step b), and stir until homogeneous to obtain a mixed solution;

[0074] d) Add the precursor of chromium to the mixture from step c) according to the predetermined ratio, and stir thoroughly.

[0075] e) Immerse the carrier material in the mixture of step d), add sodium carbonate as a precipitant to precipitate the metal ions for loading treatment, so that the components are evenly distributed on the carrier.

[0076] f) The loaded support is dried and calcined to fix the active components and form the final catalyst structure; thus obtaining the (copper-based) catalyst.

[0077] The drying temperature range is 100℃, the calcination temperature range is 470℃, the calcination time is 3.5 hours, and the calcination atmosphere is air.

[0078] g) The product (catalyst) obtained in step f) is subjected to reduction treatment (reduction atmosphere is hydrogen, reduction temperature is 300℃, reduction time is 3 hours) to activate the metal component and obtain activated catalyst 2#.

[0079] Example 3:

[0080] A catalyst for the hydrogenation of carbon dioxide to methanol reaction, comprising, by mass percentage, 8% of an additive, 15% of a support and 2% of rare earth elements, with the balance being a metal component (of which copper content is 60%, gallium content is 7%, alkali metal potassium content is 1%, and titanium (Ti) content is 7%).

[0081] Furthermore, the additive is chromium; the carrier is silicon dioxide; and the rare earth element is cerium.

[0082] The specific preparation method is as follows:

[0083] a) Weigh out copper sulfate, gallium sulfate and potassium chloride in proportion, and add water to prepare a mixed solution;

[0084] b) Mix the solution from step a) with a titanium-containing substance (such as TiO2) to form a composite solution;

[0085] c) Add a compound containing the rare earth element cerium (such as CeO2) to the composite solution in step b), and stir until homogeneous to obtain a mixed solution;

[0086] d) Add the precursor of chromium to the mixture from step c) according to the predetermined ratio, and stir thoroughly.

[0087] e) Immerse the carrier material in the mixture of step d), add sodium carbonate as a precipitant to precipitate the metal ions for loading treatment, so that the components are evenly distributed on the carrier.

[0088] f) The loaded support is dried and calcined to fix the active components and form the final catalyst structure; thus obtaining the (copper-based) catalyst.

[0089] The drying temperature range is 80℃, the calcination temperature range is 450℃, the calcination time is 4 hours, and the calcination atmosphere is air.

[0090] g) The product (catalyst) obtained in step f) is subjected to reduction treatment (reduction atmosphere is hydrogen, reduction temperature is 350℃, reduction time is 2 hours) to activate the metal component and obtain activated catalyst 3#.

[0091] Example 4:

[0092] A catalyst for the hydrogenation of carbon dioxide to methanol comprises, by mass percentage, 8% of an additive, 15% of a support, and 2% of rare earth elements, with the balance being a metal component (of which copper accounts for 60%, gallium for 7%, alkaline earth metal calcium for 1%, and zirconium (Zr) for 7%).

[0093] Furthermore, the additive is manganese; the carrier is a molecular sieve; and the rare earth element is cerium.

[0094] The specific preparation method is as follows:

[0095] a) Weigh out copper sulfate, gallium sulfate and calcium chloride in proportion, and add water to prepare a mixed solution;

[0096] b) Mix the solution from step a) with zirconium carbonate to form a composite solution;

[0097] c) Add a compound containing the rare earth element cerium (such as CeO2) to the composite solution in step b), and stir until homogeneous to obtain a mixed solution;

[0098] d) Add the precursor of manganese auxiliaries to the mixture from step c) in a predetermined ratio and mix thoroughly.

[0099] e) Immerse the carrier material in the mixture of step d), add sodium hydroxide as a precipitant to precipitate the metal ions for loading treatment, so that the components are evenly distributed on the carrier.

[0100] f) The loaded support is dried and calcined to fix the active components and form the final catalyst structure; thus obtaining the (copper-based) catalyst.

[0101] The drying temperature range is 120℃, the calcination temperature range is 470℃, the calcination time is 4 hours, and the calcination atmosphere is air.

[0102] g) The product (catalyst) obtained in step f) is subjected to reduction treatment (reduction atmosphere is hydrogen, reduction temperature is 250℃, reduction time is 3 hours) to activate the metal component and obtain activated catalyst 4#.

[0103] Comparative Example 1:

[0104] The catalyst was prepared in the same way as in Example 1, except that the metal component did not contain gallium, and the gallium content was converted to increase the copper content. All other steps were the same.

[0105] Comparative Example 2:

[0106] The catalyst was prepared in the same way as in Example 1, except that the metal component did not contain zirconium (Zr), and the content of zirconium (Zr) was converted to increase the content of copper. All other steps were the same.

