Method for electrically synthesizing carbonic ester by taking carbon dioxide and low-carbon alcohol as raw materials

Abstract

The invention discloses a method for synthesizing carbonic ester by electrocatalytic conversion of carbon dioxide and methanol. According to the method, nitrogen-containing polyion liquid is adopted as a precursor, a novel nitrogen-containing polyion liquid-based functionalized nitrogen-doped carbon nanotube material is designed and prepared as a first catalyst, and the first catalyst and a gas diffusion layer are prepared into a cathode material; and the polyion liquid-based nitrogen-doped carbon nanotube material loaded palladium is used as a second catalyst for electrolyte reaction. The overall electro-catalysis system comprises the electrode material, a second catalyst, a reaction electrolyte and a reaction device, low-carbon alcohol (methanol and ethanol) is used as an electrolyte solvent and a reactant, and carbonic ester is synthesized through a constant-potential electrolytic reaction in an electrolytic tank reaction device under the synergistic effect of the electrode material, the second catalyst and the electrolyte. According to the method for directly synthesizing carbonic ester through electro-catalysis of CO2, a novel nitrogen-containing polyion liquid-based nitrogen-doped carbon nanotube catalytic material is adopted as a main body of the first catalyst and the second catalyst at the same time, the system is simplified, preparation is convenient and fast, synthesis is efficient, and the process of electro-synthesis of organic carbonic ester through CO2 and low-carbon alcohol under mild conditions is promoted.

Description

Technical Field

[0001] The present invention belongs to the field of energy materials and electrochemistry, and relates to a method for constructing a catalytic system for preparing carbonates from electrocatalytic CO2. Functionalized carbon nanotube catalytic materials and nitrogen-containing polyionic liquid-based nitrogen-doped carbon nanotube materials loaded with palladium catalytic materials are prepared using nitrogen-containing ionic liquids as precursors, and a new electrochemical reaction system for synthesizing carbonates from CO2 is constructed to achieve efficient and mild electrosynthesis of carbonates from CO2. Background Art

[0002] CO2 is the main component of greenhouse gases. With the consumption of fossil fuels, its continuous accumulation has brought about many environmental and social problems. At the same time, CO2 is also a renewable C1 resource with abundant reserves, wide sources, non-toxicity, inexpensive and easy to obtain. Its resource utilization can realize the transformation of inorganic carbon into high value-added chemicals. However, the current large-scale treatment method of CO2 is mainly to absorb, capture and store it (CCS), and it is impossible to effectively utilize this C1 resource. Among them, using CO2 as a starting material to replace traditional toxic carbonyl sources to synthesize carbonates is an important direction for the resource utilization of CO2.

[0003] As a classic chemical and chemical product, carbonate is also an important component of battery electrolyte, supporting cutting-edge industries such as power batteries, electronic chemicals, and polycarbonate, thereby promoting the rapid development of downstream electronic appliances, automobile industry, aerospace, and energy information fields. The direct synthesis of carbonates by CO2 and low-carbon alcohols has become a research hotspot in the field of CO2 chemical low-carbon energy in recent years because its raw material low-carbon alcohols are cheap and easy to obtain, can be selected from coal-based and do not rely on petroleum resources, and have the advantages of "one-step" convenient synthesis. Common catalysts for the thermal synthesis of carbonates from CO2 and low-carbon alcohols include alkali metal carbonates, metal organic framework materials, supported metal catalysts, metal oxide catalysts, ionic liquid catalysts, etc., but there are problems such as unfavorable thermodynamics, high kinetic energy barriers, and harsh reaction conditions. The use of electrocatalytic processes to prepare carbonates from CO2 and low-carbon alcohols can effectively break through thermodynamic barriers, improve reaction efficiency, and ease reaction conditions, which is in line with the development trend of green energy driving traditional chemical industry to help carbon emission reduction.

