Nickel-based catalyst for CO2 capture-in-situ catalytic conversion as well as preparation method and application of nickel-based catalyst

Abstract

The invention discloses a CO2 capture-in-situ catalytic conversion nickel-based catalyst and a preparation method and application thereof.The method comprises the steps that nickel salt, a coordination agent and porous calcium oxide are oscillated in water, left to stand and dried, then roasted and granulated at the temperature of 400-700 DEG C in the air atmosphere, 40-60-mesh particles are screened, and the nickel-based catalyst is obtained; the preparation method of the porous calcium oxide comprises the following steps: reacting calcium salt and a surfactant in water at 80-150 DEG C, evaporating the solution to dryness to obtain gel, and drying the gel to obtain a porous calcium oxide precursor; and roasting the porous calcium oxide precursor at 600-1000 DEG C in an air atmosphere to obtain the porous calcium oxide material. The problem that an existing nickel-based catalyst is seriously inactivated in the CO2 methanation reaction process is solved, and the prepared nickel-based catalyst can remarkably improve the catalytic activity, especially the stability, of carbon dioxide methanation.

Description

Technical Field

[0001] The present invention relates to a nickel-based catalyst, and in particular to a CO2 capture-in-situ catalytic conversion nickel-based catalyst, a preparation method and an application thereof. Background Art

[0002] Carbon dioxide (CO2), while a major greenhouse gas, is also a vital C1 resource in nature. Therefore, achieving targeted catalytic conversion of CO2 is a key issue in the current CO2 conversion field. Methane (CH4) has a higher volumetric energy density than H2 and is easier to store and transport, making it a viable alternative to H2 as a clean energy source. Therefore, the selective methanation of CO2 and H2 is a key research area in achieving net-zero emissions and is crucial for developing solutions for carbon neutrality, hydrogen utilization, carbon recycling, and chemical energy storage.

[0003] Thermal power plant flue gas is a major source of CO2 emissions. Capturing CO2 from power plant flue gas and combining it with H2 produced by water electrolysis for methanation is an effective approach for CO2 capture and utilization. However, conventional technology involves capturing CO2 before reacting it with H2 in a separate reactor for methanation. This requires significant energy input, multiple reactor configurations, and the transfer of adsorbent between reactors. Consequently, conventional CO2 capture and utilization processes are technically complex and economically unsuitable.

[0004] The coupling of CO2 capture and in-situ catalytic conversion technology can intensify chemical processes, effectively reducing the number of units and shortening the process flow. The key to achieving this coupled CO2 capture-in-situ catalytic conversion process lies in the design and development of highly stable composite bifunctional catalysts. The design of bifunctional catalysts is primarily based on two considerations: the adsorption performance of the CO2 adsorbent and the stability of the CO2 methanation catalyst. Two main approaches are proposed: one is to directly load the CO2 methanation active component onto the CO2 adsorbent to create an integrated catalyst; the other is to simply mix the CO2 adsorbent and the CO2 methanation active component to achieve the coupled CO2 capture-in-situ catalytic conversion process. Therefore, improving the adsorption performance of the CO2 adsorbent and the catalytic capacity of the CO2 methanation active component remains the key to developing composite bifunctional materials for CO2 capture-in-situ catalytic conversion.

[0005] Currently, the CO₂ adsorbent used for CO₂ capture is primarily CaO, which is obtained by calcining calcium salts at high temperatures. During the CO₂ adsorption process, CaO's pore structure collapses and its specific surface area decreases, leading to a decrease in adsorption performance. Therefore, improving CaO's high-temperature stability and specific surface area is key to enhancing its CO₂ adsorption performance, especially its stability. Ni-based catalysts are considered the most promising industrial catalysts for CO₂ methanation due to their high catalytic activity and low cost. However, during the CO₂ methanation reaction, high-temperature sintering and severe carbon deposition of Ni lead to severe catalyst deactivation, hindering its industrial application.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0007] The purpose of the present invention is to provide a nickel-based catalyst for CO2 capture-in situ catalytic conversion, a preparation method and application thereof, which solves the problem that existing nickel-based catalysts are severely deactivated during the CO2 methanation reaction and can significantly improve the catalytic activity, especially stability, of carbon dioxide methanation.

