Catalyst for co2 methanation reaction and preparation method and application thereof

Abstract

The application discloses a catalyst for CO2 methanation reaction and a preparation method and application thereof, and belongs to the technical field of CO2 methanation reaction. On the basis of nickel-aluminum layered double hydroxide, basic metal beneficial to CO2 conversion and basic metal beneficial to CO2 adsorption are simultaneously doped into the nickel-aluminum layered double hydroxide, and are in-situ grown on a carrier with a large specific surface area and a CO2 adsorption effect. After calcination and reduction, the catalyst for CO2 methanation reaction is obtained. On the basis of the nickel-aluminum layered double hydroxide, the basic metal additive and the carrier are compounded, the adsorption and in-situ conversion efficiency of CO2 are enhanced, and the conversion rate of CO2 at low temperature and the stability of the catalyst are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of CO2 methanation reaction technology, specifically to a catalyst for CO2 methanation reaction, its preparation method, and its application. Background Technology

[0002] CO2, as a cheap C1 resource, can be converted into methane, methanol, dimethyl carbonate, and other hydrocarbons. Methane, a major component of natural gas, is a high-calorific-value clean fuel and also an important basic raw material that can be converted into high-value-added chemical products. Since the byproduct of CO2 hydromethanation is water, which is pollution-free and reusable, it belongs to green chemistry; therefore, research on CO2 hydromethanation is of great significance. The CO2 methanation reaction (CO2 + 4H2 → CH4 + 2H2O, Δ) r H 0 298K The reaction (-165 kJ / mol) is a strongly exothermic reaction, and thermodynamically, lower temperatures theoretically favor the methanation reaction. However, CO2 is a chemically stable inert gas, making it difficult to activate at low temperatures. Therefore, developing catalysts with high activity at low temperatures is crucial for the research of CO2 methanation reaction.

[0003] Studies have shown that active metals such as Rh, Co, and Ni all possess excellent catalytic activity for CO2 methanation. Among them, Ni-based catalysts have attracted widespread attention due to their low cost and high catalytic activity. However, Ni-based catalysts are prone to deactivation due to sintering at high temperatures. To address this issue, researchers have proposed various improvement schemes, such as changing the type of support, forming bimetallic catalysts, and adding promoters. Most supported catalysts are obtained directly using impregnation methods, resulting in low dispersion of the active component and weak interaction between the active component and the support.

[0004] Compared to traditional supported catalysts, layered double hydroxides (LDHs) offer numerous advantages. For instance, the active metal cations in LDHs are uniformly distributed at the atomic level, enhancing catalytic activity. The large specific surface area and mesoporous structure of LDH precursor materials retain their layered structure after calcination, resulting in highly dispersed metal oxides at the atomic level. The ability to alter the basicity of LDHs by changing the metal cations facilitates the construction of catalysts with basic characteristics, thus demonstrating excellent tunability. The strong metal-support interaction during the calcination stage of LDH precursors prevents the sintering of metal particles. Based on these advantages, LDHs have been used as catalyst precursors in existing technologies. For example, Ni-based catalysts prepared using layered double hydroxides as precursors have been reported for CO2 methanation, exhibiting significant advantages in CO2 catalytic conversion reactions.

[0005] However, the microporous structure of the Ni-based catalyst prepared using hydrotalcite as a precursor leads to increased diffusion resistance, restricting the transfer of CO2 molecules to the active sites, thus requiring further improvement in its low-temperature activity. Furthermore, due to the low specific surface area of ​​hydrotalcite and its low metal dispersion after reduction, the catalyst is prone to deactivation due to sintering, resulting in poor stability. Summary of the Invention

[0006] This invention provides a catalyst for CO2 methanation reaction, its preparation method, and its application. It effectively solves the technical problem of poor low-temperature activity and stability of existing Ni-based catalysts prepared with hydrotalcite as a precursor. This invention uses an alkaline metal-doped nickel-aluminum layered bimetallic hydroxide supported on a carrier, and after calcination and reduction, constructs a catalyst for CO2 methanation reaction that integrates efficient CO2 capture and utilization.

[0007] The first object of the present invention is to provide a catalyst for the CO2 methanation reaction, wherein the catalyst for the CO2 methanation reaction is based on soluble Ni 2+ Salt, soluble Al 3+ Using salts and soluble salts of other alkaline metals as raw materials, urea and ethylene glycol are added to form a precursor solution in water. The support is immersed in the precursor solution for hydrothermal reaction, and a hydrotalcite precursor is grown in situ on the support to obtain a supported precursor. The supported precursor is calcined to form a mixed metal oxide containing NiO, which is a primary catalyst. The primary catalyst is then reduced in a hydrogen atmosphere to reduce NiO to Ni.

[0008] The other alkali metals are at least one of Ba, Sr, Ca and Mg and at least one of Pr, La, Ce, Fe and Co; the support is a molecular sieve or biochar.