[0004] At present, the electrocatalytic process of CO2 to carbonate has many problems such as more hydrogen evolution byproducts and the compatibility of the catalytic system needs to be improved. By introducing and developing new efficient and green catalytic materials, improving the compatibility and catalytic performance of the first catalyst and the second catalyst, and then realizing a new process of CO2 to carbonate under mild conditions, it has important scientific and industrial significance. Metal-free carbon-based catalysts are ideal materials for electrocatalytic CO2 conversion due to their diversity of dimensions and nanostructures. The high specific surface area, excellent conductivity and chemical stability can promote the electrocatalytic CO2 reaction performance, but the pure carbon material has a weak adsorption capacity for CO2 molecules, resulting in its poor catalytic activity. Heteroatom-doped carbon materials can effectively improve the electrocatalytic performance of carbon-based catalysts by adjusting the electronic structure and surface properties and providing CO2 activation sites. Polyionic liquids have low vapor pressure, high thermal stability and structural designability. Heteroatom-doped carbon materials with high yield can be directly prepared by high-temperature carbonization of ionic liquids containing heteroatoms. Therefore, by using polyionic liquids as precursors to prepare carbon materials, it is expected to achieve efficient catalytic CO2 to carbonate. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing carbonate by electrocatalytic conversion of carbon dioxide.

[0006] The first object of the present invention is to provide a method for preparing polyionic liquid-based nitrogen-doped carbon nanotube materials using polyionic liquid as a precursor, comprising the following steps:

[0007] 1) Dissolve 10 mmol of vinyl ionic liquid monomer and divinylbenzene in 50 mL of solvent, introduce nitrogen to replace the gas and stir for 0.5 h.

[0008] 2) Add azobisisobutyronitrile as initiator, raise the temperature to 70°C, and conduct polymerization reaction for 24 hours.

[0009] 3) After the reaction is completed, the crude product in the above system is centrifuged at a rotating speed, washed, and dried to obtain a polyionic liquid precursor.

[0010] 4) The polyionic liquid precursor and carbon nanotubes are mixed and placed in a corundum boat, high-purity Ar is used as a protective gas, and high-temperature calcination is performed to obtain a polyionic liquid-based nitrogen-doped carbon nanotube material.

[0011] The vinyl-containing ionic liquids in the above preparation method include 2-methyl-6-vinylpyridine bromide, 2-methyl-6-vinylpyridine dicyanamide, 2-methyl-6-vinylpyridine tetrafluoroborate, and 2-methyl-6-vinylpyridine 2,4-dihydroxypyrimidine-5-carboxylate;

[0012] The molar ratio of the vinyl-containing ionic liquid monomer to divinylbenzene is 1:1 to 10:1, specifically 1:1;

[0013] The solvent includes one or more of methanol, ethanol, and acetonitrile, and specifically can be methanol;

[0014] The washing solvent is one or more of methanol, ethanol and deionized water, and specifically can be deionized water;

[0015] The drying temperature is 40-100° C., and the drying time is 10-48 hours, and specifically can be 100° C. for 10 hours.

[0016] The second object of the present invention is to provide an electrode material, comprising the above-mentioned polyionic liquid-based nitrogen-doped carbon nanotube material and a gas diffusion layer.

[0017] In the above-mentioned electrode material, the method for preparing the electrode material comprises the following steps:

[0018] The polyionic liquid-based nitrogen-doped carbon nanotube material is dispersed in a solvent, and Nafion 117 dispersion is added as a binder to obtain a dispersion; the dispersion is dropwise coated on the gas diffusion layer to obtain the electrode material.

