Preparation method and application of carbon dioxide methanation catalyst

Abstract

The invention belongs to the technical field of preparation of carbon dioxide methanation catalysts, and relates to a preparation method and application of a carbon dioxide methanation catalyst, in particular to a carbon dioxide methanation catalyst with high methane selectivity and good low-temperature catalytic activity and application of the carbon dioxide methanation catalyst. The preparation method comprises the following steps: dissolving a cerium source and a template agent in a mixed solvent, carrying out reflux reaction, centrifuging, washing, drying and roasting to obtain spherical cerium oxide; the preparation method comprises the following steps: dissolving a nickel source in water to obtain a nickel source steeping liquor, steeping spherical cerium oxide in the nickel source steeping liquor, drying and calcining to obtain a spherical cerium oxide loaded nickel catalyst, namely the carbon dioxide methanation catalyst. The preparation method of the carbon dioxide methanation catalyst is simple, and the catalyst is high in low-temperature conversion rate, high in methane selectivity, good in stability and good in application prospect when being used for a reaction of preparing methane through carbon dioxide hydrogenation.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide methanation catalyst preparation, and more specifically relates to a preparation method and application of a carbon dioxide methanation catalyst. Background Art

[0002] As the main energy source, the use of fossil fuels leads to global warming and climate change. Carbon dioxide is the main greenhouse gas, and carbon dioxide emissions from the oil industry, power plants, cement plants, steel, construction and ironmaking have gradually increased with the development of industrialization. Existing natural gas infrastructure can be used to produce methane through carbon dioxide methanation. Carbon dioxide methanation provides a promising way to convert carbon dioxide into valuable chemicals and energy fuels. At the same time, methane can also be used as a medium to store hydrogen.

[0003] Methanation of carbon dioxide to produce methane requires the presence of a catalyst. Existing catalysts are generally noble metal-based catalysts (Ru, Rh and Pd) and non-noble metal catalysts. Among them, Ru-based catalysts show good catalytic performance among noble metal-based catalysts, but limited noble metal resources restrict their further large-scale application; nickel-based catalysts perform well among non-noble metal catalysts, but they have disadvantages such as low low-temperature activity and poor stability.

[0004] Alkhoori et al. modified Ni / Al2O3 catalyst with CeO2. Although the performance was significantly improved compared with the unmodified catalyst, the CO2 conversion rate was still less than 70% at 300°C (ACS Appl. Energy Mater. 2023, 6, 8550-8571). The Ni@MOF-545DS R catalyst developed by Chen et al. showed a high initial activity (CO2 conversion rate greater than 80%) at 300°C, but it deactivated rapidly as the reaction proceeded. After 162 minutes of operation, the CO2 conversion rate dropped to 60% (ACS Appl. Mater. Interfaces 2024, 16, 12509-12520). The halloysite nanotube-loaded nickel catalyst Ni(17%) / HNTs-8AC developed by Yang et al. can achieve a CO2 conversion rate of 89% at 400°C, but its CO2 conversion rate at 300°C is less than 25% (ACS Appl. Nano Mater. 2024, 7, 2190-2199).

[0005] From a thermodynamic point of view, lower reaction temperature is conducive to improving methane selectivity and inhibiting the occurrence of side reactions. However, since carbon dioxide molecules are very stable, existing catalysts find it difficult to achieve high conversion rates at lower reaction temperatures.

[0006] It can be seen that the existing catalyst system has harsh reaction conditions and low catalytic activity at low temperatures, which hinders the industrialization and commercialization of carbon dioxide methanation. Although researchers have made extraordinary efforts in the development of carbon dioxide methanation, improving the catalytic performance of catalysts under low temperature conditions is still a challenge, so the development of suitable catalysts is crucial. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing a carbon dioxide methanation catalyst and its application, and more specifically to provide a carbon dioxide methanation catalyst with high methane selectivity and good low-temperature catalytic activity and its application, so as to solve the problems existing in the above-mentioned prior art.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] One of the technical solutions of the present invention is to provide a method for preparing a carbon dioxide methanation catalyst, the steps comprising:

[0010] The cerium source and the template are dissolved in a mixed solvent, and after reflux reaction, the spherical cerium oxide is obtained by centrifugation, washing, drying and calcination; wherein the mixed solvent is composed of ethylene glycol and water;

[0011] The nickel source is dissolved in water to obtain a nickel source impregnation solution, the spherical cerium oxide is immersed in the nickel source impregnation solution, and after drying and calcination, the obtained spherical cerium oxide-supported nickel catalyst is a carbon dioxide methanation catalyst.