[0008] In order to achieve the above-mentioned object, the present invention provides a method for preparing a nickel-based catalyst for CO2 capture-in-situ catalytic conversion, which comprises: shaking a nickel salt, a ligand and porous calcium oxide in water, standing, and drying, then calcining at 400-700°C in an air atmosphere, granulating, and screening 40-60 mesh particles to obtain a nickel-based catalyst; wherein the method for preparing the porous calcium oxide comprises: reacting a calcium salt and a surfactant in water at 80-150°C, evaporating the solution to obtain a gel, and then drying the gel to obtain a porous calcium oxide precursor; and placing the porous calcium oxide precursor in an air atmosphere and calcining at 600-1000°C to obtain a porous calcium oxide material.

[0009] Preferably, in the preparation of the nickel-based catalyst, the catalyst is calcined at 400-700°C in an air atmosphere for 2-6 hours; or / and, in the preparation of the nickel-based catalyst, the drying temperature is 70-120°C; or / and, in the preparation method of the porous calcium oxide, the catalyst is calcined at 600-1000°C in an air atmosphere for 2-8 hours; or / and, in the preparation method of the porous calcium oxide, the calcium salt and the surfactant are reacted in water at 80-150°C for 1-5 days; or / and, in the preparation method of the porous calcium oxide, the drying temperature is 60-150°C.

[0010] More preferably, in the preparation of the nickel-based catalyst, the drying temperature is 70-120° C. and the drying time is 10-24 h; in the preparation method of the porous calcium oxide, the drying temperature is 60-150° C. and the drying time is 4-62 h.

[0011] Preferably, in the preparation of the nickel-based catalyst, the oscillation time is 30 to 60 minutes, and the standing time at room temperature is 10 to 48 hours.

[0012] Preferably, the molar ratio of the complexing agent to the nickel salt is 1-3:1.

[0013] Preferably, the nickel salt is selected from any one or more of nickel nitrate hexahydrate, nickel acetate tetrahydrate, nickel sulfate hexahydrate and nickel chloride hexahydrate; or / and, the ligand is selected from any one or more of carboxylic acid, amino acid having a bidentate group and amine.

[0014] More preferably, the mass ratio of the nickel salt to the porous calcium oxide is 0.26~1.06:1; or / and, the carboxylic acid is selected from any one or more of formic acid, acetic acid, oxalic acid, tartaric acid and citric acid; the amino acid having a bidentate group is selected from any one or more of glycine, alanine, serine, threonine, valine, proline and lysine; and the amine is selected from urea and / or diethanolamine.

[0015] Preferably, the calcium salt is selected from any one or more of calcium nitrate tetrahydrate, calcium acetate monohydrate and calcium chloride; or / and, the surfactant is selected from quaternary ammonium salts containing polyoxyethylene chains and / or alkyl chains.

[0016] Preferably, the mass ratio of the surfactant to the calcium salt is 1-2:1-2; or / and the quaternary ammonium salt containing a polyoxyethylene chain and / or an alkyl chain contains at least one alkyl chain with a carbon chain length of 12-16.

[0017] More preferably, the quaternary ammonium salt containing a polyoxyethylene chain and / or an alkyl chain is selected from polyoxyethylene didodecylmethyl quaternary ammonium salt, polyoxyethylene ditetradecylmethyl quaternary ammonium salt, polyoxyethylene dihexadecylmethyl quaternary ammonium salt, dodecyltrimethyl quaternary ammonium salt, tetradecyltrimethyl quaternary ammonium salt, hexadecyltrimethyl quaternary ammonium salt, didodecyldimethyl quaternary ammonium salt, and dihexadecyldimethyl quaternary ammonium salt.

[0018] The second object of the present invention is to provide a CO2 capture-in-situ catalytic conversion nickel-based catalyst obtained by the preparation method.

[0019] The third object of the present invention is to provide the use of the CO2 capture-in situ catalytic conversion nickel-based catalyst in the carbon dioxide methanation reaction.

[0020] The CO2 capture-in-situ catalytic conversion nickel-based catalyst of the present invention, its preparation method, and application solve the problem of serious deactivation of existing nickel-based catalysts during the CO2 methanation reaction, and have the following advantages: (1) The present invention uses porous calcium oxide as a carrier and adjusts the pore structure, specific surface area, and final adsorption performance and cyclic stability of CaO by changing the type, amount, and calcination temperature of surfactants and calcium salts; (2) The present invention addresses the problem of deactivation of Ni-based catalysts in CO2 hydrogenation and methanation reactions due to Ni sintering and carbon deposition. A strategy is proposed to utilize the confined encapsulation of ligands and the pore structure of the carrier to regulate Ni metal particles. By changing the preparation parameters such as the type and amount of the ligands and the calcination temperature, an efficient CO2 capture-in-situ catalytic conversion integrated dual-functional material and process technology are prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The XRD patterns of the calcium oxide prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0022] Figure 2 The XRD patterns of the nickel-based catalysts prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0023] Figure 3 These are the performance test results of the nickel-based catalyst of Example 1 of the present invention in catalyzing the carbon dioxide methanation reaction. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] Note: If specific conditions are not specified in the examples, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Instruments used without manufacturer information are commercially available. Raw materials and reagents used without manufacturer information are commercially available or can be prepared by known methods.

