Ni@C catalyst and preparation method thereof, and CO2 methanation reaction catalyzed by nickel catalyst

Abstract

The application provides a Ni@C catalyst, a preparation method thereof and a CO2 methanation reaction catalyzed by the nickel catalyst. The Ni@C catalyst comprises a Ni active component and a layered porous carbon, and the Ni active component is embedded in the layered porous carbon. Compared with the prior art, the Ni active component in the Ni@C catalyst in the application is uniformly embedded in the layered porous carbon, and the layered porous structure of the layered porous carbon is used to connect the Ni active component, so that the adsorption of CO2 on the surface of the Ni active component can be improved, the agglomeration and sintering can be inhibited, and the activity, selectivity and stability of the catalyst can be improved.

Description

Technical Field

[0001] This invention relates to the field of Ni@C catalyst technology, and more specifically, to a Ni@C catalyst and its preparation method, and to CO2 methanation reaction catalyzed by a nickel catalyst. Background Technology

[0002] CO2 concentrations have reached record levels and continue to rise, with excessive CO2 emissions leading to a series of environmental problems such as greenhouse gas emissions. Therefore, catalytically converting CO2 into high-value-added chemical products such as formic acid, methanol, and dimethyl ether can achieve carbon recycling. Among these, CO2 methanation has significant advantages, as it operates under mild conditions, can be carried out at normal pressure, and produces clean and environmentally friendly products. The resulting methane, as a clean fuel, can be directly injected into existing natural gas pipelines, alleviating natural gas supply shortages and reducing environmental pressure. Furthermore, my country's increasingly sophisticated natural gas transportation network facilitates methane storage and transportation, indicating a promising future for the industry.

[0003] Electricity generated from renewable energy sources such as wind, solar, and tidal power is unstable and discontinuous, and its energy cannot be effectively utilized. However, this unstable electricity can be used to produce clean hydrogen energy through water electrolysis. Hydrogen energy has advantages such as high energy density, wide availability, easy storage, and being green and pollution-free, making it suitable for addressing environmental and energy shortages. However, the difficulty in transporting and storing hydrogen energy limits its large-scale application. Therefore, reacting hydrogen energy from renewable resources with CO2 to produce high-value-added chemicals has become a current research hotspot.

[0004] CO2 methanation, as a method of chemically fixing carbon dioxide, combined with other technologies such as CO2 capture and storage, is one of the most effective technologies for CO2 recycling and a useful pathway to convert CO2 into high-value gaseous fuels. CO2 hydrogenation produces methane, the main component of natural gas, which is a clean energy source with high safety and low environmental pollution. Considering both environmental protection and energy utilization, research on the CO2 methanation process has broad development and application prospects.

[0005] Common CO2 methanation catalysts are supported catalysts with Group VIII B metals (such as Ni, Co, Rh, Ru, and Pd) as active components, and all exhibit excellent CO2 methanation performance. Ni-based catalysts are the most widely used catalysts in CO2 methanation due to their good catalytic performance, availability, and low cost. Compared to noble metal catalysts, Ni catalysts require higher temperatures to become active. Furthermore, the strongly exothermic nature of the CO2 methanation reaction makes Ni prone to agglomeration and sintering, leading to catalyst deactivation and reduced catalytic activity. Summary of the Invention

[0006] The main objective of this invention is to provide a Ni@C catalyst and its preparation method, as well as a nickel-catalyzed CO2 methanation reaction, to solve the problem of reduced catalytic activity caused by easy deactivation of Ni-based catalysts in the CO2 methanation reaction in the prior art.

[0007] To achieve the above objectives, according to one aspect of the present invention, a Ni@C catalyst is provided, the Ni@C catalyst comprising a Ni active component and layered porous carbon, wherein the Ni active component is embedded in the layered porous carbon.

[0008] Furthermore, the mass ratio of the layered porous carbon to the Ni active component is 1 to 2:1, and preferably the Ni active component is elemental nickel particles, with a particle size of 50 to 80 nm.

[0009] Furthermore, the porosity of the aforementioned layered porous carbon is 40-60%, preferably the pore size is 5-7 nm, and preferably the pore volume is 0.040-0.060 cm³. 3 .

