Composite catalyst for methanation of carbon dioxide and simple preparation method thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a composite catalyst for methanation of carbon dioxide and a simple preparation method thereof.The composite catalyst is prepared from active metal Ni salt, rare earth metal Ce salt, metal additive Mg salt and metal precursor Al salt through the key steps of mixing, grinding, calcining and the like. The preparation process is simple, the operation is convenient, and the production difficulty and cost are greatly reduced; the process is energy-saving and environment-friendly, no waste liquid is generated in the whole process, the problem of environmental pollution of a traditional process is avoided, safety, high efficiency, greenness and no pollution are realized, and the preparation method meets the requirements of large-scale industrial production; when the prepared composite catalyst is applied to a carbon dioxide methanation reaction, the performance is excellent, the catalyst can show high catalytic activity under a low-temperature condition, and the reaction efficiency is remarkably improved; meanwhile, the selectivity to methane is extremely high, generation of by-products can be effectively reduced, and the application prospect is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a composite catalyst for carbon dioxide methanation and a simple preparation method thereof. BACKGROUND

[0002] With the continuous improvement of human living quality and the rapid development of industrialization, fossil fuels are being mined and used in large quantities, causing the concentration of carbon dioxide in the atmosphere to continue to rise. This phenomenon has triggered a series of serious environmental problems such as the intensification of the greenhouse effect and ocean acidification, which poses a great threat to the ecological balance of the earth and the living environment of mankind. In this context, the exploration and practice of carbon dioxide emission reduction and recycling strategies are particularly urgent and critical.

[0003] Among them, the technical path of preparing methane by carbon dioxide hydrogenation (chemical equation: CO2+4H2→CH4+2H2O) has shown great application potential and value. This technology not only can effectively reduce the emission of greenhouse gases and alleviate the pressure of global warming, but also can open up a new sustainable way for energy supply, which has dual strategic significance of energy and environment for promoting human society to develop in a more green, low-carbon and sustainable direction.

[0004] At present, in the field of preparation of methanation catalysts, the conventional methods mainly include sol-gel method, impregnation method, hydrothermal method, coprecipitation method, etc. However, these methods have different degrees of limitations in practical application. For example, the sol-gel method takes a long time in the gelation and aging process, and the whole reaction period is relatively long. Moreover, there may be incompletely decomposed organic matters in the reaction system, which are likely to contaminate the final product. Therefore, an additional high-temperature treatment step is needed to remove impurities, which undoubtedly increases the complexity and cost of preparation. The impregnation method causes uneven distribution of active components on the carrier due to the complex and diverse pore structure of the carrier, which further causes local performance differences of the catalyst and affects the overall catalytic effect. The hydrothermal method needs to rely on a high-temperature and high-pressure reaction kettle with high equipment cost, and there are certain safety hazards in the operation process. At the same time, small changes in parameters such as temperature, time and filling degree can cause abnormal morphology or crystal type of the product, increasing the uncertainty of the preparation process. In the drying or calcination stage of the coprecipitation method, particles are prone to sintering. In order to solve this problem, a dispersant needs to be added or the preparation conditions need to be strictly controlled. In addition, fluctuations in parameters such as pH value, temperature and stirring speed can also adversely affect the consistency of the product.

[0005] In summary, the existing CO2 methanation catalyst preparation methods generally have problems such as complicated operation, unstable catalyst activity, etc., which not only consumes a lot of time and effort, but also produces a large amount of waste liquid, bringing many inconveniences to industrial application.

[0006] In view of this, the present application aims to propose a brand new preparation method to better solve the above technical problems. SUMMARY

[0007] To solve the above problems, the present application provides a composite catalyst for carbon dioxide methanation and a simple preparation method thereof, which is simple and convenient, energy-saving and environmentally friendly, does not produce waste liquid, can realize large-scale industrial production and preparation, and has a wide application prospect.

