Halogen-mediated diaphragm-free cyclic carbonate electrosynthesis method and application thereof

Abstract

The invention discloses a method for halogen-mediated diaphragm-free electrosynthesis of cyclic carbonate and application thereof. The method comprises the following steps: carrying out electrochemical reaction by adopting a diaphragm-free flow reactor, adding halide salt, carbonate and an optionally added inorganic passivator into water and an N, N-dimethylformamide solvent to serve as a supporting electrolyte, and preparing the cyclic carbonate by a one-pot method by taking olefin and carbon dioxide as raw materials under the condition of constant current at room temperature. The method is reported for the first time for one-pot electrochemical preparation of ethylene to ethylene carbonate at present, the Faraday efficiency of ethylene carbonate is high, the productivity is high, the current density is large, the ethylene carbonate can stably run for 350 hours, and the method has industrial application prospects.

Description

Technical Field

[0001] The invention relates to the field of organic electrochemical synthesis, and in particular to a halogen-mediated cyclic carbonate non-diaphragm electrosynthesis method and application thereof. Background Art

[0002] Ethylene carbonate (EC) is an excellent solvent widely used in the field of lithium-ion batteries. The existing industrial route for EC production involves a high temperature (100-200°C) and high pressure (3.5-10MPa) thermal catalytic reaction between epoxides and carbon dioxide (CO2). In addition, the process requires a large amount of halogen-containing homogeneous catalysts, which further increases the downstream separation cost, while the corresponding raw material ethylene oxide is extracted from fossil fuels through an energy-intensive aerobic silver-catalyzed epoxidation process. Although electrochemical studies have successfully used various oxidation or reduction mechanisms to selectively electrochemically convert olefins into corresponding epoxides (intermediates of cyclic carbonates), further reactions are still required for epoxides to cyclic carbonates. Given the growing market demand for cyclic carbonates and the high requirements for green production, the direct electrosynthesis of cyclic carbonates is a simple and energy-saving method, and it is imperative to develop sustainable and mild alternative synthesis methods.

[0003] Zhang et al. studied the electrochemical addition of epoxides and CO2 in an acetonitrile system, assisted by BMIMBr as a co-catalyst, and obtained cyclic carbonate of styrene in high yield (90.7%) at 50°C. However, the reaction of gaseous epoxide (propylene oxide) was poor, and propylene carbonate was only obtained in a yield of 48.3% (Green Chem. 2013, 15(8), 2086-2090).

[0004] Jiang et al. successfully converted aromatic hydrocarbons and aliphatic olefins into iodine alcohol intermediates by electrochemical methods using an iodide-mediated oxidation pathway, and reacted them with CO2 to obtain the corresponding cyclic carbonates in high yield. However, experiments found that gaseous olefins such as ethylene and propylene in this system could not obtain corresponding cyclic carbonates (Electrochem. Commun. 2013, 34, 242-245).

[0005] In 2024, Nam et al. reported a succinimide- and bromine-mediated tandem preparation strategy for EC, which was electrochemically driven for the generation of initial bromine and base. Nevertheless, this strategy involves four independent reaction steps for the final EC synthesis, which highlights the need for a simplified one-pot EC electrosynthesis method (Nat. Synth 2024, 3, 846-857).

[0006] There is a good one-pot system for the electrochemical conversion of liquid olefins to cyclic carbonates, but the research on gaseous olefins to the corresponding cyclic carbonates is still challenging due to the inertness of gaseous olefins. It is very necessary to design an efficient electrosynthesis system and prepare high-value-added gaseous olefin cyclic carbonates in one pot under mild conditions. Summary of the invention

[0007] In view of the above-mentioned technical problems and the shortcomings in the art, the present invention provides a method for halogen-mediated membraneless electrosynthesis of cyclic carbonates and its application, which can overcome the problems of high energy consumption in the preparation process of gaseous olefins to cyclic carbonates, poor compatibility of electrochemical methods or complicated reaction steps in the prior art.

[0008] The present invention uses a diaphragm-free flow reactor to prepare high-value-added cyclic carbonates such as ethylene carbonate and propylene carbonate in one pot, which greatly reduces the reactor cost and simplifies the electrochemical operation; and the Faraday efficiency of olefins to cyclic carbonates is high, the current density is large, and the reaction time is short.