[0012] The cerium oxide-supported nickel catalyst having rich oxygen vacancies can be obtained by the above method.

[0013] Furthermore, the cerium source includes at least one of cerium nitrate hexahydrate, cerium chloride and cerium sulfate.

[0014] Furthermore, the template agent is polyvinyl pyrrolidone.

[0015] When the method adopts the above-defined raw materials, nano-spherical cerium oxide with uniform size can be obtained.

[0016] Furthermore, the volume ratio of ethylene glycol to water is 7:1.

[0017] Furthermore, the usage ratio of the cerium source, the template agent and ethylene glycol is 30g:6g:280mL.

[0018] Furthermore, the reflux reaction temperature is 140° C. and the time is 24 hours.

[0019] Furthermore, the calcination temperature is 550° C. and the calcination time is 5 hours.

[0020] Furthermore, the nickel source includes at least one of nickel nitrate hexahydrate, nickel chloride and nickel sulfate.

[0021] Furthermore, the usage ratio of the nickel source and water is 4.955 g:1.5 mL.

[0022] Furthermore, the mass ratio of the spherical cerium oxide to the nickel source is 9:4.955.

[0023] Furthermore, the drying temperature is 110°C.

[0024] Furthermore, the calcination temperature is 450° C. and the calcination time is 5 hours.

[0025] The second technical solution of the present invention is to provide a carbon dioxide methanation catalyst, which is prepared by the above-mentioned preparation method.

[0026] The third technical solution of the present invention is to provide an application of the above-mentioned carbon dioxide methanation catalyst in catalyzing carbon dioxide hydrogenation to produce methane.

[0027] Technical solution 4 of the present invention: Provide a method for improving the carbon dioxide conversion rate in the carbon dioxide hydrogenation to methane reaction, the steps comprising:

[0028] The carbon dioxide methanation catalyst and the auxiliary agent are loaded into a catalyst fixed bed, pretreated for 2 hours in a hydrogen atmosphere at 350° C., then cooled to the reaction temperature, and the hydrogen atmosphere is switched to the reaction gas to catalyze carbon dioxide hydrogenation to produce methane.

[0029] Furthermore, the mass ratio of the carbon dioxide methanation catalyst to the auxiliary agent is 1:0-1, preferably 1:1.

[0030] Furthermore, the auxiliary agent includes polydivinylbenzene and / or polystyrene.

[0031] Furthermore, the reaction temperature is 200-350°C.

[0032] Furthermore, the reaction gas is composed of hydrogen and carbon dioxide in a volume ratio of 4:1 and a space velocity of 10000 mL g - 1 h -1 .

[0033] In the present invention, the filling method is not limited, and it can be mixed and then filled, or it can be loaded in stages, that is, first fill the auxiliary agent and then fill the carbon dioxide methanation catalyst, or first fill the carbon dioxide methanation catalyst and then fill the auxiliary agent, and the particle size of the catalyst and the auxiliary agent is 40 to 60 mesh.

