Preparation method and application of carbon dioxide methanation catalyst

Abstract

The present application discloses a preparation method and application of a carbon dioxide methanation catalyst, and relates to the field of catalyst technology. The preparation method of the carbon dioxide methanation catalyst comprises steps S1 to S5. S1: introducing an alkaline solution and an active metal salt solution into a first supergravity reactor, and preparing a preliminary mixed liquid at the entrance of the first supergravity reactor; S2: spraying the preliminary mixed liquid uniformly through the metal wire mesh in the first supergravity reactor through a liquid distributor in the first supergravity reactor, and uniformly mixing the preliminary mixed liquid under high-speed rotation to obtain a uniform mixed liquid. The present application prepares a carbon dioxide methanation catalyst in a supergravity field formed by a supergravity reactor, so that the metal particles in the carbon dioxide methanation catalyst are uniform in size, more active sites are exposed, and the conversion rate in the carbon dioxide methanation reaction is improved.

Description

Technical Field

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

[0002] The production of methane from carbon dioxide hydrogenation is one of the most popular ways to utilize carbon dioxide. From a thermodynamic point of view, the carbon dioxide methanation reaction is an exothermic reaction, and low temperature is conducive to the forward reaction. However, due to the high thermodynamic stability of carbon dioxide molecules, too low a reaction temperature is not conducive to the activation of carbon dioxide molecules. Therefore, the focus of carbon dioxide methanation catalyst research is to reduce the reaction energy barrier and improve the reaction activity. Usually, carbon dioxide methanation catalysts are composed of active metals (such as Co, Fe, Ni, Pd, Ru or Rh, etc.) and auxiliary materials (such as SiO2, Al2O3, CeO2, TiO2, SiC or ZrO2, etc.).

[0003] Among them, nickel-based catalysts have been widely used in the industrial field because of their low cost and easy access. However, compared with precious metal catalysts, nickel-based catalysts need to be at a higher reaction temperature to show good activity, but high temperature conditions easily lead to agglomeration and sintering of nickel metal particles, thereby reducing the catalytic performance and even causing technical problems such as catalyst deactivation. Under high temperature reaction conditions, the active centers of nickel-based catalysts are prone to agglomeration, while the catalytic performance is poor under low temperature conditions. Therefore, improving the performance of nickel-based catalysts often requires changing the electronic properties and catalyst structure of nickel by adjusting the carrier structure. For example, Ni / CeO2 catalysts are often used in carbon dioxide methanation reactions. Nickel, as an active metal, is mainly responsible for the adsorption and dissociation of hydrogen molecules. Incorporation into the CeO2 lattice can increase surface oxygen vacancies to activate carbon dioxide molecules and reaction intermediates.

[0004] Carbon dioxide methanation is a structure-sensitive reaction. The performance of the catalyst is significantly affected by the size of the active metal particles. The particle size and the distribution of active components are closely related to the preparation method of the catalyst. It is difficult to accurately control the size of metal particles using traditional synthesis methods. For example, the chemical composition of the catalyst prepared by the coprecipitation method is prone to unevenness, and the active components are prone to agglomeration; the catalyst prepared by the impregnation method has problems such as poor dispersion of active components and easy migration and agglomeration. If the size of the active metal particles of the catalyst is uneven or unevenly distributed, it will affect the conversion rate of carbon dioxide methanation. Summary of the invention

[0005] The purpose of the present application is to provide a method for preparing a carbon dioxide methanation catalyst and its application, so as to solve the technical problem that the preparation method of Ni / CeO2 and other catalysts in the prior art easily makes the metal nickel particles in the catalyst uneven in size and distribution, thereby causing Ni / CeO2 and other catalysts to have a low conversion rate in the carbon dioxide methanation reaction.

[0006] To achieve the above objectives, this application provides the following technical solutions:

[0007] In the first aspect, the present application provides a method for preparing a carbon dioxide methanation catalyst, such as Figure 1 As shown, the method for preparing the carbon dioxide methanation catalyst includes steps S1 to S5.

[0008] S1: introducing an alkaline solution and an active metal salt solution into a first high-gravity reactor to prepare a preliminary mixed solution at the inlet of the first high-gravity reactor;

[0009] S2: spraying the preliminary mixed liquid uniformly through the metal wire mesh in the first high gravity reactor through the liquid distributor in the first high gravity reactor, and uniformly mixing the preliminary mixed liquid under high-speed rotation to obtain a uniform mixed liquid;

[0010] S3: After the uniform mixed solution is stirred and aged on a magnetic stirrer, it is centrifuged and washed with water to obtain a precipitate;

[0011] S4: drying the precipitate to obtain a precursor;

[0012] S5: calcining the precursor to obtain a carbon dioxide methanation catalyst.