[0009] [1] A method for halogen-mediated diaphragmless electrosynthesis of cyclic carbonates, comprising: using a diaphragmless flow reactor for electrochemical reaction, adding a halogen salt, a carbonate and an optional inorganic passivating agent (i.e., the inorganic passivating agent may or may not be added) as a supporting electrolyte to water and N,N-dimethylformamide (DMF) solvents, and preparing cyclic carbonates in a one-pot process using olefins and carbon dioxide as raw materials at room temperature under constant current conditions.

[0010] The halide salt may include at least one of potassium chloride, ammonium bromide, potassium bromide, cesium bromide, lithium bromide, potassium iodide, etc., preferably includes at least one of potassium bromide and cesium bromide.

[0011] The carbonate may include at least one of sodium carbonate, potassium carbonate, cesium carbonate, etc., and preferably includes at least one of potassium carbonate and cesium carbonate.

[0012] The inorganic passivating agent may include at least one of potassium dichromate, potassium molybdate, potassium ferrate, etc., and preferably includes potassium dichromate.

[0013] The olefin may include at least one of a gaseous olefin, a liquid olefin, and the like.

[0014] The gaseous olefin may include at least one of ethylene, propylene, and the like.

[0015] The liquid olefin may include at least one of styrene, allyl benzene, and the like.

[0016] In the method described in [1], the anode material may include at least one of iridium dioxide-insoluble anode (IrO2-DSA), platinum, carbon paper, graphite, etc., preferably IrO2-DSA.

[0017] In the method described in [1], the cathode material may include at least one of nickel foam, nickel sheet, etc., preferably nickel foam.

[0018] In the supporting electrolyte, the concentration of the halide salt may be 0.1-0.5M, preferably 0.15-0.5M, for example 0.3-0.5M, etc., the concentration of the carbonate may be 0.1-0.4M, for example 0.2M, etc., the concentration of the inorganic passivating agent may be 0-10mM, preferably (1 / 400)-0.01M, further preferably (1 / 400)-(1 / 150)M, and the volume ratio of water to N,N-dimethylformamide is not less than 1:1, preferably (8:2)-(6:4), for example 7:3, etc.

[0019] [1] The method described in claim 1, wherein the pH of the supporting electrolyte is adjusted by carbonate. The pH of the supporting electrolyte is preferably 7.5-8.5, and more preferably 8.0-8.4.

[0020] The current density of the constant current condition can be 5-250 mA / cm 2 , further can be 10-250mA / cm 2 , for example 20mA / cm 2 wait.

[0021] The molar ratio of the halide salt to the inorganic passivating agent may be 1:0-200, preferably 1:50-200.

[0022] In some embodiments, in the method described in [1], carbon dioxide is introduced into the supporting electrolyte until saturation, and the circulation of the supporting electrolyte is started. During the constant current electrolysis, gaseous olefin and / or liquid olefin are introduced into the membraneless flow reactor, and carbon dioxide is introduced into the supporting electrolyte. Further, after the electrolysis time is over, carbon dioxide is continued to be introduced, and gaseous olefin may or may not be introduced at the same time. The reaction stops when the active halogen is completely consumed, and a cyclic carbonate is obtained in one pot.

[0023] [2] Use of the method described in [1] in the preparation of cyclic carbonates.

[0024] The present invention successfully realizes the one-pot preparation of high value-added product cyclic carbonate by a halogen-mediated electrochemical method. The participation of halogen avoids the addition of additional oxidant, and the halohydrin generated by gaseous olefin and active halogen has high reactivity, thereby successfully realizing the high Faraday efficiency, high productivity and high current density production of the corresponding cyclic carbonate; the addition of carbonate makes the system present a bicarbonate buffer system under carbon dioxide conditions, avoids the strong acid environment caused by halogen electrolysis, enables the halohydrin to be cycloaddition with carbon dioxide to prepare the corresponding cyclic carbonate, and further ensures the environmental matching of multi-step reaction kinetics in a diaphragm-free system; the system adopts a diaphragm-free flow reactor, avoids the use of expensive ion exchange membranes, and reduces production costs; the electrochemical oxidation of halogen, the conversion of olefin to halohydrin and the production of halohydrin to cyclic carbonate in the system are all carried out simultaneously in the same reactor, simplifying the electrochemical preparation process of cyclic carbonate.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention is the first report of the one-pot electrochemical preparation of ethylene carbonate, and the ethylene carbonate has high Faraday efficiency, high productivity, and high current density, and can operate stably for 350 hours, and has prospects for industrial application.