[0008] The technical solution adopted by the present application is:

[0009] A simple preparation method of a composite catalyst for carbon dioxide methanation, comprising the following preparation steps:

[0010] S1. uniformly mixing active metal Ni salt, rare earth metal Ce salt, metal additive Mg salt and metal precursor Al salt, and fully grinding;

[0011] S2. placing the ground mixture in a calcination furnace for calcination treatment to obtain a composite catalyst precursor;

[0012] S3. high-temperature calcination treatment of the composite catalyst precursor obtained in step S2 under a reducing atmosphere to reduce NiO in the catalyst to catalytically active Ni 0 and fully expose, thereby preparing the composite catalyst.

[0013] Further, in step S1, the molar ratio between the metal Ni salt, the metal Ce salt and the metal Mg salt is 2-6:2-6:2-6 (4:2:2 is preferred).

[0014] Further, in step S1, the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 4-12:12 (8:12 is preferred); in this step, by adjusting the molar ratio of the metal Ni salt, the metal Ce salt, the metal Mg salt and the metal Al salt, the CO2 methanation composite catalyst with the highest low-temperature activity is obtained.

[0015] Further, in step S1, the active metal Ni salt, the rare earth metal Ce salt and the metal additive Mg salt are each independently selected from nitrate and / or acetate (nitrate is preferred); the Al salt is aluminum isopropoxide.

[0016] Further, in step S2, the calcination furnace is a tube furnace and a muffle furnace (a tube furnace is preferred); the calcination treatment can be carried out under N2 or air atmosphere; the calcination temperature is 300-500℃ (300℃ is preferred), the heating rate is 1-5℃ / min (5℃ / min is preferred), and the calcination time is 2h.

[0017] Further, in step S3, the reducing atmosphere is H2 / Ar mixed gas with a H2 volume fraction of 10%; the calcination temperature is 500 DEG C; and the calcination time is 90 min.

[0018] Based on the same inventive concept, the application further provides a composite catalyst for carbon dioxide methanation, which is prepared by the simple preparation method.

[0019] The beneficial effects of the application are as follows:

[0020] The composite catalyst for carbon dioxide methanation reaction provided by the application is prepared from active metal Ni salt, rare earth metal Ce salt, metal additive Mg salt and metal precursor Al salt as raw materials through key steps such as mixing, grinding and calcination, and has the advantages of simple preparation process, convenient operation, greatly reduced production difficulty and cost, energy saving and environmental protection, no waste liquid generated in the whole preparation process, avoided environmental pollution problem in the traditional process, realized safe and efficient, green and pollution-free, and the preparation method meets the needs of large-scale industrial production; when the prepared composite catalyst is applied to carbon dioxide methanization reaction, the performance is excellent, the catalyst can exhibit high catalytic activity under low temperature conditions, and the reaction efficiency is significantly improved; at the same time, the selectivity to methane is very high, which can effectively reduce the generation of by-products and improve the purity of the target product; therefore, the composite catalyst provided by the application is a high-activity and high-selectivity low-temperature carbon dioxide methanization catalyst, which has wide application prospects in the fields of energy conversion and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The activity curve of each catalyst prepared in the examples of the application for catalyzing CO2 methanation reaction is shown in the figure;

[0022] Figure 2 The product (methane) selectivity curve of the catalysts prepared in the examples 1 and comparative examples 1 and 3 of the application for catalyzing CO2 methanation at different temperatures is shown in the figure;

[0023] Figure 3 The XRD pattern of the catalyst prepared in the example 1 of the application is shown in the figure. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the application, the application will be described more fully below by examples, and the preferred embodiments of the application are given below. However, the application can be realized in many different forms, and is not limited to the embodiments described herein. Any modification or equivalent replacement of the technical solutions of the application without creative achievement will obtain other embodiments within the protection scope of the application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0026] The numerical values disclosed in the present application are approximate values, not definite values. Within the error or experimental conditions, all values within the error range can be included without being limited to the specific numerical values disclosed in the present application.

