Supported catalyst for methanation of carbon dioxide and preparation method thereof

Abstract

The invention relates to the technical field of methanation reaction catalysts, in particular to a supported catalyst for methanation of carbon dioxide and a preparation method thereof.According to the preparation method, firstly, a nickel-doped cerium dioxide carrier is prepared through a urea method, and then a metal nickel nano-catalyst is supported on the carrier through an impregnation method; the preparation process is simple, the operation repeatability is high, and the method is suitable for large-scale industrial production; according to the supported catalyst for methanation of carbon dioxide, provided by the invention, the nickel-doped improved cerium dioxide is adopted as the carrier, and the oxygen vacancy concentration in the cerium dioxide carrier is greatly improved through the nickel doping amount, so that the activation and conversion of CO2 are promoted, and the problems of low activity and poor stability of the existing nickel-based catalyst for methanation of CO2 are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of methanation reaction catalyst technology, and in particular to a supported catalyst for carbon dioxide methanation and a preparation method thereof. Background Art

[0002] In recent years, with the improvement of human living standards and the advancement of industrialization, the extensive use of fossil fuels has caused the continuous accumulation of carbon dioxide in the atmosphere, which in turn has led to a series of environmental problems such as the greenhouse effect and ocean acidification. In this context, CO2 emission reduction and recycling strategies are particularly important. In particular, the technical route of producing methane through CO2 hydrogenation not only helps to reduce greenhouse gas emissions, but also provides a new sustainable source for energy supply, thus having far-reaching dual energy and environmental significance for the sustainable development of human society.

[0003] At present, the most studied CO2 methanation catalysts are mainly divided into two categories: precious metal catalysts and non-precious metal catalysts. Each type of catalyst has its own advantages and disadvantages. Precious metal catalysts show high activity, but they are usually expensive and not suitable for large-scale industrial use. Although non-precious metal catalysts are cheap, they are prone to sintering and deactivation at high temperatures and oxidizing atmospheres.

[0004] Among non-precious metal catalysts, nickel-based catalysts are widely used in CO2 methanation reactions due to their high CO2 conversion rate, excellent CH4 selectivity and cost-effectiveness. However, existing nickel-based catalysts still have problems such as insufficient low-temperature activity, easy particle accumulation and sintering at high temperatures, and carbon deposition deactivation.

[0005] In view of this, the present application aims to provide a supported catalyst for carbon dioxide methanation reaction and a preparation method thereof, so as to better solve the above technical problems. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a supported catalyst for carbon dioxide methanation and a preparation method thereof, so as to solve the problems of low activity and poor stability of existing CO2 methanation nickel-based catalysts.

[0007] The technical solution adopted by the present invention is:

[0008] A method for preparing a supported catalyst for methanation of carbon dioxide comprises the following steps:

[0009] S1. Add cerium nitrate to deionized water and stir until completely dissolved;

[0010] S2. Add nickel nitrate to the solution of step S1 and stir until completely dissolved;

[0011] S3. Add urea to the solution of step S2 and stir until completely dissolved;

[0012] S4. The solution of step S3 is transferred to a blast drying oven and dried to obtain a solid product;

[0013] S5. The solid product of step S4 is fully ground and transferred to a crucible, the crucible is covered and wrapped with tin foil, and calcined in a muffle furnace to obtain a nickel-doped ceria carrier;

[0014] S6. Add nickel nitrate to deionized water and stir thoroughly until completely dissolved;

[0015] S7. The nickel-doped cerium oxide support obtained in step S5 is fully ground and added to the solution of step S6, ultrasonically dispersed, and dried in a water bath with stirring until solid;

[0016] S8. Grind the solid obtained in step S7 thoroughly and transfer it to a crucible. Cover the crucible and wrap it with tin foil, place it in a muffle furnace and calcine it to obtain a supported nickel-based catalyst with nickel-doped cerium dioxide as a carrier.

