Method for solid-phase synthesis of bismuth catalyst and application of catalyst in preparation of formic acid by reduction of carbon dioxide

Abstract

The invention discloses a method for solid-phase synthesis of a bismuth catalyst and application of the catalyst in preparation of formic acid by reduction of carbon dioxide, the synthesis method comprises the following steps: adding bismuth salt, a surfactant and a binder into a solution to obtain a catalyst precursor slurry; and spraying the catalyst precursor slurry onto the gas diffusion electrode, and drying and sintering to obtain the bismuth-based catalyst loaded on the gas diffusion electrode. The solid-phase synthesis strategy disclosed by the invention has the advantages of simple method, small solvent consumption, small pollution and easiness in large-scale production; the synthesized bismuth catalyst is applied to preparation of formic acid by electrocatalytic reduction of carbon dioxide, has the advantages of high activity, high formic acid selectivity and Faraday efficiency and good stability, and lays a foundation for large-scale preparation of formic acid by electroreduction of carbon dioxide.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of electrocatalysts, and specifically relates to a method for solid-phase synthesis of a bismuth catalyst and application of the catalyst in preparation of formic acid by reduction of carbon dioxide. Background Art

[0002] Effectively utilizing renewable energy to promote the capture and reuse of carbon dioxide (CO2) is an important way to solve current energy and environmental problems. CO2 conversion technologies mainly include photochemical, thermochemical and electrochemical methods. Among them, electrochemical CO2 conversion technology uses electricity generated by renewable energy to reduce CO2 to high-value gaseous or liquid products, and has therefore received widespread attention. Electrocatalytic CO2 reduction technology can effectively concentrate the application of widely distributed and low-density clean energy, and convert CO2 into high-quality carbon-based chemicals or fuels with economic value through the catalytic reduction process driven by electricity, while reducing the negative impact of CO2 on the environment. It has broad application prospects.

[0003] Based on the electrocatalytic CO2 reduction technology, electrocatalysts play an important role in it. In recent years, bismuth catalysts have become a research object that has attracted much attention in CO2 reduction technology because of their high Faraday efficiency for the preparation of formic acid by CO2 reduction. However, the existing preparation methods are mostly hydrothermal methods, solution methods, etc. Although they have achieved certain success under laboratory conditions, they also have disadvantages such as long reaction cycle, complex equipment, difficult operation, and unsuitable for large-scale production. Therefore, the development of a simple, efficient, low-cost and large-scale production method for bismuth catalysts is crucial to promote the practical application and industrial production of electrocatalytic CO2 reduction technology. Summary of the invention

[0004] The present invention is proposed to overcome the shortcomings of the prior art, and its purpose is to provide a method for solid-phase synthesis of bismuth catalyst and application of the catalyst in the preparation of formic acid by reduction of carbon dioxide.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for solid phase synthesis of a bismuth catalyst comprises the following steps:

[0007] (I) adding a bismuth salt, a surfactant and a binder into a solution, and obtaining a catalyst precursor slurry by ultrasonic dispersion;

[0008] (II) Spraying the catalyst precursor slurry obtained in step (I) onto a gas diffusion electrode, drying it, and then sintering it in a muffle furnace to obtain a bismuth-based catalyst supported on the gas diffusion electrode.

[0009] In the above technical solution, the bismuth salt is bismuth nitrate, bismuth chloride or a mixture of bismuth nitrate and bismuth chloride.

[0010] In the above technical solution, the surfactant is any one or more of hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride or tetrabutylammonium iodide.

[0011] In the above technical solution, the binder is any one or more of polyvinylidene fluoride, polytetrafluoroethylene or fluorinated ethylene propylene copolymer.

[0012] In the above technical solution, the solution is anhydrous ethanol.

[0013] In the above technical scheme, the molar ratio of bismuth salt to surfactant in step (I) is 1:(0.9-1.2).

[0014] In the above technical solution, the molar ratio of the bismuth salt to the binder is 10:1.

