A method for the preparation of a catalyst for promoting the conversion of co2 to co

Abstract

The application discloses a preparation method of a catalyst for promoting CO2 conversion into CO, which comprises the following steps: (1) mixing; (2) washing, drying; (3) calcining; (4) washing, filtering and drying. The catalyst for promoting CO2 conversion into CO provided by the application has high activity, and a high Faraday efficiency of CO2 conversion into CO can be obtained in a wide potential range. Meanwhile, the preparation method disclosed by the application is simple and controllable. Solid waste fly ash is used as a raw material to extract effective components and synthesize a high-activity CO2 electro-reduction catalyst, thereby opening up a new way for comprehensive utilization of solid waste.

Description

Technical fields:

[0001] This invention patent belongs to the field of functional catalytic material preparation technology, specifically relating to a method for preparing a catalyst that promotes the conversion of CO2 into CO. Background technology:

[0002] Since the Industrial Revolution, efficient energy utilization has always been a challenge for human society. On the one hand, the combustion of coal generates a considerable amount of solid waste (coal combustion residue, fly ash, and desulfurization gypsum, etc.); on the other hand, the excessive use of fossil fuels such as coal leads to a sharp increase in atmospheric carbon dioxide (CO2) concentration, causing environmental problems such as global warming. Carbon dioxide reduction is one of the most studied solutions, mainly including electrocatalytic CO2 reduction, photocatalytic CO2 reduction, and thermocatalytic CO2 reduction technologies. Electrocatalytic reduction of CO2 not only reduces the CO2 content in the air but also generates high-value-added carbon-containing chemicals and industrial raw materials, thus realizing carbon recycling, making it a very promising technology. The preparation methods for catalysts used in electrocatalytic CO2 reduction include: 1. Synthesizing random Pd-Au binary nanowire catalysts by self-assembling noble metals palladium and gold, achieving a Faradaic efficiency of 94.3% for CO electrochemical reduction. However, due to the high cost of palladium and gold, which are both noble metals, this catalyst is expensive. 2. Modifying fluorosilanes (FAS) using vapor deposition to obtain HE-MoS2 catalysts, achieving a Faradaic efficiency of only 81.2% for CO electrochemical reduction, and the catalyst preparation process is complex. 3. Using nitrogen-doped carbon (NC) material obtained by pyrolysis of ZIF-8 as a catalyst support, then loading nickel nanoparticles onto the NC material, followed by high-temperature treatment. During this process, the nickel nanoparticles continuously erode into the NC material, forming a porous carbon catalyst (SE-Ni). When SAs@PNC was used for the electrochemical reduction of CO2, the Faraday efficiency of CO was only 88%. Therefore, the preparation of low-cost, highly active, and highly selective catalysts through simple methods is currently a research hotspot.

[0003] This invention provides a method for preparing a catalyst that promotes the conversion of CO2 to CO. The synthesized catalyst can be used for the electrocatalytic reduction of CO2 to produce carbon monoxide with high selectivity, and at the same time provides a new direction for the comprehensive utilization of solid waste. Summary of the Invention:

[0004] In view of this, the purpose of this invention is to provide a method for preparing a catalyst that promotes the conversion of CO2 to CO. The Ni / SiO2-Al2O3-NC catalyst prepared by the method of this invention has high activity and can achieve high Faraday efficiency of CO2 to CO conversion over a wide potential range, thereby realizing high-tech and high-quality development of solid waste resource utilization.

[0005] The present invention discloses a method for preparing a catalyst that promotes the conversion of CO2 to CO, which includes the following steps:

[0006] (1) Mixing: Based on a mass percentage of 100%, thoroughly mix 0.01-0.3% silicon-aluminum mixture, 0.2-0.7% carbon black, 1.3-1.8% nickel nitrate, and the remaining 15-20% alcohol solution to obtain mixture A. Then, according to the mass ratio m 2-甲基咪唑溶液 :m 混合物A =1.5-2.5:1, add a 5-15% 2-methylimidazole solution to mixture A and stir to obtain mixture B; the 2-methylimidazole solution provides an N source and also better combines with the metal salt, thereby improving the activity of the catalyst;

[0007] (2) Washing and drying: The mixture B in step (1) is washed with ultrapure water, and then the washed mixture B is vacuum dried for 12-24 hours to obtain a black solid.

