Composite catalyst for carbon dioxide methanation reaction and preparation method thereof

Abstract

The present application relates to the technical field of carbon dioxide methanation catalyst, in particular to a composite catalyst for carbon dioxide methanation reaction and a preparation method thereof, the composite catalyst provided by the present application is composed of boron nitride and nickel-loaded cerium oxide, the nickel-loaded cerium oxide is uniformly dispersed on the surface of the boron nitride during the synthesis process, the active metal is uniformly dispersed, which is conducive to the improvement of catalytic activity, the boron nitride and the nickel-loaded cerium oxide are combined closely, which is conducive to the transfer of carriers between the boron nitride and the cerium oxide, can improve the ability of oxygen vacancies generated on the surface of the cerium oxide, is conducive to the adsorption and activation of carbon dioxide, so that the catalytic reaction can be carried out at a lower temperature, avoids the deactivation of the catalyst caused by the sintering of transition metals under the high-temperature carbon dioxide methanation reaction condition, solves the problem that the active metal is aggregated and unevenly dispersed due to the sintering of high-temperature metals in the transition metal-based catalyst in the current industry, so that the catalytic activity is not high.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide methanation catalyst technology, and in particular to a composite catalyst for carbon dioxide methanation reaction and its preparation method. Background Technology

[0002] Human activities have led to a continuous rise in the concentration of carbon dioxide (CO2), the main greenhouse gas in the atmosphere, due to the burning of large amounts of fossil fuels. This has triggered a series of severe environmental problems, such as global warming, glacial melting, and ocean acidification, seriously threatening human survival. Meanwhile, CO2 is also the world's most abundant and cheapest C1 resource, and its resource utilization has become one of the hottest research topics globally. Among these, the carbon dioxide methanation reaction (CO2 + H2 = CH4 + H2O) is considered one of the most promising reactions. Methane produced through this reaction can be transported via existing natural gas pipelines, reducing transportation costs. Therefore, developing highly active, stable, and selective catalysts for carbon dioxide methanation is of great significance for the utilization of carbon dioxide and energy production.

[0003] The carbon dioxide methanation reaction is a reversible reaction, and under normal circumstances, transition metal-based catalysts are the main catalysts. Furthermore, the carbon dioxide methanation reaction is exothermic, and low temperatures favor the conversion of carbon dioxide and the formation of methane.

[0004] Studies have found that highly dispersed transition metal particles help improve the conversion rate of carbon dioxide (Appl. Catal. B: Environ. 317 (2022) 121800). Although transition metal-based catalysts have good selectivity, they suffer from poor thermal stability, are prone to sintering at high temperatures, and have insufficient activity. Currently, reducible oxides are often used as supports, utilizing the strong interaction between the support and the active metal to promote the formation of highly dispersed metal particles. Cerium dioxide (CeO2), due to its excellent reducibility and relatively abundant surface oxygen vacancies, can promote the dissociation and activation of CO2 molecules, and as a catalyst support, it can enhance the CO2 methanation activity of nickel-based catalysts. However, because the transition metal active sites on nickel-based cerium dioxide catalysts are not sufficiently dispersed, the support's binding to the metal is not strong enough, and the oxygen vacancies are not abundant enough, the methanation reaction is difficult to carry out at low temperatures. Therefore, the catalyst still exhibits agglomeration at high temperatures. In summary, carbon dioxide methanation catalysts with high activity and good stability still need to be developed.

[0005] In view of this, this application aims to provide a composite catalyst for the carbon dioxide methanation reaction and a method for preparing the same, so as to better solve the above-mentioned technical problems. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a composite catalyst for the carbon dioxide methanation reaction and its preparation method. The catalyst is prepared by combining boron nitride with nickel-supported cerium oxide. The interaction between boron nitride and cerium oxide ensures that the nickel-supported cerium oxide is uniformly dispersed on the surface of the boron nitride. This uniform dispersion of the active metal is beneficial for improving catalytic activity and resulting in a good catalytic effect.

[0007] The technical solution adopted in this invention is:

[0008] A method for preparing a composite catalyst for carbon dioxide methanation reaction includes the following steps:

[0009] S1. Add boric acid and melamine to deionized water, heat to 55-65°C and stir thoroughly until completely dissolved, then heat to 80-90°C and stir until the solvent evaporates to obtain powder;

[0010] S2. Place the powder obtained in step S1 in a tube furnace and calcine it under a nitrogen atmosphere. Then, wash it with hot water by vacuum filtration to obtain boron nitride powder.

[0011] S3. The boron nitride powder obtained in step S2 is dispersed with cerium nitrate and nickel nitrate in deionized water, heated and stirred until the solvent evaporates, and then calcined in air atmosphere to obtain a nickel-supported cerium dioxide composite boron nitride catalyst.