[0027] The present invention uses an inorganic passivating agent to inhibit halogen reduction and thus avoids the use of an ion exchange membrane, thereby greatly reducing production costs.

[0028] The present invention uses carbonate to construct a bicarbonate buffer system (pH is about 8), and the weakly alkaline environment provides an ideal environment for the electrolysis of halogens, the addition reaction of olefins and active halogens, and the cycloaddition of halohydrins and carbon dioxide, which is an effective guarantee for the electrochemical one-pot preparation of cyclic carbonates.

[0029] The invention is applicable to the production of cyclic carbonates from other olefins, and can provide a new idea for the reaction of propylene, allylbenzene, etc. with CO2 under electrochemical conditions to prepare propylene carbonate and styrene cyclic carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the halogen-mediated electrochemical synthesis system of ethylene carbonate of the present invention.

[0031] Figure 2 This is a graph showing the stability test data results of the halogen-mediated electrochemical synthesis process of ethylene carbonate of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific 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.

[0033] In the present invention, the flow rates of CO2 and gaseous olefins are controlled by mass flow controllers (CS200-A, Beijing Sevenstarflow), and are set to 80 sccm and 30 sccm, respectively, unless otherwise specified, and the mass flow controllers and flow rates are not limited.

[0034] The present invention uses a peristaltic pump (L100-1S-2, Longer) to pass through the flow cell at a flow rate of 10 mL / min, and the peristaltic pump and the flow rate are not limited.

[0035] Example 1

[0036] Combination Figure 1 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then circulated through the flow cell at a flow rate of 10mL / min using a peristaltic pump (L100-1S-2, Longer). Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. An online pH meter was used to monitor the pH change of the system, and the pH of the electrolyte was measured to be 8.05-8.27. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed, and the reaction was stopped. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 77.3%, and its productivity was 0.58mmol / h.

[0037] Comparative Examples 1-3 studied the effect of anode materials on the electrochemical synthesis performance of ethylene to ethylene carbonate.

[0038] Comparative Example 4 studies the effect of cathode materials on the electrochemical synthesis performance of ethylene to vinyl carbonate.

[0039] Comparative Examples 5-6 studied the effect of inorganic passivators on the electrochemical synthesis performance of ethylene to vinyl carbonate.

[0040] Comparative Examples 7-8 studied the effect of the volume ratio of water to N,N-dimethylformamide on the electrochemical synthesis performance of ethylene to ethylene carbonate.

[0041] Comparative Example 1

[0042] A similar method to Example 1 was followed, except that carbon paper was used as the anode material.

[0043] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 59.2% and its productivity was 0.44 mmol / h.

[0044] Comparative Example 2

[0045] A similar method to Example 1 was used, except that a platinum sheet was used as the anode material.

[0046] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 37.9% and its productivity was 0.28 mmol / h.

[0047] Comparative Example 3

[0048] A similar method to Example 1 was followed, except that graphite was used as the anode material.

[0049] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 36.7% and its productivity was 0.31 mmol / h.

[0050] Comparative Example 4

[0051] A similar method to Example 1 was used, except that a nickel sheet was used as the cathode material.

[0052] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 41.0% and its productivity was 0.20 mmol / h.

[0053] Comparative Example 5

[0054] A similar method to Example 1 was used, except that potassium molybdate was used as the inorganic passivating agent.

[0055] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 67.4% and its productivity was 0.50 mmol / h.

[0056] Comparative Example 6

[0057] A similar method to Example 1 was followed, except that potassium ferrate was used as the inorganic passivating agent.

[0058] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 50.2% and its productivity was 0.37 mmol / h.

[0059] Comparative Example 7

[0060] A similar method to Example 1 was used, except that the volume ratio of DMF to water was 2:8.

[0061] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 65.2% and its productivity was 0.49 mmol / h.

[0062] Comparative Example 8

[0063] A similar method to Example 1 was used, except that the volume ratio of DMF to water was 5:5.

[0064] Gas phase analysis showed that the Faradaic efficiency of ethylene carbonate was 55.4% and its productivity was 0.41 mmol / h.

