Electrocatalyst based on porphyrin molecules as well as preparation method and application of electrocatalyst
By developing an electrocatalyst based on porphyrin molecules, using the loading of metal cobalt porphyrin and metal copper porphyrin complexes on carbon nanocomposites, the problems of high carbon dioxide emissions, large energy consumption, and difficult to control the ratio of hydrogen to carbon monoxide in the traditional synthesis gas preparation method are solved, and the regulation of the ratio of hydrogen to carbon monoxide in the synthesis gas and the high yield of synthesis gas preparation are achieved.
Patent Information
- Application Number
- CN202510058546.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-14
- Publication Date
- 2025-03-18
AI Technical Summary
Traditional synthesis gas preparation methods have problems such as high carbon dioxide emissions, large energy consumption, and difficult to control the ratio of hydrogen to carbon monoxide.
An electrocatalyst based on porphyrin molecules is developed to regulate the ratio of hydrogen to carbon monoxide in the product by preparing metal cobalt porphyrin and metal copper porphyrin complexes and supporting them on carbon nanocomposites.
The ratio of hydrogen to carbon monoxide in synthesis gas is easily regulated, which reduces carbon dioxide emissions, saves energy consumption, and increases the yield of synthesis gas.
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Figure CN119640318A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of electrocatalysts, and in particular to an electrocatalyst based on porphyrin molecules and a preparation method and application thereof. Background Art
[0002] Synthesis gas consists of hydrogen and carbon monoxide in different molar ratios, and can be used to produce important bulk chemicals or liquid fuels such as methanol, ammonia, formic acid, etc. through thermochemical catalysis, Fischer-Tropsch synthesis, microbial fermentation and other technologies. However, traditional synthesis gas preparation methods have problems such as high carbon dioxide emissions, high energy consumption, and difficulty in controlling the ratio of hydrogen and carbon monoxide. Electrocatalytic conversion is an environmentally friendly and simple method for producing synthesis gas. Therefore, it is necessary to develop efficient electrocatalysts that can provide a suitable hydrogen to carbon monoxide ratio and a high synthesis gas yield.
[0003] Porphyrin molecules can stably bind metal ions through four N atoms to form rigid and stable metal complexes. Metalloporphyrin catalysts have good catalytic performance in the electrocatalytic reduction of carbon dioxide and hydrogen evolution. The performance of electrocatalytic carbon dioxide reduction and hydrogen evolution reactions can be regulated by changing the metal at the center of the porphyrin molecule. These results show that metalloporphyrin can be used as a catalyst for the efficient preparation of synthesis gas.
[0004] Therefore, the present invention proposes an electrocatalyst based on porphyrin molecules, a preparation method thereof, and application of the electrocatalyst in synthesis gas preparation. Summary of the invention
[0005] The purpose of the present invention is to provide an electrocatalyst based on porphyrin molecules and its preparation method and application, so as to solve the problems of high carbon dioxide emissions and high energy consumption in traditional synthesis gas preparation methods, and to achieve easy regulation of the ratio of hydrogen to carbon monoxide in synthesis gas preparation.
[0006] To achieve the above object, the present invention provides a method for preparing an electrocatalyst based on porphyrin molecules, comprising the following steps:
[0007] S1, preparing porphyrin ligand;
[0008] S2, using the porphyrin ligand prepared in S1 to react with metal cobalt and metal copper ions to prepare a metal cobalt porphyrin complex and a metal copper porphyrin complex;
[0009] S3, co-loading the metal cobalt porphyrin complex and the metal copper porphyrin complex prepared in S2 on a carbon paper electrode to obtain a carbon nanocomposite material, i.e., a target electrocatalyst product;
[0010] The synthetic route is as follows:
[0011]
[0012] Preferably, S1 is specifically: benzaldehyde, pyrrole, trifluoroacetic acid, and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone are added to dichloromethane, and the mixture is reacted in the dark for 10 to 15 minutes at room temperature and pressure, and after the reaction is completed, the mixture is separated and purified to obtain a porphyrin ligand.