[0017] Furthermore, in step S2, the molar ratio of cerium nitrate to nickel nitrate is 1:0.005 to 1:0.05, so as to obtain a CO2 methanation supported catalyst with the highest low-temperature activity by adjusting the molar ratio of cerium nitrate to nickel nitrate.

[0018] Furthermore, in step S2, the optimal molar ratio of cerium nitrate to nickel nitrate is 1:0.02.

[0019] Furthermore, in step S4, the drying temperature is 60-80°C.

[0020] Furthermore, in step S5, the calcination temperature is 500-600°C, the heating rate is 5°C / min, and the calcination time is 2-4 hours.

[0021] Furthermore, in step S5, the optimal calcination temperature is 550°C.

[0022] Furthermore, in step S7, the ultrasonic power is 300-400 W, the ultrasonic interval is 2 s, and the ultrasonic time is 10 minutes.

[0023] Furthermore, in step S8, the calcination temperature is 450-550°C, the heating rate is 5°C / min, and the calcination time is 2-4 hours.

[0024] Furthermore, in step S8, the optimal calcination temperature is 500°C.

[0025] Based on the same inventive concept, the present application also provides a supported catalyst for carbon dioxide methanation prepared using the above-mentioned preparation method.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1. The preparation method of the supported catalyst for carbon dioxide methanation provided by the present invention comprises the following steps: firstly preparing a nickel-doped cerium dioxide carrier by a urea method, and then loading a metal nickel nanocatalyst on the carrier by an impregnation method, so as to increase the oxygen vacancy concentration on the surface of the cerium dioxide carrier by nickel doping, thereby promoting the adsorption and activation of carbon dioxide, so that the prepared supported nickel-based catalyst exhibits excellent low-temperature activity and stability in the CO2 methanation reaction. At the same time, the preparation process provided by the present invention is simple, the operation repeatability is high, and it is suitable for large-scale industrial production;

[0028] 2. The supported catalyst for carbon dioxide methanation provided by the present invention adopts nickel-doped improved cerium dioxide as a carrier. The oxygen vacancy concentration in the cerium dioxide carrier is greatly improved by the nickel doping amount, thereby promoting the activation and conversion of CO2, and effectively solving the problems of low activity and poor stability of existing CO2 methanation nickel-based catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The activity curves of the CO2 methanation reaction catalyzed by the catalysts provided in Examples 1-8 and Comparative Examples 1-2 of the present invention;

[0030] Figure 2 The product (methane) selectivity curve of the catalyst provided in Example 1 of the present invention for catalytic CO2 methanation at different temperatures;

[0031] Figure 3 The stability curve of the catalyst provided in Example 1 of the present invention and Comparative Example 1 catalyzing the CO2 methanation reaction at 300°C;

[0032] Figure 4 This is a transmission electron microscope photograph of the catalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively by way of examples, and preferred embodiments of the present invention are given below. However, the present invention can be implemented in a variety of different forms and is not limited to the embodiments described herein. Any other implementation schemes obtained by modifying or equivalently replacing the technical scheme of the present invention without creative results are within the protection scope of the present invention.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0035] The numerical values ​​disclosed in the embodiments of the present invention are approximate values, not definite values. When the error or experimental conditions permit, all values ​​within the error range may be included without being limited to the specific numerical values ​​disclosed in the embodiments of the present invention.

[0036] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0037] Example 1

[0038] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0039] S1. Add 10 mmol of cerium nitrate to 60 ml of deionized water and stir for 2 min until completely dissolved;

[0040] S2. Add 0.2 mmol nickel nitrate to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.02), and stir for 2 min until completely dissolved;

[0041] S3. 19.53 g of urea was added to the solution of step S2 and stirred for 30 min until the solution was clear and transparent;

[0042] S4. The solution of step S3 was transferred to a forced air drying oven and dried overnight at 60°C to obtain a solid product;

[0043] S5. The solid product of step S4 was fully ground and transferred to a crucible, the crucible was covered and wrapped with tin foil, and placed in a muffle furnace for calcination. After calcination at 200 ° C for 1 h, the temperature was increased to 550 ° C for 2 h, and the heating rate was 5 ° C / min to obtain a nickel-doped cerium dioxide carrier;