[0065] Example 2

[0066] 0.2M Cs2CO3, 0.5M CsBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. An online pH meter was used to monitor the pH change of the system, and the pH of the electrolyte was measured to be 8.13-8.39. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed, and the reaction was stopped. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 77.8%, and its productivity was 0.58mmol / h.

[0067] Example 3

[0068] 0.2M K2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 26.9%, and its productivity was 0.20mmol / h.

[0069] Example 4

[0070] 0.2M Li2CO3, 0.5M LiBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 17.8%, and its productivity was 0.13mmol / h.

[0071] Example 5

[0072] 0.2M K2CO3, 0.1M KBr, 0.4M CsBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 71.1%, and its productivity was 0.53mmol / h.

[0073] Example 6

[0074] 0.2M Cs2CO3, 0.5M LiBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 size, 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. An online pH meter was used to monitor the pH change of the system, and the pH of the electrolyte was measured to be 8.07-8.48. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed, and the reaction was stopped. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 41.7%, and its productivity was 0.31mmol / h.

[0075] Example 7

[0076] 0.2M Cs2CO3, 0.5M KCl and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 size, 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. An online pH meter was used to monitor the pH change of the system, and the pH of the electrolyte was measured to be 7.86-8.05. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed, and the reaction stopped. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 24.5%, and its productivity was 0.183mmol / h.

[0077] Example 8

[0078] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 10mA / cm 2 The current density was charged at room temperature for 26 h, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 78.0%, and its productivity was 0.29mmol / h.

[0079] Example 9

[0080] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 30mA / cm 2 The current density was energized for 8.67 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 57.5%, and its productivity was 0.64mmol / h.

[0081] Example 10

[0082] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 60mA / cm 2The current density was charged for 4.33 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 49.2%, and its productivity was 1.10mmol / h.

[0083] Embodiment 11

[0084] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 100mA / cm 2 The current density was charged for 2.6 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 46.7%, and its productivity was 1.74mmol / h.

[0085] Example 12

[0086] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 150mA / cm 2 The current density was charged for 1.73 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2, 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 46.5%, and its productivity was 2.61mmol / h.

[0087] Example 13

[0088] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 250mA / cm 2 The current density was charged for 1.04 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 46.8%, and its productivity was 4.37mmol / h.

[0089] Embodiment 14

[0090] 0.2M Cs2CO3, 0.5M KBr and 0mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 55.3%, and its productivity was 0.41mmol / h.

[0091] Embodiment 15

[0092] 0.2M Cs2CO3, 0.5M KBr and (1 / 150)M K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 68.6%, and its productivity was 0.51mmol / h.

[0093] Example 16

[0094] 0.2M Cs2CO3, 0.5M KBr and 10mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, while CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide were continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 63%, and its productivity was 0.47mmol / h.

[0095] Embodiment 17

[0096] 0.2M Cs2CO3, 0.1M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 19.6%, and its productivity was 0.15mmol / h.

[0097] Embodiment 18

[0098] 0.2M Cs2CO3, 0.3M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of ethylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2 The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, ethylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, ethylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of ethylene carbonate was 54.1%, and its productivity was 0.40mmol / h.

[0099] Embodiment 19

[0100] The stability of the system was tested according to the method of Example 1, and 30 mL of fresh electrolyte was replaced after each reaction. The results showed that the Faradaic efficiency of ethylene carbonate remained stable (>75.8%, Figure 2 ).

[0101] Embodiment 20

[0102] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of propylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 20mA / cm 2The current density was charged for 13 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, propylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, propylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed. According to gas phase analysis, the Faraday efficiency of propylene carbonate was 57.7%, and its productivity was 0.43mmol / h.

[0103] Embodiment 21

[0104] 0.2M Cs2CO3, 0.5M KBr and 3mM K2Cr2O7 were dissolved in a mixed solution of 30mL DMF-water (volume ratio of 3:7) as the electrolyte for the electrosynthesis of propylene carbonate. Before electrolysis, CO2 was bubbled until the solution was saturated, and then a peristaltic pump (L100-1S-2, Longer) was used to circulate through the flow cell at a flow rate of 10mL / min. Subsequently, the flow rate was 100mA / cm 2 The current density was charged for 2.6 h at room temperature, and the IrO2-DSA anode was used as the anode (2 cm 2 , 1mm thick), nickel foam cathode (2cm 2 , 1mm thick) as the cathode. During the power-on period, propylene was bubbled directly into the membraneless flow reactor using a three-way valve, and CO2 was bubbled in the solvent bottle. After the reaction was completed, propylene and carbon dioxide continued to be bubbled until the active halogen was completely consumed, and the reaction was stopped. According to gas phase analysis, the Faraday efficiency of propylene carbonate was 45.1%, and its productivity was 1.68mmol / h.