[0010] According to another aspect of the present invention, a method for preparing a Ni@C catalyst is provided, the method comprising: step S1, heating and gelling a raw material comprising a nickel source, a complexing agent, a template agent and a co-solvent to obtain a gel; step S2, subjecting the gel to a first drying and annealing treatment in sequence to obtain a nickel carbide precursor; and step S3, reducing the nickel carbide precursor to obtain the Ni@C catalyst.

[0011] Further, in step S1 above, the mass ratio of nickel source, complexing agent, template agent, and co-solvent is 5-10:6-12:0.5-5:1-8; preferably, the nickel source is a nickel-containing compound; preferably, the nickel-containing compound is selected from any one or more of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate; preferably, the complexing agent is selected from any one or more of citric acid, sodium citrate, ammonium citrate, and potassium citrate; preferably, the co-solvent is selected from any one or more of ethanol, ethylene glycol, and glycerol; preferably, the template agent is sodium chloride and / or potassium chloride; preferably, the temperature of the heating gelation reaction is 70-90°C, and preferably, the time of the heating gelation reaction is 2-4 hours.

[0012] Furthermore, in step S2 above, the temperature of the first drying is 80-120°C, and the time of the first drying is preferably 10-14 hours; the temperature of the annealing treatment is preferably 300-500°C, and the time of the annealing treatment is preferably 2-4 hours.

[0013] Furthermore, in step S3 above, a reduction treatment is carried out under the action of a reducing agent. Preferably, the temperature of the reduction treatment is 200-600°C, and the time of the reduction treatment is 1-4 hours. Preferably, the reducing agent is H2 or CO.

[0014] Furthermore, prior to the reduction treatment described above, the preparation method further includes: sequentially washing the nickel carbide precursor with water and then drying it, preferably at a temperature of 80–120°C and preferably for a time of 10–14 h.

[0015] According to another aspect of the present invention, a CO2 methanation reaction catalyzed by a nickel catalyst is provided, wherein the nickel catalyst is the Ni@C catalyst described above.

[0016] Furthermore, the conditions for the CO2 methanation reaction include: a feed gas composition of H2:CO2:N2 mass ratio of 11–13:2–4:4–6; a reaction pressure of 0.1–4 MPa; a preferred reaction temperature of 200–400 °C; and a preferred reaction space velocity of 1000–9000 h⁻¹. -1 .

[0017] Compared with the prior art, the Ni active component in the Ni@C catalyst of this application is uniformly embedded in layered porous carbon. The layered porous structure of the layered porous carbon can be used to connect the Ni active component, which can improve the adsorption of CO2 on the surface of the Ni active component and inhibit agglomeration and sintering, thereby improving the activity, selectivity and stability of the catalyst. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A scanning electron microscope (SEM) schematic diagram of a Ni@C catalyst provided in Example 1 of the present invention is shown. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] As analyzed in the background section of this application, the methanation reaction of CO2 is a strongly exothermic reaction. High temperatures are unfavorable for the forward propagation of the methanation reaction and easily lead to deactivation. Therefore, the key research issue in methanation technology is preventing catalyst deactivation due to carbon buildup and preparing highly efficient CO2 methanation catalysts. Furthermore, improving the dispersion of the Ni active component in the catalyst can effectively address issues such as agglomeration and deflaking. Therefore, the prepared catalyst should possess advantages such as high activity, strong resistance to sintering, and high stability. Addressing the current problems of high-temperature sintering and carbon buildup, poor stability, and low activity in methanation catalysts, research on catalysts for methanation reactions often focuses on achieving both high activity and stability. Therefore, in the prior art, Ni-based catalysts catalyzing the CO2 methanation reaction suffer from the problem of easy catalyst deactivation leading to reduced catalytic activity. To solve this problem, this application provides a Ni@C catalyst and its preparation method, as well as a nickel-catalyzed CO2 methanation reaction.

[0022] In a typical embodiment of this application, a Ni@C catalyst is provided, which includes a Ni active component and layered porous carbon, wherein the Ni active component is embedded in the layered porous carbon.

[0023] Compared with the prior art, in the Ni@C catalyst of this application, the Ni active component is uniformly embedded in layered porous carbon. The layered porous structure of the layered porous carbon can connect the Ni active component, which can improve the adsorption of CO2 on the surface of the Ni active component and inhibit agglomeration and sintering, thereby improving the activity, selectivity and stability of the catalyst.