[0013] It should be noted that in the technical solution of the present application, by preparing the carbon dioxide methanation catalyst in the supergravity field formed by the supergravity reactor, the metal nickel particles in the carbon dioxide methanation catalyst can be made uniform in size, more active sites are exposed, and the conversion rate in the carbon dioxide methanation reaction is improved, that is, the yield is improved.

[0014] As a specific solution in the technical solution of the present application, the alkaline solution is any one of sodium hydroxide solution, sodium carbonate solution and ammonium bicarbonate solution or a combination of multiple solutions; the active metal salt solution is Ni salt and Ce salt or Co salt and Salt solution formed by Ce salt.

[0015] As a specific solution in the technical solution of the present application, the total ion concentration of the active metal salt solution can be greater than or equal to 0.05 mol / L and less than or equal to 0.5 mol / L. Specifically, the total ion concentration of the active metal salt solution can be any one of 0.05 mol / L, 0.10 mol / L, 0.15 mol / L, 0.20 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.40 mol / L and 0.50 mol / L, or any concentration value between the above two adjacent concentration values.

[0016] As a specific solution in the technical solution of the present application, the weight percentage of nickel metal in the carbon dioxide methanation catalyst is greater than or equal to 5% and less than or equal to 20%. Specifically, the weight percentage of active metal in the carbon dioxide methanation catalyst can be any percentage value among 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% and 20%, or any percentage value between the above two adjacent percentage values.

[0017] As a specific solution in the technical solution of the present application, the rotation speed of the first supergravity reactor in step S2 is greater than or equal to 400r / min and less than or equal to 2400r / min. Specifically, the rotation speed of the first supergravity reactor can be any one of 400r / min, 500r / min, 600r / min, 700r / min, 800r / min, 900r / min, 1000r / min, 1100r / min, 1200r / min, 1300r / min, 1400r / min, 1500r / min, 1600r / min, 1700r / min, 1800r / min, 1900r / min, 2000r / min, 2100r / min, 2200r / min, 2300r / min and 2400r / min, or any speed value between the above two adjacent speed values.

[0018] As a specific solution in the technical solution of the present application, the time of stirring and aging in step S3 is greater than or equal to 60 minutes and less than or equal to 240 minutes. Specifically, the time of stirring and aging can be any time value among 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes, 180 minutes, 190 minutes, 200 minutes, 210 minutes, 220 minutes, 230 minutes and 240 minutes, or any time value between the above two adjacent time values.

[0019] As a specific solution in the technical solution of the present application, in step S4, the drying temperature is greater than or equal to 70°C and less than or equal to 90°C; the drying time is greater than or equal to 8 hours and less than or equal to 16 hours. Specifically, the drying temperature can be any temperature value among 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C and 90°C, or any temperature value between the above two adjacent temperature values. Specifically, the drying time can be any time value among 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours and 16 hours, or any time value between the above two adjacent time values.

[0020] As a specific solution in the technical solution of the present application, the calcination temperature in step S5 is greater than or equal to 350°C and less than or equal to 500°C; the calcination time is greater than or equal to 2 hours and less than or equal to 5 hours. Specifically, the calcination temperature can be any one of 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C and 500°C, or any temperature value between the above two adjacent temperature values. The calcination time can be any one of 2 hours, 3 hours, 4 hours and 5 hours, or any time value between the above two adjacent time values.

[0021] In a second aspect, the present application proposes a technical solution for a method for methanation of carbon dioxide, which method comprises obtaining a carbon dioxide methanation catalyst prepared by the method for preparing a carbon dioxide methanation catalyst as described in any one of the first aspects, and using the carbon dioxide methanation catalyst to methanate the carbon dioxide.

[0022] As a specific solution in the technical solution of this application, Figure 2 As shown, the method for methanation of carbon dioxide includes steps N1 to N3.

[0023] N1: loading the carbon dioxide methanation catalyst into the packed bed of the second high gravity reactor;

[0024] N2: introducing the reaction materials into the packed bed from the inlet of the second high gravity reactor, and keeping the packed bed rotating at a high speed all the time, and reacting to obtain products; the reaction materials include hydrogen and carbon dioxide;

[0025] N3: The product is discharged from the outlet of the second high gravity reactor.