[0027] Unless otherwise specifically indicated, various materials, reagents, instruments and equipment and the like used in the present application can be purchased in the market or can be prepared by the existing methods.

[0028] Example 1

[0029] The present embodiment provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0030] S1. 4 mmol of nickel nitrate, 2 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 4:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 8:12);

[0031] S2. The mixture in S1 was placed in a tube furnace and calcined at 300℃ for 2h under N2 atmosphere, with a heating rate of 5℃ / min, to obtain a composite catalyst precursor;

[0032] S3. The composite catalyst precursor obtained in S2 was treated by high-temperature calcination at 500℃ for 90min under H2 atmosphere, so that the NiO in the catalyst was reduced to Ni 0 and exposed, to obtain a composite catalyst.

[0033] Example 2

[0034] The present embodiment provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0035] S1. 2 mmol of nickel nitrate, 2 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 2:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 6:12);

[0036] S2. The mixture in S1 is placed in a tube furnace and calcined at 300°C for 2h under N2 atmosphere at a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0037] S3. The composite catalyst precursor obtained in S2 is treated by high-temperature calcination at 500°C for 90min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, to obtain a composite catalyst.

[0038] Example 3

[0039] The embodiment provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0040] S1. 3mmol of nickel nitrate, 2mmol of cerium nitrate, 2mmol of magnesium nitrate and 12mmol of aluminum isopropoxide are mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 3:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 7:12);

[0041] S2. The mixture in S1 is placed in a tube furnace and calcined at 300°C for 2h under N2 atmosphere at a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0042] S3. The composite catalyst precursor obtained in S2 is treated by high-temperature calcination at 500°C for 90min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, to obtain a composite catalyst.

[0043] Example 4

[0044] The embodiment provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0045] S1. 5mmol of nickel nitrate, 2mmol of cerium nitrate, 2mmol of magnesium nitrate and 12mmol of aluminum isopropoxide are mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 5:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 9:12);

[0046] S2. The mixture in S1 is placed in a tube furnace and calcined at 300°C for 2h under N2 atmosphere at a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0047] S3. The composite catalyst precursor obtained in S2 is treated by high-temperature calcination at 500°C for 90min under H2 atmosphere to reduce NiO in the catalyst to Ni0 and exposed, to obtain the composite catalyst.

[0048] Example 5

[0049] The embodiment provides a preparation method of a composite catalyst for a carbon dioxide methanation reaction, and comprises the following steps:

[0050] S1. 6 mmol of nickel nitrate, 2 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide are mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 6:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 10:12);

[0051] S2. The mixture in S1 is placed in a tube furnace and calcined at 300 DEG C for 2 h under N2 atmosphere, with a temperature rising rate of 5 DEG C / min, to obtain a composite catalyst precursor;

[0052] S3. The composite catalyst precursor obtained in S2 is treated by high-temperature calcination at 500 DEG C for 90 min under H2 atmosphere, so that NiO in the catalyst is reduced to Ni 0 and exposed, to obtain the composite catalyst.

[0053] Example 6

[0054] The embodiment provides a preparation method of a composite catalyst for a carbon dioxide methanation reaction, and comprises the following steps:

[0055] S1. 4 mmol of nickel nitrate, 2 mmol of cerium nitrate, 6 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide are mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 4:2:6, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 12:12);

[0056] S2. The mixture in S1 is placed in a tube furnace and calcined at 300 DEG C for 2 h under N2 atmosphere, with a temperature rising rate of 5 DEG C / min, to obtain a composite catalyst precursor;

[0057] S3. The composite catalyst precursor obtained in S2 is treated by high-temperature calcination at 500 DEG C for 90 min under H2 atmosphere, so that NiO in the catalyst is reduced to Ni 0 and exposed, to obtain the composite catalyst.