[0019] In the above electrode material, the solvent is selected from at least one of acetone, ethanol, isopropanol and deionized water, and specifically can be isopropanol;

[0020] The catalyst ratio of the Nafion 117 dispersion to the polyionic liquid-based nitrogen-doped carbon nanotube material is 10-100 μL:1 mg, specifically 10 μL:1 mg;

[0021] In the above-mentioned electrode materials, the gas diffusion layer can be selected from at least one of carbon fiber paper, carbon fiber woven cloth and carbon black paper, and can be specifically carbon fiber paper;

[0022] In the above electrode material, the amount of the polyionic liquid-based nitrogen-doped carbon material on the gas diffusion layer can be 0.1 to 10 mg / cm 2 , specifically 1mg / cm 2 .

[0023] The third object of the present invention is to provide a method for loading a palladium catalytic material on a polyionic liquid-based nitrogen-doped carbon nanotube material, comprising the following steps:

[0024] 1) The polyionic liquid-based nitrogen-doped carbon material was stirred and refluxed in a 10% nitric acid solution for 4 hours at a heating temperature of 80° C. After the reflux, it was washed with deionized water until it was neutral.

[0025] 2) The palladium compound is dissolved in a 10% hydrochloric acid solution, transferred into the treated polyionic liquid-based nitrogen-doped carbon material, and stirred and immersed for 2 hours.

[0026] 3) Dissolve sodium borohydride in deionized water, add to the solution in step (2), and stir for 2 hours.

[0027] 4) Centrifuge, wash and dry the above product to obtain palladium / carbon material.

[0028] In the polyionic liquid-based nitrogen-doped carbon nanotube material-supported palladium catalytic material, the palladium compound is one of palladium chloride and sodium tetrachloropalladate (II);

[0029] The mass fraction of palladium is 1% to 20%, specifically 10%;

[0030] The molar ratio of sodium borohydride to palladium is 1:1 to 10:1, specifically 1:1;

[0031] The washing solvent is one or more of methanol, ethanol and deionized water, and specifically methanol;

[0032] The drying temperature is 40-100° C., and the drying time is 10-48 hours, and specifically can be 100° C. for 10 hours.

[0033] The fourth object of the present invention is to provide an electrochemical catalytic system, comprising the above-mentioned electrode material, a second catalyst, a reaction electrolyte and a reaction device.

[0034] In the above electrochemical system, the reaction electrolyte includes an electrolyte and a reaction solvent, the electrolyte is selected from at least one of tetrabutylammonium bromide, tetrabutylammonium iodide, tetrabutylammonium chloride, sodium bromide and potassium bromide, and the reaction solvent is selected from at least one of methanol and ethanol.

[0035] The concentration of the reaction electrolyte is 0.1 to 10 M; specifically, it can be 1 M tetrabutylammonium bromide / methanol solution;

[0036] The ratio of the second catalyst to the electrolyte is 1-100 mg:10 mL;

[0037] The reaction device is a single cell or H-type electrolytic cell.

[0038] The fifth object of the present invention is to provide the use of the above-mentioned electrode material and catalyst material or the above-mentioned electrochemical catalytic system in the electrocatalytic conversion of carbon dioxide to synthesize carbonates.

[0039] The sixth object of the present invention is to provide a method for electrocatalytic conversion of carbon dioxide to synthesize carbonate, using carbon dioxide and electrolyte solvent as raw materials, and synthesizing carbonate by constant potential electrolysis reaction in the electrolytic cell device through the action of the electrode material, polyionic liquid-based nitrogen-doped carbon nanotube material loaded with palladium catalytic material and the electrolyte.

[0040] In the above method, the electrolyte is selected from at least one of tetrabutylammonium bromide, tetrabutylammonium iodide, tetrabutylammonium chloride, sodium bromide and potassium bromide, and the electrolyte solvent is selected from at least one of methanol and ethanol, and specifically can be tetrabutylammonium bromide methanol solution;

[0041] The reaction device in the above method is a single electrolytic cell or an H-type electrolytic cell system, specifically a single electrolytic cell;

[0042] The potential of the electrolysis reaction may be -0.5 to -3 V vs. Ag / Ag + , specifically -1.5V vs.Ag / Ag +

[0043] The electrolysis reaction time may be 0.1 to 100 hours, and specifically may be 50 hours.