[0026] It should be noted that in the present technical solution, the carbon dioxide methanation catalyst is loaded into the packed bed of the second supergravity reactor, and the catalyst in the packed bed is driven to rotate at high speed by bearings. During the reaction, the relative speed between the solid-phase catalyst and the gas-phase reactants (i.e., hydrogen and carbon dioxide) can be increased, thereby increasing the degree of turbulence at the phase interface, reducing the thickness of the boundary layer between the catalyst surface and the reactants, and reducing the external diffusion resistance of the reactants. More reactants can contact the active sites of the catalyst for reaction, thereby improving the conversion rate of carbon dioxide methanation.

[0027] In this technical solution, the second supergravity reactor can be the same supergravity reactor as the first supergravity reactor in step S1 and step S2 above. Of course, the first supergravity reactor and the second supergravity reactor can also be different supergravity reactors.

[0028] As a specific solution in the technical solution of the present application, the molar ratio of hydrogen to carbon dioxide in the reaction material is greater than or equal to 2 and less than or equal to 5. Specifically, the molar ratio of hydrogen to carbon dioxide in the reaction material can be any value among 2, 3, 4 and 5, or any value between the above two adjacent values.

[0029] As a specific scheme in the technical scheme of the present application, the reaction temperature in step N2 is greater than or equal to 200°C and less than or equal to 500°C; the reaction pressure is greater than or equal to 0.1MPaG and less than or equal to 3MPaG; the gas space velocity is greater than or equal to 2000ml / g·h and less than or equal to 40000ml / g·h. Specifically, the reaction temperature in step N2 can be any one of 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C and 500°C, or any temperature value between two adjacent temperature values ​​mentioned above. The reaction pressure in step N2 can be any one of 0.1 MPaG, 0.2 MPaG, 0.3 MPaG, 0.4 MPaG, 0.5 MPaG, 0.6 MPaG, 0.7 MPaG, 0.8 MPaG, 0.9 MPaG, 1.0 MPaG, 1.1 MPaG, 1.2 MPaG, 1.3 MPaG, 1.4 MPaG, 1.5 MPaG, 1.6 MPaG, 1.7 MPaG, 1.8 MPaG, 1.9 MPaG, 2.0 MPaG, 2.1 MPaG, 2.2 MPaG, 2.3 MPaG, 2.4 MPaG, 2.5 MPaG, 2.6 MPaG, 2.7 MPaG, 2.8 MPaG, 2.9 MPaG and 3.0 MPaG, or it can be any pressure value between two adjacent pressure values ​​mentioned above. The gas space velocity in step N2 can be any one of 2000ml / g·h, 5000ml / g·h, 10000ml / g·h, 15000ml / g·h, 20000ml / g·h, 25000ml / g·h, 30000ml / g·h, 35000ml / g·h, 40000ml / g·h, 45000ml / g·h, 50000ml / g·h, 55000ml / g·h and 60000ml / g·h, or it can be any space velocity value between two adjacent space velocity values ​​mentioned above.

[0030] As a specific solution in the technical solution of the present application, the speed of the packed bed in step N2 is greater than or equal to 600 r / min and less than or equal to 2600 r / min. Specifically, the speed of the packed bed in step N2 can be any one of 600 r / min, 700 r / min, 800 r / min, 900 r / min, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, 1900 r / min, 2000 r / min, 2100 r / min, 2200 r / min, 2300 r / min, 2400 r / min, 2500 r / min and 2600 r / min, or any speed between two adjacent speeds.

[0031] Compared with the prior art, the beneficial effects of this application are:

[0032] The present application prepares a carbon dioxide methanation catalyst in a hypergravity field formed by a hypergravity reactor, so that the metal nickel particles in the carbon dioxide methanation catalyst can be made uniform in size, more active sites are exposed, and the conversion rate in the carbon dioxide methanation reaction is improved, that is, the yield is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic flow chart of a method for preparing a carbon dioxide methanation catalyst proposed in an embodiment of the present application;

[0034] Figure 2 This is a schematic flow chart of a method for methanation of carbon dioxide proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The present application is further described below by way of examples, but the present application is not limited to the scope of the examples.

[0036] The experimental methods in the following examples without specifying specific conditions were carried out according to conventional methods and conditions, or selected according to the product instructions.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0038] The raw materials in the following examples are all commercially available.

[0039] Specifically, in the present application, the examples of the preparation of the carbon dioxide methanation catalyst are as follows:

[0040] Embodiment a

[0041] 2.663 g of cerium nitrate hexahydrate and 0.628 g of nickel nitrate hexahydrate were dissolved in deionized water to prepare an active metal salt solution with a total ion concentration of 0.14 mol / L; 0.864 g of sodium hydroxide was dissolved in deionized water to prepare a sodium hydroxide solution with a concentration of 0.36 mol / L as an alkaline solution.