[0024] In one embodiment of this application, the mass ratio of the layered porous carbon to the Ni active component is 1 to 2:1, and preferably the Ni active component is elemental nickel particles, preferably with a particle size of 50 to 80 nm.

[0025] Controlling the mass ratio of layered porous carbon to Ni active component within the above range is beneficial for providing more embedding sites and space for Ni active component, thereby improving CO2 adsorption on the surface of Ni active component.

[0026] Increasing the porosity of layered porous carbon helps provide more space for CO2 adsorption on the surface of Ni active components. However, excessive porosity also increases the risk of agglomeration and sintering. To balance CO2 adsorption on the surface of Ni active components with effective suppression of agglomeration and sintering, the porosity of the layered porous carbon is preferably 40-60%, the pore size is preferably 5-7 nm, and the pore volume is preferably 0.040-0.060 cm³. 3 .

[0027] In another typical embodiment of this application, a method for preparing a Ni@C catalyst is provided, the method comprising: step S1, heating and gelling a raw material including a nickel source, a complexing agent, a template agent and a co-solvent to obtain a gel; step S2, subjecting the gel to a first drying and annealing treatment in sequence to obtain a nickel carbide precursor; and step S3, reducing the nickel carbide precursor to obtain the Ni@C catalyst.

[0028] A co-solvent enhances the solubility of the raw materials, ultimately yielding a homogeneous and stable gel. Combining the dissolution, crystallization, and redissolution process of sodium chloride, high-temperature drying and annealing decompose citrate ions, creating secondary pores. These pores then react with nickel ions to produce a nickel carbide precursor. This precursor is further reduced to obtain the Ni@C catalyst. Transition metal carbides (Ni@C catalysts) not only possess excellent electrical conductivity but also exhibit high melting points and hardness, often displaying exceptional catalytic product selectivity and catalytic performance stability. They also possess advantages similar to noble metals, including good stability, excellent carbon-oxygen bond activation ability, wide applicability in hydrogenation reactions, and high product selectivity. Therefore, using nickel carbide as a precursor, carbon-coated Ni@C catalysts are prepared through calcination and reduction. Utilizing its layered porous structure, a catalyst with uniformly embedded Ni active components is obtained. This porous structure connecting the Ni active components enhances CO2 adsorption on the Ni active component surface, inhibits agglomeration and sintering, thereby improving the activity, selectivity, and stability of the Ni@C catalyst.

[0029] In some embodiments of this application, it is preferred that in step S1 above, the mass ratio of the nickel source, complexing agent, template agent, and co-solvent is 5-10:6-12:0.5-5:1-8; preferably, the nickel source is a nickel-containing compound; preferably, the nickel-containing compound is selected from any one or more of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate; preferably, the complexing agent is selected from any one or more of citric acid, sodium citrate, ammonium citrate, and potassium citrate; preferably, the co-solvent is selected from any one or more of ethanol, ethylene glycol, and glycerol; preferably, the template agent is sodium chloride and / or potassium chloride. Too little co-solvent will lead to insolubility, while too much will inhibit the hydrolysis reaction. It is preferred that the mass ratio and types of each component are within the above range to help improve the synergistic effect between the components. It is preferred that the temperature of the heating gelation reaction is 70-90°C, and the heating gelation reaction time is 2-4 hours, thereby helping to improve the efficiency and effect of the heating gelation reaction.

[0030] In one embodiment of this application, in step S2 above, the temperature of the first drying is 80-120°C, and the time of the first drying is preferably 10-14 hours; the temperature of the annealing treatment is preferably 300-500°C, and the time of the annealing treatment is preferably 2-4 hours.

[0031] Performing a first drying process on the gel, and controlling the temperature and time of the first drying within the above range, helps to remove residual moisture and other substances from the gel as much as possible, thereby reducing the interference of moisture and other substances on the annealing process. The preferred annealing temperature and time described above help to improve the efficiency and effectiveness of the annealing process.

[0032] In one embodiment of this application, in step S3 above, a reduction treatment is performed under the action of a reducing agent. Preferably, the temperature of the reduction treatment is 200-600°C, and the time of the reduction treatment is 1-4 hours. Preferably, the reducing agent is H2 or CO.