[0013] Preferably, the molar ratio of benzaldehyde, pyrrole, trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in S1 is 1:1-1.2:0.1-0.5:1-1.2.
[0014] Preferably, S2 is specifically: dissolving the porphyrin ligand in dichloromethane, then adding a methanol solution of cobalt acetate tetrahydrate to obtain a first mixed solution, heating and reflux at 65° C. for 10 h, and separating and purifying after the reaction is completed to obtain a metal cobalt porphyrin complex;
[0015] The porphyrin ligand is dissolved in dichloromethane, and then a methanol solution of copper acetate tetrahydrate is added to obtain a second mixed solution, which is stirred at room temperature and pressure for 20 minutes. After the reaction is completed, the solution is separated and purified to obtain a metal copper porphyrin complex.
[0016] Preferably, the molar ratio of the porphyrin ligand to cobalt acetate tetrahydrate in the first mixed solution is 1:10 to 20;
[0017] The molar ratio of the porphyrin ligand to copper acetate tetrahydrate in the second mixed solution is 1:10-20.
[0018] Preferably, S3 specifically comprises: adding the metal cobalt porphyrin complex, carbon nanotubes, and commercial Nafion to N,N-dimethylformamide for ultrasonic dispersion to obtain a metal cobalt porphyrin dispersion;
[0019] The copper-metal porphyrin complex, carbon nanotubes and commercial Nafion are added into N,N-dimethylformamide for ultrasonic dispersion to obtain a copper-metal porphyrin dispersion;
[0020] The obtained metal cobalt porphyrin dispersion and metal copper porphyrin dispersion are mixed and drop-coated on commercial carbon paper to obtain a carbon nanocomposite material loaded with cobalt porphyrin and copper porphyrin.
[0021] Preferably, the molar ratio between the metal cobalt porphyrin dispersion and the metal copper porphyrin dispersion is any one of 3:25, 5:25, 6:25, and 10:25.
[0022] The present invention also provides an electrocatalyst based on porphyrin molecules prepared by the above preparation method.
[0023] The present invention also provides the use of the above-mentioned porphyrin molecule-based electrocatalyst in preparing synthesis gas.
[0024] The present invention first obtains a metal porphyrin complex by using a porphyrin ligand to react rapidly with metal cobalt and copper ions, and utilizes the characteristics of cobalt porphyrin and copper porphyrin complexes showing different catalytic activities in the electrocatalytic process, and simply mixes cobalt porphyrin and copper porphyrin complex molecules of different molar ratios with commercial carbon nanotubes and loads them on a carbon paper electrode, and obtains a carbon nanocomposite material of cobalt porphyrin and copper porphyrin loaded with different proportions, i.e., an electrocatalyst, and applies the electrocatalyst to electrocatalytic carbon dioxide reduction reaction and hydrogen evolution reaction to prepare synthesis gas, and performs an electrochemical performance test in a 0.5 mol / LKHCO3 carbon dioxide saturated solution, and analyzes the composition of each gas phase product in the product by gas chromatography. Among them, cobalt porphyrin catalyzes the progress of carbon dioxide reduction reaction within the applied voltage range, and maintains a high carbon monoxide Faraday efficiency; copper porphyrin catalyzes hydrogen evolution reaction within the applied voltage range to generate hydrogen. By adjusting the loading ratio of cobalt porphyrin and copper porphyrin in carbon nanomaterials, the ratio of hydrogen and carbon monoxide in the product can be ultimately adjusted.
[0025] Therefore, the present invention provides an electrocatalyst based on porphyrin molecules and a preparation method and application thereof, which have the following beneficial effects:
[0026] (1) The present invention is the first to simply mix cobalt porphyrin and copper porphyrin complex molecules with commercial carbon nanotubes and then load them on a carbon paper electrode. The catalyst is easy to prepare and is used for electrocatalytic reduction reactions. By simply mixing and adjusting the molecular ratio, synthesis gas with an adjustable ratio of hydrogen and carbon monoxide can be prepared.