[0034] The present invention discloses the following technical effects:

[0035] The preparation method of the carbon dioxide methanation catalyst of the present invention is simple. When used for the carbon dioxide hydrogenation to methane reaction, the catalyst has high low-temperature conversion rate, high methane selectivity and good stability, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0037] Figure 1 This is a SEM image of the spherical cerium oxide-supported nickel catalyst prepared in Example 1;

[0038] Figure 2 This is a SEM image of the spherical cerium oxide-supported nickel catalyst and polydivinylbenzene after being uniformly mixed in Example 2;

[0039] Figure 3 This is a stability performance diagram of the spherical cerium oxide-supported nickel catalyst prepared in Example 1 when used for carbon dioxide methanation catalysis;

[0040] Figure 4 This is a stability performance diagram of the alumina-supported nickel catalyst prepared in Comparative Example 1 when used for carbon dioxide methanation catalysis. DETAILED DESCRIPTION

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0045] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0046] Cerium oxide is an inorganic substance with the chemical formula CeO2. It is a light yellow or yellowish brown powder. Density 7.13g / cm 3 , melting point 2397℃, insoluble in water and alkali, slightly soluble in acid. At 2000℃ and 15MPa, cerium oxide can be reduced with hydrogen to obtain cerium trioxide. When the temperature is between 2000℃ and the pressure is between 5MPa, cerium oxide is slightly yellowish with a slight red, and pink. Its performance is to make polishing materials, catalysts, catalyst carriers (auxiliaries), ultraviolet absorbers, fuel cell electrolytes, automobile exhaust absorbers, electronic ceramics, etc. At present, the main methods for preparing nano cerium dioxide are precipitation method, sol-gel method, combustion method, hydrothermal method, etc. Among them, oxalic acid precipitation method is a commonly used production method, that is, cerium chloride or cerium nitrate solution is used as raw material, and cerium oxide is obtained through a series of chemical reactions.

[0047] Templates are auxiliary materials that play a key role in the process of material synthesis. They can guide or control the morphology, structure and properties of synthetic materials. Templates can be defined as substances that have specific morphology, structure or properties, or substances that can form specific morphological structures through self-assembly. During the synthesis process, templates are introduced into the reaction system. As the reaction proceeds and the templates are removed, materials with morphology, structure or properties similar to those of the templates can be prepared. Templates are mainly divided into the following categories: surfactant templates, which are usually composed of long-chain alkyl or aryl groups and quaternary ammonium salt groups, forming micelle structures in solution. These micelles can be used as mesoporous templates to guide the development of the pore structure of synthetic materials. Surfactant templates are widely used in the synthesis of molecular sieves, porous materials, etc.; carbon material templates, including activated carbon, carbon nanotubes, etc., have unique pore structures and surface properties, and can be used as templates to guide the formation of mesopores in synthetic materials. Carbon material templates can be removed at high temperatures without leaving impurities in the synthetic materials; organic templates, usually organic polymers, provide mesoporous or macroporous templates during the synthesis process. Through subsequent chemical or thermal treatment, the organic template can be removed, leaving behind a synthetic material with a specific pore structure; inorganic templates include metal oxides, salts, such as diatomite, zeolite, etc. They provide a skeleton structure during the synthesis process, and can guide the pore formation of the synthetic material by controlling the conditions. In addition, according to the ease of removal of the template, it can also be divided into soft templates and hard templates. Soft templates such as surfactants and organic polymers are relatively easy to remove; while hard templates such as certain metal oxides and carbon materials require higher temperatures and complex treatment processes to remove. The template mainly plays the following roles in the synthesis process: spatial guidance, the template provides spatial guidance for the skeleton structure of the synthetic material, so that it grows according to the predetermined morphology and structure; pore template role, the template can guide the development of the pore structure of the synthetic material to form a material with a specific pore size and pore structure; performance regulation role, by selecting a suitable template, the performance of the synthetic material can be regulated, such as adsorption, separation, catalysis, etc. Template agents have a wide range of applications in multiple fields, including but not limited to the following aspects: molecular sieve materials, template agents are key auxiliary materials in the synthesis process of molecular sieve materials, and can guide the formation of the molecular sieve pore structure; porous materials, template agents can be used to prepare porous materials with specific pore sizes and pore structures, such as porous carbon materials, porous ceramic materials, etc.; catalysts, template agents can be used to prepare catalysts with high catalytic properties, such as metal oxide catalysts, zeolite catalysts, etc.; nanomaterials, template agents also play an important role in the synthesis of nanomaterials, and can prepare nanomaterials with specific morphology and structure.