[0058] Example 7

[0059] The embodiment provides a preparation method of a composite catalyst for a carbon dioxide methanation reaction, and comprises the following steps:

[0060] S1. 4 mmol of nickel nitrate, 6 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (the molar ratio between the metal Ni salt, the metal Ce salt and the metal Mg salt was 4:6:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt was 12:12) ;

[0061] S2. The mixture in S1 was placed in a tube furnace and calcined at 300°C for 2 h under an N2 atmosphere at a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0062] S3. The composite catalyst precursor obtained in S2 was subjected to high-temperature calcination treatment at 500°C for 90 min under an H2 atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, thereby obtaining a composite catalyst.

[0063] Example 8

[0064] The present example provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0065] S1. 4 mmol of nickel nitrate, 2 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (the molar ratio between the metal Ni salt, the metal Ce salt and the metal Mg salt was 4:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt was 8:12) ;

[0066] S2. The mixture in S1 was placed in a tube furnace and calcined at 400°C for 2 h under an N2 atmosphere at a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0067] S3. The composite catalyst precursor obtained in S2 was subjected to high-temperature calcination treatment at 500°C for 90 min under an H2 atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, thereby obtaining a composite catalyst.

[0068] Example 9

[0069] The present example provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0070] S1. 4 mmol of nickel nitrate, 2 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (the molar ratio between the metal Ni salt, the metal Ce salt and the metal Mg salt was 4:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt was 8:12) ;

[0071] S2. The mixture in S1 was placed in a tube furnace and calcined at 500°C for 2h under N2 atmosphere with a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0072] S3. The composite catalyst precursor obtained in S2 was treated by high-temperature calcination at 500°C for 90min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, thereby obtaining a composite catalyst.

[0073] Example 10

[0074] The present embodiment provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0075] S1. 4mmol of nickel nitrate, 2mmol of cerium nitrate, 2mmol of magnesium nitrate and 12mmol of aluminum isopropoxide were mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 4:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 8:12);

[0076] S2. The mixture in S1 was placed in a tube furnace and calcined at 500°C for 2h under N2 atmosphere with a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0077] S3. The composite catalyst precursor obtained in S2 was treated by high-temperature calcination at 500°C for 90min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, thereby obtaining a composite catalyst.

[0078] Example 11

[0079] The present embodiment provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0080] S1. 4mmol of nickel nitrate, 2mmol of cerium nitrate, 2mmol of magnesium nitrate and 12mmol of aluminum isopropoxide were mixed and uniformly ground (wherein the molar ratio among the metal Ni salt, the metal Ce salt and the metal Mg salt is 4:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt is 8:12);

[0081] S2. The mixture in S1 was placed in a tube furnace and calcined at 500°C for 2h under N2 atmosphere with a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0082] S3. The composite catalyst precursor obtained in S2 was calcined at 500°C for 90 min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and exposed, to obtain the composite catalyst.

[0083] Comparative Example 1

[0084] The present comparative example provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0085] (a) 4 mmol of nickel nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (wherein the molar ratio between the metal Ni salt and the metal Mg salt is 4:2, and the molar ratio between the total moles of the metal Ni salt and the metal Mg salt and the metal Al salt is 6:12) ;

[0086] (b) The mixture in (a) was placed in a tube furnace and calcined at 300°C for 2 h under N2 atmosphere, with a heating rate of 1°C / min, to obtain a composite catalyst precursor;

[0087] (c) The composite catalyst precursor obtained in (b) was calcined at 500°C for 90 min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and exposed, to obtain the composite catalyst.

[0088] Comparative Example 2

[0089] The present comparative example provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0090] (a) 2 mmol of cerium nitrate, 2 mmol of magnesium nitrate and 12 mmol of aluminum isopropoxide were mixed and uniformly ground (wherein the molar ratio between the metal Ce salt and the metal Mg salt is 2:2, and the molar ratio between the total moles of the metal Ce salt and the metal Mg salt and the metal Al salt is 4:12) ;

[0091] (b) The mixture in (a) was placed in a tube furnace and calcined at 300°C for 2 h under N2 atmosphere, with a heating rate of 5°C / min, to obtain a composite catalyst precursor;

[0092] (c) The composite catalyst precursor obtained in (b) was calcined at 500°C for 90 min under H2 atmosphere to reduce NiO in the catalyst to Ni 0 and exposed, to obtain the composite catalyst.

