Difunctional composite membrane for preparing carbon monoxide and co-producing chlorine and carbonate by electrolyzing carbon dioxide and use method of difunctional composite membrane

Abstract

The invention relates to a bifunctional composite membrane which is formed by overlapping and compounding a cation exchange layer and a hydrophobic porous layer, the cation exchange layer has a function of selectively passing through cations, and the hydrophobic porous layer has a function of inhibiting water molecules from passing through. The use method of the difunctional composite membrane comprises the following steps: dividing an electrolytic tank into an anode chamber and a cathode chamber by using the difunctional composite membrane, enabling the cation exchange layer to face one side of the anode chamber, enabling the hydrophobic porous layer to face one side of the cathode chamber, injecting an aqueous solution containing metal chloride into the anode chamber, injecting an organic electrolyte dissolved with carbon dioxide into the cathode chamber, and carrying out electrolysis to obtain the difunctional composite membrane. In the electrolytic reaction process, chloride ions in the anolyte are subjected to oxidation reaction to generate chlorine, carbon dioxide in the catholyte is subjected to reduction reaction to generate carbon monoxide and carbonate ions, and metal cations in the anolyte penetrate through the bifunctional composite membrane, enter the cathode chamber and are combined with carbonate to generate carbonate; the obtained carbon monoxide and chlorine are used for synthesizing phosgene. The electrolytic tank constructed on the basis of the difunctional composite membrane has the advantages of compact structure, convenience in operation, easiness in large-scale production and the like.

Description

Technical Field

[0001] The invention relates to a dual-function composite membrane for electrolyzing carbon dioxide to prepare carbon monoxide and co-produce chlorine and carbonate, belonging to the technical field of carbon dioxide electric reduction and carbonate preparation. Background Art

[0002] Since the Industrial Revolution, the massive consumption of fossil fuels has led to a continuous increase in global carbon dioxide emissions, exacerbating global warming. Using renewable energy to electrolyze carbon dioxide into value-added chemicals is a green and sustainable way to utilize carbon resources, which can synergistically solve important problems such as carbon emission reduction, energy conversion and pollution control. Carbon dioxide can be electrolyzed into a variety of chemicals, among which carbon monoxide has attracted much attention due to its high added value, simple electroreduction path and wide application in synthetic chemistry. At present, the reaction devices for electroreduction of carbon dioxide to carbon monoxide mainly include H-type electrolytic cells, gas diffusion electrode electrolytic cells and solid oxide electrolytic cells. They have disadvantages such as low carbon dioxide electroreduction efficiency, unstable electrolytic cell performance and excessive energy consumption, which are difficult to meet the requirements of industrial applications.

[0003] Electrochemical membranes are widely used in carbon dioxide electroreduction research. They are the core components of electrolytic cell systems and have a crucial impact on the carbon dioxide electroreduction reaction. In the field of carbon dioxide electroreduction research, there are four main types of electrochemical membranes commonly used: cation exchange membranes, anion exchange membranes, porous membranes, and bipolar membranes. However, to date, no electrochemical membrane has been able to achieve large-scale industrial application. Therefore, the development of new electrochemical membranes to construct new electrolytic cell systems is a major practical issue that urgently needs to be addressed in carbon dioxide electroreduction research. Summary of the Invention

[0004] To address the problems and shortcomings of existing technologies, the present invention provides a bifunctional composite membrane. Based on this membrane, a diaphragm electrolysis cell system is constructed for the electrolysis of carbon dioxide to produce carbon monoxide and co-produce chlorine and carbonates. This invention is achieved through the following technical solutions: a cation exchange layer and a hydrophobic porous layer are superimposed and composited together using methods such as hot pressing, solution casting, interfacial grafting and crosslinking, electrostatic layer self-assembly, blending and composite film drawing, or in-situ polymerization to form an integrated bifunctional composite membrane. This bifunctional composite membrane is used to separate the electrolytic cell into a cathode chamber and an anode chamber, wherein the cation exchange layer faces the anode chamber side, and the hydrophobic porous layer faces the cathode chamber side. The electrolyte in the anode chamber is an aqueous solution containing metal chloride, and the electrolyte in the cathode chamber is an organic electrolyte dissolved with carbon dioxide. During the electrolysis reaction, chloride ions are oxidized to chlorine gas at the anode, and the metal cations pass through the bifunctional composite membrane and migrate into the cathode chamber. The carbon dioxide undergoes an electroreduction reaction at the cathode to generate carbon monoxide and carbonate ions. The latter combines with the metal cations that migrate into the cathode chamber to form a carbonate precipitate, which is separated by filtration or water washing extraction.