[0008] (3) Calcination: The black solid in step (2) is added to a tube furnace, and the temperature in the tube furnace is controlled to rise to 500-800℃ at a rate of 2-5℃ / min. The temperature is then maintained at this temperature for 0-4h, during which a protective gas is introduced into the tube furnace. After the temperature maintenance is completed, the furnace is naturally cooled to room temperature to obtain a crude Ni / SiO2-Al2O3-NC catalyst. The 2-methylimidazolium and metal salt are fully sintered and fixed on the carbon black with added silicon-aluminum mixture to form a metal-nitrogen active structure.

[0009] Furthermore, the content of SiO2 and Al2O3 in the silicon-aluminum mixture in step (1) is 70-80%.

[0010] Furthermore, the preparation method of the silicon-aluminum mixture in step (1) includes the following steps:

[0011] (a) Alkali treatment: according to mass ratio m 粉煤灰 :m 氢氧化钾 =1:3-7, add fly ash to a 2 mol / L potassium hydroxide solution, then heat to 70-100℃ and keep the reaction at that temperature for 2-8 hours, then let it cool naturally to room temperature to obtain the reactants;

[0012] (b) Washing and drying: The reactants in step (a) are washed with deionized water, then acid-leached with 1 mol / L dilute hydrochloric acid for 3-8 hours at a temperature of 70-80°C, then ultrasonically washed with ultrapure water until neutral, and finally dried at a temperature of 80-110°C for 1-2 hours.

[0013] (c) High-temperature calcination: The reactants dried in step (b) are calcined at 600-1000℃ for 0.5-2h to obtain the silicon-aluminum mixture.

[0014] Furthermore, the alcohol in the alcohol solution in step (1) is one or more of ethanol, methanol, and isopropanol.

[0015] Furthermore, in step (1), the stirring speed is 600-1000 rpm and the stirring time is 0.5-6 h.

[0016] Furthermore, in step (2), the drying temperature of vacuum drying is 40-100℃ and the vacuum degree is less than -0.07mPa.

[0017] Furthermore, the protective gas in step (3) is one or more of oxygen, nitrogen, argon, or an argon-hydrogen mixture.

[0018] Furthermore, the step after step (3) also includes the following steps: washing, filtering and drying: the crude catalyst from step (3) is added to dilute hydrochloric acid with a concentration of 1 mol / L, then heated and stirred at a temperature of 50-70℃ for 0.5-4 hours. The mass of the dilute hydrochloric acid is 11-14 times that of the crude catalyst. Then, the catalyst is centrifuged and separated. The separated solid material is then repeatedly washed with ultrapure water until neutral. Finally, it is dried at a temperature of 40-100℃ for 8-36 hours to obtain the finished catalyst product.

[0019] Advantages of this invention:

[0020] 1. The method for preparing a catalyst that promotes the conversion of CO2 to CO provided by the present invention produces a Ni / SiO2-Al2O3-NC catalyst with high activity. It can achieve a high Faradaic efficiency for the conversion of CO2 to CO over a wide potential range. At the same time, the preparation method disclosed in the present invention is simple and controllable.

[0021] 2. The method for preparing a catalyst that promotes the conversion of CO2 to CO provided by the present invention uses fly ash, a solid waste, as raw material, extracts its effective components, and synthesizes a highly active CO2 electroreduction catalyst, opening up new avenues for the comprehensive utilization of solid waste and realizing high-tech and high-quality development of solid waste resource utilization. Attached image description:

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram showing the test results of the electrocatalytic reduction performance of CO2 in this invention. Detailed implementation method:

[0024] The present invention will be further described in detail below through embodiments.

[0025] Example 1: A method for preparing a catalyst that promotes the conversion of CO2 to CO, comprising the following steps:

[0026] (1) Mixing: 40 mg of silicon-aluminum mixture, 100 mg of K90 carbon black, 290 mg of nickel nitrate and 18 mL of 15-20% alcohol solution are thoroughly mixed to obtain mixture A. Then, 11.64 g of 5-15% 2-methylimidazole solution is added to mixture A and stirred at 800 rpm for 3.5 h to obtain mixture B. The content of SiO2 and Al2O3 in the silicon-aluminum mixture is 70-80%. The alcohol in the alcohol solution is one or more of ethanol, methanol and isopropanol.

[0027] The method for preparing the silicon-aluminum mixture includes the following steps:

[0028] (a) Alkali treatment: according to mass ratio m 粉煤灰 :m 氢氧化钾 The ratio of fly ash to potassium hydroxide solution was 1:5. The mixture was then heated to 80°C and kept at that temperature for 3 hours. After that, it was allowed to cool naturally to room temperature to obtain the reactants.