[0044] S6. Add 1 g of nickel nitrate to 20 ml of deionized water and stir for 2 min until completely dissolved;

[0045] S7. Grind the carrier of step S5 thoroughly, take 2 g of the powder and add it to the solution of step S6, ultrasonically disperse at 300w for 10min, with an ultrasonic interval of 2S, and evaporate the solvent in a water bath at 80°C until solid;

[0046] S8. Grind the solid from step S7 thoroughly and transfer it to a crucible. Cover the crucible and wrap it with tin foil, place it in a muffle furnace and calcine it at 200°C for 1 hour and then increase the temperature to 500°C for 2 hours. The heating rate is 5°C / min to obtain a supported nickel-based catalyst with nickel-doped cerium dioxide as the carrier.

[0047] Example 2

[0048] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, which differs from Example 1 only in that, in step S2, 0.05 mmol nickel nitrate is added to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.005); in step S8, calcination at 200°C for 1 hour is followed by heating to 450°C for 4 hours.

[0049] The remaining steps are the same as those in Example 1.

[0050] Example 3

[0051] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, which differs from Example 1 only in that, in step S2, 0.1 mmol nickel nitrate is added to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.01); in step S8, calcination at 200°C for 1 hour is followed by heating to 550°C for 2 hours.

[0052] The remaining steps are the same as those in Example 1.

[0053] Example 4

[0054] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, which differs from Example 1 only in that, in step S2, 0.3 mmol nickel nitrate is added to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.03); in step S4, the solid product is dried at 80°C overnight.

[0055] The remaining steps are the same as those in Example 1.

[0056] Example 5

[0057] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, which differs from Embodiment 1 only in that, in step S2, 0.5 mmol nickel nitrate is added to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.05).

[0058] The remaining steps are the same as those in Example 1.

[0059] Example 6

[0060] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, which differs from Example 1 only in that, in step S2, 0.5 mmol nickel nitrate is added to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.05); in step S5, after calcining at 200°C for 1 hour, the temperature is raised to 500°C and calcined for 4 hours.

[0061] The remaining steps are the same as those in Example 1.

[0062] Example 7

[0063] This embodiment provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, which differs from Embodiment 1 only in that, in step S2, 0.5 mmol nickel nitrate is added to the solution of step S1 (wherein the molar ratio of cerium nitrate to nickel nitrate is 1:0.05); in step S5, after calcining at 200°C for 1 hour, the temperature is raised to 600°C and calcined for 2 hours.

[0064] The remaining steps are the same as those in Example 1.

[0065] Example 8

[0066] This embodiment provides a method for preparing a multi-supported catalyst for carbon dioxide methanation reaction, which is different from Embodiment 1 only in that, in step S7, ultrasonic dispersion is performed at 400W for 10 minutes.

[0067] The remaining steps are the same as those in Example 1.

[0068] Comparative Example 1

[0069] This comparative example provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0070] (a) Add 10 mmol of cerium nitrate to 60 ml of deionized water and stir for 2 min until it is completely dissolved;

[0071] (b) adding 19.53 g of urea to the solution of step (a) and stirring for 30 min until the solution becomes clear and transparent;

[0072] (c) transferring the solution of step (b) into a forced air drying oven and drying at 60° C. overnight to obtain a solid product;

[0073] (d) grinding the solid product of step (c) thoroughly and transferring it to a crucible, covering the crucible and wrapping it with tin foil, placing it in a muffle furnace for calcination, calcining it at 200° C. for 1 h and then heating it to 550° C. for 2 h, with a heating rate of 5° C. / min, to obtain a cerium dioxide carrier;

[0074] (e) Add 1 g of nickel nitrate to 20 ml of deionized water and stir for 2 min until it is completely dissolved;

[0075] (f) Grind the carrier of step (e) thoroughly, take 2 g of the powder and add it to the solution of step S6, disperse it ultrasonically at 300 W for 10 min, with an ultrasonic interval of 2 s, and evaporate the solvent in a water bath at 80° C. until solid;

[0076] (g) The solid obtained in step (f) is fully ground and transferred to a crucible. The crucible is covered and wrapped with tin foil, and then placed in a muffle furnace for calcination. After calcination at 200° C. for 1 h, the temperature is increased to 500° C. for calcination for 2 h, with a heating rate of 5° C. / min, to obtain a supported nickel-based catalyst with cerium dioxide as the carrier.