[0009] In the above technical solution, Ba, Sr, Ca, and Mg are alkaline metals that are beneficial for CO2 adsorption, while Pr, La, Ce, Fe, and Co are alkaline metals that are beneficial for CO2 conversion. Calcination is used to burn off nitrates and carbonates in the hydrotalcite precursor to obtain a mixed oxide precursor, while maintaining the layered structure of the hydrotalcite and keeping it uniformly mixed. For example, by adding urea and ethylene glycol to various nitrate and carrier molecular sieves, a mixture of NiBaLaAl-LDH hydrotalcite grown on the molecular sieve is obtained by solvothermal method, with the composition [Ni2Ba 0.1 La 0.1 Al 0.9 (OH)3] 4.2+ (A 2- ) 2.1 And molecular sieves, where A is the interlayer anion CO3. 2-Nitrate ions, after calcination and decomposition, yield a mixed oxide with the chemical composition of NiO, Al2O3, BaO, and La2O3. Since metallic Ni has catalytic activity in converting CO2 to methane, the purpose of the reduction treatment is to reduce NiO to metallic Ni. For example, the chemical composition of the NiBaLaAl-LDH hydrotalcite after calcination is NiO, Al2O3, BaO, and La2O3. 3， After reduction with H2, catalysts Ni, Al2O3, BaO, La2O3 and molecular sieves were obtained.

[0010] In a preferred embodiment, the mass fraction of the other alkali metals is ≤60% and the mass fraction of nickel is 5%~30% based on the total mass of the hydrotalcite precursor.

[0011] In a preferred embodiment, the molecular sieve is ZSM-5 zeolite molecular sieve.

[0012] In a preferred embodiment, the mass fraction of the support is 0.5% to 40% based on the total mass of the catalyst used in the CO2 methanation reaction.

[0013] A second objective of this invention is to provide a method for preparing the catalyst for the CO2 methanation reaction as described in any one of the above claims, comprising the following steps: With soluble Ni 2+ Salt, soluble Al 3+ Using salts and soluble salts of other alkaline metals as raw materials, urea and ethylene glycol are added to form a precursor solution in water. The support is immersed in the precursor solution for hydrothermal reaction, and a hydrotalcite precursor is formed in situ on the support to obtain a supported precursor. The supported precursor is calcined to form a mixed metal oxide containing NiO, thus obtaining a primary catalyst.

[0014] The primary catalyst was reduced in a hydrogen atmosphere to reduce NiO to Ni.

[0015] The other alkali metals are at least one of Ba, Sr, Ca and Mg, and at least one of Pr, La, Ce, Fe and Co.

[0016] In a preferred embodiment, the method for preparing the supported precursor is as follows: [The text abruptly shifts to a seemingly unrelated topic about Ni...] 2+ Salt, soluble Al 3+ Urea and ethylene glycol are added to a mixed aqueous solution of the salt and the other soluble salts of the alkaline metals to obtain a precursor solution. The carrier is immersed in the precursor solution and subjected to a hydrothermal reaction at 120℃~160℃ for 10h~24h to obtain a supported precursor.

[0017] In the above reaction, urea and ethylene glycol can be replaced by pure water, ethanol, and glycerol.

[0018] In a preferred embodiment, the calcination is performed at 400℃~600℃ for 1h~4h.

[0019] In a preferred embodiment, the flow rate of the hydrogen atmosphere is 10 mL / min to 40 mL / min, and the reduction treatment time is 1 h to 5 h.

[0020] The third objective of this invention is to provide an application of the above-mentioned catalyst for CO2 methanation reaction in the catalytic hydrogenation of CO2 to methane reaction, wherein the application is as follows: using H2, CO2 and N2 as raw materials, the catalyst for CO2 methanation reaction is used to carry out the catalytic hydrogenation of CO2 to methane reaction at 150℃~350℃.

[0021] In a preferred embodiment, based on the amount of catalyst used in the CO2 methanation reaction (0.1 g), the total flow rate of the feed gas is 10 mL / min. -1 ~150mL·min -1 The volume ratio of H2, CO2 and N2 in the raw gas is 16:4:5.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for preparing a catalyst for CO2 methanation reaction. Based on a nickel-aluminum layered bimetallic hydroxide, this invention simultaneously incorporates an alkaline metal that is beneficial for CO2 adsorption and an alkaline metal that is beneficial for CO2 conversion into the nickel-aluminum layered bimetallic hydroxide, and grows it in situ on a support with a large specific surface area that has CO2 adsorption capacity. After calcination and reduction, a supported catalyst modified with closely contacted dual alkaline metal promoters is obtained, which is the catalyst for CO2 methanation reaction of this invention.