[0044] The products of the reaction include dimethyl carbonate and diethyl carbonate.

[0045] The advantages and effects of the present invention are as follows:

[0046] (1) The use of nitrogen-containing polyionic liquid as a precursor to prepare carbon nanotube catalytic materials uses polyionic liquid as a template and directing agent, which is conducive to the construction of different carbon-nitrogen microstructures, provides adsorption sites at the catalytic interface, promotes CO2 adsorption activation conversion, and inhibits hydrogen evolution side reactions;

[0047] (2) There is no need to dope metal materials at the cathode, the method is simple, has good economy, controllability, operability and performance stability, and promotes the synthesis of carbonates under mild conditions;

[0048] (3) The use of nitrogen-containing polyionic liquid as a precursor to prepare carbon nanotube-loaded palladium catalytic materials can promote the dispersion of catalytic sites, prevent catalyst agglomeration, improve the performance of catalytic materials, and promote the compatibility of the system. It has demonstrated excellent performance in the process of converting CO2 to carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Scanning electron microscope (SEM) image of NCNT-PVCN-1

[0050] Figure 2 The SEM-EDS Mapping of Pd / NCNT-PVCN-1 DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below through specific implementation methods. However, the present invention is not limited to the following embodiments.

[0052] Example 1 Preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material

[0053] The preparation of a catalyst polyionic liquid-based nitrogen-doped carbon nanotube catalytic material with a molar ratio of 2-methyl-6-vinylpyridine dicyanamide and divinylbenzene of 1:1 is taken as an example.

[0054] First, 10mmol 2-methyl-6-vinylpyridine dicyanamide and 10mmol divinylbenzene were dissolved in 50mL solvent and stirred at room temperature for 0.5h. Then, 1mmol azobisisobutyronitrile was added as an initiator. The air was replaced by N2 through Schlenk technology. The temperature was raised to 70℃ for reaction for 24h. The solvent was separated by centrifugation to obtain a crude polyionic liquid product. The product was washed repeatedly with water and ethanol for 3 times and dried under vacuum at 50℃ for 24h to obtain a white powdery polyionic liquid precursor. 0.3g of the polyionic liquid precursor and 0.2g of carbon nanotubes were mixed and placed in a corundum boat. High-purity Ar was used as a protective gas. The product was calcined at 800℃ to obtain a polyionic liquid-based nitrogen-doped carbon nanotube material (NCNT-PVCN-1).

[0055] NCNT-PVCN-1 was systematically characterized, and the scanning electron microscope (SEM) image showed that NCNT-PVCN-1 was composed of flake particles ( Figure 1 ). Elemental analysis (EA) showed the presence of nitrogen, and the results are shown in the following table.

[0056]

[0057] Example 2 Preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material

[0058] The preparation of a catalyst polyionic liquid-based nitrogen-doped carbon nanotube catalytic material with a molar ratio of 2-methyl-6-vinylpyridine dicyanamide and divinylbenzene of 10:1 is taken as an example.

[0059] First, 10mmol 2-methyl-6-vinylpyridine dicyanamide and 1mmol divinylbenzene were dissolved in 50mL solvent and stirred at room temperature for 0.5h. Then, 1mmol azobisisobutyronitrile was added as an initiator. The air was replaced by N2 through Schlenk technology. The temperature was raised to 70℃ for reaction for 24h. The solvent was separated by centrifugation to obtain a crude polyionic liquid product. The product was washed repeatedly with water and ethanol for 3 times and dried under vacuum at 50℃ for 24h to obtain a white powdery polyionic liquid precursor. 0.3g of the polyionic liquid precursor and 0.2g of carbon nanotubes were mixed and placed in a corundum boat. High-purity Ar was used as a protective gas and calcined at 800℃ to obtain a polyionic liquid-based nitrogen-doped carbon nanotube material (NCNT-PVCN-10).

