Preparation method and application of low-temperature high-activity nickel-based mesoporous catalyst

Abstract

The application belongs to the field of coal chemical industry and relates to a preparation method and application of a low-temperature high-activity nickel-based mesoporous catalyst, which is designed scientifically and reasonably, a Ni-based catalyst with a mesoporous material TUD-1 as a carrier is synthesized by using a gel-assisted one-pot synthesis method, the Ni is uniformly dispersed by using the large specific surface area of the carrier, the anchoring effect of the TUD-1 skeleton inhibits the agglomeration of the active center Ni, and more active sites are provided for the reaction. Meanwhile, the catalyst has high catalytic activity at a relatively low reaction temperature.

Description

Technical Field

[0001] This invention belongs to the field of coal chemical industry and relates to catalyst preparation technology, especially a method for preparing a low-temperature, highly active nickel-based mesoporous catalyst and its application. Background Technology

[0002] CO2 methanation converts polluting CO2 into useful CH4, a crucial reaction that addresses both environmental and energy needs. Compared to the conversion of CO2 into other value-added chemicals, CO2 methanation offers significant advantages: a faster reaction rate, milder reaction conditions, and the ability to proceed at atmospheric pressure. The hydrogenation product, CH4, a major component of natural gas, can be effectively used as fuel or chemical, thus forming a new carbon cycle. However, CO2 methanation still faces several challenges, including catalyst sintering at high temperatures, low catalytic activity at low temperatures, and low CH4 selectivity.

[0003] Ni-based catalysts are considered an effective alternative to noble metal catalysts due to their low cost, ease of availability, and high CH4 selectivity. However, Ni catalysts require high activation energies and are only active at relatively high temperatures. Furthermore, the strongly exothermic CO2 methanation reaction easily leads to Ni particle agglomeration and sintering, resulting in catalyst deactivation and reduced catalytic activity. At lower reaction temperatures, kinetic limitations result in low reaction rates and low catalytic activity. Therefore, a key breakthrough for Ni-based catalysts in CO2 methanation lies in improving their low-temperature reaction activity. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a low-temperature, highly active nickel-based mesoporous catalyst and its application. The CO2 methanation reaction can realize the recycling of carbon resources, which is of great significance for energy conservation, emission reduction, and energy structure adjustment.

[0005] The technical problem solved by this invention is achieved through the following technical solution:

[0006] A low-temperature, highly active nickel-based mesoporous catalyst comprises an active component and a support, wherein the active component is Ni and the support is TUD-1 with a specific surface area of ​​555.25 m². 2 / g, pore volume 0.69cm 3 / g.

[0007] The catalyst preparation method includes the following steps:

[0008] a. Dissolve 4.96 g of nickel nitrate hexahydrate in 10 mL of anhydrous ethanol to obtain solution A;

[0009] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0010] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0011] d. The dry rubber C was placed in a hydrothermal reactor for crystallization at a temperature of 150–200℃ for 5–8 h. After crystallization, it was removed and placed in a muffle furnace for high-temperature calcination at a temperature of 450–600℃ for 8–12 h. After calcination, 40 wt% Ni-TUD-1 catalyst was obtained for use in CO2 methanation reaction.

[0012] Furthermore, the Ni metal content in nickel nitrate hexahydrate is 30–50 wt%.

[0013] The above-mentioned low-temperature, highly active nickel-based mesoporous catalyst was applied to the catalytic hydrogenation methanation reaction of CO2, with a reaction pressure of 1.0–3.0 MPa, a reaction temperature of 200–300 °C, and a reaction space velocity of 4000–8000 h⁻¹. -1 The feed gas composition is H2:CO2 = 4:1. The optimal conditions are: reaction pressure 2.0-2.5 MPa, reaction temperature 200-250℃, and reaction space velocity 4000-5000 h⁻¹. -1 .