[0023] This invention utilizes a support that not only enhances CO2 adsorption but also improves the dispersibility of Ni and other metal components, ensuring close contact between the components and further increasing the CO2 adsorption capacity and the efficiency of in-situ CO2 conversion to methane. Due to the strong interaction between the metal components and the support, after reduction, Ni nanoparticles are in close contact with the alkaline metal promoter ions while remaining highly dispersed on the support. This effectively prevents particle sintering caused by Ni nanoparticle migration, thereby improving catalyst stability. When using a catalyst for the CO2 methanation reaction to catalyze the hydrogenation of CO2 to methane, the doped alkaline metal not only enhances the chemisorption of CO2 but also regulates the electronic properties of Ni, inducing oxygen vacancy generation and promoting H2 dissociation and CH4 formation, thus facilitating the efficient conversion of CO2.

[0024] This invention enhances the adsorption and in-situ conversion efficiency of CO2 by combining it with alkaline metal additives and a carrier, based on nickel-aluminum layered bimetallic hydroxide, thereby greatly improving the CO2 conversion rate at low temperatures. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the preparation of the hydrotalcite precursor in Embodiment 1 of the present invention.

[0026] Figure 2 This is a process flow diagram of the preparation of the catalyst for the CO2 methanation reaction in Example 1 of the present invention.

[0027] Figure 3 These are XRD comparison diagrams of the hydrotalcite precursor, primary catalyst, and CO2 methanation catalyst prepared in Examples 1, 2, 6, and 10 of this invention. In these diagrams, a represents the hydrotalcite precursor, b represents the primary catalyst, and c represents the CO2 methanation catalyst. NiSrPrAl-LDH represents Example 1, NiAl-LDH represents Comparative Example 10, NiSrAl-LDH represents Comparative Example 2, and NiPrAl-LDH represents Comparative Example 6. NiSrPrAl-LDO represents Example 1, NiAl-LDO represents Comparative Example 10, NiSrAl-LDO represents Comparative Example 2, and NiPrAl-LDO represents Comparative Example 6. NiSrPrAl represents Example 1, NiAl represents Comparative Example 10, NiSrAl represents Comparative Example 2, and NiPrAl represents Comparative Example 6.

[0028] Figure 4 These are scanning electron microscope (SEM) images of the catalyst used in the CO2 methanation reaction of Example 1 of the present invention, wherein a is a 2kx SEM image, b is a 5kx SEM image, c is a 10kx SEM image, and d is a 20kx SEM image.

[0029] Figure 5 These are transmission electron microscopy (TEM) images and particle size distribution diagrams of the catalyst used in the CO2 methanation reaction of Example 1 of the present invention, wherein a and b are TEM images at different magnifications, and a' is a particle size distribution diagram.

[0030] Figure 6 These are scanning transmission electron microscope (STEM) images of the catalyst used in the CO2 methanation reaction of Example 1 of the present invention, as well as line and surface scan images of the corresponding elements Ni, Sr, Pr, Al and Si. Among them, a and b are STEM images at different magnifications, b' is a line and surface scan image, Ni is the elemental distribution map of Ni in a, Sr is the elemental distribution map of Sr in a, Al is the elemental distribution map of Al in a, and Si is the elemental distribution map of Si in a.

[0031] Figure 7This is a comparison chart of the catalytic performance of the CO2 methanation catalysts of Examples 1, 2, 6 and 10 of the present invention, wherein NiSrPrAl is Example 1, NiSrAl is Comparative Example 2, NiPrAl is Comparative Example 6 and NiAl is Comparative Example 10.

[0032] Figure 8 This is a comparison chart of the methane selectivity of the CO2 methanation catalysts of Examples 1, 2, 6 and 10 of the present invention, wherein NiSrPrAl is Example 1, NiSrAl is Comparative Example 2, NiPrAl is Comparative Example 6 and NiAl is Comparative Example 10.

[0033] Figure 9 This is a stability test diagram of the catalyst used in the CO2 methanation reaction of Example 1 of the present invention.

[0034] Figure 10 This is a comparison chart of the catalytic performance of the CO2 methanation catalysts of Example 7, Comparative Example 1, Comparative Example 6 and Comparative Example 10 of the present invention, wherein NiBaPrAl is Example 7, NiBaAl is Comparative Example 1, NiPrAl is Comparative Example 6 and NiAl is Comparative Example 10.

[0035] Figure 11 This is a comparison chart of the catalytic performance of the CO2 methanation catalysts of Examples 12, 3, 6 and 10 of the present invention. In the figure, NiCaPrAl is Example 12, NiCaAl is Comparative Example 3, NiPrAl is Comparative Example 6 and NiAl is Comparative Example 10.