[0015] In the above technical solution, the concentration range of bismuth salt in the catalyst precursor slurry in step (I) is 3 to 7 mg / ml.

[0016] In the above technical solution, the gas diffusion electrode is any one or more of YLS-30T, Sigracet 28BC and Sigracet39BB;

[0017] The spraying amount of the catalyst precursor slurry is 0.8-1 mg / cm 2 .

[0018] In the above technical solution, the drying condition is: spraying the gas diffusion electrode on a heating plate at 60-80°C.

[0019] In the above technical solution, the sintering conditions are: heating to 200°C to 400°C at a heating rate of 5°C / min to 10°C / min, and staying for 0.5h to 2.5h. The sintering temperature has a great influence on the electrocatalytic activity. Using the optimized sintering temperature can prepare an electrocatalyst with better performance for effective carbon dioxide reduction to produce formic acid, and can effectively inhibit the occurrence of cathode hydrogen evolution reaction.

[0020] An application of the bismuth catalyst prepared by the above method in the electrocatalytic reduction of carbon dioxide to prepare formic acid, wherein the bismuth catalyst supported by a gas diffusion electrode is assembled into an electrochemical reactor as a cathode, and after power is applied, carbon dioxide is reduced at the cathode to obtain formic acid.

[0021] The beneficial effects of the present invention are:

[0022] The present invention provides a method for solid-phase synthesis of a bismuth catalyst and application of the catalyst in the preparation of formic acid by carbon dioxide reduction. The solid-phase synthesis strategy has the advantages of simple method, small amount of solvent used, low pollution, easy scale-up, etc. The bismuth catalyst obtained by the method is applied to the preparation of formic acid by electrocatalytic carbon dioxide reduction, and has the advantages of high activity, formic acid selectivity, high Faraday efficiency, and good stability, laying a foundation for the large-scale preparation of formic acid by carbon dioxide electroreduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the XRD diagram of the bismuth catalyst synthesized in Examples 1, 2, and 3 provided by the present invention;

[0024] Figure 2 This is a SEM image of the bismuth oxychloride catalyst in Example 1 provided by the present invention;

[0025] Figure 3 This is a SEM image of the bismuth iodide catalyst in Example 2 provided by the present invention;

[0026] Figure 4 This is a SEM image of the bismuth oxybromide catalyst in Example 3 provided by the present invention.

[0027] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0029] Example 1

[0030] Accurately weigh 1 mol of bismuth nitrate and 1 mol of hexadecyltrimethylammonium chloride and add them to 50 ml of anhydrous ethanol, add a small amount of polytetrafluoroethylene solution, and obtain a catalyst precursor slurry by stirring and ultrasonic dispersion for 30 minutes. The precursor slurry is evenly sprayed on a gas diffusion electrode, and then the sprayed gas diffusion electrode is transferred to a muffle furnace, heated to 300°C at a heating rate of 5-10°C / min in an air atmosphere, and heat treated for 2 hours to obtain a bismuth oxychloride nanosheet catalyst.

[0031] The XRD patterns of the prepared catalysts are shown in Figure 1 , its SEM shows Figure 2 , it can be seen that the catalyst presents a nanosheet structure.

[0032] The bismuth oxychloride catalyst prepared in Example 1 was used as the cathode material, and the highest Faradaic efficiency of electrocatalytic reduction of CO2 to formic acid was about 83.6%.

[0033] Example 2

[0034] Accurately weigh 1 mol of bismuth nitrate and 1 mol of tetrabutylammonium iodide and add them to 50 ml of anhydrous ethanol, add a small amount of polytetrafluoroethylene solution, and obtain a catalyst precursor slurry by stirring and ultrasonic dispersion for 30 minutes. The precursor slurry is evenly sprayed on a gas diffusion electrode, and then the sprayed gas diffusion electrode is transferred to a muffle furnace, heated to 300°C at a heating rate of 5-10°C / min in an air atmosphere, and heat treated for 2 hours to obtain an iodine bismuth nanosheet catalyst.