[0033] The preferred types of reducing agents, reduction temperatures, and reduction times are conducive to reducing the nickel carbide precursor to obtain the Ni@C catalyst as much as possible.

[0034] In one embodiment of this application, prior to the reduction treatment described above, the preparation method further includes: sequentially washing the nickel carbide precursor with water and then drying it, preferably at a temperature of 80–120°C and preferably for a time of 10–14 hours.

[0035] Preferred water washing and second drying, as well as the control of the temperature and time of the second drying, help to remove impurities and moisture from the nickel carbide precursor as much as possible, thereby reducing the interference of impurities and moisture on the reduction process.

[0036] In another typical embodiment of this application, a CO2 methanation reaction catalyzed by a nickel catalyst is provided, wherein the nickel catalyst is the Ni@C catalyst described above.

[0037] Using the Ni@C catalyst in this application to catalyze the CO2 methanation reaction helps to suppress agglomeration and sintering, thereby improving the efficiency and selectivity of the CO2 methanation reaction.

[0038] In one embodiment of this application, the conditions for the above-mentioned CO2 methanation reaction include: the feed gas composition is H2:CO2:N2 with a mass ratio of 11-13:2-4:4-6; the reaction pressure is 0.1-4 MPa; the preferred reaction temperature is 200-400°C; and the preferred reaction space velocity is 1000-9000 h⁻¹. -1 .

[0039] Under the above conditions, it is more conducive to improving the synergistic effect between Ni@C catalyst and CO2, thereby maximizing the catalytic activity and stability of Ni@C catalyst.

[0040] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0041] Example 1

[0042] This invention relates to a method for preparing and applying a carbon-coated nickel carbon dioxide methanation catalyst, the method comprising the following steps:

[0043] a. At room temperature, weigh out ethanol, ethylene glycol, nickel nitrate hexahydrate, citric acid monohydrate, and sodium chloride in a mass ratio of 2:5:7:8:1 and dissolve them in deionized water to obtain a mixed solution;

[0044] b. The resulting mixed solution was stirred at 70°C for 2 hours in a water bath to obtain a green gel;

[0045] c. The obtained green gel was dried thoroughly in an oven at 80°C for 10 hours to obtain a green dry gel. Then, the obtained green dry gel was placed in a tube furnace and annealed at 300°C for 2 hours to obtain a nickel carbide precursor.

[0046] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 200℃ to obtain a carbon-coated Ni@C catalyst, which is used for CO2 methanation reaction.

[0047] e. At a reaction temperature of 200℃, a reaction pressure of 0.1MPa, and a reaction space velocity of 1000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 12:3:5.

[0048] Example 2

[0049] The difference from Example 1 is that,

[0050] b. The resulting mixed solution was stirred at 80°C for 3 hours in a water bath to obtain a green gel;

[0051] c. The obtained green gel was dried thoroughly in an oven at 110°C for 12 hours to obtain a green dry gel. Then, the obtained green dry gel was placed in a tube furnace and annealed at 350°C for 3 hours to obtain a nickel carbide precursor.

[0052] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 400℃ to obtain a Ni@C catalyst, which is used for CO2 methanation reaction.

[0053] e. At a reaction temperature of 200℃, a reaction pressure of 0.1MPa, and a reaction space velocity of 1000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 12:3:5.

[0054] Example 3:

[0055] The difference from Example 1 is that,

[0056] b. The resulting mixed solution was stirred at 90°C for 4 hours in a water bath to obtain a green gel;

[0057] c. The obtained green gel was dried thoroughly in an oven at 120°C for 14 hours to obtain a green dry gel. Then, the obtained green dry gel was placed in a tube furnace and annealed at 500°C for 3 hours to obtain a nickel carbide precursor.

[0058] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 600℃ to obtain a Ni@C catalyst, which is used for CO2 methanation reaction.

[0059] e. At a reaction temperature of 200℃, a reaction pressure of 0.1MPa, and a reaction space velocity of 1000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 12:3:5.