[0036] Figure 12 This is a comparison chart of the catalytic performance of the CO2 methanation catalysts of Examples 17, 4, 6 and 10 of the present invention. In the figure, NiMgPrAl is Example 12, NiMgAl is Comparative Example 4, NiPrAl is Comparative Example 6 and NiAl is Comparative Example 10. Detailed Implementation

[0037] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0038] Currently available Ni-based catalysts for CO methanation exhibit poor low-temperature activity due to their microporous structure, which increases diffusion resistance and restricts the transfer of CO2 molecules to active sites. Furthermore, the low specific surface area of ​​hydrotalcite leads to low metal dispersion after reduction, making the catalyst prone to deactivation due to sintering and resulting in poor stability. To address these technical problems, this invention provides a catalyst for CO methanation, its preparation method, and its applications.

[0039] The technical solution of the present invention will be analyzed and described in detail below.

[0040] The technical effects of the present invention will be described below with reference to specific embodiments and comparative examples.

[0041] Example 1 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Sr(NO3)2·4H2O (0.2 mmol, 0.042 g), Pr(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all solutes are dissolved, add urea, then add 50 mL of ethylene glycol solution, stir for 2.5 h to mix thoroughly, and obtain the precursor solution. Add 0.095 g of ZSM-5 zeolite molecular sieve (its morphology is as follows) Figure 5 The sample (as shown) was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain the hydrotalcite precursor, denoted as NiSrPrAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol solvent and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor, denoted as NiSrPrAl-LDH.

[0042] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiSrPrAl-LDO, to obtain the primary catalyst.

[0043] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiSrPrAl.

[0044] Example 2 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Sr(NO3)2·4H2O (0.2 mmol, 0.042 g), La(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of [unspecified solution]. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.097 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiSrLaAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0045] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiSrLaAl-LDO, to obtain the primary catalyst.

[0046] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiSrLaAl.

[0047] Example 3 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Sr(NO3)2·4H2O (0.2 mmol, 0.042 g), Ce(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea, then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.095 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiSrCeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0048] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiSrCeAl-LDO, to obtain the primary catalyst.

[0049] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiSrCeAl.

[0050] Example 4 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Sr(NO3)2·4H2O (0.2 mmol, 0.042 g), Fe(NO3)3·9H2O (0.094 mmol, 0.038 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiSrFeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve support, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0051] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiSrFeAl-LDO, to obtain the primary catalyst.

[0052] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiSrFeAl.

[0053] Example 5 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Sr(NO3)2·4H2O (0.2 mmol, 0.042 g), Co(NO3)3·6H2O (0.2 mmol, 0.058 g) and Al(NO3)3·9H2O (0.94 mmol, 0.353 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of ethyl acetate. The glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.09 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiSrCoAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve support, centrifuged, and washed alternately with ethylene glycol solvent and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0054] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiSrCoAl-LDO, to obtain the primary catalyst.

[0055] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiSrCoAl.

[0056] Example 6 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ba(NO3)2·4H2O (0.2 mmol, 0.066 g), La(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea, then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.088 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiBaLaAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0057] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiBaLaAl-LDO, to obtain the primary catalyst.

[0058] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiBaLaAl.

[0059] Example 7 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ba(NO3)2·4H2O (0.2 mmol, 0.066 g), Pr(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.087 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiBaPrAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0060] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiBaPrAl-LDO, to obtain the primary catalyst.

[0061] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiBaPrAl.

[0062] Example 8 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ba(NO3)2·4H2O (0.2 mmol, 0.066 g), Ce(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea, then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.087 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiBaCeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0063] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiBaCeAl-LDO, to obtain the primary catalyst.

[0064] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiBaCeAl.

[0065] Example 9 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ba(NO3)2·4H2O (0.2 mmol, 0.066 g), Fe(NO3)3·9H2O (0.094 mmol, 0.038 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.095 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiBaFeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0066] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiBaFeAl-LDO, to obtain the primary catalyst.

[0067] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiBaFeAl.

[0068] Example 10 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ba(NO3)2·4H2O (0.2 mmol, 0.066 g), Co(NO3)3·6H2O (0.2 mmol, 0.058 g) and Al(NO3)3·9H2O (0.94 mmol, 0.353 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of... The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.08 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiBaCoAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0069] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiBaCoAl-LDO, to obtain the primary catalyst.

[0070] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiBaCoAl.

[0071] Example 11 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ca(NO3)2·4H2O (0.2 mmol, 0.047 g), La(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea, then add 50 mL of deionized water. A mL ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, yielding a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was reacted at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCaLaAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0072] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCaLaAl-LDO, to obtain the primary catalyst.

[0073] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCaLaAl.

[0074] Example 12 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ca(NO3)2·4H2O (0.2 mmol, 0.047 g), Pr(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50... A mL ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, yielding a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was reacted at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCaPrAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0075] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCaPrAl-LDO, to obtain the primary catalyst.

[0076] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCaPrAl.

[0077] Example 13 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ca(NO3)2·4H2O (0.2 mmol, 0.047 g), Ce(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea, then add 50 mL of deionized water. A mL ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, yielding a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was reacted at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCaCeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0078] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCaCeAl-LDO, to obtain the primary catalyst.