[0014] The advantages and positive effects of this invention are:

[0015] The design of this invention is scientific and reasonable. Compared with the prior art, the Ni-TUD-1 catalyst prepared in this invention has a large specific surface area, which enables the active metal Ni to be uniformly dispersed on the surface of the support. Furthermore, the anchoring effect of TUD-1 restricts the migration and agglomeration of the active metal Ni during the reaction process, thereby improving the low-temperature activity of the catalyst. Detailed Implementation

[0016] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0017] This invention employs a gel-assisted one-pot synthesis method to synthesize a Ni-based catalyst using the mesoporous material TUD-1 as a support. The large specific surface area of ​​the support ensures uniform Ni dispersion, while the anchoring effect of the TUD-1 framework inhibits the aggregation of Ni active sites, providing more active sites for the reaction. Furthermore, the catalyst exhibits high catalytic activity at relatively low reaction temperatures.

[0018] Based on the above technical points, this invention provides a low-temperature, highly active nickel-based mesoporous catalyst, comprising an active component and a support dual unit. The active component is Ni, and the support is TUD-1 with a specific surface area of ​​555.25 m². 2 / g, pore volume 0.69cm 3 / g, the catalyst preparation method includes the following steps:

[0019] a. Dissolve 4.96 g of nickel nitrate hexahydrate (Ni metal content is 30–50 wt%) in 10 mL of anhydrous ethanol to obtain solution A;

[0020] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0021] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0022] d. The dry rubber C was placed in a hydrothermal reactor for crystallization at a temperature of 150–200℃ for 5–8 h. After crystallization, it was removed and placed in a muffle furnace for high-temperature calcination at a temperature of 450–600℃ for 8–12 h. After calcination, 40 wt% Ni-TUD-1 catalyst was obtained for use in CO2 methanation reaction.

[0023] Example 1

[0024] Preparation steps of 30wt% Ni-TUD-1 catalyst:

[0025] a. Dissolve 3.19g of a certain mass of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0026] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0027] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0028] d. After the dry gel C was crystallized in a hydrothermal reactor at 160°C for 6 hours, it was taken out and placed in a muffle furnace at 600°C for 8 hours of high-temperature calcination. After calcination, 30wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0029] Evaluation of CO2 hydrogenation performance of 30wt% Ni-TUD-1 catalyst:

[0030] The prepared 30wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 300℃, 2.0MPa, and 5000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0031] Example 2

[0032] Preparation steps of 40wt% Ni-TUD-1 catalyst:

[0033] a. Dissolve 4.96g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0034] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0035] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0036] d. After the dry gel C was crystallized in a hydrothermal reactor at 160°C for 6 hours, it was taken out and placed in a muffle furnace at 600°C for 8 hours of high-temperature calcination. After calcination, 40wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0037] Evaluation of CO2 hydrogenation performance of 40wt% Ni-TUD-1 catalyst:

[0038] The prepared 40wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 2.0MPa, and 4000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0039] Example 3

[0040] Preparation steps of 50wt% Ni-TUD-1 catalyst:

[0041] a. Dissolve 7.44 g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0042] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0043] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0044] d. After the dry gel C was crystallized in a hydrothermal reactor at 160°C for 6 hours, it was taken out and placed in a muffle furnace at 600°C for 8 hours of high-temperature calcination. After calcination, 50wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0045] Evaluation of CO2 hydrogenation performance of 50wt% Ni-TUD-1 catalyst:

[0046] The prepared 50wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 2.5MPa, and 7000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0047] Example 4

[0048] Preparation steps of 30wt% Ni-TUD-1 catalyst:

[0049] a. Dissolve 3.19 g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0050] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0051] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0052] d. After the dry gel C was crystallized in a hydrothermal reactor at 160°C for 6 hours, it was taken out and placed in a muffle furnace at 600°C for 8 hours of high-temperature calcination. After calcination, 30wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0053] Evaluation of CO2 hydrogenation performance of 30wt% Ni-TUD-1 catalyst:

[0054] The prepared 30wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 1.0MPa, and 5000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0055] Example 5

[0056] Preparation steps of 40wt% Ni-TUD-1 catalyst:

[0057] a. Dissolve 4.96g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0058] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0059] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0060] d. After the dry gel C was crystallized in a hydrothermal reactor at 160°C for 6 hours, it was taken out and placed in a muffle furnace at 600°C for 8 hours of high-temperature calcination. After calcination, 40wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0061] Evaluation of CO2 hydrogenation performance of 40wt% Ni-TUD-1 catalyst:

[0062] The prepared 40wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 250℃, 2.0MPa, and 8000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0063] Example 6

[0064] Preparation steps of 40wt% Ni-TUD-1 catalyst:

[0065] a. Dissolve 4.96g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0066] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0067] c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C;

[0068] d. After the dry gel C was crystallized in a hydrothermal reactor at 180°C for 8 hours, it was taken out and placed in a muffle furnace at 450°C for 12 hours of high-temperature calcination. After calcination, 40wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0069] Evaluation of CO2 hydrogenation performance of 40wt% Ni-TUD-1 catalyst:

[0070] The prepared 40wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 200℃, 3.0MPa, and 5000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0071] Example 7

[0072] Preparation steps of 50wt% Ni-TUD-1 catalyst:

[0073] a. Dissolve 7.44 g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0074] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0075] c. After aging gel B at room temperature, dry it in an oven at 100℃ for 24 hours to obtain dry gel C;

[0076] d. After the dry gel C was crystallized in a hydrothermal reactor at 180°C for 8 hours, it was taken out and placed in a muffle furnace at 450°C for 12 hours of high-temperature calcination. After calcination, 50wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0077] Evaluation of CO2 hydrogenation performance of 50wt% Ni-TUD-1 catalyst:

[0078] The prepared 50wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 1.0MPa, and 4000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0079] Example 8

[0080] Preparation steps of 40wt% Ni-TUD-1 catalyst:

[0081] a. Dissolve 4.96g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0082] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0083] c. After aging gel B at room temperature, dry it in an oven at 100℃ for 24 hours to obtain dry gel C;

[0084] d. After the dry gel C was crystallized in a hydrothermal reactor at 180°C for 8 hours, it was taken out and placed in a muffle furnace at 450°C for 12 hours of high-temperature calcination. After calcination, 40wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0085] Evaluation of CO2 hydrogenation performance of 40wt% Ni-TUD-1 catalyst:

[0086] The prepared 40wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 2.0MPa, and 4000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0087] Example 9

[0088] Preparation steps of 30wt% Ni-TUD-1 catalyst:

[0089] a. Dissolve 3.19 g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0090] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0091] c. After aging gel B at room temperature, dry it in an oven at 100℃ for 24 hours to obtain dry gel C;

[0092] d. After the dry gel C was crystallized in a hydrothermal reactor at 180°C for 6 hours, it was taken out and placed in a muffle furnace at 500°C for 10 hours of high-temperature calcination. After calcination, 30wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0093] Evaluation of CO2 hydrogenation performance of 30wt% Ni-TUD-1 catalyst:

[0094] The prepared 30wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 275℃, 1.5MPa, and 8000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0095] Example 10

[0096] Preparation steps of 40wt% Ni-TUD-1 catalyst:

[0097] a. Dissolve 4.96g of nickel nitrate hexahydrate in anhydrous ethanol to obtain solution A;

[0098] b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B;

[0099] c. After aging gel B at room temperature, dry it in an oven at 100℃ for 24 hours to obtain dry gel C;

[0100] d. After the dry gel C was crystallized in a hydrothermal reactor at 180°C for 6 hours, it was taken out and placed in a muffle furnace at 500°C for 10 hours of high-temperature calcination. After calcination, 40wt% Ni-TUD-1 catalyst was obtained, which was used for CO2 methanation reaction.