[0060] Example 4:

[0061] a. At room temperature, weigh out ethanol, ethylene glycol, nickel nitrate hexahydrate, citric acid monohydrate, and sodium chloride in a mass ratio of 1:7:10:6:5 and dissolve them in deionized water to obtain a mixed solution;

[0062] b. The resulting mixed solution was stirred at 80°C for 3 hours in a water bath to obtain a green gel;

[0063] c. The obtained green gel was dried thoroughly in an oven at 110°C for 12 hours to obtain a green dry gel. Then, the obtained green dry gel was placed in a tube furnace and annealed at 350°C for 3 hours to obtain a nickel carbide precursor.

[0064] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 400℃ to obtain a carbon-coated Ni@C catalyst, which is used for CO2 methanation reaction.

[0065] e. At a reaction temperature of 300℃, a reaction pressure of 2MPa, and a reaction space velocity of 5000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 12:3:5.

[0066] Example 5:

[0067] The difference from Example 4 is that,

[0068] a. At room temperature, ethanol, ethylene glycol, nickel nitrate hexahydrate, citric acid monohydrate, and sodium chloride were weighed and dissolved in deionized water in a mass ratio of 0.5:0.5:5:12:0.5 to obtain a mixed solution;

[0069] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0070] Example 6:

[0071] The difference from Example 4 is that,

[0072] a. At room temperature, weigh out ethanol, ethylene glycol, nickel nitrate hexahydrate, citric acid monohydrate, and sodium chloride in a mass ratio of 2:5:7:4:4 and dissolve them in deionized water to obtain a mixed solution;

[0073] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0074] Example 7:

[0075] The difference from Example 4 is that,

[0076] a. At room temperature, weigh out ethanol, ethylene glycol, nickel nitrate hexahydrate, citric acid monohydrate, and sodium chloride in a mass ratio of 8:7:2:6:1 and dissolve them in deionized water to obtain a mixed solution;

[0077] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0078] Example 8:

[0079] The difference from Example 5 is that,

[0080] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 600℃ to obtain a carbon-coated Ni@C catalyst, which is used for CO2 methanation reaction.

[0081] e. At a reaction temperature of 400℃, a reaction pressure of 4MPa, and a reaction space velocity of 9000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 12:3:5.

[0082] Example 9:

[0083] The difference from Example 8 is that,

[0084] e. At a reaction temperature of 300℃, a reaction pressure of 2MPa, and a reaction space velocity of 1000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 12:3:5.

[0085] Example 10

[0086] The difference from Example 4 is that,

[0087] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 200℃ to obtain a carbon-coated Ni@C catalyst, which is used for CO2 methanation reaction.

[0088] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0089] Example 11

[0090] The difference from Example 4 is that,

[0091] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 600℃ to obtain a carbon-coated Ni@C catalyst, which is used for CO2 methanation reaction.

[0092] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0093] Example 12

[0094] The difference from Example 4 is that,

[0095] d. The nickel carbide precursor in c is washed with water, dried, and then reduced at 150°C to obtain a carbon-coated Ni@C catalyst, which is used for CO2 methanation reaction.

[0096] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0097] Example 13

[0098] The difference from Example 4 is that,

[0099] c. The obtained green dry adhesive was placed in a tube furnace and annealed at 300°C for 3 hours to obtain nickel carbide precursor.

[0100] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0101] Example 14

[0102] The difference from Example 4 is that,

[0103] c. The obtained green dry adhesive was placed in a tube furnace and annealed at 500°C for 3 hours to obtain nickel carbide precursor.

[0104] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0105] Example 15

[0106] The difference from Example 4 is that,

[0107] c. The obtained green dry adhesive was placed in a tube furnace and annealed at 250°C for 3 hours to obtain nickel carbide precursor.

[0108] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0109] Example 16

[0110] The difference from Example 4 is that,

[0111] c. The obtained green dry adhesive was placed in a tube furnace and annealed at 550°C for 3 hours to obtain nickel carbide precursor.

[0112] e. Evaluate the performance of the catalyst in the carbon dioxide hydrogenation methanation reaction.

[0113] Example 17

[0114] The difference from Example 4 is that,

[0115] e. At a reaction temperature of 300℃, a reaction pressure of 2MPa, and a reaction space velocity of 5000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 11:2:4.