[0042] S1: introducing the alkaline solution and the active metal salt solution in equal proportions into a first high-gravity reactor to form a preliminary mixed solution at the inlet of the first high-gravity reactor.

[0043] S2: The preliminary mixed liquid is uniformly sprayed through the metal wire mesh in the first high gravity reactor by the liquid distributor in the first high gravity reactor, and the preliminary mixed liquid is uniformly mixed under high-speed rotation to obtain a uniform mixed liquid. In this step, the rotation speed of the first high gravity reactor is controlled to be 1200r / min.

[0044] S3: After the uniform mixed solution is stirred and aged on a magnetic stirrer, it is centrifuged and washed with water to obtain a precipitate. In this step, the stirring and aging time is 120 minutes, and the number of centrifugal washings is 3 times.

[0045] S4: Dry the precipitate to obtain a precursor. In this step, the precipitate is dried in a forced air drying oven at a drying temperature of 80° C. for 12 hours.

[0046] S5: calcining the precursor to obtain a carbon dioxide methanation catalyst. In this step, the precursor is calcined in a muffle furnace at a calcination temperature of 400° C. for 4 hours.

[0047] Finally, a carbon dioxide methanation catalyst with a nickel metal weight percentage of 10.5% was obtained.

[0048] Embodiment b

[0049] Except that the total ion concentration of the active metal salt solution is 0.05 mol / L and that of the alkali solution is 0.12 mol / L, the remaining preparation steps are the same as those in Example a.

[0050] Example c

[0051] Except that the total ion concentration of the active metal salt solution is 0.5 mol / L and the alkali solution is 1.5 mol / L, the remaining preparation steps are the same as those in Example a.

[0052] Embodiment d

[0053] Except that the rotation speed of the first high gravity reactor in step S2 is controlled to 600 r / min, the remaining preparation steps are the same as those in Example a.

[0054] Embodiment e

[0055] Except that the rotation speed of the first high gravity reactor in step S2 is controlled to 1600 r / min, the remaining preparation steps are the same as those in Example a.

[0056] Embodiment f

[0057] Except that the stirring aging time in step S3 is 60 minutes, the remaining preparation steps are the same as those in Example a.

[0058] Embodiment g

[0059] Except that the stirring aging time in step S3 is 240 minutes, the remaining preparation steps are the same as those in Example a.

[0060] Embodiment h

[0061] Except that the drying temperature in step S4 is 70° C., the remaining preparation steps are the same as those in Example a.

[0062] Embodiment 1

[0063] Except that the drying temperature in step S4 is 90° C., the remaining preparation steps are the same as those in Example a.

[0064] Embodiment j

[0065] Except that the drying time in step S4 is 8 hours, the remaining preparation steps are the same as those in Example a.

[0066] Example k

[0067] Except that the drying time in step S4 is 16 hours, the remaining preparation steps are the same as those in Example a.

[0068] Embodiment 1

[0069] Except that the calcination temperature in step S5 is 350° C., the remaining preparation steps are the same as those in Example a.

[0070] Embodiment m

[0071] Except that the calcination temperature in step S5 is 500° C., the remaining preparation steps are the same as those in Example a.

[0072] Example n

[0073] Except that the calcination time in step S5 is 2 hours, the remaining preparation steps are the same as those in Example a.

[0074] Embodiment o

[0075] Except that the calcination time in step S5 is 5 hours, the remaining preparation steps are the same as those in Example a.

[0076] Embodiment p

[0077] Except that 2.663 g of cerium nitrate hexahydrate and 0.280 g of nickel nitrate hexahydrate are dissolved in deionized water to prepare an active metal salt solution with a total ion concentration of 0.14 mol / L, the remaining preparation steps are the same as those in Example a.

[0078] Finally, a carbon dioxide methanation catalyst with a nickel metal weight percentage of 5% is obtained.

[0079] Embodiment q

[0080] Except that 2.663 g of cerium nitrate hexahydrate and 1.320 g of nickel nitrate hexahydrate are dissolved in deionized water to prepare an active metal salt solution with a total ion concentration of 0.14 mol / L, the remaining preparation steps are the same as those in Example a.

[0081] Finally, a carbon dioxide methanation catalyst with a nickel metal weight percentage of 20% is obtained.

[0082] Example r

[0083] Except that 2.663 g of cerium nitrate hexahydrate and 0.629 g of cobalt nitrate hexahydrate are dissolved in deionized water to prepare an active metal salt solution with a total ion concentration of 0.14 mol / L, the remaining preparation steps are the same as those in Example a.