[0026] Throughout this disclosure, all features, such as values, amounts, amounts, and concentrations, specified in numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible subranges and individual values within those ranges (including integers and fractions).

[0027] The features described in this disclosure may be combined in any manner, and as long as there are no conflicts between the combinations of these features, all possible combinations should be considered within the scope of this specification. Each feature disclosed in this specification may be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the features disclosed are merely general examples of equivalent or similar features.

[0028] Example 1 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium nitrate tetrahydrate and 8.0 g of polyoxyethylene didodecylmethylammonium bromide (the mass ratio of polyoxyethylene didodecylmethylammonium bromide to calcium nitrate tetrahydrate is 1:1, wherein polyoxyethylene didodecylmethylammonium bromide is purchased from Henan Daochun New Material Technology Co., Ltd.) are dissolved in 30 mL of distilled water to obtain a solution, which is reacted at 150 °C for 2 days. After the solution is evaporated to dryness, a gel is obtained, which is then transferred to an oven and dried at 80 °C for 12 h to obtain a calcium oxide precursor; (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 900 °C in air atmosphere for 4 h to obtain a porous calcium oxide material. The XRD pattern of the material can be found in Figure 1 As can be seen from the figure, the CaO prepared under this condition has good crystallinity. Compared with the comparative example, the intensity of its characteristic diffraction peak is weaker and the half-peak width is wider, indicating that the particle size of the prepared CaO is smaller, thereby showing more specific surface area; (3) 0.80 g (0.004 mol) of citric acid and 0.55 g (0.002 mol) of nickel nitrate hexahydrate (the molar ratio of citric acid to nickel nitrate is 2:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 30 min, then allowed to stand at room temperature for 24 h, dried at 100 °C for 12 h, and calcined at 500 °C in air atmosphere for 5 h. The catalyst was pressed, granulated, and screened to obtain particles of 40-60 mesh. The XRD pattern of the catalyst is shown in [1]. Figure 2 ,Depend on Figure 2 It can be seen that compared with Comparative Example 1, the intensity of NiO prepared in this example is significantly weaker and the half-peak width is wider, indicating that its NiO particle size is smaller, thereby having better carbon dioxide methanation reaction performance, especially higher stability.

[0029] Example 2 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium nitrate tetrahydrate and 16.0 g of polyoxyethylene dicetylmethylammonium bromide (the mass ratio of polyoxyethylene dicetylmethylammonium bromide to calcium nitrate tetrahydrate is 2:1, wherein polyoxyethylene dicetylmethylammonium bromide is purchased from Henan Daochun New Materials Technology Co., Ltd.) are dissolved in 30 mL of distilled water to obtain a solution, which is reacted at 120 °C for 5 days. After the solution is evaporated to dryness, a gel is obtained, which is then transferred to an oven and dried at 120 °C for 4 h to obtain a calcium oxide precursor; (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 800 °C in an air atmosphere for 6 h to obtain a porous calcium oxide material; (3) 0.40 g (0.003 mol) of tartaric acid and 0.26 g (0.001 mol) of nickel nitrate hexahydrate (the molar ratio of tartaric acid to nickel nitrate is 3:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 60 min, then allowed to stand at room temperature for 12 h, dried at 110 °C for 10 h, and calcined at 600 °C in air atmosphere for 4 h. The mixture was tableted, granulated, and screened to obtain particles of 40-60 mesh. A nickel-based catalyst was obtained.