[0093] Comparative Example 3

[0094] The present comparative example provides a preparation method of a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0095] (a) 4 mmol of nickel acetate, 2 mmol of cerium acetate, 2 mmol of magnesium acetate and 12 mmol of aluminum isopropoxide were mixed and ground uniformly (the molar ratio between the metal Ni salt, the metal Ce salt and the metal Mg salt was 4:2:2, and the molar ratio between the total moles of the metal Ni salt, the metal Ce salt and the metal Mg salt and the metal Al salt was 8:12);

[0096] (b) the mixture in (a) was placed in a tube furnace and calcined at 300°C for 2 h under N2atmosphere at a heating rate of 5°C / min to obtain a composite catalyst precursor;

[0097] (c) the composite catalyst precursor obtained in (b) was treated by high-temperature calcination at 500°C for 90 min under H2atmosphere to reduce NiO in the catalyst to Ni 0 and expose it, to obtain a composite catalyst.

[0098] Referring to the following table, the CO2conversion rate and CH4selectivity of the different catalysts prepared in the examples and the comparative examples of the present application in the CO2methanation reaction at 300°C, a space velocity of 24000 mL g -1 h -1

[0099] Catalyst CO2 conversion (%) CH4 selectivity (%) Example 1 NiCeMgAl 87.5 100 Example 2 NiCeMgAl 54.1 100 Example 3 NiCeMgAl 80.2 100 Example 4 NiCeMgAl 85.5 100 Example 5 NiCeMgAl 84.8 100 Example 6 NiCeMgAl 59.7 98.8 Example 7 NiCeMgAl 62.1 100 Example 8 NiCeMgAl 72.8 100 Example 9 NiCeMgAl 71.9 100 Example 10 NiCeMgAl 75.7 100 Example 11 NiCeMgAl 71.0 100 Comparative Example 1 NiCeAl 42.9 100 Comparative Example 2 CeMgAl 0 0 Comparative Example 3 NiCeMgAl acetate 18.8 97.1

[0100] As shown in the above table, the CO2conversion rate and CH4selectivity of the catalysts prepared in the examples of the present application in the CO2methanation reaction process are all better than those of the catalysts prepared in the comparative examples.

[0101] The following is a test of catalytic performance:

[0102] The catalysts prepared in the above examples 1-11 and comparative examples 1-3 were respectively used in the gas-solid phase reaction of carbon dioxide methanation, and the specific operation was as follows:

[0103] 0.2 g of catalyst was taken and diluted with 0.8 g of quartz sand, and then filled into a quartz reaction tube. The reaction gas was introduced under normal pressure (0.1 MPa), the molar ratio of the reaction gas components was H2:CO2:Ar = 4:1:5, the reaction temperature was 200-400°C, the gas flow rate was 24000 mL g -1 h -1 , and the carbon dioxide conversion rate and the methane selectivity were calculated according to the following formula using the test values.

[0104]

[0105] In the above formula, [CO2] in and [CO2] out ​respectively represent the molar concentration of CO2 in the import and export gas, [CH4] out is the molar concentration of CH4 in the export gas.

[0106] Referring to Figure 1 Fig. 2 shows the CO2 conversion curves of the catalysts prepared in the examples and comparative examples for the carbon dioxide methanation reaction. From Figure 1 It can be seen from Fig. 2 that the catalytic performance of the catalysts prepared by the examples of the present application is significantly better than that of the catalysts prepared in the comparative examples, and the catalyst of Example 1 has the highest activity and CO2 conversion.