[0084] Finally, a carbon dioxide methanation catalyst with a cobalt metal weight percentage of 10.5% was obtained.

[0085] Comparative Example a

[0086] A Ni / CeO2 catalyst with a nickel metal weight percentage of 10.5% was prepared by a co-precipitation method.

[0087] Comparative Example b

[0088] A Ni / CeO2 catalyst with a nickel metal weight percentage of 10.5% was prepared by an impregnation method.

[0089] Specifically, in the present application, an embodiment of the method for methanation of carbon dioxide is as follows:

[0090] Example 1

[0091] The carbon dioxide methanation catalyst was reduced in a hydrogen atmosphere at 400° C. for 2 hours before the reaction started.

[0092] N1: Loading the carbon dioxide methanation catalyst into the packed bed of the second high gravity reactor. In this step, the carbon dioxide methanation catalyst used is the catalyst in Example a.

[0093] N2: The reaction materials are introduced into the packed bed from the inlet of the second high gravity reactor, and the packed bed is kept rotating at a high speed to obtain the product. In this step, the reaction materials are hydrogen and carbon dioxide; the molar ratio of hydrogen and carbon dioxide is controlled to be 4; the reaction temperature is 400°C; the reaction pressure is 1MPaG; the gas space velocity is 8000ml / g·h; and the speed of the packed bed is 1650r / min.

[0094] N3: The product is discharged from the outlet of the second high gravity reactor.

[0095] In this embodiment, the CO2 conversion rate is 93.49% and the CH4 selectivity is 100%.

[0096] Example 2

[0097] Except that the molar ratio of hydrogen to carbon dioxide is controlled to 5, the remaining steps are the same as those in Example 1.

[0098] In this embodiment, the CO2 conversion rate is 96.92% and the CH4 selectivity is 100%.

[0099] Example 3

[0100] Except that the molar ratio of hydrogen to carbon dioxide is controlled to 2, the remaining steps are the same as those in Example 1.

[0101] In this embodiment, the CO2 conversion rate is 48.07% and the CH4 selectivity is 100%.

[0102] Example 4

[0103] Except that the reaction temperature in step N2 is controlled to 300° C., the remaining steps are the same as those in Example 1.

[0104] In this embodiment, the CO2 conversion rate is 85.79% and the CH4 selectivity is 100%.

[0105] Example 5

[0106] Except that the reaction temperature in step N2 is controlled to 200° C., the remaining steps are the same as those in Example 1.

[0107] In this embodiment, the CO2 conversion rate is 3.16% and the CH4 selectivity is 100%.

[0108] Example 6

[0109] Except that the reaction pressure in step N2 is controlled to 0.1 MPaG, the remaining steps are the same as those in Example 1.

[0110] In this embodiment, the CO2 conversion rate is 89.51% and the CH4 selectivity is 100%.

[0111] Example 7

[0112] Except that the reaction pressure in step N2 is controlled to 3 MPaG, the remaining steps are the same as those in Example 1.

[0113] In this embodiment, the CO2 conversion rate is 95.87% and the CH4 selectivity is 100%.

[0114] Example 8

[0115] Except that the gas space velocity in step N2 is controlled to 12000 ml / g·h, the remaining steps are the same as those in Example 1.

[0116] In this embodiment, the CO2 conversion rate is 92.14% and the CH4 selectivity is 100%.

[0117] Example 9

[0118] Except that the gas space velocity in step N2 is controlled to 2000 ml / g·h, the remaining steps are the same as those in Example 1.

[0119] In this embodiment, the CO2 conversion rate is 93.58% and the CH4 selectivity is 100%.

[0120] Example 10

[0121] Except that the gas space velocity in step N2 is controlled to 30000 ml / g·h, the remaining steps are the same as those in Example 1.

[0122] In this embodiment, the CO2 conversion rate is 91.12% and the CH4 selectivity is 100%.

[0123] Embodiment 11

[0124] Except that the gas space velocity in step N2 is controlled to 60000 ml / g·h, the remaining steps are the same as those in Example 1.

[0125] In this embodiment, the CO2 conversion rate is 82.22% and the CH4 selectivity is 100%.

[0126] Example 12

[0127] Except that the rotation speed of the packed bed in step N2 is controlled to 800 r / min, the remaining steps are the same as those in Example 8.

[0128] In this embodiment, the CO2 conversion rate is 89.63% and the CH4 selectivity is 100%.