[0116] Example 18

[0117] The difference from Example 4 is that,

[0118] e. At a reaction temperature of 300℃, a reaction pressure of 2MPa, and a reaction space velocity of 5000h⁻¹. -1 The performance of the catalyst in the carbon dioxide hydrogenation methanation reaction was evaluated under the condition that the feed gas composition was H2:CO2:N2 = 13:4:6.

[0119] Comparative Example 1

[0120] The difference from Example 1 is that nickel nitrate hexahydrate (in the same amount as in Example 1) was directly used in the carbon dioxide hydrogenation methanation reaction.

[0121] The CO2 conversion rate, CH4 selectivity, mass ratio m of layered porous carbon to Ni active component, particle size r of nickel elemental particles, porosity o of layered porous carbon, pore size of layered porous carbon, and pore volume p of layered porous carbon obtained from the above examples and comparative examples are listed in Table 1.

[0122] Table 1

[0123]

[0124]

[0125] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0126] Compared with the prior art, in the Ni@C catalyst of this application, the Ni active component is uniformly embedded in layered porous carbon. The layered porous structure of the layered porous carbon can connect the Ni active component, which can improve the adsorption of CO2 on the surface of the Ni active component and inhibit agglomeration and sintering, thereby improving the activity, selectivity and stability of the catalyst.

[0127] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Ni@C catalyst for CO2 methanation, characterized in that, The Ni@C catalyst for CO2 methanation comprises a Ni active component and a layered porous carbon, and the Ni active component is embedded in the layered porous carbon; The mass ratio of the layered porous carbon to the Ni active component is 1-2:1, the Ni active component is a nickel elemental particle, and the particle size of the nickel elemental particle is 50-80 nm; The layered porous carbon has a porosity of 40-60%, and a pore volume of 0.040-0.060 cm 3 / g.

2. The Ni@C catalyst for CO2 methanation according to claim 1, characterized in that, The pore size of the layered porous carbon is 5-7 nm.

3. A process for the preparation of the Ni@C catalyst for CO2 methanation according to claim 1 or 2, characterized in that, The preparation method comprises: Step S1, a raw material comprising a nickel source, a complexing agent, a template agent and a co-solvent is subjected to a heating gelation reaction to obtain a gel; Step S2, the gel is sequentially subjected to first drying and annealing treatment to obtain a nickel carbide precursor; Step S3, the nickel carbide precursor is subjected to reduction treatment to obtain the Ni@C catalyst for CO2 methanation; The mass ratio of the nickel source, the complexing agent, the template agent and the co-solvent is 5-10:6-12:0.5-5:1-8; The template agent is sodium chloride and / or potassium chloride.

4. The production method according to claim 3, characterized by, In the step S1, the nickel source is a nickel-containing compound; the nickel-containing compound is selected from any one or more of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate; the complexing agent is selected from any one or more of citric acid, sodium citrate, ammonium citrate and potassium citrate; and the co-solvent is selected from any one or more of ethanol, ethylene glycol and glycerol. The heating gelation reaction is performed at a temperature of 70-90°C for 2-4 h.

5. The production method according to claim 3 or 4, characterized by, In the step S2, the first drying is performed at a temperature of 80-120°C for 10-14 h; and the annealing treatment is performed at a temperature of 300-500°C for 2-4 h.

6. The production method according to claim 3 or 4, characterized by, In the step S3, the reduction treatment is performed under the action of a reducing agent, the reduction treatment is performed at a temperature of 200-600°C for 1-4 h, and the reducing agent is H2 or CO.

7. The production method according to claim 3 or 4, characterized by, Before the reduction treatment, the preparation method further comprises sequentially performing water washing and second drying on the nickel carbide precursor, the second drying is performed at a temperature of 80-120°C for 10-14 h.

8. A CO2 methanation reaction catalyzed by a nickel catalyst, characterized in that, The nickel catalyst is the Ni@C catalyst for CO2 methanation according to claim 1 or 2.

9. The CO2 methanation reaction of claim 8, wherein, The conditions of the CO2 methanation reaction comprise: The mass ratio of the raw material gas composition H2:CO2:N2 is 11-13:2-4:4-6; The reaction pressure is 0.1-4 MPa; the reaction temperature is 200-400℃; the reaction space velocity is 1000-9000 h −1 .

Images