[0005] The bifunctional composite membrane plays a key role in the electrolysis process, which is mainly manifested in the following aspects: First, the cation exchange layer of the bifunctional composite membrane allows cations to pass through but not anions, so the bifunctional composite membrane has a cation selective permeability function; Second, the introduction of a hydrophobic porous layer into the bifunctional composite membrane can reduce the amount of water migrating from the anode chamber to the cathode chamber, so the bifunctional composite membrane has a water-blocking effect. This method can reduce the water content in the organic electrolyte, inhibit the occurrence of hydrogen evolution side reactions, and improve the Faradaic efficiency of the carbon dioxide electroreduction reaction; Third, the bifunctional composite membrane can prevent the cathode gas phase reaction products from mixing with the anode gas phase reaction products, thereby ensuring the purity of the products and the safety of the system; Fourth, the bifunctional composite membrane has a compact structure, which reduces the total resistance of the electrolytic cell and the difficulty of assembly, and improves the long-term stability of the system operation;

[0006] For the bifunctional composite membrane, the cation exchange layer that meets the technical requirements is a polystyrene sulfonic acid layer, a sulfonated polyethylene layer, a sulfonated polyetheretherketone layer, a sulfonated polyvinylidene fluoride layer, a perfluorosulfonic acid type cation exchange layer, and one of sulfonated polybenzimidazole, sulfonated polysulfone, sulfonated polyarylethersulfone, sulfonated polyaryletherketone or chitosan modified layer, and the thickness of the cation exchange layer is 20 to 200 microns; the hydrophobic porous layer that meets the technical requirements is one of a polytetrafluoroethylene porous layer, a polyethylene porous layer, a polyvinylidene fluoride porous layer, a polypropylene porous layer, a polysulfone porous layer, a polyimide porous layer or a polyetherimide porous layer, and the thickness of the hydrophobic porous layer is 10 to 200 microns.

[0007] For diaphragm electrolytic cells constructed with bifunctional composite membranes, the catholyte that meets the technical requirements is an organic electrolyte composed of three functional components: an organic solvent, a supporting electrolyte, and an additive. The organic solvent that meets the technical requirements is one of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, tetrahydrofuran, 1,2-dimethoxyethane, acetonitrile, dimethyl sulfoxide, thioacetamide, N,N-dimethylformamide, and N-methylpyrrolidone, or a mixture of the above solvents in any proportion. The supporting electrolyte that meets the technical requirements is a quaternary ammonium salt or an ionic liquid, or a mixture of the above electrolytes in any proportion. The additive that meets the technical requirements is one of imidazole, pyridine, triethylamine, metalloporphyrin, metal phthalocyanine, and water, or a mixture of the above additives in any proportion.

[0008] The chemical structure of quaternary ammonium salt as supporting electrolyte of organic electrolyte is:

[0009]

[0010] R1, R2, R3, R4 are C1-C5 hydrocarbon chains, X - NC-N-CN - CF3SO3 - 、ClO4 - 、(CF3SO2)2N - CF3COO - 、H2PO4 - 、HCO3 - 、Cl - 、HSO4 - Br - , I - Any one of .

[0011] There are two main types of ionic liquids used as supporting electrolytes for organic electrolytes: imidazole ionic liquids and pyridine ionic liquids. The chemical structure of imidazole ionic liquids is:

[0012]

[0013] R1 and R2 are C1-C5 hydrocarbon chains; M and N are hydrogen atoms or functional groups connected to the hydrocarbon chains, and the functional groups are: -CN, -NH2 or -OH; X - NC-N-CN - 、(CF3SO2)2N - CF3COO - CF3SO3 - 、HCO3 - 、HSO4 - 、H2PO4 - Br -、Cl - Any one of .

[0014] The structural formula of pyridine ionic liquid is:

[0015]

[0016] R is a C1-C5 hydrocarbon chain, M is a functional group or hydrogen atom connected to the hydrocarbon chain, and the functional group is: -NH2, -CN or -OH; X - NC-N-CN - CF3SO3 - CF3COO - 、(CF3SO2)2N - 、HCO3 - 、H2PO4 - 、HSO4 - 、Cl - Br - , I - Any one of .

[0017] The metal porphyrin compound used as an organic electrolyte additive has the chemical formula:

[0018]

[0019] M1 is any one of iron, cobalt, and nickel, and R1, R2, R3, and R4 are hydrogen atoms or C1-C5 hydrocarbon chains, or benzene substituents.