[0129] Embodiment 13

[0130] Except that the rotation speed of the packed bed in step N2 is controlled to 600 r / min, the remaining steps are the same as those in Example 1.

[0131] In this embodiment, the CO2 conversion rate is 88.89% and the CH4 selectivity is 100%.

[0132] Embodiment 14

[0133] Except that the rotation speed of the packed bed in step N2 is controlled to 2600 r / min, the remaining steps are the same as those in Example 1.

[0134] In this embodiment, the CO2 conversion rate is 91.09% and the CH4 selectivity is 100%.

[0135] Embodiment 15

[0136] Except that the carbon dioxide methanation catalyst is replaced by the catalyst in Example b, the remaining steps are the same as those in Example 1.

[0137] In this embodiment, the CO2 conversion rate is 92.33% and the CH4 selectivity is 100%.

[0138] Example 16

[0139] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example C, the remaining steps are the same as Example 1.

[0140] In this embodiment, the CO2 conversion rate is 93.42% and the CH4 selectivity is 100%.

[0141] Embodiment 17

[0142] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example d, the remaining steps are the same as Example 1.

[0143] In this embodiment, the CO2 conversion rate is 93.39% and the CH4 selectivity is 100%.

[0144] Embodiment 18

[0145] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example e, the remaining steps are the same as Example 1.

[0146] In this embodiment, the CO2 conversion rate is 93.22% and the CH4 selectivity is 100%.

[0147] Embodiment 19

[0148] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example f, the remaining steps are the same as Example 1.

[0149] In this embodiment, the CO2 conversion rate is 92.79% and the CH4 selectivity is 100%.

[0150] Embodiment 20

[0151] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example g, the remaining steps are the same as Example 1.

[0152] In this embodiment, the CO2 conversion rate is 91.56% and the CH4 selectivity is 100%.

[0153] Embodiment 21

[0154] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example h, the remaining steps are the same as Example 1.

[0155] In this embodiment, the CO2 conversion rate is 93.25% and the CH4 selectivity is 100%.

[0156] Embodiment 22

[0157] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example 1, the remaining steps are the same as Example 1.

[0158] In this embodiment, the CO2 conversion rate is 93.18% and the CH4 selectivity is 100%.

[0159] Embodiment 23

[0160] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example j, the remaining steps are the same as Example 1.

[0161] In this embodiment, the CO2 conversion rate is 93.38% and the CH4 selectivity is 100%.

[0162] Embodiment 24

[0163] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example k, the remaining steps are the same as Example 1.

[0164] In this embodiment, the CO2 conversion rate is 93.07% and the CH4 selectivity is 100%.

[0165] Embodiment 25

[0166] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example 1, the remaining steps are the same as Example 1.

[0167] In this embodiment, the CO2 conversion rate is 91.93% and the CH4 selectivity is 100%.

[0168] Embodiment 26

[0169] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example m, the remaining steps are the same as Example 1.

[0170] In this embodiment, the CO2 conversion rate is 87.46% and the CH4 selectivity is 100%.

[0171] Embodiment 27

[0172] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example n, the remaining steps are the same as Example 1.

[0173] In this embodiment, the CO2 conversion rate is 92.41% and the CH4 selectivity is 100%.

[0174] Embodiment 28

[0175] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example o, the remaining steps are the same as Example 1.

[0176] In this embodiment, the CO2 conversion rate is 89.96% and the CH4 selectivity is 100%.

[0177] Embodiment 29

[0178] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example p, the remaining steps are the same as Example 1.

[0179] In this embodiment, the CO2 conversion rate is 85.33% and the CH4 selectivity is 100%.

[0180] Embodiment 30

[0181] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example q, the remaining steps are the same as Example 1.

[0182] In this embodiment, the CO2 conversion rate is 91.26% and the CH4 selectivity is 100%.

[0183] Embodiment 31

[0184] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Example r, the remaining steps are the same as Example 1.

[0185] In this embodiment, the CO2 conversion rate is 85.00% and the CH4 selectivity is 100%.

[0186] Embodiment 32

[0187] Except that the carbon dioxide methanation catalyst is replaced by the catalyst in Comparative Example a, the remaining steps are the same as those in Example 1.

[0188] In this embodiment, the CO2 conversion rate is 82.34% and the CH4 selectivity is 99.3%.

[0189] Embodiment 33

[0190] Except that the carbon dioxide methanation catalyst is replaced by the catalyst in Comparative Example b, the remaining steps are the same as those in Example 1.

[0191] In this embodiment, the CO2 conversion rate is 76.55% and the CH4 selectivity is 98.8%.