[0107] To verify the effectiveness of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 in the hydrogenation of carbon dioxide to methanol, the following tests were conducted, and the specific methods and steps are as follows:

[0108] (a) The copper-based catalyst is loaded into the reactor;

[0109] (b) A mixture of carbon dioxide and hydrogen is introduced into the reactor; the molar ratio of carbon dioxide to hydrogen is 1:4.

[0110] (c) Methanol is produced at a reaction temperature of 280℃, a reaction pressure of 3MPa, and a reaction time of 3 hours; the space velocity of the feed is 10000mL / (h·g).

[0111] For ease of comparison, the catalysts prepared in Examples 1-4 and the results of methanol synthesis reactions are listed in Table 1.

[0112] Table 1:

[0113] reaction temperature Reaction pressure <![CDATA[CO2 conversion rate, %]]> Methanol selectivity, % Example 1 280℃ 3MPa 25.3 86.4 Example 2 280℃ 3MPa 26.1 85.5 Example 3 280℃ 3MPa 24.9 83.7 Example 4 280℃ 3MPa 25.8 85.1 Comparative Example 1 280℃ 3MPa 6.3 59.6 Comparative Example 2 280℃ 3MPa 12.4 62.8

[0114] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0115] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A catalyst for the hydrogenation of carbon dioxide to methanol, characterized in that: The catalyst comprises a metal component, an additive, a support, and rare earth elements; the metal component includes at least one of copper, gallium, alkali metal or alkaline earth metal, and zirconium or titanium oxide; wherein the additive is added at 2-10%, the support at 5-20%, the rare earth elements at 0.1-5%, and the balance is the metal component, with a total mass percentage of 100%. Of the metal components, the copper content is 30-70%, the gallium content is 1-10%, the alkali metal or alkaline earth metal content is 0.1-3%, and the zirconium or titanium oxide content is 1-10%. The additive is at least one of zinc, aluminum, zirconium, titanium, chromium, manganese, iron, cobalt, nickel, tin and their oxides; the carrier is at least one of alumina, silicon dioxide, molecular sieve and porous materials. The preparation method of the catalyst for the carbon dioxide hydrogenation to methanol reaction includes the following steps: a) Prepare a soluble salt solution containing at least one of copper salt, gallium salt, and alkali metals and alkaline earth metals; b) Mix the solution from step a) with a transition metal oxide precursor containing zirconium or titanium to form a composite solution; c) Add a compound containing rare earth elements to the composite solution in step b), and stir until homogeneous to obtain a mixed solution; d) Add the precursor of the auxiliary agent to the mixture from step c) according to the predetermined ratio, and stir thoroughly. e) Immerse the carrier in the mixture of step d), add a precipitant to allow the metal ions to precipitate and load the carrier, so that the components are evenly distributed on the carrier. f) The supported material after loading in step e) is dried and / or calcined to fix the active components and form the final catalyst structure; g) The product obtained in step f) is subjected to reduction treatment to activate the metal component.

2. The catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that: The rare earth element is cerium; the amount of rare earth element added is 0.5 wt%-3 wt%.

3. The catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that, The gallium salt in step a) is selected from gallium nitrate, gallium sulfate, or gallium chloride; the precursor of the auxiliary in step d) is a zinc salt or an aluminum salt; the zinc salt is selected from zinc nitrate, zinc sulfate, or zinc chloride; and the aluminum salt is selected from aluminum nitrate, aluminum sulfate, or aluminum chloride.

4. The catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that, The precipitant in step e) is selected from sodium carbonate, potassium carbonate, sodium hydroxide, or potassium hydroxide; the drying temperature in step f) is in the range of 80℃-200℃, the calcination temperature is in the range of 300℃-600℃, the calcination time is 2-6 hours, and the calcination atmosphere is air, inert gas, or reducing gas.

5. The catalyst for the hydrogenation of carbon dioxide to methanol according to claim 1, characterized in that, The reduction process in step g) is carried out in the presence of hydrogen at a temperature range of 200℃-400℃ for 1-3 hours.

6. The application of the catalyst according to any one of claims 1 to 5 in the hydrogenation of carbon dioxide to methanol.

7. The application according to claim 6, characterized in that, The catalyst is a copper-based catalyst, and the method includes the following steps: (a) Loading a copper-based catalyst into the reactor; (b) Introduce a mixture of carbon dioxide and hydrogen into the reactor; the molar ratio of carbon dioxide to hydrogen is 1:3 to 1:5; (c) The reaction is carried out at a reaction temperature of 200-300℃ and a reaction pressure of 1-10 MPa to produce methanol; the reaction time is 1-5 hours.