[0027] (2) Compared with the traditional hydrothermal method for preparing synthesis gas, it does not require high temperature and high pressure reaction conditions, which saves costs, and the preparation device is simple and easy to operate. At the same time, the product ratio is adjustable and the yield is high;
[0028] (3) The prepared electrocatalyst will not release a large amount of carbon dioxide in the electrocatalytic process. On the contrary, it can complete the conversion of carbon dioxide and improve the utilization rate of carbon dioxide.
[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 is the ultraviolet spectrum of the cobalt porphyrin molecular complex prepared by S2 in Example of the present invention;
[0031] Figure 2 is the ultraviolet spectrum of the copper porphyrin molecular complex prepared by S2 in the embodiment of the present invention;
[0032] Figure 31 is a comparison diagram of the electrocatalytic current of cobalt porphyrin and copper porphyrin catalysts of different ratios prepared by S3 in the embodiment of the present invention; wherein a is 3:25; b is 5:25; c is 6:25; d is 10:25;
[0033] Figure 4 1-Co@1-Cu / CNT catalysts prepared in different proportions by S3 in the present invention are Faraday efficiency diagrams corresponding to various gas products produced by the carbon dioxide reduction reaction; wherein a is 3:25; b is 5:25; c is 6:25; d is 10:25;
[0034] Figure 5 It reflects the ratio of hydrogen to carbon monoxide in the product. DETAILED DESCRIPTION
[0035] The technical solution of the present invention is further described below by means of the accompanying drawings and embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, simplifications made without violating the spirit and principle of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention. In addition, it should be understood that after reading the content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application and belong to the scope of protection of the present invention.
[0036] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.
[0037] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.
[0038] Unless otherwise specified in the present invention, the reagents, instruments, and equipment used are those commonly used by technicians in this field.
[0039] Example
[0040] This embodiment provides a method for preparing an electrocatalyst based on porphyrin molecules, comprising the following steps:
[0041] S1. Preparation of porphyrin ligand
[0042] Add 305 μL (3 mmol) of benzaldehyde to a 100 mL round-bottom flask equipped with a magnetic stirring bar, then quickly add 207 μL of pyrrole (3 mmol) and 40 μL of trifluoroacetic acid. After stirring for 10 min in the dark, add 681 mg (3 mmol) of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone DDQ and continue stirring for 25 min. Separate by thin layer chromatography (using a mixed solution of petroleum ether and dichloromethane with a volume ratio of 5:1 as the developing solvent), and then remove the solvent by vacuum rotary evaporation to obtain a purple solid, i.e., a tetraphenylporphyrin ligand, chemically named 5,10,15,20-tetraphenylporphyrin, with a yield of 10%. Its structural characterization data are as follows:
[0043] 1HNMR (400MHz, Chloroform-d): δ [ppm] = 8.85 (s, 8H), 8.22 (d, J = 5.4Hz, 8H), 7.77 (t, J = 7.1Hz, 12H), -2.78 (s, 2H).
[0044] S2. Preparation of cobalt and copper porphyrin molecular complexes
[0045] In a 100mL round-bottom flask equipped with a magnetic stirring bar, 122mg (2mmol) of tetraphenylporphyrin ligand was added, and 20mL of dichloromethane was added and stirred for 5min. Then, 4.98g (20mmol) of cobalt acetate tetrahydrate methanol solution uniformly dispersed by ultrasound was added, and heated to reflux at 65°C for 10h. After the reaction, the solvent was removed by rotary evaporation, and the remaining cobalt salt was removed by extraction with dichloromethane and water to obtain a cobalt porphyrin molecule, namely CoTPP. Its characterization data are as follows:
[0046] HRMS(ESI)m / z:C44H29CoN4,[M+H] + , theoretical value 672.1719; measured value 672.1713.