[0192] Comparative Example 1

[0193] The catalyst in Example a was selected and loaded into a gas-solid reactor. During the reaction, the molar ratio of hydrogen to carbon dioxide was controlled to be 4; the reaction temperature was controlled to be 400° C.; the reaction pressure was controlled to be 1 MPaG; and the gas space velocity was controlled to be 2400 ml / g·h.

[0194] In this comparative example, the CO2 conversion rate is 88.12% and the CH4 selectivity is 100%.

[0195] Comparative Example 2

[0196] Except that the carbon dioxide methanation catalyst is replaced by the catalyst in Comparative Example a, the remaining steps are the same as those in Comparative Example 1.

[0197] In this comparative example, the CO2 conversion rate is 77.02% and the CH4 selectivity is 96.7%.

[0198] Comparative Example 3

[0199] Except for replacing the carbon dioxide methanation catalyst with the catalyst in Comparative Example b, the remaining steps are the same as Comparative Example 1.

[0200] In this comparative example, the CO2 conversion rate is 70.79% and the CH4 selectivity is 94.6%.

[0201] Specifically, in order to clearly understand the differences between Examples a to q, Comparative Example a and Comparative Example b, the experimental conditions of the above examples are summarized, and the summary results are shown in Table 1.

[0202] Table 1 Comparison of catalyst preparation conditions

[0203]

[0204] Specifically, the test results and differences of Examples 1 to 31 and Comparative Examples 1 to 3 are summarized, and the summary table is shown in Table 2 below.

[0205] Table 2 Test results and difference comparison table

[0206]

[0207] As can be seen from Table 2, by comparing the test results of Examples 1 to 30 with the test results of Examples 32 and 33, it can be clearly seen that the catalyst prepared by the preparation method of the carbon dioxide methanation catalyst proposed in the present application can be applied to the carbon dioxide methanation reaction to greatly improve the conversion rate of carbon dioxide. By comparing the test results of Example 1 with Comparative Example 1, the test results of Example 32 with Comparative Example 2, and the test results of Example 33 with Comparative Example 3, it can be clearly seen that the carbon dioxide methanation method proposed in the present application can also further improve the conversion rate and selectivity of carbon dioxide methanation.

[0208] It should be noted that in the prior art, the closer the actual conversion rate of carbon dioxide is to the theoretical equilibrium conversion rate, the more difficult it is to improve the conversion rate of carbon dioxide. The carbon dioxide methanation catalyst prepared by the preparation method of the carbon dioxide methanation catalyst proposed in the present application in combination with the carbon dioxide methanation method proposed in the present application can make the carbon dioxide conversion rate in the reaction process close to the theoretical equilibrium conversion rate. For example, under the reaction conditions of Example 1, the actual conversion rate of carbon dioxide is 93.49%, while the theoretical equilibrium conversion rate of carbon dioxide is 94.06%; under the reaction conditions of Example 2, the actual conversion rate of carbon dioxide is 96.92%, while the theoretical equilibrium conversion rate of carbon dioxide is 99.96%. It is easy to understand that if the actual conversion rate of carbon dioxide is closer to the theoretical equilibrium conversion rate, the reaction yield will be higher and the cost will be lower.

[0209] The carbon dioxide methanation catalyst prepared by the preparation method of the carbon dioxide methanation catalyst proposed in the present application has a reaction selectivity of 100%, which is significantly better than the prior art. It is easy to understand that if the reaction selectivity is higher, it means that the by-products are less, and the purity and yield of methane obtained are higher.

[0210] Finally, it should be noted that in this application, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0211] Although the present application has been disclosed above through the description of the specific embodiments of the present application, it should be understood that those skilled in the art can design various modifications, improvements or equivalents to the present application within the spirit and scope of the attached scheme. These modifications, improvements or equivalents should also be considered to be included in the scope of protection claimed in the present application.

Claims

1. A method for methanation of carbon dioxide, characterized in that: The method comprises: N1: loading the carbon dioxide methanation catalyst into the packed bed of the second high gravity reactor; N2: introducing the reaction materials into the packed bed from the inlet of the second high gravity reactor, and keeping the packed bed rotating at a high speed all the time, and reacting to obtain products; the reaction materials include hydrogen and carbon dioxide; N3: discharging the product from the outlet of the second high gravity reactor; The method for preparing the carbon dioxide methanation catalyst comprises: S1: introducing an alkaline solution and an active metal salt solution into a first high-gravity reactor to prepare a preliminary mixed solution at the inlet of the first high-gravity reactor; S2: spraying the preliminary mixed liquid uniformly through the metal wire mesh in the first high gravity reactor through the liquid distributor in the first high gravity reactor, and uniformly mixing the preliminary mixed liquid under high-speed rotation to obtain a uniform mixed liquid; S3: After the uniform mixed solution is stirred and aged on a magnetic stirrer, it is centrifuged and washed with water to obtain a precipitate; S4: drying the precipitate to obtain a precursor; S5: calcining the precursor to obtain a carbon dioxide methanation catalyst.