[0020] The metal phthalocyanine compound used as an organic electrolyte additive has the following chemical structure:

[0021]

[0022] M2 is iron, manganese, copper or nickel.

[0023] For a diaphragm electrolytic cell constructed based on a bifunctional composite membrane, the anode electrolyte that meets the technical requirements is a metal chloride aqueous solution, and the metal chloride that meets the technical requirements is one of sodium chloride, potassium chloride, lithium chloride, and rubidium chloride, or a mixture of the above metal chlorides in any proportion.

[0024] The diaphragm electrolytic cell constructed based on a bifunctional composite membrane has a cathode that meets the technical requirements and is one of copper, silver, gold, zinc, gallium, indium, and nickel electrodes, or an alloy electrode composed of the above metals in any proportion, and the anode is any of a coated titanium electrode, a graphite electrode, and a conductive ceramic electrode.

[0025] Specific operating steps of the present invention

[0026] Step 1: preparing an integrated dual-functional composite membrane by methods such as hot pressing, solution casting, interface grafting and cross-linking, electrostatic layer self-assembly, blending and drawing, composite drawing or in-situ polymerization;

[0027] Step 2: Using a bifunctional composite membrane to separate the electrolytic cell into a cathode chamber and an anode chamber, the cation exchange layer of the bifunctional composite membrane faces the anode chamber, and the hydrophobic porous layer faces the cathode chamber. An anode and a cathode are set in the electrolytic cell, and an organic electrolyte containing carbon dioxide is injected into the cathode chamber. The organic electrolyte contains a supporting electrolyte and an additive, wherein the concentration of the supporting electrolyte is 0.1 to 5.0 mol / L and the concentration of the additive is 1 to 300 mmol / L. The electrolyte in the anode chamber is a metal chloride aqueous solution with a concentration of 5% to 81%;

[0028] Step 3: Power on to start the electrolysis process, controlling the cell voltage to 3.9-8.0V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide reduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. The metal ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate carbonates.

[0029] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the carbonate precipitate is separated by filtration or water washing extraction. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing the metal chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0030] The present invention provides a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate, and a method for using the membrane. The membrane is a complete technical system, in which the various components have a synergistic coupling mechanism of mutual influence and mutual restriction, and are inseparable from each other.

[0031] Beneficial effects of the present invention

[0032] (1) Improved the current efficiency of the carbon dioxide electroreduction reaction: Since the bifunctional composite membrane has a water-blocking effect, the water content in the cathode electrolyte is reduced, the hydrogen evolution side reaction is suppressed, and the current efficiency of the carbon dioxide electroreduction reaction is improved, overcoming the serious problem of hydrogen evolution side reaction in traditional aqueous phase systems.

[0033] (2) Improved service life of the membrane: The introduction of a hydrophobic porous layer into the bifunctional composite membrane can avoid direct contact between the organic electrolyte and the cation exchange layer, preventing it from deforming and failing due to swelling or chemical erosion, thereby improving the service life of the bifunctional composite membrane and reducing operation and maintenance costs.

[0034] (3) Improved structural stability of the electrolytic cell: The dual-function composite membrane electrolytic cell proposed in the present invention has the advantages of simple structure, good sealing, and easy maintenance, which is conducive to the long-term stable operation of the electrolytic cell.

[0035] (4) Improved product added value of carbon dioxide electroreduction technology: The diaphragm electrolysis cell system constructed based on the dual-functional composite membrane can produce chlorine and carbonates while electrolyzing carbon dioxide to produce carbon monoxide. The obtained carbon monoxide and chlorine are used to synthesize phosgene. Phosgene and carbonates are high-value-added chemicals. Through this method, economic benefits can be created and carbon dioxide electroreduction technology can be promoted from basic research to industrial application.

[0036] (5) Achieved carbon dioxide emission reduction in the phosgene chemical industry: The traditional method uses coal as a carbon source to produce phosgene, while this patent uses carbon dioxide as a carbon source to produce phosgene. The latter has the advantages of a short process flow, simple operation method, low production cost, easy start and stop, and no pollutant emissions, which can greatly reduce carbon dioxide emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of a dual-function composite membrane electrolytic cell system.