[0035] The XRD patterns of the prepared catalysts are shown in Figure 1 , its SEM shows Figure 3 , it can be seen that the catalyst presents a nanosheet structure.

[0036] The bismuth iodide catalyst prepared in Example 2 was used as the cathode material, and the highest Faradaic efficiency of electrocatalytic reduction of CO2 to formic acid was about 80.1%.

[0037] Example 3

[0038] Accurately weigh 1 mol of bismuth nitrate and 1 mol of hexadecyltrimethylammonium bromide and add them to 50 ml of anhydrous ethanol, add a small amount of polytetrafluoroethylene solution, and obtain a catalyst precursor slurry by stirring and ultrasonic dispersion for 30 minutes. The precursor slurry is evenly sprayed on a gas diffusion electrode, and then the sprayed gas diffusion electrode is transferred to a muffle furnace, heated to 300°C at a heating rate of 5-10°C / min in an air atmosphere, and heat treated for 2 hours to obtain a bismuth bromide nanosheet catalyst.

[0039] The XRD patterns of the prepared catalysts are shown in Figure 1 , its SEM shows Figure 4 , it can be seen that the catalyst presents a nanosheet structure.

[0040] The bismuth oxybromide catalyst prepared in Example 3 was used as the cathode material, and the highest Faradaic efficiency of electrocatalytic reduction of CO2 to formic acid was about 91%.

[0041] The solid phase synthesis method of the present invention has the advantages of simple operation, low solvent consumption, low pollution and easy scale-up. The bismuth catalyst prepared by the method is applied to the electrocatalytic reduction of carbon dioxide to synthesize formic acid, showing high catalytic activity, excellent formic acid selectivity and Faraday efficiency, and good stability, which provides a solid foundation for the large-scale application of carbon dioxide electroreduction to prepare formic acid.

[0042] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0043] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for solid phase synthesis of bismuth catalyst, characterized in that: The following steps are involved: (I) adding a bismuth salt, a surfactant and a binder into a solution to obtain a catalyst precursor slurry; (II) Spraying the catalyst precursor slurry obtained in step (I) onto a gas diffusion electrode, and obtaining a bismuth-based catalyst supported on the gas diffusion electrode through drying and sintering.

2. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The bismuth salt is bismuth nitrate, bismuth chloride or a mixture of bismuth nitrate and bismuth chloride.

3. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The surfactant is any one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride or tetrabutylammonium iodide.

4. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The binder is any one or more of polyvinylidene fluoride, polytetrafluoroethylene or fluorinated ethylene propylene copolymer.

5. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The solution is anhydrous ethanol.

6. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The molar ratio of the bismuth salt to the surfactant in step (I) is 1:(0.9-1.2); In step (I), the molar ratio of the bismuth salt to the binder is 10:1; The concentration range of the bismuth salt in the catalyst precursor slurry in step (I) is 3 mg / mL to 7 mg / mL.

7. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The gas diffusion electrode is any one or more of YLS-30T, Sigracet 28BC or Sigracet 39BB; The spraying amount of the catalyst precursor slurry is 0.8 mg / cm 2 ~1mg / cm 2 .

8. The method for solid phase synthesis of bismuth catalyst according to claim 1, characterized in that: The drying condition is to spray the gas diffusion electrode on a heating plate at 60°C to 80°C; The sintering conditions are: heating to 200° C. to 400° C. at a heating rate of 5° C. / min to 10° C. / min, and staying for 0.5 h to 2.5 h.

9. Use of a bismuth catalyst prepared by the method according to any one of claims 1 to 8 in the electrocatalytic reduction of carbon dioxide to produce formic acid, characterized in that: The bismuth catalyst supported by the gas diffusion electrode is assembled into an electrochemical reactor as a cathode, and after power is applied, carbon dioxide is reduced at the cathode to obtain formic acid.

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