[0105] Embodiment 22

[0106] 0.2M Cs2CO3, 0.15M KBr and 1mM K2Cr2O7 were dissolved in 20mL DMF-water (volume ratio 3:7) mixed solution as electrolyte for electrosynthesis of phenylpropylene cyclic carbonate. IrO2-DSA was used as anode (2cm 2 , 1mm thick), nickel foam (2cm 2 , 1 mm thick) as the cathode. Before electrolysis, CO2 was bubbled until the solution was saturated, and then 1 mmol of allylbenzene was added to the solvent bottle. A peristaltic pump (L100-1S-2, Longer) was then used to circulate through the flow cell at a flow rate of 10 mL / min and a current of 5 mA / cm 2The reaction was carried out at room temperature with a current density of 10000 mol until 3 F / mol of electricity was provided. During the power-on period, CO2 was bubbled in the solvent bottle. After the reaction was completed, carbon dioxide was bubbled continuously until the active halogen was completely consumed. According to gas phase analysis, the yield of allylbenzene cyclic carbonate was 82%.

[0107] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may 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.

Claims

1. A method for halogen-mediated membraneless electrosynthesis of cyclic carbonates, characterized in that: include: The electrochemical reaction was carried out in a diaphragmless flow reactor. Halogen salts, carbonates and optionally inorganic passivators were added to water and N,N-dimethylformamide solvents as supporting electrolytes. Cyclic carbonates were prepared in a one-pot process using olefins and carbon dioxide as raw materials under constant current conditions at room temperature.

2. The method according to claim 1, characterized in that The halide salt includes at least one of potassium chloride, ammonium bromide, potassium bromide, cesium bromide, lithium bromide and potassium iodide.

3. The method according to claim 1, characterized in that The carbonate includes at least one of sodium carbonate, potassium carbonate and cesium carbonate.

4. The method according to claim 1, characterized in that The inorganic passivating agent includes at least one of potassium dichromate, potassium molybdate and potassium ferrate.

5. The method according to claim 1, characterized in that The olefin includes at least one of a gaseous olefin and a liquid olefin; The gaseous olefin includes at least one of ethylene and propylene; The liquid olefin includes at least one of styrene and allylbenzene.

6. The method according to claim 1, characterized in that The anode material includes at least one of iridium dioxide-insoluble anode, platinum, carbon paper, and graphite; The cathode material includes at least one of nickel foam and nickel sheet.

7. The method according to claim 1, characterized in that In the supporting electrolyte, the concentration of the halide salt is 0.1-0.5M, preferably 0.15-0.5M, for example, 0.3-0.5M, etc., the concentration of the carbonate is 0.1-0.4M, for example, 0.2M, etc., the concentration of the inorganic passivating agent is 0-10mM, preferably (1 / 400)-0.01M, further preferably (1 / 400)-(1 / 150)M, and the volume ratio of water to N,N-dimethylformamide is not less than 1:1, preferably (8:2)-(6:4), for example, 7:3, etc.; The pH of the supporting electrolyte is 7.5-8.5, preferably 8.0-8.4; The current density under the constant current condition is 5-250 mA / cm 2 , further can be 10-250mA / cm 2 .

8. The method according to claim 1, characterized in that The molar ratio of the halide salt to the inorganic passivating agent is 1:0-200, preferably 1:50-200.

9. The method according to claim 1, characterized in that: Carbon dioxide is introduced into the supporting electrolyte until saturation occurs, circulation of the supporting electrolyte is started, gaseous olefins and / or liquid olefins are introduced into the membraneless flow reactor during constant current electrolysis, and carbon dioxide is introduced into the supporting electrolyte; After the electrolysis time is over, carbon dioxide is continued to be introduced, with or without the introduction of gaseous olefins, and the reaction stops when the active halogen is completely consumed, and cyclic carbonate is obtained in one pot.

10. Use of the method according to any one of claims 1 to 9 in the preparation of cyclic carbonates.

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