[0038] In the figure: 1-gas absorption tower, 2-cathode, 3-dual-function composite membrane, 4-hydrophobic porous layer, 5-cation exchange layer, 6-anode, 7-liquid storage tank. Specific implementation methods

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0042] Step 1: Using a 200-micron-thick polystyrene sulfonic acid cation exchange layer and a 10-micron-thick polytetrafluoroethylene hydrophobic porous layer, a bifunctional composite membrane is prepared by hot-pressing. This composite membrane is used to separate the electrolytic cell into a cathode chamber and an anode chamber, with the cation exchange layer facing the anode chamber and the hydrophobic porous layer facing the cathode chamber.

[0043] Step 2: A gold electrode is used as the cathode, an IrO2-coated titanium electrode is used as the anode, a 0.1 mol / L tetrabutylammonium chloride / propylene carbonate solution containing carbon dioxide is used as the cathode electrolyte, the concentration of the additive cobalt phthalocyanine is 1 mmol / L, and a 35% sodium chloride aqueous solution is used as the anode electrolyte;

[0044] Step 3: Power on to start the electrolysis process, controlling the cell voltage at 3.9V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. Sodium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate sodium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 94.2%, and the current density is maintained at 93mA / cm 2 ;

[0045] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the sodium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte circulation. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing sodium chloride, it is passed into the bottom of the anode chamber again to form an anode electrolyte circulation.

[0046] Example 2

[0047] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0048] Step 1: Using a 200-μm-thick sulfonated polyaryletherketone (SPEK) as a cation exchange layer and a 200-μm-thick polyetherimide (PEI) as a hydrophobic porous layer, a bifunctional composite membrane is prepared by a blending and drawing method. This composite membrane is used to separate the electrolytic cell into a cathode chamber and an anode chamber, wherein the cation exchange layer faces the anode chamber and the hydrophobic porous layer faces the cathode chamber.

[0049] Step 2: Using a silver electrode as the cathode, an IrO2 / RuO2 coated titanium electrode as the anode, a 1.0 mol / L tetrabutyl trifluoromethanesulfonic acid / N-methylpyrrolidone solution containing dissolved carbon dioxide as the cathode electrolyte, a 100 mmol / L cobalt porphyrin additive, and an 81% lithium chloride aqueous solution as the anode electrolyte;

[0050] Step 3: Power on to start the electrolysis process, controlling the cell voltage to 8.0V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. Lithium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate lithium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 91.1%, and the current density is maintained at 116.2 mA / cm 2 ;

[0051] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the lithium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing lithium chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0052] Example 3

[0053] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0054] Step 1: Prepare a bifunctional composite membrane by solution casting using a 200-micron thick sulfonated polyethylene layer as a cation exchange layer and a 50-micron thick polyethylene layer as a hydrophobic porous layer. Use this composite membrane to separate the electrolytic cell into a cathode chamber and an anode chamber, wherein the cation exchange layer faces the anode chamber and the hydrophobic porous layer faces the cathode chamber.

[0055] Step 2: Using a zinc electrode as the cathode, a graphite electrode as the anode, a 5 mol / L tetraethylammonium chloride / propylene carbonate solution containing dissolved carbon dioxide as the cathode electrolyte, a 50 mmol / L cobalt porphyrin additive, and a 20% potassium chloride aqueous solution as the anode electrolyte;

[0056] Step 3: Power on to start the electrolysis process, controlling the cell voltage at 6.5V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. Potassium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate potassium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 94.6%, and the current density is maintained at 103.2 mA / cm 2 ;

[0057] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the potassium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing potassium chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0058] Example 4

[0059] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0060] Step 1: Using a 180-micron-thick sulfonated polyetheretherketone layer as a cation exchange layer and a 100-micron-thick polypropylene layer as a hydrophobic porous layer, a bifunctional composite membrane is prepared by electrostatic layer self-assembly. This composite membrane is used to separate the electrolytic cell into a cathode chamber and an anode chamber, wherein the cation exchange layer faces the anode chamber and the hydrophobic porous layer faces the cathode chamber.