[0047] In a 100mL round-bottom flask equipped with a magnetic stirring bar, 122mg (2mmol) of tetraphenylporphyrin ligand was added, and 20mL of dichloromethane was added and stirred for 5min. Then, 5.08g (20mmol) of methanol solution of copper acetate tetrahydrate uniformly dispersed by ultrasound was added, and stirred for 20min at room temperature and pressure. After the reaction, the solvent was removed by rotary evaporation, and the remaining copper salt was removed by extraction with dichloromethane and water to obtain copper porphyrin molecule, namely CuTPP. Its characterization data are as follows:
[0048] HRMS(ESI)m / z:C44H29CuN4,[M+H] + , theoretical value 676.1683; measured value 676.1677.
[0049] S3. Preparation of carbon nanocomposites loaded with cobalt porphyrin and copper porphyrin in different proportions
[0050] 980 μL of N,N-dimethylformamide was added to a 1.5 mL centrifuge tube, and 1 mg of carbon nanotubes (CNTs), 1 mg of cobalt porphyrin molecules and 20 μL of commercial Nafion were added thereto and dispersed uniformly by ultrasonication, i.e., 1-Co.
[0051] 980 μL of N,N-dimethylformamide was added to a 1.5 mL centrifuge tube, and 1 mg of carbon nanotubes (CNTs), 1 mg of copper porphyrin molecules and 20 μL of commercial Nafion were added thereto and dispersed uniformly by ultrasonication, namely 1-Cu.
[0052] 1-Co and 1-Cu were mixed in molar ratios of 3:25, 5:25, 6:25, and 10:25, respectively, and then drop-coated on commercial carbon paper to obtain carbon nanocomposites loaded with cobalt porphyrin and copper porphyrin in different ratios, namely 1-Co@1-Cu / CNT.
[0053] The cobalt porphyrin molecular complex and the copper porphyrin molecular complex obtained in step S2 of this embodiment were detected by ultraviolet spectroscopy. The results are as follows: Figure 1 and Figure 2 As shown, Figure 1 is the ultraviolet spectrum of the cobalt porphyrin molecule in this embodiment, Figure 2 It is the ultraviolet spectrum of the copper porphyrin molecule in this example. Compared with the literature, it confirms the successful synthesis of cobalt porphyrin and copper porphyrin.
[0054] The carbon nanocomposite material obtained in step S3 and loaded with cobalt porphyrin and copper porphyrin in different proportions is used for electrocatalytic carbon dioxide reduction reaction.
[0055] For the electrocatalytic carbon dioxide reduction test, 50 μL of the dispersion of the carbon nanocomposite material co-loaded with cobalt porphyrin and copper porphyrin was dropped on a 1 cm 2 The electrocatalytic carbon dioxide reduction performance was tested in a carbon dioxide saturated solution of 0.5 mol / L KHCO3 on carbon paper, with carbon paper as the working electrode, Ag / AgCl as the reference electrode, and carbon rod as the counter electrode. Figure 3 This is a test diagram of the electrocatalytic carbon dioxide oxygen reduction performance of 1-Co@1-Cu / CNT prepared in this embodiment. Figure 3 It can be seen that 1-Co@1-Cu / CNT exhibits excellent electrocatalytic activity for carbon dioxide reduction.
[0056] Figure 4 This is a test diagram of the electrocatalytic product of 1-Co@1-Cu / CNT prepared in this example. Figure 4Figures ad in the middle are the Faraday efficiency diagrams corresponding to various gas products produced by the catalytic carbon dioxide reduction reaction of 1-Co@1-Cu / CNT catalysts with different ratios. By changing the ratio of 1-Co to 1-Cu in 1-Co@1-Cu / CNT, the Faraday efficiency of hydrogen and carbon monoxide is regulated. As the ratio of 1-Co increases, the Faraday efficiency of carbon monoxide gradually increases, while the Faraday efficiency of hydrogen gradually decreases.