[0029] (b) Washing and drying: The reactants in step (a) are washed with deionized water, then acid-leached with 1 mol / L dilute hydrochloric acid for 5.5 h at a temperature of 90 °C, then ultrasonically washed with ultrapure water until neutral, and finally dried at a temperature of 80 °C for 2 h.

[0030] (c) High-temperature calcination: The reactants dried in step (b) are calcined at 800°C for 1.5 h to obtain the silicon-aluminum mixture.

[0031] (2) Washing and drying: The mixture B in step (1) is washed with ultrapure water, and then the washed mixture B is vacuum dried at a temperature of 80°C, a vacuum degree of less than -0.07 mPa, and a drying time of 18 h to obtain a black solid.

[0032] (3) Calcination: The black solid from step (2) is added to a tube furnace, and the temperature in the tube furnace is raised to 700°C at a rate of 2-5°C / min. The temperature is then maintained at this temperature for 2 hours. During this period, a protective gas is introduced into the tube furnace. After the heat preservation is completed, the furnace is naturally cooled to room temperature to obtain crude Ni / SiO2-Al2O3-NC catalyst. The protective gas is one or more of oxygen, nitrogen, argon, or an argon-hydrogen mixture.

[0033] (4) Washing, filtering and drying: Add the crude catalyst from step (3) to dilute hydrochloric acid with a concentration of 1 mol / L, then heat and stir at 60°C for 3 hours. The mass of the dilute hydrochloric acid is 11-14 times that of the crude catalyst. Then, centrifuge and wash the separated solid material repeatedly with ultrapure water until neutral. Finally, dry the material at 80°C for 24 hours to obtain the finished catalyst.

[0034] Example 2: A method for preparing a catalyst that promotes the conversion of CO2 to CO, comprising the following steps:

[0035] (1) Mixing: 40 mg of silicon-aluminum mixture, 100 mg of K90 carbon black, 290 mg of nickel nitrate and 18 mL of 15-20% alcohol solution are thoroughly mixed to obtain mixture A. Then, 11.64 g of 5-15% 2-methylimidazole solution is added to mixture A and stirred at 1000 rpm for 0.5 h to obtain mixture B. The content of SiO2 and Al2O3 in the silicon-aluminum mixture is 70-80%. The alcohol in the alcohol solution is one or more of ethanol, methanol and isopropanol.

[0036] The method for preparing the silicon-aluminum mixture includes the following steps:

[0037] (a) Alkali treatment: according to mass ratio m 粉煤灰 :m 氢氧化钾 The ratio of fly ash to potassium hydroxide solution was 1:3. The mixture was then heated to 100°C and kept at that temperature for 2 hours. After that, it was allowed to cool naturally to room temperature to obtain the reactants.

[0038] (b) Washing and drying: The reactants in step (a) are washed with deionized water, then acid-leached with 1 mol / L dilute hydrochloric acid for 3 hours at a temperature of 95°C, then ultrasonically washed with ultrapure water until neutral, and finally dried at a temperature of 80°C for 2 hours.

[0039] (c) High-temperature calcination: The reactants dried in step (b) are calcined at 600°C for 2 hours to obtain the silicon-aluminum mixture.

[0040] (2) Washing and drying: The mixture B in step (1) is washed with ultrapure water, and then the washed mixture B is vacuum dried at a temperature of 40°C, a vacuum degree of less than -0.07mPa, and a drying time of 24h to obtain a black solid.

[0041] (3) Calcination: The black solid from step (2) is added to a tube furnace, and the temperature in the tube furnace is controlled to rise to 500°C at a rate of 2-5°C / min. The temperature is then maintained at this temperature for 4 hours. During this period, a protective gas is introduced into the tube furnace. After the heat preservation is completed, the furnace is naturally cooled to room temperature to obtain crude Ni / SiO2-Al2O3-NC catalyst. The protective gas is one or more of oxygen, nitrogen, argon, or an argon-hydrogen mixture.

[0042] (4) Washing, filtration and drying: The crude catalyst from step (3) is added to a 1 mol / L dilute hydrochloric acid solution, then heated and stirred at 50°C for 4 hours. The mass of the dilute hydrochloric acid is 11-14 times that of the crude catalyst. After centrifugation, the separated solid material is repeatedly washed with ultrapure water until neutral. Finally, it is dried at 100°C for 8 hours to obtain the finished catalyst product.