[0030] Example 3 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium acetate monohydrate and 4.0 g of polyoxyethylene ditetradecylmethylammonium bromide (the mass ratio of polyoxyethylene ditetradecylmethylammonium bromide to calcium acetate monohydrate is 1:2, wherein polyoxyethylene ditetradecylmethylammonium bromide is purchased from Henan Daochun New Materials Technology Co., Ltd.) are dissolved in 30 mL of distilled water to obtain a solution, which is reacted at 130 °C for 3 days. After the solution is evaporated to dryness, a gel is obtained, which is then transferred to an oven and dried at 100 °C for 12 h to obtain a calcium oxide precursor; (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 600 °C in an air atmosphere for 8 h to obtain a porous calcium oxide material; (3) 0.23 g (0.003 mol) of glycine and 0.87 g (0.003 mol) of nickel nitrate hexahydrate (the molar ratio of glycine to nickel nitrate is 1:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 30 min, then allowed to stand at room temperature for 48 h, dried at 120 °C for 12 h, and calcined at 700 °C in air atmosphere for 2 h. The mixture was tableted, granulated, and screened to obtain particles of 40-60 mesh. A nickel-based catalyst was obtained.

[0031] Example 4 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium acetate monohydrate and 8.0 g of hexadecyltrimethylammonium bromide (the mass ratio of hexadecyltrimethylammonium bromide to calcium acetate monohydrate is 1:1) were dissolved in 30 mL of distilled water to obtain a solution, which was reacted at 90 °C for 5 days. The solution was evaporated to dryness to obtain a gel, which was then transferred to an oven and dried at 60 °C for 24 h to obtain a calcium oxide precursor. (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 700 °C in an air atmosphere for 4 h to obtain a porous calcium oxide material; (3) 0.22 g of proline (0.002 mol) and 0.47 g (0.002 mol) of nickel acetate tetrahydrate (the molar ratio of proline to nickel acetate is 1:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 60 min, then allowed to stand at room temperature for 10 h, dried at 90 °C for 24 h, and calcined at 400 °C in air atmosphere for 6 h. The catalyst was then tableted, granulated, and screened to obtain particles of 40-60 mesh.

[0032] Example 5 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium chloride and 4.0 g of tetradecyltrimethylammonium bromide (the mass ratio of tetradecyltrimethylammonium bromide to calcium chloride is 1:2) were dissolved in 30 mL of distilled water to obtain a solution, which was reacted at 80 °C for 5 days. The solution was evaporated to dryness to obtain a gel, which was then transferred to an oven and dried at 150 °C for 62 h to obtain a calcium oxide precursor. (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 1000 °C in an air atmosphere for 2 h to obtain a porous calcium oxide material; (3) 0.76 g (0.01 mol) of urea and 1.06 g (0.004 mol) of nickel acetate tetrahydrate (the molar ratio of urea to nickel acetate is 3:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 40 min, then allowed to stand at room temperature for 24 h, dried at 80 °C for 24 h, and calcined at 700 °C in air atmosphere for 3 h. The mixture was pressed into tablets, granulated, and screened into 40-60 mesh particles to obtain a nickel-based catalyst.

[0033] Example 6 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium acetate monohydrate and 16.0 g of dodecyltrimethylammonium bromide (the mass ratio of dodecyltrimethylammonium bromide to calcium acetate is 2:1) were dissolved in 30 mL of distilled water to obtain a solution, which was reacted at 130 °C for 3 days. The solution was evaporated to dryness to obtain a gel, which was then transferred to an oven and dried at 90 °C for 10 h to obtain a calcium oxide precursor. (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 800 °C in an air atmosphere for 4 h to obtain a porous calcium oxide material; (3) Dissolve 0.63 g (0.006 mol) of diethanolamine and 0.79 g (0.003 mol) of nickel sulfate hexahydrate (the molar ratio of diethanolamine to nickel sulfate is 2:1) in 1.0 mL of distilled water, add 1.00 g of the porous calcium oxide material prepared above, shake thoroughly for 50 min, then let stand at room temperature for 18 h, dry at 70 °C for 24 h, and calcine at 600 °C in air atmosphere for 4 h. Press into tablets, granulate, and screen 40-60 mesh particles to obtain a nickel-based catalyst.

[0034] Example 7 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium acetate monohydrate and 4.0 g of dihexadecyldimethylammonium bromide (the mass ratio of dihexadecyldimethylammonium bromide to calcium acetate is 1:2) were dissolved in 30 mL of distilled water to obtain a solution, which was reacted at 150 °C for 1 day. The solution was evaporated to dryness to obtain a gel, which was then transferred to an oven and dried at 110 °C for 15 h to obtain a calcium oxide precursor. (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 700 °C in an air atmosphere for 5 h to obtain a porous calcium oxide material; (3) Dissolve 0.51 g (0.006 mol) of oxalic acid and 0.50 g (0.002 mol) of nickel sulfate hexahydrate (the molar ratio of oxalic acid to nickel sulfate is 3:1) in 1.0 mL of distilled water, add 1.00 g of the porous calcium oxide material prepared above, shake thoroughly for 40 min, then stand at room temperature for 12 h, dry at 100 °C for 10 h, and calcine at 500 °C in air atmosphere for 6 h. Press into tablets, granulate, and screen particles of 40-60 mesh to obtain a nickel-based catalyst.

