Preparation method of BiOI-based catalyst, BiOI-based catalyst and application thereof
By preparing S-BiOI nanosheets through S-doping of BiOI, the stability and yield problems of BiOI catalysts in the process of carbon dioxide reduction to formic acid were solved, and high-efficiency catalytic performance was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2024-12-27
- Publication Date
- 2026-06-30
AI Technical Summary
Existing BiOI catalysts have insufficient stability and low product yield in the process of carbon dioxide reduction to prepare formic acid.
S-BiOI nanosheets were prepared by doping BiOI with sulfur. By controlling the doping amount and timing of sulfur source addition, the electronic structure was improved, CO2 adsorption and activation were promoted, and the reaction energy barrier of key intermediates was reduced.
It improves the yield of carbon dioxide reduction to formate or formic acid, exhibits good stability, and can maintain high activity during long-term electrocatalysis.
Smart Images
Figure CN122303930A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of carbon dioxide conversion and utilization, specifically relating to a method for preparing a BiOI-based catalyst, the BiOI-based catalyst and its application. Background Technology
[0002] Carbon dioxide (CO2) is a significant greenhouse gas, and its increasing concentration is one of the main causes of global warming. Therefore, developing efficient CO2 conversion technologies is crucial for mitigating climate change and achieving sustainable development. Electrocatalytic carbon dioxide reduction (ECR) is a technology that converts CO2 into valuable chemicals, among which the electrocatalytic production of formic acid is a promising method because formic acid is an important chemical feedstock and a clean energy source.
[0003] Existing ECR formic acid production technologies mainly employ bismuth-based catalysts, with BiOI being a typical example. BiOI possesses a unique layered structure, which is beneficial for CO2 adsorption and activation.
[0004] The yield of products prepared by the reduction of formate or formic acid using existing BiOI catalysts requires further improvement. Furthermore, BiOI catalysts exhibit insufficient stability and are prone to losing activity during the reaction process, necessitating the development of more stable BiOI-based catalysts. Summary of the Invention
[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of insufficient stability and low product yield when BiOI is used as an ECR catalyst in the prior art, thereby providing a method for preparing BiOI-based catalysts, BiOI-based catalysts and their applications.
[0006] Therefore, the present invention provides the following technical solution:
[0007] In a first aspect, the present invention provides a method for preparing a BiOI-based catalyst, comprising the following steps:
[0008] Step 1: Obtain BiOI;
[0009] Step 2: Mix the BiOI, sulfur source, and first solvent, and heat to react to obtain S-BiOI powder;
[0010] The mass ratio of BiOI to sulfur source is 35.2:(0.25-4).
[0011] For example, the mass ratio of BiOI to sulfur source can be 35.2:0.25, 35.2:0.5, 35.2:0.75, 35.2:1.0, 35.2:1.25, 35.2:1.5, 35.2:2, 35.2:2.5, 35.2:3, 35.2:3.5 or 35.2:4.
[0012] BiOI can be obtained by purchasing it directly or making it yourself.
[0013] In one possible implementation, the heating reaction is carried out at a temperature of 160–220°C for a time of 12–30 hours. For example, the heating temperature can be 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, or 220°C; the time can be 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 28 hours, or 30 hours.
[0014] In one possible implementation, the sulfur source includes at least one of thiourea and thioacetamide.
[0015] In one possible implementation, the first solvent includes one or more of deionized water, ethylene glycol, and ethanol.
[0016] In one possible implementation, the concentration of BiOI in the mixture obtained by mixing BiOI, sulfur source, and first solvent is 5 to 100 g / L.
[0017] In one possible implementation, step 1 includes: mixing a bismuth salt, a metal iodide, and a second solvent, and heating the mixture to react and obtain BiOI.
[0018] In one possible implementation, the bismuth salt comprises bismuth nitrate;
[0019] In one possible implementation, the metal iodide includes one or more of potassium iodide and sodium iodide;
[0020] In one possible implementation, the molar ratio of Bi in the bismuth salt to iodine in the metal iodide is 1:(1-5);
[0021] In one possible implementation, the second solvent includes one or more of deionized water, ethylene glycol, and ethanol.
[0022] In one possible implementation, in step 1, the heating reaction is carried out at a temperature of 150–180°C for 2–24 hours.
[0023] Secondly, the present invention provides a BiOI-based catalyst prepared according to the preparation method described above.
[0024] Thirdly, the present invention provides an application of the BiOI-based catalyst in the electrocatalytic reduction of CO2 to formic acid.
[0025] The technical solution of this invention has the following advantages:
[0026] 1. The preparation method of the BiOI-based catalyst of the present invention includes the following steps: Step 1, obtaining BiOI; Step 2, mixing the BiOI, sulfur source and first solvent, heating and reacting to obtain S-BiOI powder; the mass ratio of BiOI to sulfur source is 35.2:(0.25~4).