[0043] Example 3: A method for preparing a catalyst that promotes the conversion of CO2 to CO, comprising the following steps:

[0044] (1) Mixing: 40 mg of silicon-aluminum mixture, 100 mg of K90 carbon black, 290 mg of nickel nitrate and 18 mL of 15-20% alcohol solution are thoroughly mixed to obtain mixture A. Then, 11.64 g of 5-15% 2-methylimidazole solution is added to mixture A and stirred at 600 rpm for 6 h to obtain mixture B. The content of SiO2 and Al2O3 in the silicon-aluminum mixture is 70-80%. The alcohol in the alcohol solution is one or more of ethanol, methanol and isopropanol.

[0045] The method for preparing the silicon-aluminum mixture includes the following steps:

[0046] (a) Alkali treatment: according to mass ratio m 粉煤灰 :m 氢氧化钾 The ratio of fly ash to potassium hydroxide solution was 1:7. The mixture was then heated to 70°C and kept at that temperature for 8 hours. After that, it was allowed to cool naturally to room temperature to obtain the reactants.

[0047] (b) Washing and drying: The reactants in step (a) are washed with deionized water, then acid-leached with 1 mol / L dilute hydrochloric acid for 8 hours at a temperature of 70°C, then ultrasonically washed with ultrapure water until neutral, and finally dried at a temperature of 110°C for 1 hour.

[0048] (c) High-temperature calcination: The reactants dried in step (b) are calcined at 1000°C for 0.5 h to obtain the silicon-aluminum mixture.

[0049] (2) Washing and drying: The mixture B in step (1) is washed with ultrapure water, and then the washed mixture B is vacuum dried at a temperature of 100°C, a vacuum degree of less than -0.07 mPa, and a drying time of 12 h to obtain a black solid.

[0050] (3) Calcination: The black solid from step (2) is added to a tube furnace, and the temperature in the tube furnace is raised to 800°C at a rate of 2-5°C / min. The temperature is then maintained at this temperature for 1 hour, during which a protective gas is introduced into the tube furnace. After the heat preservation is completed, the furnace is naturally cooled to room temperature to obtain a crude Ni / SiO2-Al2O3-NC catalyst. The protective gas is one or more of oxygen, nitrogen, argon, or an argon-hydrogen mixture.

[0051] (4) Washing, filtration and drying: The crude catalyst from step (3) is added to a 1 mol / L dilute hydrochloric acid solution, then heated and stirred at 70°C for 0.5 h. The mass of the dilute hydrochloric acid is 11-14 times that of the crude catalyst. After centrifugation, the separated solid material is repeatedly washed with ultrapure water until neutral, and finally dried at 40°C for 36 h to obtain the finished catalyst product.

[0052] Example 4: The overall method is the same as in Example 1, except that the amount of silicon-aluminum mixture used in step (1) is 5 mg.

[0053] Example 5: The overall method is the same as in Example 1, except that the amount of silicon-aluminum mixture used in step (1) is 10 mg.

[0054] Example 6: The overall method is the same as in Example 1, except that the amount of silicon-aluminum mixture used in step (1) is 20 mg.

[0055] Comparative Example 1: The overall method is the same as in Example 1, except that the amount of silicon-aluminum mixture used in step (1) is 0 mg.

[0056] The catalysts prepared in Examples 1, 4-6, and Comparative Example 1 were used to test the electrocatalytic reduction performance of CO2:

[0057] 1) Weigh 5 mg of catalyst and add it to 0.9 mL of anhydrous ethanol, then add 0.1 mL of 5 wt.% Nafion solution, and sonicate for 20 min to form a uniformly dispersed solution.

[0058] 2) Take 1.0cm 2 Carbon paper was placed in a diluted sulfuric acid solution overnight to remove impurities and oxides, and then ultrasonically cleaned with deionized water and anhydrous ethanol. 200 μL of the solution obtained in step 1) was coated onto the surface of the carbon paper and dried at room temperature for later use.

[0059] 3) The reaction gas is 99.999% CO2. CO, CO2, and H2 are separated by gas chromatography. The carrier gas is high-purity nitrogen, and the flow rate is 20 mL / min. -1 The electrochemical workstation is a CHI660e.

[0060] like Figure 1 As shown, the test results are as follows:

[0061] Example 1: FE at -0.9 to 1.1V vs. RHE CO Between 94% and 97%.

[0062] Example 4: FE at -0.9 to 1.1V vs. RHE CO Between 94% and 96%.

[0063] Example 5: FE at -0.9 to 1.1V vs. RHE CO Between 91% and 96%.