[0035] Example 8 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium acetate monohydrate and 4.0 g of didodecyldimethylammonium bromide (the mass ratio of didodecyldimethylammonium bromide to calcium acetate is 1:2) were dissolved in 30 mL of distilled water to obtain a solution, which was reacted at 100 °C for 3 days. The solution was evaporated to dryness to obtain a gel, which was then transferred to an oven and dried at 70 °C for 20 h to obtain a calcium oxide precursor. (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 600 °C in an air atmosphere for 8 h to obtain a porous calcium oxide material; (3) 1.19 g (0.006 mol) of citric acid and 0.45 g (0.002 mol) of nickel chloride hexahydrate (the molar ratio of citric acid to nickel sulfate is 3:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 30 min, then allowed to stand at room temperature for 36 h, dried at 120 °C for 16 h, and calcined at 400 °C in air atmosphere for 6 h. The mixture was tableted, granulated, and screened to obtain particles of 40-60 mesh. A nickel-based catalyst was obtained.

[0036] Example 9 A CO2 capture-in-situ catalytic conversion nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium nitrate tetrahydrate and 16.0 g of didodecyldimethylammonium bromide (the mass ratio of didodecyldimethylammonium bromide to calcium acetate is 2:1) were dissolved in 30 mL of distilled water to obtain a solution, which was reacted at 140 °C for 3 days. The solution was evaporated to dryness to obtain a gel, which was then transferred to an oven and dried at 100 °C for 14 h to obtain a calcium oxide precursor. (2) The calcium oxide precursor was placed in a muffle furnace and calcined at 900 °C in an air atmosphere for 3 h to obtain a porous calcium oxide material; (3) 0.38 g (0.004 mol) of alanine and 1.01 g (0.004 mol) of nickel chloride hexahydrate (the molar ratio of alanine to nickel sulfate is 1:1) were dissolved in 1.0 mL of distilled water, and 1.00 g of the porous calcium oxide material prepared above was added. The mixture was fully shaken for 60 min, then allowed to stand at room temperature for 24 h, dried at 100 °C for 24 h, and calcined at 500 °C in air atmosphere for 3 h. The mixture was tableted, granulated, and screened to obtain particles of 40-60 mesh to obtain a nickel-based catalyst.

[0037] Comparative Example 1 A nickel-based catalyst, the preparation method of which comprises the following steps: (1) 8.0 g of calcium nitrate tetrahydrate was calcined in a muffle furnace at 800 °C for 4 h in air atmosphere to obtain CaO material. Its XRD pattern is shown in Figure 1 ; (2) Dissolve 0.55 g of nickel nitrate hexahydrate in water, add 1.00 g of the CaO material obtained in step (1), shake thoroughly for 30 min, then stand at room temperature for 24 h, dry at 100 °C for 12 h, calcine at 500 °C in air atmosphere for 4 h, press into tablets, granulate, and screen 40-60 mesh particles to obtain a 10% Ni / CaO catalyst. Its XRD pattern is shown in Figure 2 .

[0038] Experimental Example 1 Evaluation of the performance of catalytic carbon dioxide methanation reaction The CO2 methanation performance of the nickel-based catalysts prepared in Examples 1 to 9 of the present invention and Comparative Example 1 was evaluated. The specific experimental results are as follows: 0.10 g of nickel-based catalyst was placed in a fixed-bed reactor, and 20% (H2 content accounts for 20% of the total gas) H2 / N2 was introduced at a flow rate of 50 mL min-1 under normal pressure. -1 , at 4 ℃·min -1 The heating rate was increased from room temperature to 700 °C and the reduction was carried out for 2.5 h.

[0039] Subsequently, H2 was turned off and N2 was continued to be introduced, and the temperature was lowered to 400 °C. After the temperature stabilized, the reaction gas was switched to a mixture of CO2 and H2 with a volume ratio of 1:4. The total amount of reaction gas was 100 mL min -1 , at P = 1.0 atm, T = 400 °C, CO2 / H4 = 4.0, space velocity = 60000 mL·g -1 ·h -1 The reaction was carried out under the following conditions, and the gases after the reaction were detected and analyzed by a chromatograph equipped with a Zhejiang Fuli GC9720Ⅱ thermal conductivity cell detector (with 5A and PQ columns). The experimental results are shown in Table 1.