[0101] Evaluation of CO2 hydrogenation performance of 40wt% Ni-TUD-1 catalyst:

[0102] The prepared 40wt% Ni-TUD-1 was compressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor and reduced in high-purity H2 under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 2.0MPa, and 5000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0103] Comparative Example 1

[0104] Preparation steps of NiO catalyst:

[0105] 2.0g of Ni(NO3)2·6H2O was weighed and placed in an agate mortar, ground into powder, and then placed in a porcelain boat and fully calcined in a muffle furnace at 350℃ for 3 hours to obtain gray-black NiO.

[0106] Evaluation of the catalytic performance of NiO catalysts in CO2 hydrogenation:

[0107] NiO powder was compressed into tablets and then sieved to obtain granular catalyst with a particle size of 20–40 mesh. 0.2 g of the catalyst was loaded into a fixed-bed reactor and reduced in pure H2 under programmed temperature rise conditions of 400 °C, 0.1 MPa, and 5000 h⁻¹. –1 After 2 hours, the reduction process is complete. The temperature is then lowered to allow the reaction to proceed with CO2 and H2. The reaction conditions are 300℃, 2.0MPa, and 5000 hours. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0108] Comparative Example 2

[0109] Preparation steps of 40wt% Ni / TUD-1 catalyst:

[0110] Metallic Ni was impregnated onto TUD-1 using an equal-volume impregnation method. The specific operation was as follows: 1.98 g of Ni(NO3)2·6H2O was weighed to prepare an equal-volume impregnation solution. The same volume of impregnation solution was added dropwise to the weighed carrier TUD-1 while stirring. The mixture was ultrasonicated to ensure thorough mixing. This operation was repeated in small batches. The substrate was then placed in a drying oven at 80°C and dried overnight. Finally, it was calcined in a muffle furnace at 350°C for 3 hours to obtain 40% Ni / TUD-1.

[0111] Performance evaluation of 40wt% Ni / TUD-1 catalyst for CO2 hydrogenation:

[0112] The prepared 40wt% Ni / TUD-1 was tableted and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor, and reduction was performed in pure hydrogen under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 2.0MPa, and 4000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0113] Comparative Example 3:

[0114] Preparation steps of 40wt% Ni / SiO2 catalyst:

[0115] Metallic Ni was impregnated onto SiO2 using an equal-volume impregnation method. The specific operation was as follows: 1.98 g of Ni(NO3)2·6H2O was weighed to prepare an equal-volume impregnation solution. The same volume of impregnation solution was added dropwise to the SiO2 carrier while stirring. The mixture was ultrasonicated to ensure thorough mixing. This operation was repeated in small batches. The mixture was then placed in a drying oven at 80°C and dried overnight. Finally, it was calcined in a muffle furnace at 350°C for 3 hours to obtain 40% Ni / SiO2.

[0116] Performance evaluation of 40wt% Ni / SiO2 catalyst for CO2 hydrogenation:

[0117] The prepared 40wt% Ni / SiO2 was pressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor, and reduction was performed in pure hydrogen under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 225℃, 3.0MPa, and 4000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0118] Comparative Example 4:

[0119] Preparation steps of 40wt% Ni / Al2O3 catalyst:

[0120] Metallic Ni was impregnated onto Al2O3 using an equal-volume impregnation method. The specific operation was as follows: 1.98 g of Ni(NO3)2·6H2O was weighed to prepare an equal-volume impregnation solution. The same volume of impregnation solution was added dropwise to the Al2O3 carrier while stirring. The mixture was ultrasonicated to ensure thorough mixing. This operation was repeated in small batches. The mixture was then placed in a drying oven at 80°C and dried overnight. Finally, it was calcined in a muffle furnace at 350°C for 3 hours to obtain 40% Ni / Al2O3.

[0121] Performance evaluation of 40wt% Ni / Al2O3 catalyst for CO2 hydrogenation:

[0122] The prepared 40wt% Ni / Al2O3 was pressed into tablets and sieved to obtain particles with a size of 20–40 mesh. 0.2 g of the above catalyst was loaded into a fixed-bed reactor, and reduction was performed in pure hydrogen under programmed temperature rise conditions of 400℃, 0.1 MPa, and 5000 h⁻¹. –1 2 hours. After reduction, the temperature is lowered and the reaction is switched to feed gas. The reaction conditions are 250℃, 2.0MPa, and 5000h. –1 H2:CO2 = 4:1. The reaction results are shown in Table 1.