[0061] Step 2: A gallium electrode is used as the cathode, a tin dioxide conductive ceramic is used as the anode, a 1.2 mol / L N-methylpyridinium salt / tetrahydrofuran solution containing dissolved carbon dioxide is used as the cathode electrolyte, a manganese porphyrin additive has a concentration of 30 mmol / L, and a 26% rubidium chloride aqueous solution is used as the anode electrolyte;

[0062] Step 3: Power on to start the electrolysis process, controlling the cell voltage at 6.6V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. The rubidium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate rubidium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 89%, and the current density is maintained at 95.3mA / cm 2 ;

[0063] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the rubidium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower for dissolving and absorbing carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing metal rubidium chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0064] Example 5

[0065] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0066] Step 1: Using 120 micrometers of sulfonated polyvinylidene fluoride as a cation exchange layer and 50 micrometers of polyethylene as a hydrophobic porous layer, a bifunctional composite membrane is prepared by interfacial grafting and crosslinking. This composite membrane is used to separate the electrolytic cell into a cathode chamber and an anode chamber, wherein the cation exchange layer faces the anode chamber and the hydrophobic porous layer faces the cathode chamber;

[0067] Step 2: A zinc / copper alloy electrode containing 34% zinc is used as the cathode, an IrO2-coated titanium electrode is used as the anode, a 5.0 mol / L tetraethylammonium chloride / propylene carbonate solution containing dissolved carbon dioxide is used as the cathode compartment electrolyte, the concentration of the additive iron phthalocyanine is 55.5 mmol / L, and a 53% lithium chloride aqueous solution is used as the anode compartment electrolyte;

[0068] Step 3: Power on to start the electrolysis process, controlling the cell voltage at 5.8V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. Lithium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate lithium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 90.6%, and the current density is maintained at 93.5 mA / cm 2 ;

[0069] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the lithium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing lithium chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0070] Example 6

[0071] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0072] Step 1: Prepare a bifunctional composite membrane by in situ polymerization using a 125-μm-thick perfluorosulfonic acid cation exchange layer as the cation exchange layer and a 150-μm-thick polytetrafluoroethylene hydrophobic porous layer. Use this composite membrane to separate the electrolytic cell into a cathode chamber and an anode chamber, with the cation exchange layer facing the anode chamber and the hydrophobic porous layer facing the cathode chamber.

[0073] Step 2: Using an Au / Cu alloy electrode as the cathode, graphite as the anode, a 4.8 mol / L tetrabutylammonium chloride solution containing carbon dioxide as the cathode electrolyte (the organic solvent is a propylene carbonate solution containing 5% acetonitrile), a 42 mmol / L nickel phthalocyanine additive, and a 34% sodium chloride aqueous solution as the anode electrolyte;

[0074] Step three, start electrolysis process by power on, control cell voltage at 7.5V, chlorine ion oxidation reaction occurs on anode to generate chlorine, carbon dioxide electro-reduction reaction occurs on cathode to generate carbon monoxide and carbonate ion, sodium ion in anode chamber penetrates through the dual-function composite membrane into cathode chamber to combine with carbonate ion to generate sodium carbonate, 24-hour long-period electrolysis experiment result shows that current efficiency of carbon monoxide generation reaches 89.6%, current density is maintained at 103.5mA / cm 2 ;

[0075] Step four, organic electrolyte flows out from the upper part of cathode chamber during electrolysis reaction, sodium carbonate precipitate is separated by filtration, separated precipitate is introduced into gas absorption tower to dissolve and absorb carbon dioxide, carbon dioxide-dissolved organic electrolyte is introduced into the bottom of cathode chamber to form cathode electrolyte circulation, at the same time, electrolyte discharged from the upper part of anode chamber is collected in liquid storage tank, after supplement of sodium chloride, it is introduced into the bottom of anode chamber again to form anode electrolyte circulation.

[0076] Example 7

[0077] As shown in Figure 1 , a dual-function composite membrane for electrolysis of carbon dioxide to generate carbon monoxide, chlorine and carbonate, and a method of using the same, the specific operation steps are as follows:

[0078] Step one, a dual-function composite membrane is prepared by solution casting method with sulfonated polybenzimidazole with a thickness of 100 microns as cation exchange layer and polyimide with a thickness of 150 microns as hydrophobic porous layer, the electrolytic cell is separated into cathode chamber and anode chamber by the composite membrane, wherein the cation exchange layer faces the anode chamber side and the hydrophobic porous layer faces the cathode chamber side;

[0079] Step two, gold electrode is used as cathode, conductive ceramic electrode is used as anode, 4.2mol / L N-methylpyridinium salt / 1,2-dimethoxyethane solution dissolved with carbon dioxide is used as cathode chamber electrolyte, the concentration of additive copper phthalocyanine is 79mmol / L, and 40% potassium chloride aqueous solution is used as anode chamber electrolyte;