[0057] Figure 5 It reflects the ratio of hydrogen to carbon monoxide in the product. The results show that the regulated catalyst can produce synthesis gas with a hydrogen to carbon monoxide ratio ranging from 3 to 0.5.
[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.
Claims
1. A method for preparing an electrocatalyst based on porphyrin molecules, characterized in that: The following steps are involved: S1, preparing porphyrin ligand; S2, using the porphyrin ligand prepared in S1 to react with metal cobalt and metal copper ions to prepare a metal cobalt porphyrin complex and a metal copper porphyrin complex; S3, co-loading the metal cobalt porphyrin complex and the metal copper porphyrin complex prepared in S2 on a carbon paper electrode to obtain a carbon nanocomposite material, i.e., a target electrocatalyst product; The synthetic route is as follows:
2. The method for preparing an electrocatalyst based on porphyrin molecules according to claim 1, characterized in that: S1 specifically comprises: adding benzaldehyde, pyrrole, trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone into dichloromethane, reacting in the dark for 10 to 15 minutes at room temperature and pressure, and separating and purifying after the reaction to obtain a porphyrin ligand.
3. The method for preparing an electrocatalyst based on porphyrin molecules according to claim 2, characterized in that: The molar ratio of benzaldehyde, pyrrole, trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in S1 is 1:1-1.2:0.1-0.5:1-1.
2.
4. The method for preparing an electrocatalyst based on porphyrin molecules according to claim 1, characterized in that: S2 is specifically as follows: dissolving the porphyrin ligand in dichloromethane, then adding a methanol solution of cobalt acetate tetrahydrate to obtain a first mixed solution, heating and refluxing at 65° C. for 10 hours, and separating and purifying after the reaction is completed to obtain a metal cobalt porphyrin complex; The porphyrin ligand is dissolved in dichloromethane, and then a methanol solution of copper acetate tetrahydrate is added to obtain a second mixed solution, which is stirred at room temperature and pressure for 20 minutes. After the reaction is completed, the solution is separated and purified to obtain a metal copper porphyrin complex.
5. The method for preparing an electrocatalyst based on porphyrin molecules according to claim 4, characterized in that: The molar ratio of the porphyrin ligand to cobalt acetate tetrahydrate in the first mixed solution is 1:10-20; The molar ratio of the porphyrin ligand to copper acetate tetrahydrate in the second mixed solution is 1:10-20.
6. The method for preparing an electrocatalyst based on porphyrin molecules according to claim 1, characterized in that: S3 specifically comprises: adding the metal cobalt porphyrin complex, carbon nanotubes, and commercial Nafion into N,N-dimethylformamide for ultrasonic dispersion to obtain a metal cobalt porphyrin dispersion; The copper-metal porphyrin complex, carbon nanotubes and commercial Nafion are added into N,N-dimethylformamide for ultrasonic dispersion to obtain a copper-metal porphyrin dispersion; The obtained metal cobalt porphyrin dispersion and metal copper porphyrin dispersion are mixed and drop-coated on commercial carbon paper to obtain a carbon nanocomposite material loaded with cobalt porphyrin and copper porphyrin.
7. The method for preparing an electrocatalyst based on porphyrin molecules according to claim 6, characterized in that: The molar ratio between the metal cobalt porphyrin dispersion and the metal copper porphyrin dispersion is any one of 3:25, 5:25, 6:25 and 10:
25.
8. An electrocatalyst based on porphyrin molecules, characterized in that: The porphyrin molecule-based electrocatalyst is prepared by the preparation method according to any one of claims 1 to 7.
9. The electrocatalyst based on porphyrin molecules according to claim 8, characterized in that: The porphyrin molecule-based electrocatalyst is used for the production of synthesis gas.