[0060] Example 3 Preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material

[0061] The preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material with a molar ratio of 2-methyl-6-vinylpyridinium bromide and divinylbenzene of 1:1 is taken as an example.

[0062] First, 10mmol 2-methyl-6-vinylpyridinium bromide and 10mmol divinylbenzene were dissolved in 50mL solvent and stirred at room temperature for 0.5h. Then, 1mmol azobisisobutyronitrile was added as an initiator. The air was replaced by N2 through Schlenk technology. The temperature was raised to 70℃ for reaction for 24h. The solvent was separated by centrifugation to obtain a crude polyionic liquid product. The product was washed repeatedly with water and ethanol for 3 times and dried under vacuum at 50℃ for 24h to obtain a white powdery polyionic liquid precursor. 0.3g of the polyionic liquid precursor and 0.2g of carbon nanotubes were mixed and placed in a corundum boat. High-purity Ar was used as a protective gas. The product was calcined at 800℃ to obtain a polyionic liquid-based nitrogen-doped carbon nanotube material (NCNT-PVBr-1).

[0063] Example 4 Preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material

[0064] The preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material with a molar ratio of 2-methyl-6-vinylpyridine tetrafluoroborate and divinylbenzene of 1:1 is taken as an example.

[0065] First, 10mmol 2-methyl-6-vinylpyridine tetrafluoroborate and 10mmol divinylbenzene were dissolved in 50mL solvent and stirred at room temperature for 0.5h. Then, 1mmol azobisisobutyronitrile was added as an initiator. The air was replaced by N2 through Schlenk technology. The temperature was raised to 70℃ for reaction for 24h. The solvent was separated by centrifugation to obtain a crude polyionic liquid product. The product was washed repeatedly with water and ethanol for 3 times and dried under vacuum at 50℃ for 24h to obtain a white powdery polyionic liquid precursor. 0.3g of the polyionic liquid precursor and 0.2g of carbon nanotubes were mixed and placed in a corundum boat. High-purity Ar was used as a protective gas. The product was calcined at 800℃ to obtain a polyionic liquid-based nitrogen-doped carbon nanotube material (NCNT-PVBF4-1).

[0066] Example 5 Preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material

[0067] The preparation of polyionic liquid-based nitrogen-doped carbon nanotube catalytic material with a molar ratio of 2-methyl-6-vinylpyrrolidone 2,4-dihydroxypyrimidine-5-carboxylate and divinylbenzene of 1:1 is taken as an example.

[0068] First, 10mmol 2-methyl-6-vinylpyrrolidone 2,4-dihydroxypyrimidine-5-carboxylate and 10mmol divinylbenzene were dissolved in 50mL solvent and stirred at room temperature for 0.5h. Then, 1mmol azobisisobutyronitrile was added as an initiator. The air was replaced by N2 through Schlenk technology. The temperature was raised to 70℃ for reaction for 24h. The solvent was separated by centrifugation to obtain a crude polyionic liquid product. The product was washed repeatedly with water and ethanol for 3 times and dried under vacuum at 50℃ for 24h to obtain a white powdery polyionic liquid precursor. 0.3g of the polyionic liquid precursor and 0.2g of carbon nanotubes were mixed and placed in a corundum boat. High-purity Ar was used as a protective gas. The product was calcined at 800℃ to obtain a polyionic liquid-based nitrogen-doped carbon nanotube material (NCNT-PVPym)-1).

[0069] Example 6 The method for preparing a nitrogen-containing polyionic liquid-doped carbon material-supported Pd catalytic material takes the preparation of Pd / NCNT-PVCN-1 with a palladium mass fraction of 1% as an example.