[0040] Table 1 Carbon dioxide methanation reaction performance of nickel-based catalysts of Examples 1 to 9 of the present invention As shown in Table 1, compared with Comparative Example 1, the nickel-based catalyst prepared by the method of the present invention has higher reaction activity and stability for the carbon dioxide methanation reaction, the initial CO2 conversion rate is about 60%, and the initial CH4 selectivity is also above 70%. After 20 hours of reaction, the CO2 conversion rate and CH4 selectivity remain basically unchanged. Figure 3 Shown are the test results of the carbon dioxide methanation reaction performance of the nickel-based catalyst prepared in Example 1 of the present invention.

[0041] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for preparing a nickel-based catalyst for CO2 capture-in-situ catalytic conversion, characterized in that: The method includes: The nickel salt, the complexing agent and the porous calcium oxide are shaken in water, allowed to stand, dried, calcined at 400-700° C. in an air atmosphere, granulated, and screened to obtain particles of 40-60 mesh to obtain a nickel-based catalyst; The method for preparing the porous calcium oxide comprises: Calcium salt and surfactant are reacted in water at 80-150°C, the solution is evaporated to obtain a gel, and the gel is dried to obtain a porous calcium oxide precursor; The porous calcium oxide precursor is placed and calcined at 600-1000° C. in an air atmosphere to obtain a porous calcium oxide material.

2. The preparation method according to claim 1, characterized in that In the preparation of the nickel-based catalyst, the catalyst is calcined at 400-700° C. in an air atmosphere for 2-6 hours; Or / and, in the preparation of the nickel-based catalyst, the drying temperature is 70-120° C.; or / and, in the method for preparing the porous calcium oxide, calcining the porous calcium oxide at 600-1000° C. in an air atmosphere for 2-8 hours; Or / and, in the method for preparing the porous calcium oxide, the calcium salt and the surfactant are reacted in water at 80-150° C. for 1-5 days; Or / and, in the method for preparing porous calcium oxide, the drying temperature is 60-150°C.

3. The preparation method according to claim 1, characterized in that The molar ratio of the complexing agent to the nickel salt is 1-3:

1.

4. The preparation method according to claim 1, characterized in that The nickel salt is selected from any one or more of nickel nitrate hexahydrate, nickel acetate tetrahydrate, nickel sulfate hexahydrate and nickel chloride hexahydrate; Or / and, the ligand is selected from any one or more of carboxylic acid, amino acid having a bidentate group and amine.

5. The preparation method according to claim 4, characterized in that The mass ratio of the nickel salt to the porous calcium oxide is 0.26-1.06:1; Or / and, the carboxylic acid is selected from any one or more of formic acid, acetic acid, oxalic acid, tartaric acid and citric acid; the amino acid having a bidentate group is selected from any one or more of glycine, alanine, serine, threonine, valine, proline and lysine; and the amine is selected from urea and / or diethanolamine.

6. The preparation method according to claim 1, characterized in that The calcium salt is selected from any one or more of calcium nitrate tetrahydrate, calcium acetate monohydrate and calcium chloride; Or / and, the surfactant is selected from quaternary ammonium salts containing polyoxyethylene chains and / or alkyl chains.

7. The preparation method according to claim 6, characterized in that The mass ratio of the surfactant to the calcium salt is 1-2:1-2; Or / and, the quaternary ammonium salt containing a polyoxyethylene chain and / or an alkyl chain contains at least one alkyl chain with a carbon chain length of 12 to 16.

8. The preparation method according to claim 7, characterized in that The quaternary ammonium salt containing a polyoxyethylene chain and / or an alkyl chain is selected from polyoxyethylene didodecylmethyl quaternary ammonium salt, polyoxyethylene ditetradecylmethyl quaternary ammonium salt, polyoxyethylene dihexadecylmethyl quaternary ammonium salt, dodecyltrimethyl quaternary ammonium salt, tetradecyltrimethyl quaternary ammonium salt, hexadecyltrimethyl quaternary ammonium salt, didodecyldimethyl quaternary ammonium salt, and dihexadecyldimethyl quaternary ammonium salt.

9. A nickel-based catalyst for CO2 capture and in-situ catalytic conversion obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the CO2 capture-in-situ catalytic conversion nickel-based catalyst according to claim 9 in a carbon dioxide methanation reaction.

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