[0079] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCaCeAl.

[0080] Example 14 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ca(NO3)2·4H2O (0.2 mmol, 0.047 g), Fe(NO3)3·9H2O (0.094 mmol, 0.038 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea, then add 50... A mL ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, yielding a precursor solution. 0.11 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCaFeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0081] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCaFeAl-LDO, to obtain the primary catalyst.

[0082] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCaFeAl.

[0083] Example 15 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ca(NO3)2·4H2O (0.2 mmol, 0.047 g), Co(NO3)3·6H2O (0.2 mmol, 0.058 g) and Al(NO3)3·9H2O (0.94 mmol, 0.353 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCaCoAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0084] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCaCoAl-LDO, to obtain the primary catalyst.

[0085] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCaCoAl.

[0086] Example 16 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Mg(NO3)2·6H2O (0.2 mmol, 0.05 g), La(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiMgLaAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0087] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiMgLaAl-LDO, to obtain the primary catalyst.

[0088] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiMgLaAl.

[0089] Example 17 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Mg(NO3)2·6H2O (0.2 mmol, 0.05 g), Pr(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was reacted at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiMgPrAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0090] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiMgPrAl-LDO, to obtain the primary catalyst.

[0091] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiMgPrAl.

[0092] Example 18 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Mg(NO3)2·6H2O (0.2 mmol, 0.05 g), Ce(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was reacted at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiMgCeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0093] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiMgCeAl-LDO, to obtain the primary catalyst.

[0094] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiMgCeAl.

[0095] Example 19 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Mg(NO3)2·6H2O (0.2 mmol, 0.05 g), Fe(NO3)3·9H2O (0.094 mmol, 0.038 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of deionized water. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.11 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiMgFeAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0096] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiMgFeAl-LDO, to obtain the primary catalyst.

[0097] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiMgFeAl.

[0098] Example 20 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh out Ni(NO3)2·6H2O (2 mmol, 0.582 g), Mg(NO3)2·6H2O (0.2 mmol, 0.05 g), Co(NO3)3·6H2O (0.2 mmol, 0.058 g) and Al(NO3)3·9H2O (0.94 mmol, 0.353 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, and then add 50 mL of urea solution. The ethylene glycol solution was stirred for 2.5 h to ensure thorough mixing, resulting in a precursor solution. 0.1 g of ZSM-5 zeolite molecular sieve was added to the precursor solution and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was carried out at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiMgCoAl-LDH. This precursor was then loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol and water. The mixture was then dried at 80 °C for 12 h to obtain the loaded precursor.

[0099] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiMgCoAl-LDO, to obtain the primary catalyst.

[0100] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiMgCoAl.

[0101] To further illustrate the technical effects of the present invention, comparative examples are also provided, as follows: Comparative Example 1 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ba(NO3)2·4H2O (0.2 mmol, 0.066 g), and Al(NO3)3·9H2O (0.94 mmol, 0.353 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.097 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiBaAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0102] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiBaAl-LDO, to obtain the primary catalyst.

[0103] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiBaAl.

[0104] Comparative Example 2 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Sr(NO3)2·4H2O (0.2 mmol, 0.042 g), and Al(NO3)3·9H2O (0.94 mmol, 0.353 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.1 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiSrAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0105] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiSrAl-LDO, to obtain the primary catalyst.

[0106] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiSrAl.

[0107] Comparative Example 3 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ca(NO3)2·4H2O (0.2 mmol, 0.047 g), and Al(NO3)3·9H2O (0.94 mmol, 0.353 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.11 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCaAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0108] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCaAl-LDO, to obtain the primary catalyst.

[0109] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCaAl.

[0110] Comparative Example 4 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Mg(NO3)2·6H2O (0.2 mmol, 0.05 g), and Al(NO3)3·9H2O (0.94 mmol, 0.353 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.12 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiMgAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0111] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiMgAl-LDO, to obtain the primary catalyst.

[0112] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiMgAl.

[0113] Comparative Example 5 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), La(NO3)3·6H2O (0.094 mmol, 0.04 g) and Al(NO3)3·9H2O (0.846 mmol, 0.318 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, then add 50 mL of ethylene glycol solution, stir for 2.5 h to mix thoroughly, and obtain a precursor solution. Add 0.11 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiLaAl-LDH, and load it onto the ZSM-5 zeolite molecular sieve support. Centrifuge, wash with alternating ethylene glycol solvent and water, and dry at 80 °C for 12 h to obtain the loaded precursor.

[0114] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiLaAl-LDO, to obtain the primary catalyst.

[0115] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiLaAl.

[0116] Comparative Example 6 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Pr(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.11 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiPrAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0117] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiPrAl-LDO, to obtain the primary catalyst.

[0118] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiPrAl.

[0119] Comparative Example 7 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Ce(NO3)3·6H2O (0.094 mmol, 0.04 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.11 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCeAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0120] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCeAl-LDO, to obtain the primary catalyst.