[0107] Referring to Figure 2 Fig. 3 shows the product (methane) selectivity curves of the catalysts prepared in Example 1 and Comparative Examples 1 and 3 for the CO2 methanation reaction at different temperatures. From Figure 2 It can be seen from Fig. 3 that the selectivity of the product (methane) of the catalysts prepared in the present application is better than that of the comparative examples at different temperatures, and has high selectivity, so that the catalytic reaction can be carried out at a lower temperature, avoiding the deactivation of the catalyst caused by the sintering of the transition metal under the high-temperature carbon dioxide methanation reaction conditions, thereby better meeting the catalytic application requirements.

[0108] Referring to Figure 3 Fig. 4 shows the XRD pattern of the catalyst prepared in Example 1. From the figure, it can be seen that the catalyst prepared in Example 1 of the present application, at 2θ = 28.5°, 33.1°, 47.5°, 56.3°, 59.1°, 69.4°, 76.7° and 79.1°, the diffraction peaks of the (111), (200), (220), (311), (222), (400), (331) and (420) crystal planes of CeO2 (PDF # 34-0394) are observed, and the cubic fluorite structure CeO2 is the main phase of the catalyst. At the same time, at 2θ = 37.1°, 43.1°, 62.6°, 75.1° and 79.1°, the diffraction peaks of the (111), (200), (220), (311) and (222) crystal planes of MgNiO2 (PDF # 24-0712) are observed, and the cubic structure MgNiO2 is the main phase of the catalyst. In addition, in the XRD pattern, no related diffraction peaks of Al element are found, which can be inferred that the Al element is in amorphous state, which can effectively enhance the thermal stability of the catalyst and is conducive to the progress of the CO2 methanation reaction.

[0109] To sum up, the catalyst prepared in each embodiment of the present application can exhibit good catalytic performance in the CO2 methanation reaction, and after a long time stability test, the selectivity of the product remains stable, without obvious deactivation, showing excellent stability performance, having extremely high application value. As can be seen, the composite nickel-based catalyst provided by the present application exhibits excellent low-temperature activity and selectivity in the CO2 methanation reaction, and has broad application prospect. At the same time, the preparation method provided by the present application is simple and convenient, energy-saving and environment-friendly, without waste liquid, safe, efficient, pollution-free, and can be mass industrialized production and preparation.

[0110] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be understood as limiting the scope of the patent of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A simple preparation method of a composite catalyst for carbon dioxide methanation, characterized in that: The method comprises the following preparation steps: S1. The Ni salt, Ce salt, Mg salt and Al salt are mixed and fully ground; S2. The ground mixture is placed in a calciner for calcination, or placed at room temperature to obtain a composite catalyst precursor; S3. The composite catalyst precursor obtained in step S2 is calcined at high temperature under a reducing atmosphere to reduce the NiO in the catalyst to Ni with catalytic activity. 0 and fully exposed, thereby preparing the composite catalyst.

2. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S1 , the molar ratio of the Ni salt, the Ce salt and the Mg salt is 2-6:2-6:2-6.

3. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 2, characterized in that: In step S1, the molar ratio of Ni salt, Ce salt and Mg salt is 4:2:

2.

4. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 2, characterized in that: In step S1, the molar ratio of the total mole of Ni salt, Ce salt and Mg salt to Al salt is 4 to 12:

12.

5. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 4, characterized in that: In step S1, the molar ratio of the total mole of Ni salt, Ce salt and Mg salt to Al salt is 8:

12.

6. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S1, the Ni salt, Ce salt and Mg salt are each independently selected from nitrate and / or acetate; and the Al salt is aluminum isopropoxide.

7. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S2, the calcination furnace is a tubular furnace and a muffle furnace; the calcination treatment can be carried out under N2 or air atmosphere; the calcination temperature is 300-500°C, the heating rate is 1-5°C / min, and the calcination time is 2h.

8. The simple preparation method of the composite catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S3, the reducing atmosphere is a H2 / Ar mixed gas with an H2 volume fraction of 10%; the calcination temperature is 500°C; and the calcination time is 90 minutes.

9. A composite catalyst for carbon dioxide methanation prepared by the simple preparation method according to any one of claims 1 to 8.

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