[0048] Reflux reaction refers to a chemical reaction carried out in the presence of a reflux solvent, in which the role of the reflux solvent is crucial. The reflux solvent mainly plays the following roles in the reflux reaction: it transforms the heterogeneous phase into a homogeneous reaction, the reflux solvent can dissolve the reactants in it, so that the reactants are fully in contact with each other, thereby improving the reaction rate and efficiency; it provides the necessary and constant temperature, and the boiling point of the reflux solvent can be used as the constant temperature of the reaction system, which helps to control the temperature conditions of the reaction and ensure that the reaction is carried out at an appropriate temperature. The commonly used equipment for reflux reaction mainly consists of a distillation flask, a distillation head and a condenser. The distillation flask is used to hold the reactants and the solvent, the distillation head is used to connect the condenser, and the condenser is used to condense the steam into liquid and reflux it into the reaction system. The process of reflux reaction usually includes the following steps: heating, using a heating device (such as a heating jacket) to heat the distillation flask, so that the reactants and solvents are heated and begin to vaporize; steam rises, and the vaporized steam enters the condenser along the distillation head; condensation, cold water or other cooling medium is passed into the condenser to cool and liquefy the steam in the condenser; reflux, the liquefied liquid flows back to the distillation flask along the condenser, re-enters the reaction system, and continues to participate in the reaction. Reflux reaction has a wide range of applications in organic chemistry experiments and industrial production, such as esterification reaction, polycondensation reaction, etc. Through reflux reaction, various compounds with specific structures and properties can be prepared, such as polyester resins, pharmaceutical intermediates, etc. When performing reflux reaction, the following matters need to be noted: select a suitable reflux solvent, according to the properties of the reactants and reaction conditions, select a suitable reflux solvent; control the heating temperature to avoid excessive heating temperature leading to runaway reaction or solvent decomposition; regularly check the condensation effect to ensure that the condenser is unobstructed and the condensation effect is good; pay attention to safe operation, and during the reflux reaction, pay attention to prevent steam scalds and toxic gas emissions. Reflux reaction is an important type of chemical reaction. By selecting appropriate reflux solvents and equipment, various compounds with specific structures and properties can be prepared. When performing reflux reactions, it is necessary to pay attention to controlling the heating temperature, regularly checking the condensation effect, and paying attention to safe operation.

[0049] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products.

[0050] Note on particle size:

[0051] 40-60 mesh refers to the undersize of the 40-mesh sieve, and then the oversize of the 60-mesh sieve, that is, the particle size is between 40 and 60 mesh;

[0052] 60 mesh refers to the material that passes through the 60 mesh sieve.

[0053] Example 1

[0054] A method for preparing a carbon dioxide methanation catalyst, comprising the following steps:

[0055] S1. Weigh 30.0 g of cerium nitrate hexahydrate and 6.0 g of polyvinyl pyrrolidone into a flask, add 280 mL of ethylene glycol and 40 mL of deionized water, stir to completely dissolve the solid, then place in an oil bath, stir and reflux at 140 ° C for 24 hours, add 100 mL of deionized water after the reaction is completed, centrifuge (10000 rpm, 10 min), collect the solid product, wash it three times with water, then wash it once with ethanol, dry it at 60 ° C overnight, and finally roast it at 550 ° C in a muffle furnace for 5 hours to obtain spherical cerium oxide;

[0056] S2, weigh 4.955g of nickel nitrate hexahydrate and dissolve it in 1.5mL of deionized water, then add 9.0g of spherical cerium oxide prepared in step S1, dry it at 110°C overnight, and then calcine it in a muffle furnace at 450°C for 5 hours to obtain a spherical cerium oxide supported nickel catalyst (SEM image see Figure 1 ), which is a carbon dioxide methanation catalyst; wherein the nickel loading is 10wt%.

[0057] Example 2

[0058] The spherical cerium oxide supported nickel catalyst and polydivinylbenzene prepared in Example 1 were ground through a 60-mesh sieve, and 0.3 g of the sieve was taken and mixed evenly (the SEM image of the spherical cerium oxide supported nickel catalyst and polydivinylbenzene after being mixed evenly is shown in FIG. Figure 2 ) and loaded into a stainless steel fixed bed reactor for catalytic performance evaluation.