[0070] First, place 0.5g NCNT-PVCN-1 in 50mL 10% nitric acid solution, heat to 80℃, stir and reflux for 4h, and wash with deionized water until neutral. Take 5mg palladium chloride and dissolve it in 1mL hydrochloric acid solution, dilute it with 20mL water, stir the solution evenly, add the treated NCNT-PVCN-1, stir and soak for 2h, dissolve 150mg sodium borohydride in 10mL water, slowly add it to the solution, stir and reduce for 2h, centrifuge the solution, wash it with deionized water until neutral, and vacuum dry it at 60℃ for 12h to obtain Pd / NCNT-PCN-1.

[0071] Pd / NCNT-PVCN-1, Pd / NCNT-PVBr-1, Pd / NCNT-PVBF4-1, and Pd / NCNT-PVPym)-1 were prepared using the same method as above.

[0072] NCNT-PVCN-1 was characterized, and the scanning electron microscope (SEM) image showed that Pd / NCNT-PVCN-1 was composed of nanoparticles ( Figure 2 ). Element distribution map (EDS Mapping) research shows that Pd element is evenly distributed on the catalyst surface ( Figure 2 ).

[0073] Example 7 Application of electrode materials and second catalyst in CO2 electrocatalytic synthesis of carbonate system

[0074] An electrosynthesis system was constructed by taking NCNT-PVCN-1 and a gas diffusion layer as electrode materials and Pd / NCNT-PCN-1-1 as the second catalyst.

[0075] To prepare the working electrode, 1.5 mg NCNT-PCN-1 catalyst was first dispersed in 0.5 mL isopropanol with 10 μL Nafion 117 dispersion (5 wt%), and then ultrasonicated for 30 min to make it uniformly dispersed. The dispersion was evenly drop-coated on the surface of the gas diffusion layer carbon fiber paper and allowed to stand at room temperature for 12 h. The loading amount of each electrode catalyst was 1 mg / cm 2 .

[0076] The electrolysis experiment was carried out at 25°C. The electrolytic cell used was a three-electrode single-cell system. The three electrodes included the above-mentioned working electrode, glassy carbon counter electrode and Ag / Ag + Reference electrode, electrolyte 0.1M tetrabutylammonium bromide / methanol solution, electrolyte dosage 10mL, 50mg Pd / NCNT-PVCN-1 catalyst added to the electrolyte as the second catalyst. First, CO2 gas was introduced for 0.5h to saturate the electrolyte, and then the electrocatalytic synthesis of carbonate was started in the closed electrolytic cell. The potential range was -2.0Vvs.Ag / Ag+ The electrolysis time was 1 h. The liquid product was analyzed by gas chromatography (GC, Agilent 8890), and the Faraday efficiency of dimethyl carbonate was 59.3%.

[0077] Example 8 Application of electrode materials and second catalyst in CO2 electrocatalytic synthesis of carbonate system

[0078] The only difference from Example 7 is that the NCNT-PVCN-1 in the electrode material is replaced by NCNT-PVBr-1, the second catalyst Pd / NCNT-PVCN-1 is replaced by Pd / NCNT-PVBr-1, and the Faradaic efficiency of dimethyl carbonate is 55.8%.

[0079] Example 9 Application of electrode materials and second catalyst in CO2 electrocatalytic synthesis of carbonate system

[0080] The only difference from Example 7 is that the NCNT-PVCN-1 in the electrode material is replaced by NCNT-PVBF4-1, the second catalyst Pd / NCNT-PVCN-1 is replaced by Pd / NCNT-PV BF4-1, and the Faradaic efficiency of dimethyl carbonate is 51.7%.

[0081] Example 10 Application of electrode materials and second catalyst in CO2 electrocatalytic synthesis of carbonate system

[0082] The only difference from Example 7 is that the NCNT-PVCN-1 in the electrode material is replaced by NCNT-PVPymAc-1, the second catalyst Pd / NCNT-PVCN-1 is replaced by Pd / NCNT-PVPymAc-1, and the Faradaic efficiency of dimethyl carbonate is 49.9%.