2. The method for methanation of carbon dioxide according to claim 1, characterized in that: The alkaline solution is any one of sodium hydroxide solution, sodium carbonate solution and ammonium bicarbonate solution or a combination of multiple solutions; the active metal salt solution is a salt solution formed by Ni salt and Ce salt or Co salt and Ce salt.

3. The method for methanation of carbon dioxide according to claim 1, characterized in that: The total ion concentration of the active metal salt solution is greater than or equal to 0.05 mol / L and less than or equal to 0.5 mol / L; the weight percentage of the active metal in the carbon dioxide methanation catalyst is greater than or equal to 5% and less than or equal to 20%.

4. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step S2, the rotation speed of the first high gravity reactor is greater than or equal to 400 r / min and less than or equal to 2400 r / min; in step S3, the stirring aging time is greater than or equal to 60 minutes and less than or equal to 240 minutes.

5. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step S4, the drying temperature is greater than or equal to 70° C. and less than or equal to 90° C.; the drying time is greater than or equal to 8 hours and less than or equal to 16 hours; in step S5, the calcination temperature is greater than or equal to 350° C. and less than or equal to 500° C.; the calcination time is greater than or equal to 2 hours and less than or equal to 5 hours.

6. The method for methanation of carbon dioxide according to claim 1, characterized in that: The total ion concentration of the active metal salt solution is greater than or equal to 0.1 mol / L and less than or equal to 0.2 mol / L.

7. The method for methanation of carbon dioxide according to claim 1, characterized in that: The concentration of the alkaline solution is greater than or equal to 0.2 mol / L and less than or equal to 0.6 mol / L.

8. The method for methanation of carbon dioxide according to claim 1, characterized in that: The weight percentage of active metal in the carbon dioxide methanation catalyst is greater than or equal to 10% and less than or equal to 12%.

9. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step S2, the rotation speed of the first supergravity reactor is greater than or equal to 800 r / min and less than or equal to 1200 r / min.

10. The method for methanation of carbon dioxide according to claim 1, characterized in that: The stirring and aging time in step S3 is greater than or equal to 120 minutes and less than or equal to 180 minutes.

11. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step S4, the drying temperature is greater than or equal to 75°C and less than or equal to 85°C.

12. The method for methanation of carbon dioxide according to claim 1, characterized in that: The drying time in step S4 is greater than or equal to 10 hours and less than or equal to 14 hours.

13. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step S5, the calcination temperature is greater than or equal to 400°C and less than or equal to 450°C.

14. The method for methanation of carbon dioxide according to claim 1, characterized in that: The calcination time in step S5 is greater than or equal to 3 hours and less than or equal to 4 hours.

15. The method for methanation of carbon dioxide according to claim 1, characterized in that: The molar ratio of hydrogen to carbon dioxide in the reaction material is greater than or equal to 2 and less than or equal to 5; the reaction temperature in step N2 is greater than or equal to 200°C and less than or equal to 500°C; the reaction pressure is greater than or equal to 0.1MPaG and less than or equal to 3MPaG; the gas space velocity is greater than or equal to 2000ml / g·h and less than or equal to 60000ml / g·h; the rotation speed of the packed bed in step N2 is greater than or equal to 600r / min and less than or equal to 2600r / min.

16. The method for methanation of carbon dioxide according to claim 1, characterized in that: The molar ratio of hydrogen to carbon dioxide in the reaction material is greater than or equal to 4 and less than or equal to 5.

17. The method for methanation of carbon dioxide according to claim 1, characterized in that: The reaction temperature in step N2 is greater than or equal to 350° C. and less than or equal to 450° C.

18. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step N2, the reaction pressure is greater than or equal to 1 MPaG and less than or equal to 2 MPaG.

19. The method for methanation of carbon dioxide according to claim 1, characterized in that: The gas space velocity in step N2 is greater than or equal to 2000 ml / g·h and less than or equal to 20000 ml / g·h.

20. The method for methanation of carbon dioxide according to claim 1, characterized in that: In step N2, the rotation speed of the packed bed is greater than or equal to 800 r / min and less than or equal to 1800 r / min.

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