[0121] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCeAl.

[0122] Comparative Example 8 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1. Weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Fe(NO3)3·9H2O (0.094 mmol, 0.038 g), and Al(NO3)3·9H2O (0.846 mmol, 0.318 g). Add 10 mL of deionized water to a beaker and stir with a magnetic stirrer until all the solutes are dissolved. Add urea and then 50 mL of ethylene glycol solution. Stir for 2.5 h to ensure thorough mixing and obtain a precursor solution. Add 0.12 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer it to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiFeAl-LDH. Load the hydrotalcite precursor onto the ZSM-5 zeolite molecular sieve support, centrifuge, and wash alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0123] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiFeAl-LDO, to obtain the primary catalyst.

[0124] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiFeAl.

[0125] Comparative Example 9 A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g), Co(NO3)2·6H2O (0.2 mmol, 0.058 g) and Al(NO3)3·9H2O (0.94 mmol, 0.353 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solutes are dissolved, add urea, then add 50 mL of ethylene glycol solution, stir for 2.5 h to mix thoroughly, and obtain a precursor solution. Add 0.11 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiCoAl-LDH, which is loaded onto the ZSM-5 zeolite molecular sieve support, centrifuged, and washed alternately with ethylene glycol solvent and water, and dried at 80 °C for 12 h to obtain the loaded precursor.

[0126] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiCoAl-LDO, to obtain the primary catalyst.

[0127] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiCoAl.

[0128] Comparative Example 10 The difference compared to Example 1 is that alkali metals are not used for doping, that is, Sr(NO3)2·4H2O and Pr(NO3)3·6H2O are not added to S2.

[0129] A method for preparing a catalyst for CO2 methanation reaction includes the following steps: S1, weigh Ni(NO3)2·6H2O (2 mmol, 0.582 g) and Al(NO3)3·9H2O (0.94 mmol, 0.353 g), add 10 mL of deionized water to a beaker, stir with a magnetic stirrer until all the solute is dissolved, add urea, then add 50 mL of ethylene glycol solution, stir for 2.5 h to mix thoroughly, and obtain a precursor solution. Add 0.12 g of ZSM-5 zeolite molecular sieve to the precursor solution and transfer to a 100 mL polytetrafluoroethylene reactor. React at 120 °C for 12 h to obtain a hydrotalcite precursor, denoted as NiAl-LDH, which is loaded onto the ZSM-5 zeolite molecular sieve, centrifuged, and washed alternately with ethylene glycol solvent and water. Dry at 80 °C for 12 h to obtain the loaded precursor.

[0130] S2, the supported precursor is calcined at 550°C for 2 hours to convert the hydrotalcite precursor supported on the supported precursor into a mixed metal oxide containing NiO, denoted as NiAl-LDO, to obtain the primary catalyst.

[0131] S3, the primary catalyst is reduced in a hydrogen atmosphere with a flow rate of 32 mL / min for 2 h to obtain a catalyst for CO2 methanation reaction, denoted as NiAl.

[0132] The morphology and performance of the catalysts for CO2 methanation prepared in Examples 1 to 20 and Comparative Examples 1 to 10 of the present invention were tested, and the results are as follows.

[0133] Catalyst performance testing Catalytic performance was tested and analyzed using a micro fixed-bed reactor, including CO2 conversion, methane selectivity, and catalyst stability for CO2 methanation.

[0134] In testing the catalytic performance of this invention, a micro fixed-bed reactor with a reaction tube diameter of 6 mm and a length of 450 mm is used. First, the catalyst for the CO2 methanation reaction of this invention (0.1 g to 0.5 g, 40 mesh to 60 mesh) is loaded into the reactor. Then, feed gas (H2 / CO2 / N2 = 16:4:5) is introduced into the reactor to carry out the reaction, with a total flow rate of 50 mL / min. -1 ~150mL·min -1 The temperature of the catalyst bed was controlled by K-type thermocouples inside and outside the reaction tube and by a PID controller, with the test temperature ranging from 150℃ to 350℃. The tail gas after the reaction was dried with color-changing silica gel to absorb H2O, and then entered the chromatograph through a six-way valve. The percentage content of each component in the feed gas and tail gas was calculated using the internal standard method, and the conversion rate and product selectivity were calculated. The catalytic performance was comprehensively evaluated in conjunction with catalyst stability.

[0135] XRD was used to determine the compositional changes of the catalyst, while SEM and TEM were used to understand the morphology of the catalyst, the dispersion of metals, particle size and relative distribution. The results of each characterization were analyzed in detail.