[0059] Catalytic performance evaluation process: Pre-treatment at 350°C for 2 hours in a 10 mL / min hydrogen atmosphere to reduce the active metal nickel to a metallic state, and then lower the temperature to the reaction temperature. The atmosphere is switched to a reaction gas (V(H2):V(CO2)=4), with a space velocity of 10000 ml g -1 h -1 The reaction temperatures were 200°C, 250°C, 300°C and 350°C respectively. Catalytic data were collected at different reaction temperatures. The experimental results are shown in Table 2.

[0060] Embodiments 3 to 9

[0061] Compared with Example 2, the difference lies in the difference in particle size and / or filling method, as shown in Table 1 for details.

[0062] Table 1

[0063]

[0064] The catalytic performance evaluation process is the same as in Example 2, and the experimental results are shown in Table 2.

[0065] Comparative Example 1

[0066] Compared with Example 2, the only difference is that the spherical cerium oxide-supported nickel catalyst is replaced with an alumina-supported nickel catalyst, and the preparation steps are as follows:

[0067] 4.955 g of nickel nitrate hexahydrate was weighed and dissolved in 15 mL of deionized water, followed by the addition of 9.0 g of alumina (60 mesh particle size), dried at 110° C. overnight, and then calcined in a muffle furnace at 450° C. for 5 hours to obtain a commercial alumina-supported nickel catalyst, wherein the nickel loading was 10 wt%.

[0068] The catalytic performance evaluation process is the same as in Example 2, and the experimental results are shown in Table 2.

[0069] Comparative Example 2

[0070] Compared with Example 9, the only difference is that the same catalyst as that of Comparative Example 1 is used. The catalytic performance evaluation process is the same as that of Example 2, and the experimental results are shown in Table 2.

[0071] Table 2 Catalytic performance of catalysts for carbon dioxide methanation

[0072]

[0073]

[0074] It can be seen from the data in Table 2 that the catalyst prepared by the present invention has a higher carbon dioxide conversion rate at a lower temperature and a higher methane selectivity when used for carbon dioxide methanation catalysis. Among them, the difference between Example 2 and Examples 6-7, and between Examples 3-5 is only the loading method. It can be seen from the data that the catalytic performance of the catalyst and the auxiliary agent after mixing is better than that of the two separately loaded; the difference between Example 2 and Example 3, between Example 4 and Example 6, and between Example 5 and Example 7 is the difference in particle size. It can be seen from the data that the performance of the 40-60 mesh catalyst is slightly better than that of the 60 mesh catalyst; Examples 8-9 are schemes without auxiliary agents. It can be seen from the comparison between the data that after adding auxiliary agents, the catalytic performance of the catalyst is significantly improved.

[0075] Comparative Examples 1 and 2 use alumina-supported nickel catalysts. By comparison with the examples, it can be seen that the carbon dioxide conversion rate and methane selectivity of the spherical cerium oxide-supported nickel catalyst are higher than those of the alumina-supported nickel catalyst.

[0076] It can be seen that the spherical cerium oxide-supported nickel catalyst prepared by the present invention is a type of carbon dioxide methanation catalyst with great application prospects.

[0077] Stability test:

[0078] The spherical cerium oxide-supported nickel catalyst and polydivinylbenzene prepared in Example 1 were ground through a 60-mesh sieve, and 0.3 g of the sieve was taken and mixed evenly, and then loaded into a stainless steel fixed bed reactor, and pretreated at 350°C for 2 hours in a 10 mL / min hydrogen atmosphere, and then the temperature was lowered to the reaction temperature (300°C). The atmosphere was switched to a reaction gas (V(H2):V(CO2)=4), with a space velocity of 10000 ml g -1 h -1 , collect 50h of catalytic data, the experimental results are shown in Figure 3 .