[0083] Example 11 Application of Potassium Bromide as Electrolyte in CO2 Electrocatalytic Synthesis of Carbonate System

[0084] The only difference from Example 7 is that the electrolyte used is 0.1 M potassium bromide / methanol, and other conditions remain unchanged. The Faraday efficiency of dimethyl carbonate is 60.4%.

[0085] Example 12 Application of Extending the Electrolysis Time to 6h in the CO2 Electrocatalytic Synthesis of Carbonate System

[0086] The only difference from Example 7 is that the electrolysis reaction time is extended to 6 hours, and other conditions remain unchanged. The Faradaic efficiency of dimethyl carbonate is 66.2%.

[0087] Example 13 Application of ethanol as solvent in CO2 electrocatalytic synthesis of carbonate system

[0088] The difference from Example 7 is that the electrolyte used is 0.1 M tetrabutylammonium bromide / ethanol, and other conditions remain unchanged. The Faradaic efficiency of diethyl carbonate is 39.2%.

[0089] The applicant declares that the above description 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 modification, equivalent substitution, improvement, etc. made by those skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing carbonate esters by electrocatalytic reaction using CO2 as raw material, characterized in that: The method uses a polyionic liquid-based nitrogen-doped carbon nanotube material as a first catalyst, the first catalyst and a gas diffusion electrode form an electrode material, the polyionic liquid-based nitrogen-doped carbon nanotube material loads palladium as a second catalyst for electrolyte reaction, a glassy carbon electrode is a counter electrode, and Ag / Ag + The electrode is a reference electrode, tetrabutylammonium bromide is a supporting electrolyte, low-carbon alcohols (methanol, ethanol) serve as both electrolyte and reactant, and carbonate is obtained after the reaction is completed.

2. The first catalyst synthesis method of the method for electrochemical synthesis of carbonates from CO2 according to claim 1 is: 1) Dissolve 10 mmol of vinyl ionic liquid monomer and divinylbenzene in 50 mL of solvent, introduce nitrogen to replace the gas and stir for 0.5 h. 2) Add azobisisobutyronitrile as initiator, raise the temperature to 70°C, and conduct polymerization reaction for 24 hours. 3) After the reaction is completed, the crude product in the above system is centrifuged at a rotating speed, washed, and dried to obtain a polyionic liquid precursor. 4) The polyionic liquid precursor and carbon nanotubes are mixed and placed in a corundum boat, high-purity argon is used as a protective gas, and high-temperature calcination is performed to obtain polyionic liquid-based nitrogen-doped carbon nanotube materials.

3. The first catalyst synthesis method of the method for electrochemically synthesizing carbonate from CO2 according to claim 1, characterized in that: The vinyl-containing ionic liquids include methyl-6-vinylpyridine dicyanamide, 2-methyl-6-vinylpyridine bromide, 22-methyl-6-vinylpyridine tetrafluoroborate, and 2-methyl-6-vinylpyridine 2,4-dihydroxypyrimidine-5-carboxylate; The molar ratio of the vinyl-containing ionic liquid monomer to divinylbenzene is 1:1 to 10:1; The solvent includes one or more of methanol, ethanol and acetonitrile; The washing solvent is one or more of methanol, ethanol and deionized water; The drying temperature is 40-100° C. and the drying time is 10-48 hours.

4. The polyionic liquid-based nitrogen-doped carbon nanotube material is prepared by the first catalyst synthesis method according to claim 2 or 3.

5. An electrode material, comprising the polyionic liquid-based nitrogen-doped carbon nanotube material according to claim 4 and a gas diffusion layer.