[0136] 1. XRD detection: Figure 3Figure a shows the XRD patterns of the precursors NiAl-LDH, NiSrAl-LDH, NiPrAl-LDH, and NiSrPrAl-LDH. Four diffraction peaks appear at diffraction angles of 9.3°, 19.2°, 34.8°, and 61.5°, indicating that the precursors have a typical hydrotalcite-like structure, corresponding to the (003), (006), (009), and (112) crystal planes of hydrotalcite-like crystals, respectively (PDF number #48–0594). The characteristic peak intensities on the NiPrAl-LDH and NiSrPrAl-LDH precursors are significantly reduced, indicating that the introduction of Pr is detrimental to the formation of the hydrotalcite-like structure. The XRD results of the primary catalysts formed after calcination of the above four precursors are shown below. Figure 3 As shown in b. Obviously, the characteristic hydrotalcite-like diffraction peaks disappeared after calcination, indicating that the hydrotalcite-like structure collapsed during calcination. The diffraction peaks at diffraction angles of 37.1°, 43.1°, 63.0°, and 75.4° correspond to the (111), (200), (220), and (311) crystal planes of NiO (PDF-#47-1049). No diffraction peaks of Al2O3, SrO, and Pr2O3 were found in the XRD pattern because Al2O3, SrO, and Pr2O3 exist in an amorphous state or are highly dispersed in the catalyst. The XRD of the catalyst applied to the CO2 methanation reaction is shown in Figure 1. Figure 3 As shown in Figure c, after reduction by H2, the diffraction peaks of NiO disappear, indicating that NiO is almost completely reduced to elemental Ni. The diffraction peaks at diffraction angles of 44.5°, 51.8°, and 76.3° correspond to the (111), (200), and (220) crystal planes of elemental Ni (PDF-#04-0850).

[0137] 2. SEM analysis: from Figure 4 As can be seen from a, at low magnification, the catalyst exhibits a porous structure composed of a large number of tightly packed nanoparticles, and the overall structure is relatively compact. Figure 4 As the magnification increases, particles b~c can be seen to exhibit a plate-like or block-like structure with a rough surface and irregular edges. This rough surface and irregular edges may be due to the structural changes during crystal growth, calcination, and reduction processes in the hydrothermal preparation method. Figure 4 At high magnification (d), the fine structure of individual particles can be observed. Ni particles are tightly attached to the molecular sieve support, and obvious pores exist on the surface of the molecular sieve. These pores and defects are likely formed by structural rearrangement during calcination and reduction. These pores not only increase the specific surface area of ​​the catalyst but also provide more channels for the adsorption and diffusion of reactant molecules, which is beneficial to improving the efficiency of the catalytic reaction.

[0138] 3. TEM analysis: like Figure 5 As shown in Figure a, the lighter-colored portion is the carrier ZSM-5, while the darker-colored portion is a mixture of metallic Ni and Al₂O₃, SrO, and Pr₂O₃. Figure 5 As shown in Figure a', the average particle size of the NiSrPrAl catalyst is approximately 7.5 nm. High-magnification transmission electron microscopy (HRTEM) images of the catalyst are shown below. Figure 5 b, where the lattice spacing of 2.03 Å is the (111) crystal plane of metallic Ni, and the lattice spacing of 1.76 Å is the (200) crystal plane of metallic Ni. Figure 6 b' is the line scan diagram of the NiSrPrAl catalyst. Obviously, the variation trend of Ni particles is similar to that of Al and Si elements, indicating that Ni nanoparticles are distributed on the support zsm-5. Figure 6 Image 'a' shows the STEM image and corresponding elemental surface scans of the NiSrPrAl catalyst. In the Ni-enriched areas, Sr, Pr, and Al are also enriched, indicating close contact and uniform distribution between Ni and the oxides of Sr, Pr, and Al. Simultaneously, the line scan results show that SrO-Pr₂O₃-Al₂O₃ are uniformly distributed on the ZSM-5 support, and the black areas represent Ni nanoparticles.

[0139] 4. Catalytic performance: Conversion rate and selectivity: From Figure 7 It can be seen that the catalyst for CO2 methanation prepared by adding Sr and Pr significantly improves the CO2 conversion rate. At 240℃, the conversion rate of NiAl is only 5.5%, while the conversion rate after adding Sr and Pr is 57.5%, greatly improving the catalytic activity of the catalyst for CO2 methanation at low temperatures. Meanwhile, from... Figure 8 It can be seen that the CH4 selectivity of the catalyst is significantly enhanced after adding Sr and Pr as dual promoters.

[0140] Stability: A high-performance catalyst for CO2 methanation requires not only high low-temperature catalytic activity but also high stability. Therefore, this invention achieves this stability at 300°C, 0.1 MPa, and a space velocity of 30000 mL·g⁻¹. −1 ·h −1 The lifespan of the NiSrPrAl catalyst prepared in Example 1 of this invention was tested under the following conditions: Figure 8 As shown, the CO2 conversion rate decreases slightly at the beginning of the reaction because the reaction has not yet reached a steady state. Figure 9 As can be seen, the conversion rate of the NiSrPrAl catalyst remained at 65% after 200 hours of continuous reaction, indicating that the performance of the NiSrPrAl catalyst was not deactivated.