[0027] BiOI-based catalysts are prone to losing activity during the reaction process, resulting in insufficient stability. This invention prepares S-BiOI nanosheet material with abundant oxygen vacancies by doping with sulfur and controlling the doping amount and timing of sulfur source addition. S doping can improve the electronic structure around Bi element, promote CO2 adsorption and activation, and reduce the reaction energy barrier of key intermediate (*OCHO), thereby improving the catalytic performance of ECR in the preparation of formate or formic acid.
[0028] The BiOI-based catalyst of this invention improves the product yield and exhibits good stability during the reduction of carbon dioxide to formate or formic acid, and can maintain high activity during long-term ECR formic acid production.
[0029] Due to its superior performance in improving yield and stability, S-BiOI shows great promise in the reduction of carbon dioxide to formic acid / formate. It can not only improve the production efficiency of formic acid / formate and reduce energy waste, but also provide high-quality chemicals for the chemical, pharmaceutical, and food industries, thus possessing significant economic and environmental value. Attached Figure Description
[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0031] Figure 1 This is a scanning electron microscope image of the BiOI-based catalyst prepared in Example 3;
[0032] Figure 2 This is a scanning electron microscope image of the BiOI-based catalyst prepared in Comparative Example 3. Detailed Implementation
[0033] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.
[0034] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.
[0035] Example 1
[0036] This embodiment provides a method for preparing a BiOI-based catalyst, including the following steps:
[0037] Step 1, Preparation of BiOI:
[0038] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water. The mixture was stirred to obtain a first suspension. The first suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was complete, BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0039] Step 2: Perform S doping:
[0040] BiOI powder and thiourea (CH4N2S) were added to deionized water to obtain a second suspension with a BiOI concentration of 35.2 g / L and a thiourea concentration of 0.5 g / L. The second suspension was then transferred to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the S-BiOI product was obtained by centrifugation, washed multiple times with deionized water, and finally dried at 60°C for 12 hours to obtain S-BiOI powder.
[0041] Example 2
[0042] This embodiment provides a method for preparing a BiOI-based catalyst, including the following steps:
[0043] Step 1, Preparation of BiOI:
[0044] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water. The mixture was stirred to obtain a first suspension. The first suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was complete, BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0045] Step 2: Perform S doping:
[0046] BiOI powder and thiourea (CH4N2S) were added to deionized water to obtain a second suspension with a BiOI concentration of 35.2 g / L and a thiourea concentration of 0.75 g / L. The second suspension was then transferred to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the S-BiOI product was obtained by centrifugation, washed multiple times with deionized water, and finally dried at 60°C for 12 hours to obtain S-BiOI powder.
[0047] Example 3
[0048] This embodiment provides a method for preparing a BiOI-based catalyst, including the following steps:
[0049] Step 1, Preparation of BiOI:
[0050] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water. The mixture was stirred to obtain a first suspension. The first suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was complete, BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0051] Step 2: Perform S doping:
[0052] BiOI powder and thiourea (CH4N2S) were added to deionized water to obtain a second suspension with a BiOI concentration of 35.2 g / L and a thiourea concentration of 1 g / L. The second suspension was then transferred to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the S-BiOI product was obtained by centrifugation, washed multiple times with deionized water, and finally dried at 60°C for 12 hours to obtain S-BiOI powder.
[0053] Example 4
[0054] This embodiment provides a method for preparing a BiOI-based catalyst, including the following steps:
[0055] Step 1, Preparation of BiOI:
[0056] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water. The mixture was stirred to obtain a first suspension. The first suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was complete, BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0057] Step 2: Perform S doping:
[0058] BiOI powder and thiourea (CH4N2S) were added to deionized water to obtain a second suspension with a BiOI concentration of 35.2 g / L and a thiourea concentration of 1.25 g / L. The second suspension was then transferred to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the S-BiOI product was obtained by centrifugation, washed multiple times with deionized water, and finally dried at 60°C for 12 hours to obtain S-BiOI powder.
[0059] Example 5
[0060] This embodiment provides a method for preparing a BiOI-based catalyst, including the following steps:
[0061] Step 1, Preparation of BiOI:
[0062] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water. The mixture was stirred to obtain a first suspension. The first suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was complete, BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0063] Step 2: Perform S doping:
[0064] BiOI powder and thiourea (CH4N2S) were added to deionized water to obtain a second suspension with a BiOI concentration of 35.2 g / L and a thiourea concentration of 1.5 g / L. The second suspension was then transferred to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the S-BiOI product was obtained by centrifugation, washed multiple times with deionized water, and finally dried at 60°C for 12 hours to obtain S-BiOI powder.
[0065] Comparative Example 1
[0066] This comparative example provides a method for preparing a BiOI-based catalyst, comprising the following steps:
[0067] 0.1 mol Bi(NO3)3·5H2O, 0.1 mol KI, and thiourea were added to deionized water to obtain 1 L of suspension with a thiourea concentration of 0.5 g / L. The suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 180 °C for 24 hours. After the reaction, S-BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60 °C for 12 hours to obtain S-BiOI powder.