[0123] Table 1. Comparison of the effects of each embodiment and comparative example.

[0124]

[0125] High specific surface area and strong interactions are the guarantee of excellent catalytic performance of CO2 hydrogenation to methane catalysts. Examples 1-10 are 40wt% Ni-TUD-1 catalysts with different Ni contents prepared by gel-assisted one-pot synthesis under different crystallization temperatures, crystallization times, calcination temperatures, and calcination times, and their CO2 methanation performance was investigated. In Example 2, crystallization was carried out in a hydrothermal reactor at 160℃ for 6 h, followed by high-temperature calcination in a muffle furnace at 600℃ for 8 h to obtain a 40wt% Ni-TUD-1 catalyst, which exhibited excellent performance at 225℃, 2.0 MPa, and 4000 h. –1 Under the specified conditions, the catalytic performance was optimal, achieving a CO2 conversion of 65.72% and a CH4 selectivity of 99.56%. Compared to the 40wt% Ni / TUD-1 prepared by the medium-volume impregnation method in Comparative Example 2, the CO2 conversion was increased by 47%. In the Comparative Example, the 40wt% Ni / TUD-1 catalyst with TUD-1 as the support showed nearly twice the CO2 conversion compared to 40wt% Ni / SiO2. Characterization by hydrogen temperature-programmed reduction (H2-TPR) revealed that, among the catalysts prepared by the equal-volume impregnation method, the catalyst with TUD-1 as the support was more difficult to reduce than that with SiO2, indicating a stronger interaction between the metal and the support. Furthermore, the 40wt% Ni-TUD-1 catalyst prepared by the gel-assisted one-pot synthesis method with TUD-1 as the support was more difficult to reduce than the 40wt% Ni / TUD-1 prepared by the equal-volume impregnation method, exhibiting a stronger interaction between the metal and the support.

[0126] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A low-temperature, highly active nickel-based mesoporous catalyst, characterized in that: It comprises two units: an active component and a support. The active component is Ni, and the support is TUD-1 with a specific surface area of ​​555.25 m². 2 / g, pore volume 0.69cm 3 The method for preparing the low-temperature, highly active nickel-based mesoporous catalyst, as described above, includes the following steps: a. Dissolve 4.96 g of nickel nitrate hexahydrate in 10 mL of anhydrous ethanol to obtain solution A; b. Stir solution A at room temperature, then add tetraethylammonium silicate, tetraethylammonium hydroxide, triethanolamine and water in a molar ratio of 1:0.5:1:13 in sequence, and stir for 4 hours to obtain gel B; c. After aging gel B at room temperature, dry it in an oven at 100°C for 24 hours to obtain dry gel C; d. Dry gel C is placed in a hydrothermal reactor for crystallization at a temperature of 150–200℃ for 5–8 hours. After crystallization, it is removed and placed in a muffle furnace for high-temperature calcination at a temperature of 450–600℃ for 8–12 hours. After calcination, 40 wt% Ni-TUD-1 catalyst is obtained for CO2 methanation reaction. The Ni metal content in nickel nitrate hexahydrate is 30–50 wt%.

2. The application of the low-temperature, highly active nickel-based mesoporous catalyst as described in claim 1, characterized in that: The reaction pressure was 1.0–3.0 MPa, the reaction temperature was 200–300 °C, and the reaction space velocity was 4000–8000 h⁻¹. -1 Under the condition that the raw gas composition is H2:CO2=4:1, the catalyst CO2 is hydrogenated and methanated.

3. The application of the low-temperature, highly active nickel-based mesoporous catalyst according to claim 2, characterized in that: The reaction pressure is 2.0-2.5 MPa, the reaction temperature is 200-250℃, and the reaction space velocity is 4000-5000 h⁻¹. -1 .

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