[0012] Furthermore, in step S1, the concentration of the melamine aqueous solution is 0.5–5 wt% to ensure that boric acid and melamine can be fully dissolved.

[0013] Furthermore, in step S1, the molar ratio of boric acid to melamine is 1 / 3 to 3 / 1, with 1:1 being preferred. By adjusting the molar ratio of boric acid to melamine, the highest boron nitride yield can be obtained.

[0014] Furthermore, in step S2, the calcination temperature is 700–900℃ (800℃ is preferred), the heating rate is controlled at 1–5℃ / min, and the calcination time is 2–4 hours. By adjusting the calcination temperature, the highest boron nitride yield can be obtained.

[0015] Furthermore, in step S2, hot water at 85–95°C is used for vacuum filtration and washing.

[0016] Furthermore, in step S2, the sample is washed 4 to 6 times with hot water.

[0017] Furthermore, in step S3, the molar ratio of nickel nitrate to cerium nitrate is 0.05 to 1 (0.2 is preferred). By adjusting the molar ratio of nickel to cerium, a suitable carbon dioxide adsorption and catalytic hydrogenation capacity is obtained, which is beneficial to the carbon dioxide methanation reaction.

[0018] Furthermore, in step S3, the mass ratio of the sum of the masses of cerium nitrate and nickel nitrate to the mass ratio of boron nitride is 0.1 to 5 (2 is preferred). By adjusting the mass ratio of the boron nitride support to the nickel-loaded cerium oxide, a suitable dispersion and number of active sites can be obtained, which is beneficial to the carbon dioxide methanation reaction.

[0019] Furthermore, in step S3, the calcination temperature is 400–600℃ (500℃ is preferred), the heating rate is controlled at 1–5℃ / min, and the calcination time is 2–4 hours. By adjusting the calcination temperature, a suitable bonding strength between boron nitride and nickel-loaded cerium oxide is obtained, which is beneficial to the carbon dioxide methanation reaction.

[0020] Based on the same inventive concept, this application also provides a composite catalyst for carbon dioxide methanation reaction prepared using the above-described preparation method.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. The composite catalyst for carbon dioxide methanation provided by this invention combines boron nitride with nickel-supported cerium oxide. The interaction between boron nitride and cerium oxide allows the nickel-supported cerium oxide to be uniformly dispersed on the surface of boron nitride. The uniform dispersion of the active metal is beneficial to the improvement of catalytic activity. The boron nitride is conducive to CO2 adsorption. The tight bond between boron nitride and nickel-supported cerium oxide is conducive to the transfer of charge carriers between boron nitride and cerium oxide. It can enhance the ability of cerium oxide to generate oxygen vacancies, which is beneficial to the adsorption and activation of carbon dioxide. This allows the catalytic reaction to be carried out at a lower temperature, avoiding catalyst deactivation caused by the sintering of transition metals under high-temperature carbon dioxide methanation reaction conditions.

[0023] 2. The preparation method provided by the present invention can obtain the composite catalyst through two-step calcination. The process is simple and the preparation is easy. Attached Figure Description

[0024] Figure 1 The carbon dioxide conversion curves are shown for different catalysts used in the carbon dioxide methanation reaction.

[0025] Figure 2 Selectivity curves of methane product at different temperatures when the catalyst prepared in Example 1 is used in the carbon dioxide methanation reaction;

[0026] Figure 3 This is a scanning electron microscope image of the catalyst prepared in Example 1. Detailed Implementation

[0027] To facilitate understanding of the present invention, it will be described more fully below through embodiments, and preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Any other implementation schemes obtained by modifying or equivalently substituting the technical solutions of the present invention without inventive step are all within the protection scope of the present invention.

[0028] 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. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0029] The numerical values ​​disclosed in the embodiments of this invention are approximate values, not definitive values. Where error or experimental conditions permit, all values ​​within the error range may be included, and the specific numerical values ​​disclosed in the embodiments of this invention are not limited to those specified in the embodiments.

[0030] Unless otherwise specified, all parts and percentages in this invention are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0031] Example 1

[0032] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0033] S1. Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60°C and stir thoroughly until dissolved, then heat to 90°C and stir until the solvent evaporates;

[0034] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800℃, a heating rate of 2℃ / min, and a time of 3 hours. The powder is then filtered and washed five times with hot water at 90℃ to obtain boron nitride powder.

[0035] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 1.764g of cerium nitrate and 0.236g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0036] Example 2

[0037] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0038] S1. Dissolve 0.3 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60 °C and stir thoroughly until dissolved, then heat to 90 °C and stir until the solvent evaporates;

[0039] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 700℃, a heating rate of 1℃ / min, and a time of 2 hours. The powder is then filtered and washed five times with hot water at 80℃ to obtain boron nitride powder.