[0141] Figures 10-12 Performance analysis: From Figure 10 It can be seen that the CO2 methanation catalyst prepared by adding Ba and Pr significantly improved the CO2 conversion rate. At 240℃, the conversion rate of NiAl was only 5.5%, while the conversion rate after adding Ba and Pr as dual promoters was 57%, which greatly improved the catalytic activity of the catalyst for CO2 methanation at low temperatures.

[0142] from Figure 11 It can be seen that the addition of Ca and Pr as dual promoters significantly improves the CO2 methanation reaction conversion rate. At 240℃, the conversion rate of NiAl is only 5.5%, while the conversion rate after adding Ca and Pr is 56%, greatly improving the catalyst's catalytic activity for CO2 methanation at low temperatures.

[0143] from Figure 12 It can be seen that the catalyst for CO2 methanation prepared by adding Mg and Pr elements significantly improves the CO2 conversion rate. At 240℃, the conversion rate of NiAl is only 5.5%, while the conversion rate increases to 55% after adding Mg and Pr as dual promoters, greatly improving the catalytic activity of the catalyst for CO2 methanation at low temperatures.

[0144] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A catalyst for CO2 methanation reaction, characterized in that, The catalyst used in the CO2 methanation reaction is soluble Ni. 2+ Salt, soluble Al 3+ Using salts and soluble salts of other alkali metals as raw materials, urea and ethylene glycol are added to form a precursor solution in water. The support is immersed in the precursor solution for hydrothermal reaction, and a hydrotalcite precursor is grown in situ on the support to obtain a supported precursor. The supported precursor is calcined to form a mixed metal oxide containing NiO, which is a primary catalyst. The primary catalyst is then reduced in a hydrogen atmosphere to reduce NiO to Ni. The other alkali metals are at least one of Ba, Sr, Ca and Mg and at least one of Pr, La, Ce, Fe and Co; the support is a molecular sieve or biochar.

2. The catalyst for CO2 methanation reaction according to claim 1, characterized in that, Based on the total mass of the hydrotalcite precursor, the mass fraction of the other alkali metals is ≤60%, and the mass fraction of nickel is 5%~30%.

3. The catalyst for CO2 methanation reaction according to claim 1, characterized in that, The molecular sieve is ZSM-5 zeolite molecular sieve.

4. The catalyst for CO2 methanation reaction according to claim 3, characterized in that, The mass fraction of the support is 0.5% to 40% based on the total mass of the catalyst used in the CO2 methanation reaction.

5. A method for preparing a catalyst for CO2 methanation reaction according to any one of claims 1 to 4, characterized in that, Includes the following steps: With soluble Ni 2+ Salt, soluble Al 3+ Using salts and soluble salts of other alkaline metals as raw materials, urea and ethylene glycol are added to form a precursor solution in water. The support is immersed in the precursor solution for hydrothermal reaction, and a hydrotalcite precursor is formed in situ on the support to obtain a supported precursor. The supported precursor is calcined to form a mixed metal oxide containing NiO, thus obtaining a primary catalyst. The primary catalyst was reduced in a hydrogen atmosphere to reduce NiO to Ni. The other alkali metals are at least one of Ba, Sr, Ca and Mg, and at least one of Pr, La, Ce, Fe and Co.

6. The method for preparing the catalyst for CO2 methanation reaction according to claim 5, characterized in that, The preparation method of the supported precursor is as follows: [The method involves applying a soluble Ni...] 2+ Salt, soluble Al 3+ Urea and ethylene glycol are added to a mixed aqueous solution of the salt and the other soluble salts of the alkaline metals to obtain a precursor solution. The carrier is immersed in the precursor solution and subjected to a hydrothermal reaction at 120℃~160℃ for 10h~24h to obtain a supported precursor.

7. The method for preparing the catalyst for CO2 methanation reaction according to claim 5, characterized in that, The calcination is carried out at 400℃~600℃ for 1h~4h.

8. The method for preparing the catalyst for CO2 methanation reaction according to claim 5, characterized in that, The flow rate of the hydrogen atmosphere is 10 mL / min to 40 mL / min, and the reduction treatment time is 1 h to 5 h.

9. The application of the catalyst for the CO2 methanation reaction as described in claims 1-4 in the catalytic hydrogenation of CO2 to methane reaction, characterized in that, The application is as follows: using H2, CO2 and N2 as raw materials, and employing the catalyst for the CO2 methanation reaction at 150℃~350℃, a catalytic CO2 hydrogenation to methane reaction is carried out.

10. The application according to claim 9, characterized in that, Based on a catalyst dosage of 0.1 g for the CO2 methanation reaction, the total flow rate of the feed gas is 10 mL·min. -1 ~150mL·min -1 The volume ratio of H2, CO2 and N2 in the raw gas is 16:4:5.

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