[0077] Comparative Example 2

[0078] This comparative example provides a method for preparing a supported catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0079] (a) Add 10 mmol of cerium nitrate to 60 ml of deionized water and stir for 2 min until it is completely dissolved;

[0080] (b) adding 0.2 mmol nickel nitrate to the solution of step (a) and stirring for 2 min until completely dissolved;

[0081] (c) adding 19.53 g of urea to the solution of step (b) and stirring for 30 min until the solution becomes clear and transparent;

[0082] (d) transferring the solution of step (c) into a forced air drying oven and drying at 60° C. overnight to obtain a solid product;

[0083] (e) grinding the solid product of step (d) thoroughly and transferring it to a crucible, covering the crucible and wrapping it with tin foil, placing it in a muffle furnace for calcination, calcining it at 200° C. for 1 h and then heating it to 550° C. for 2 h, with a heating rate of 5° C. / min, to obtain a nickel-doped ceria carrier;

[0084] (f) The solid obtained in step (e) is fully ground and transferred to a crucible. The crucible is covered and wrapped with tin foil, and then placed in a muffle furnace for calcination at 300° C. for 1 h at a heating rate of 5° C. / min to obtain a nickel-doped cerium dioxide catalyst.

[0085] Catalytic performance test:

[0086] The catalysts prepared in the above Examples 1-8 and Comparative Examples 1-2 were used for the gas-solid phase reaction of carbon dioxide methanation, and the specific operation was as follows:

[0087] Take 0.2g of catalyst, dilute with 0.8g of quartz sand, and fill into a quartz reaction tube. Pass the reaction gas under normal pressure (0.1MPa), the reaction gas component molar ratio H2:CO2:Ar=4:1:5, the reaction temperature is 200-350℃, and the gas flow rate is 24000mL g -1 h -1 , and use the test values ​​to calculate the carbon dioxide conversion rate and methane selectivity according to the following formula.

[0088]

[0089]

[0090] In the above formula, [CO2] in and [CO2] out Respectively represent the molar concentration of CO2 in the inlet and outlet gases, [CH4] out is the molar concentration of CH4 in the outlet gas.

[0091] See also Figure 1 The graphs shown are the carbon dioxide conversion curves when the catalysts prepared in Examples 1-8 and Comparative Examples 1-2 are used in the carbon dioxide methanation reaction. Figure 1 It can be seen that the catalytic performance of the catalysts prepared in the examples of the present application is significantly better than that of the catalysts prepared in the comparative examples, and the catalyst in Example 1 has the highest activity and CO2 conversion rate.

[0092] See also Figure 2 The following are the product (methane) selectivity curves of CO2 methanation catalyzed by the catalyst prepared in Example 1 at different temperatures. Figure 2 It can be seen that the catalyst prepared in the present application has a product (methane) selectivity of 100% at different temperatures, and has high selectivity, which enables the catalytic reaction to be carried out at a lower temperature, avoiding the deactivation of the catalyst caused by sintering of the transition metal under high-temperature carbon dioxide methanation reaction conditions, thereby better meeting the needs of catalytic applications.

[0093] See also Figure 3 The stability curves of the catalysts prepared in Example 1 and Comparative Example 1 for catalytic CO2 methanation reaction at 300°C are shown in FIG. Figure 3 It can be seen that the catalyst prepared in Example 1 of the present application maintains a stable CO2 conversion rate, and its performance decreases by only less than 4% after 60 hours of reaction. In contrast, the catalyst prepared in Comparative Example 1 is more obviously deactivated after 60 hours of reaction, and the decrease is about 10% after 60 hours of reaction.