[0064] Example 6: FE at -0.9 to 1.1V vs. RHE CO Between 92% and 95%.

[0065] Comparative Example 1: When -0.9 to 1.1V vs. RHE, FE CO Between 81% and 90%.

[0066] As can be seen from the above tests, the fly ash-containing catalysts in Examples 1 and 4-6 all have excellent CO2-to-CO Faradaic efficiency. Compared with the fly ash-free catalyst in Comparative Example 1, the catalysts prepared by the methods of Examples 1 and 4-6 of this invention have significantly higher Faradaic efficiency. Furthermore, the CO2-to-CO Faradaic efficiency of Example 1 is better than that of Examples 4-6.

[0067] The above are preferred embodiments of the present invention. For those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst that promotes the conversion of CO2 to CO, characterized in that, It includes the following steps: (1) Mixing: Based on a mass percentage of 100%, thoroughly mix 0.01-0.3% silicon-aluminum mixture, 0.2-0.7% carbon black, 1.3-1.8% nickel nitrate, and the remaining 15-20% alcohol solution to obtain mixture A. Then, according to the mass ratio m 2-甲基咪唑溶液 :m 混合物A =1.5-2.5:1, add a 5-15% 2-methylimidazole solution to mixture A and stir to obtain mixture B; wherein the content of SiO2 and Al2O3 in the silicon-aluminum mixture is above 70-80%; (2) Washing and drying: The mixture B in step (1) is washed with ultrapure water, and then the washed mixture B is vacuum dried for 12-24 hours to obtain a black solid. (3) Calcination: The black solid in step (2) is added to a tube furnace, and the temperature in the tube furnace is controlled to rise to 500-800℃ at a rate of 2-5℃ / min. The temperature is then maintained at this temperature for 0-4h. During this period, a protective gas is introduced into the tube furnace. After the temperature maintenance is completed, the furnace is naturally cooled to room temperature to obtain the crude Ni / SiO2-Al2O3-NC catalyst.

2. The method for preparing a catalyst for promoting the conversion of CO2 to CO according to claim 1, characterized in that, The preparation method of the silicon-aluminum mixture in step (1) includes the following steps: (a) Alkali treatment: according to mass ratio m 粉煤灰 :m 氢氧化钾 The ratio of fly ash to potassium hydroxide solution is 1:3-7. Fly ash is added to a 2 mol / L potassium hydroxide solution, then heated to 70-100℃ and kept at that temperature for 2-8 hours. The solution is then allowed to cool naturally to room temperature to obtain the reactants. (b) Washing and drying: The reactants in step (a) are washed with deionized water, then acid-leached with dilute hydrochloric acid with a concentration of 1 mol / L for 3-8 hours at a temperature of 70-80°C, then ultrasonically washed with ultrapure water until neutral, and finally dried at a temperature of 80-110°C for 1-2 hours. (c) High-temperature calcination: The reactants dried in step (b) are calcined at 600-1000℃ for 0.5-2h to obtain the silicon-aluminum mixture.

3. The method for preparing a catalyst for promoting the conversion of CO2 to CO according to claim 1, characterized in that, The alcohol in the alcohol solution in step (1) is one or more of ethanol, methanol, and isopropanol.

4. The method for preparing a catalyst for promoting the conversion of CO2 to CO according to claim 1, characterized in that, In step (1), the stirring speed is 600-1000 rpm and the stirring time is 0.5-6 h.

5. The method for preparing a catalyst for promoting the conversion of CO2 to CO according to claim 1, characterized in that, In step (2), the drying temperature of vacuum drying is 40-100℃ and the vacuum degree is less than -0.07mPa.

6. The method for preparing a catalyst for promoting the conversion of CO2 to CO according to claim 1, characterized in that, The protective gas in step (3) is one or more of oxygen, nitrogen, argon, or an argon-hydrogen mixture.

7. The method for preparing a catalyst for promoting the conversion of CO2 to CO according to claim 1, characterized in that, The steps following step (3) are: washing, filtering and drying: the crude catalyst from step (3) is added to dilute hydrochloric acid with a concentration of 1 mol / L, and then heated and stirred at a temperature of 50-70°C for 0.5-4 hours. The mass of the dilute hydrochloric acid is 11-14 times that of the crude catalyst. Then, the catalyst is separated by centrifugation and the separated solid material is repeatedly washed with ultrapure water until neutral. Finally, it is dried at a temperature of 40-100°C for 8-36 hours to obtain the finished catalyst product.

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