[0040] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 1.764g of cerium nitrate and 0.236g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0041] Example 3

[0042] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0043] S1. Dissolve 0.1 mol boric acid and 0.3 mol melamine in 750 mL of deionized water, heat to 60 °C and stir thoroughly until dissolved, then heat to 80 °C and stir until the solvent evaporates;

[0044] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 900℃, a heating rate of 5℃ / min, and a time of 4 hours. The powder is then filtered and washed five times with hot water at 90℃ to obtain boron nitride powder.

[0045] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 1.764g of cerium nitrate and 0.236g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0046] Example 4

[0047] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0048] S1. Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60°C and stir thoroughly until dissolved, then heat to 90°C and stir until the solvent evaporates;

[0049] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800℃, a heating rate of 2℃ / min, and a time of 3 hours. The powder is then filtered and washed five times with hot water at 90℃ to obtain boron nitride powder.

[0050] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 0.088g of cerium nitrate and 0.012g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0051] Example 5

[0052] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0053] S1. Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60°C and stir thoroughly until dissolved, then heat to 90°C and stir until the solvent evaporates;

[0054] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800℃, a heating rate of 2℃ / min, and a time of 3 hours. The powder is then filtered and washed five times with hot water at 90℃ to obtain boron nitride powder.

[0055] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 4.41g of cerium nitrate and 0.59g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0056] Example 6

[0057] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0058] S1. Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60°C and stir thoroughly until dissolved, then heat to 90°C and stir until the solvent evaporates;

[0059] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800℃, a heating rate of 2℃ / min, and a time of 3 hours. The powder is then filtered and washed five times with hot water at 90℃ to obtain boron nitride powder.

[0060] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 1.935g of cerium nitrate and 0.065g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0061] Example 7

[0062] This embodiment provides a method for preparing a composite catalyst for carbon dioxide methanation reaction, comprising the following steps:

[0063] S1. Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60°C and stir thoroughly until dissolved, then heat to 90°C and stir until the solvent evaporates;

[0064] S2. The powder obtained in step S1 is placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800℃, a heating rate of 2℃ / min, and a time of 3 hours. The powder is then filtered and washed five times with hot water at 90℃ to obtain boron nitride powder.

[0065] S3. Take 1g of the boron nitride powder obtained in step S2, disperse it with 1.20g of cerium nitrate and 0.80g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine it in air atmosphere for 3 hours at a calcine temperature of 500℃ and a heating rate of 2℃ / min to obtain a nickel-based cerium dioxide composite boron nitride catalyst.

[0066] Comparative Example 1

[0067] This comparative example provides a nickel-based boron nitride catalyst for the carbon dioxide methanation reaction, and the preparation steps are as follows:

[0068] (a) Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60 °C and stir thoroughly until dissolved, then heat to 90 °C and stir until the solvent evaporates;

[0069] (b) The powder obtained in (a) was placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800°C, a heating rate of 2°C / min, and a time of 3 hours. The powder was then filtered and washed five times with hot water at 90°C to obtain boron nitride powder.

[0070] (c) Take 1g of the boron nitride powder obtained in (b) and disperse it with 2g of nickel nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine in air atmosphere for 3 hours, calcine temperature of 500℃, and heating rate of 2℃ / min to obtain nickel-based boron nitride catalyst.

[0071] Comparative Example 2

[0072] This comparative example provides a cerium oxide-boron nitride composite catalyst for the carbon dioxide methanation reaction, and the preparation steps are as follows:

[0073] (a) Dissolve 0.1 mol boric acid and 0.1 mol melamine in 300 mL of deionized water, heat to 60 °C and stir thoroughly until dissolved, then heat to 90 °C and stir until the solvent evaporates;

[0074] (b) The powder obtained in (a) was placed in a tube furnace under a nitrogen atmosphere and calcined at a temperature of 800°C, a heating rate of 2°C / min, and a time of 3 hours. The powder was then filtered and washed five times with hot water at 90°C to obtain boron nitride powder.

[0075] (c) Take 1g of the boron nitride powder obtained in (b) and disperse it with 2g of cerium nitrate in deionized water, heat and stir until the solvent evaporates, and then calcine in air atmosphere for 3 hours, calcine temperature of 500℃, and heating rate of 2℃ / min to obtain cerium oxide composite boron nitride catalyst.

[0076] Catalytic performance test:

[0077] The catalysts prepared in Examples 1-7 and Comparative Examples 1-2 were used in the gas-solid phase reaction of carbon dioxide methanation, and the specific operation was as follows:

[0078] Take 0.1g of catalyst and dilute with 0.8g of quartz sand, then fill the quartz reaction tube. Introduce the reaction gas at atmospheric pressure (0.1MPa), with a molar ratio of H2:CO2:Ar = 4:1:5. The reaction temperature is 200-400℃, and the gas flow rate is 24000mL gcat. -1 h -1 .