[0094] See also Figure 4 , is a transmission electron microscope photo of the catalyst prepared in Example 1 of the present application, from Figure 4 Lattice fringes belonging to CeO2 and NiO can be observed. The lattice spacings of CeO2 (111) and (200) planes are approximately 0.312nm and 0.271nm, respectively. In addition, lattice fringes belonging to NiO (111) plane are also observed, with a lattice spacing of 0.241nm. Figure 4 It can be seen that the active metals of the catalyst are evenly dispersed, which improves the catalytic activity and achieves a better catalytic effect.

[0095] It can be seen that the catalysts prepared in each embodiment of the present application can exhibit good catalytic performance in the CO2 methanation reaction, and after undergoing long-term stability testing, the selectivity of the product remains stable without obvious deactivation, showing excellent stability and having extremely high application value.

[0096] In summary, the preparation method of the supported catalyst for carbon dioxide methanation provided by the present invention first prepares a nickel-doped cerium dioxide carrier by a urea method, and then loads a metal nickel nanocatalyst on the carrier by an impregnation method, so as to increase the oxygen vacancy concentration on the surface of the cerium dioxide carrier by nickel doping, thereby promoting the adsorption and activation of carbon dioxide, so that the prepared supported nickel-based catalyst exhibits excellent low-temperature activity and stability in the CO2 methanation reaction. At the same time, the preparation process provided by the present invention is simple, the operation repeatability is high, and it is suitable for large-scale industrial production; the supported catalyst for carbon dioxide methanation provided by the present invention adopts nickel-doped improved cerium dioxide as a carrier, and the oxygen vacancy concentration in the cerium dioxide carrier is greatly improved by the nickel doping amount, thereby promoting the activation and conversion of CO2, and effectively solving the problems of low activity and poor stability of existing CO2 methanation nickel-based catalysts.

[0097] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a supported catalyst for carbon dioxide methanation, characterized in that: The steps include: S1. Add cerium nitrate to deionized water and stir until completely dissolved; S2. Add nickel nitrate to the solution of step S1 and stir until completely dissolved; S3. Add urea to the solution of step S2 and stir until completely dissolved; S4. The solution of step S3 is transferred to a blast drying oven and dried to obtain a solid product; S5. The solid product of step S4 is fully ground and transferred to a crucible, the crucible is covered and wrapped with tin foil, and calcined in a muffle furnace to obtain a nickel-doped ceria carrier; S6. Add nickel nitrate to deionized water and stir thoroughly until completely dissolved; S7. The nickel-doped cerium oxide support obtained in step S5 is fully ground and added to the solution of step S6, ultrasonically dispersed, and dried in a water bath with stirring until solid; S8. Grind the solid obtained in step S7 thoroughly and transfer it to a crucible. Cover the crucible and wrap it with tin foil, place it in a muffle furnace and calcine it to obtain a supported nickel-based catalyst with nickel-doped cerium dioxide as a carrier.

2. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S2, the molar ratio of cerium nitrate to nickel nitrate is 1:0.005 to 1:0.

05.

3. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 2, characterized in that: In step S2, the molar ratio of cerium nitrate to nickel nitrate is 1:0.

02.

4. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S4, the drying temperature is 60 to 80°C.

5. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S5, the calcination temperature is 500-600°C, the heating rate is 5°C / min, and the calcination time is 2-4 hours.

6. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 5, characterized in that: In step S5, the calcination temperature is 550°C.

7. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S7, the ultrasonic power is 300-400 W, the ultrasonic interval is 2 s, and the ultrasonic time is 10 minutes.

8. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 1, characterized in that: In step S8, the calcination temperature is 450-550°C, the heating rate is 5°C / min, and the calcination time is 2-4 hours.

9. The method for preparing a supported catalyst for carbon dioxide methanation according to claim 8, characterized in that: In step S8, the calcination temperature is 500°C.

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

Images