[0079] The alumina-supported nickel catalyst and polydivinylbenzene prepared in Comparative Example 1 were ground through a 60-mesh sieve, and 0.3 g of the sieve was taken and mixed evenly, and then loaded into a stainless steel fixed bed reactor, and pretreated at 350°C for 2 hours in a 10 mL / min hydrogen atmosphere, and then the temperature was lowered to the reaction temperature (300°C). The atmosphere was switched to the reaction gas (V(H2):V(CO2)=4), and the space velocity was 10000 ml g -1 h -1 , collect 50h of catalytic data, the experimental results are shown in Figure 4 .

[0080] Figure 3 This is a stability performance diagram of the spherical cerium oxide-supported nickel catalyst prepared in Example 1 when used for carbon dioxide methanation catalysis; Figure 4 This is a stability performance diagram of the alumina-supported nickel catalyst prepared in Comparative Example 1 when used for carbon dioxide methanation catalysis. Figure 3-4 It can be seen that the catalyst of Example 1 remains basically stable within the reaction time of 50 hours, with a carbon dioxide conversion rate greater than 65% and a methane selectivity greater than 99%; while the catalyst prepared in Comparative Example 1 has a carbon dioxide conversion rate of about 50% and a methane selectivity less than 90%.

[0081] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0082] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a carbon dioxide methanation catalyst, comprising the steps of: The cerium source and the template agent are dissolved in a mixed solvent, and after reflux reaction, the spherical cerium oxide is obtained by centrifugation, washing, drying and calcination; The nickel source is dissolved in water to obtain a nickel source impregnation solution, the spherical cerium oxide is immersed in the nickel source impregnation solution, and after drying and calcination, the obtained spherical cerium oxide-supported nickel catalyst is the carbon dioxide methanation catalyst; Wherein, the mixed solvent consists of ethylene glycol and water; and / or, The cerium source includes at least one of cerium nitrate hexahydrate, cerium chloride and cerium sulfate; and / or, The template agent is polyvinyl pyrrolidone.

2. The preparation method according to claim 1, characterized in that The volume ratio of ethylene glycol to water is 7:1; and / or, The usage ratio of the cerium source, the template agent and ethylene glycol is 30g:6g:280mL.

3. The preparation method according to claim 1, characterized in that: The reflux reaction temperature is 140° C. and the time is 24 hours; and / or, The calcination temperature is 550° C. and the calcination time is 5 hours.

4. The preparation method according to claim 1, characterized in that: The nickel source comprises at least one of nickel nitrate hexahydrate, nickel chloride and nickel sulfate; and / or, The nickel source and water are used in a ratio of 4.955 g:1.5 mL; and / or, The mass ratio of the spherical cerium oxide to the nickel source is 9:4.

955.

5. The preparation method according to claim 1, characterized in that: The drying temperature is 110°C; and / or, The calcination temperature is 450° C. and the calcination time is 5 h.

6. A carbon dioxide methanation catalyst, characterized in that: The carbon dioxide methanation catalyst is prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the carbon dioxide methanation catalyst as claimed in claim 6 in catalytic hydrogenation of carbon dioxide to produce methane.

8. A method for improving the carbon dioxide conversion rate in the carbon dioxide hydrogenation to methane reaction, characterized in that the steps include: The carbon dioxide methanation catalyst and the auxiliary agent described in claim 6 are loaded into a catalyst fixed bed, pretreated in a hydrogen atmosphere at 350° C. for 2 h, then cooled to the reaction temperature, the hydrogen atmosphere is switched to the reaction gas, and catalytic carbon dioxide hydrogenation to methane is performed; Wherein, the mass ratio of the carbon dioxide methanation catalyst to the auxiliary agent is 1:0-1.

9. The method according to claim 8, characterized in that The mass ratio of the carbon dioxide methanation catalyst to the auxiliary agent is 1:1; and / or, The auxiliary agent includes polydivinylbenzene and / or polystyrene.

10. The method according to claim 8, characterized in that The reaction gas is composed of hydrogen and carbon dioxide in a volume ratio of 4:1 and a space velocity of 10000 mL g -1 h -1 and / or, The reaction temperature is 200-350°C.

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