[0079] See Figure 1 The figure shows the carbon dioxide conversion curves when the catalysts prepared in each embodiment and comparative example are used in the carbon dioxide methanation reaction. Figure 1 As can be seen from the examples, the catalytic performance of the catalysts prepared in the embodiments of this application is significantly better than that of the catalysts prepared in the comparative examples, and the catalyst prepared in Example 1 has the highest activity.

[0080] See also: Figure 2The figure shows the selectivity curves of the product methane at different temperatures when the catalysts prepared in Examples 1-7 and Comparative Examples 1-2 are used in the carbon dioxide methanation reaction. As can be seen from the figure, the catalyst prepared in this application has high selectivity at different temperatures, which enables the catalytic reaction to be carried out at a lower temperature. This avoids catalyst deactivation caused by the sintering of transition metals under high temperature carbon dioxide methanation reaction conditions, and thus can better meet the needs of catalytic applications.

[0081] See also: Figure 3 The image shows a scanning electron microscope (SEM) image of the catalyst prepared in Example 1 of this application. It can be clearly seen from the image that the boron nitride and cerium oxide composites are very uniform, which ensures that the active metal is uniformly dispersed, thereby improving the catalytic activity and achieving a better catalytic effect.

[0082] In summary, the composite catalyst provided in this application combines boron nitride with nickel-supported cerium oxide, and utilizes the interaction between boron nitride and cerium oxide to ensure that the nickel-supported cerium oxide is uniformly dispersed on the surface of boron nitride, resulting in uniform dispersion of the active metal, which is beneficial to improving catalytic activity.

[0083] Boron nitride is beneficial for CO2 adsorption. Boron nitride and nickel-loaded cerium oxide are tightly bonded, which facilitates the transfer of charge carriers between boron nitride and cerium oxide. This enhances the ability of cerium oxide to generate oxygen vacancies on its surface, which is beneficial for the adsorption and activation of carbon dioxide. This allows the catalytic reaction to proceed at a lower temperature, avoiding catalyst deactivation caused by the sintering of transition metals under high-temperature carbon dioxide methanation reaction conditions.

[0084] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a composite catalyst for the methanation of carbon dioxide, characterized in that, Includes the following steps: S1. Add boric acid and melamine to deionized water, heat to 55-65°C and stir thoroughly until completely dissolved, then heat to 80-90°C and stir until the solvent evaporates to obtain powder; S2. Place the powder obtained in step S1 in a tube furnace and calcine it under a nitrogen atmosphere. Then, wash it with hot water by vacuum filtration to obtain boron nitride powder. S3. The boron nitride powder obtained in step S2 is dispersed with cerium nitrate and nickel nitrate in deionized water, heated and stirred until the solvent evaporates, and then calcined in air atmosphere to obtain a nickel-supported cerium dioxide composite boron nitride catalyst.

2. The method for preparing the composite catalyst for carbon dioxide methanation reaction according to claim 1, characterized in that, In step S1, the concentration of the melamine aqueous solution is 0.5–5 wt%.

3. The method for preparing the composite catalyst for the carbon dioxide methanation reaction according to claim 2, characterized in that, In step S1, the molar ratio of boric acid to melamine is 1 / 3 to 3 / 1.

4. The method for preparing the composite catalyst for carbon dioxide methanation reaction according to claim 1, characterized in that, In step S2, the calcination temperature is 700–900℃, the heating rate is controlled at 1–5℃ / min, and the calcination time is 2–4 hours.

5. The method for preparing the composite catalyst for the carbon dioxide methanation reaction according to claim 1, characterized in that, In step S2, hot water at 85-95℃ is used for vacuum filtration and washing.

6. The method for preparing the composite catalyst for the carbon dioxide methanation reaction according to claim 5, characterized in that, In step S2, the sample is washed 4 to 6 times with hot water.

7. The method for preparing the composite catalyst for the carbon dioxide methanation reaction according to claim 1, characterized in that, In step S3, the molar ratio of nickel nitrate to cerium nitrate is 0.05 to 1.

8. The method for preparing the composite catalyst for the carbon dioxide methanation reaction according to claim 7, characterized in that, In step S3, the mass ratio of the sum of the masses of cerium nitrate and nickel nitrate to the mass of boron nitride is 0.1 to 5.

9. The method for preparing the composite catalyst for the carbon dioxide methanation reaction according to claim 1, characterized in that, In step S3, the calcination temperature is 400-600℃, the heating rate is controlled at 1-5℃ / min, and the calcination time is 2-4 hours.

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

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