6. The electrode material according to claim 4, characterized in that The method for preparing the electrode material comprises the following steps: Dispersing the polyionic liquid-based nitrogen-doped carbon nanotube material in a solvent, adding Nafion 117 dispersion as a binder to obtain a dispersion, and applying the dispersion dropwise onto the gas diffusion layer to obtain the electrode material; Preferably, the solvent is selected from at least one of acetone, ethanol, isopropanol and deionized water; Preferably, the catalyst ratio of the Nafion 117 dispersion to the polyionic liquid-based nitrogen-doped carbon material is 10-100 μL:1 mg; Preferably, in the electrode material, the gas diffusion layer can be selected from at least one of carbon fiber paper, carbon fiber woven cloth and carbon black paper; Preferably, on the gas diffusion layer, the polyionic liquid-based nitrogen-doped carbon nanotube material may be used in an amount of 0.1 to 10 mg / cm 2 .

7. The second catalyst of the method for electrochemical synthesis of organic carbonates from CO2 according to claim 1 is a polyionic liquid-based nitrogen-doped carbon nanotube material loaded with palladium, comprising the polyionic liquid-based nitrogen-doped carbon material according to claim 4 and a palladium compound.

8. The second catalyst polyionic liquid-based nitrogen-doped carbon nanotube material supported palladium according to claim 7, characterized in that: A method for preparing a second catalyst polyionic liquid-based nitrogen-doped carbon nanotube material loaded with palladium comprises the following steps: 1) The polyionic liquid-based nitrogen-doped carbon material was stirred and refluxed in a 10% nitric acid solution for 4 hours at a heating temperature of 80° C. After the reflux, it was washed with deionized water until it was neutral. 2) The palladium compound is dissolved in a 10% hydrochloric acid solution, and the treated polyionic liquid-based nitrogen-doped carbon material is added thereto, followed by stirring and impregnation for 2 hours. 3) Dissolve sodium borohydride in deionized water, add it to the solution in step (2), and stir to reduce for 2 hours. 4) Centrifuge, wash and dry the above product to obtain palladium / carbon material.

9. The method for preparing the second catalyst polyionic liquid-based nitrogen-doped carbon nanotube material loaded with palladium according to claim 7 or 8, characterized in that: The palladium compound is one of palladium chloride and sodium tetrachloropalladate (II); The palladium mass fraction is 1% to 20%; The molar ratio of sodium borohydride to palladium is 1:1 to 10:1; The washing solvent is one or more of methanol, ethanol and deionized water; The drying temperature is 40-100° C. and the drying time is 10-48 hours.

10. An electrocatalytic system comprising the electrode material according to claim 5 or 6, the second catalyst according to claim 7 or 8, a reaction electrolyte and a reaction device.

11. The electrocatalytic system according to claim 10, characterized in that: The reaction electrolyte comprises a supporting electrolyte and an electrolyte solvent, the supporting electrolyte is selected from at least one of tetrabutylammonium bromide, tetrabutylammonium iodide, tetrabutylammonium chloride, sodium bromide and potassium bromide, and the electrolyte solvent is selected from at least one of methanol and ethanol; The concentration of the reaction electrolyte is 0.1 to 10 M; The ratio of the second catalyst to the electrolyte is 1-100 mg:10 mL; The reaction device is one of a single cell and an H-type electrolytic cell.

12. Use of the electrode material according to claim 5 or 6, the second catalyst according to claim 7 or 8, and the electrocatalytic system according to claim 10 or 11 in electrocatalytic synthesis of organic carbonates from carbon dioxide.

13. A method for electrocatalytically synthesizing organic carbonates from carbon dioxide, comprising the following steps: using a glassy carbon electrode as a counter electrode, Ag / Ag + The electrode is a reference electrode. The constant potential electrolysis method is used. Carbon dioxide and electrolyte are used as raw materials. The organic carbonate is synthesized by constant potential electrolysis reaction in an electrolytic cell reaction device through the action of electrode materials, a second catalyst and electrolyte.

14. The method according to claim 13, characterized in that: The potential of the electrolysis reaction is -0.5 to -3 V vs. Ag / Ag + ; The electrolytic cell reaction device adopts one of the single cell or the H-type electrolytic cell system; The electrolysis reaction time is 0.1 to 100 hours.

Images