[0068] Comparative Example 2
[0069] This comparative example provides a method for preparing a BiOI catalyst, including the following steps:
[0070] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water to obtain a suspension. The suspension was transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was completed, the BiOI product was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0071] Comparative Example 3
[0072] This comparative example provides a method for preparing a BiOI-based catalyst, comprising the following steps:
[0073] Step 1, Preparation of BiOI:
[0074] Bi(NO3)3·5H2O and KI were mixed at a molar ratio of 1:1 and added to deionized water. The mixture was stirred to obtain a first suspension. The first suspension was then transferred to a polytetrafluoroethylene-lined reactor and kept at 160°C for 12 hours. After the reaction was complete, BiOI was obtained by centrifugation, washed several times with deionized water, and finally dried at 60°C for 12 hours to obtain BiOI powder.
[0075] Step 2: Perform S doping:
[0076] BiOI powder and thiourea (CH4N2S) were added to deionized water to obtain a second suspension with a BiOI concentration of 35.2 g / L and a thiourea concentration of 5 g / L. The second suspension was then transferred to a polytetrafluoroethylene-lined reactor for hydrothermal reaction at 180°C for 24 hours. After the reaction, the S-BiOI product was obtained by centrifugation, washed multiple times with deionized water, and finally dried at 60°C for 12 hours to obtain S-BiOI powder.
[0077] Test case
[0078] (1) The SEM image of the BiOI-based catalyst prepared in Example 3 is shown in [reference needed]. Figure 1 The SEM image of the BiOI-based catalyst prepared in Comparative Example 3 is shown in Figure 3. Figure 2 .Depend on Figure 1 , Figure 2 It is known that excessive addition of thiourea can cause the sheet-like structure to collapse, making it impossible to expose the active sites, resulting in reduced yield and stability.
[0079] (2) Yield and stability testing:
[0080] The catalysts prepared in each example and comparative example were made into electrodes and placed in a flow electrolysis cell. The electrolyte volume in the cathode chamber was 70 ml. CO2 was introduced into the gas chamber at a rate of 20 sccm. The DC power supply current was adjusted to 100 mA to conduct CO2RR experiments.
[0081] Faraday efficiency (FE) = 1.6 × 10 6 ×C×V liquid ×K / (i×t)×100%
[0082] C: Formate concentration, determined by liquid chromatography, in mol / L;
[0083] V liquid Volume of electrolyte in the cathode chamber, ml;
[0084] K = 2;
[0085] i: Total current during the reaction process, mA;
[0086] t: reaction time, min.
[0087] The test results are shown in Table 1.
[0088] Table 1
[0089]
[0090]
[0091] As shown in Table 1, the BiOI-based catalyst prepared by the method of the present invention has improved product yield and exhibits good stability in the process of carbon dioxide reduction to formate or formic acid, and can maintain high activity in the long-term ECR formic acid production process.
[0092] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A method for preparing a BiOI-based catalyst, characterized by, Includes the following steps: Step 1: Obtain BiOI; Step 2: Mix the BiOI, sulfur source, and first solvent, and heat to react to obtain S-BiOI powder; The mass ratio of BiOI to sulfur source is 35.2:(0.25-4).
2. The method of claim 1, wherein the BiOI-based catalyst is prepared by the steps of: The heating reaction is carried out at a temperature of 160–220°C for a time of 12–30 h.
3. The method for preparing the BiOI-based catalyst according to claim 1, characterized in that, The sulfur source includes at least one of thiourea and thioacetamide.
4. The method for preparing the BiOI-based catalyst according to claim 1, characterized in that, The first solvent includes one or more of deionized water, ethylene glycol, and ethanol.
5. The method for preparing the BiOI-based catalyst according to claim 1, characterized in that, The concentration of BiOI in the mixture obtained by mixing BiOI, sulfur source and first solvent is 5-100 g / L.
6. The method for preparing the BiOI-based catalyst according to claim 1, characterized in that, Step 1 includes: mixing bismuth salt, metal iodide, and a second solvent, heating and reacting to obtain BiOI.
7. The method for preparing the BiOI-based catalyst according to claim 6, characterized in that, At least one of the following conditions must be met: (1) The bismuth salts include bismuth nitrate; (2) The metal iodide includes one or more of potassium iodide and sodium iodide; (3) The molar ratio of Bi element in the bismuth salt to iodine element in the metal iodide is 1:(1~5); (4) The second solvent includes one or more of deionized water, ethylene glycol, and ethanol.
8. The method for preparing the BiOI-based catalyst according to claim 6, characterized in that, In step 1, the heating reaction temperature is 150–180°C, and the time is 2–24 hours.
9. A BiOI-based catalyst prepared by the method according to any one of claims 1-8.
10. The application of the BiOI-based catalyst according to claim 9 in the electrocatalytic reduction of CO2 to formic acid.