[0080] Step three, start electrolysis process by power on, control cell voltage at 5.7V, chlorine ion oxidation reaction occurs on anode to generate chlorine, carbon dioxide electro-reduction reaction occurs on cathode to generate carbon monoxide and carbonate ion, potassium ion in anode chamber penetrates through the dual-function composite membrane into cathode chamber to combine with carbonate ion to generate potassium carbonate, 24-hour long-period electrolysis experiment result shows that current efficiency of carbon monoxide generation reaches 84.9%, current density is maintained at 79.6mA / cm 2 ;

[0081] Step four, during the electrolysis process, the organic electrolyte flows out from the upper part of the cathode chamber, and the potassium carbonate precipitate is separated by filtration. The separated organic electrolyte enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte containing dissolved carbon dioxide is introduced into the bottom of the cathode chamber to form a cathode electrolyte circulation. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a storage tank, supplemented with lithium chloride, and then introduced into the bottom of the anode chamber to form an anode electrolyte circulation.

[0082] Example 8

[0083] As Figure 1 shown, a bifunctional composite membrane for electrolyzing carbon dioxide to produce carbon monoxide, co-produced chlorine and carbonate, and a method of using the same, the specific operation steps are as follows:

[0084] Step one, a sulfonated polyvinylidene fluoride layer with a thickness of 180 microns is used as the cation exchange layer, and a polyether sulfone porous layer with a thickness of 90 microns is used as the hydrophobic porous layer. A bifunctional composite membrane is prepared by blending and drawing the membrane. The electrolytic cell is divided into a cathode chamber and an anode chamber by using this composite membrane, wherein the cation exchange layer faces the anode chamber side, and the hydrophobic porous layer faces the cathode chamber side.

[0085] Step two, a silver electrode is used as the cathode, an IrO2-coated titanium electrode is used as the anode, and a 3.6 mol / L tetraethylammonium bromide solution containing dissolved carbon dioxide is used as the cathode chamber electrolyte (the organic solvent is a propylene carbonate mixed solvent containing 8% dimethyl sulfoxide), the concentration of the additive copper porphyrin is 35 mmol / L, and a 72% lithium chloride aqueous solution is used as the anode chamber electrolyte.

[0086] Step three, the electrolysis process is started by applying electricity, and the cell voltage is controlled at 6.2V. Chloride ion oxidation reaction occurs on the anode to generate chlorine, and carbon dioxide electro-reduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. Lithium ions in the anode chamber pass through the bifunctional composite membrane into the cathode chamber, combine with carbonate ions to form lithium carbonate. The results of a 24-hour long-period electrolysis experiment show that the current efficiency of generating carbon monoxide reaches 87.6%, and the current density remains at 89.6 mA / cm 2 ;

[0087] Step four, during the electrolysis process, the organic electrolyte flows out from the upper part of the cathode chamber, and the lithium carbonate precipitate is separated by filtration. The separated organic electrolyte enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte containing dissolved carbon dioxide is introduced into the bottom of the cathode chamber to form a cathode electrolyte circulation. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a storage tank, supplemented with lithium chloride, and then introduced into the bottom of the anode chamber to form an anode electrolyte circulation.

[0088] Example 9

[0089] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0090] Step 1: Using a 120-micron-thick sulfonated polybenzimidazole as a cation exchange layer and a 160-micron-thick polyvinylidene fluoride as a hydrophobic porous layer, a bifunctional composite membrane is prepared by hot pressing. This composite membrane is used to separate the electrolytic cell into a cathode chamber and an anode chamber, wherein the cation exchange layer faces the anode chamber and the hydrophobic porous layer faces the cathode chamber;

[0091] Step 2: A zinc / silver alloy electrode containing 16% zinc is used as the cathode, an IrO2 / RuO2 coated titanium electrode is used as the anode, a 3.1 mol / L pyridine tetrafluoroborate / dimethyl sulfoxide solution containing dissolved carbon dioxide is used as the cathode chamber electrolyte, the concentration of the additive zinc phthalocyanine is 100 mmol / L, and a 5% rubidium chloride aqueous solution is used as the anode chamber electrolyte;

[0092] Step 3: Power on to start the electrolysis process, controlling the cell voltage to 7.9V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. The rubidium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate rubidium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 72.6%, and the current density is maintained at 110.2 mA / cm 2 ;

[0093] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the rubidium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower for dissolving and absorbing carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing rubidium chloride, it is passed into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0094] Example 10

[0095] like Figure 1 As shown, a dual-function composite membrane for electrolyzing carbon dioxide to produce carbon monoxide and co-producing chlorine and carbonate and a method for using the same, the specific operating steps are as follows:

[0096] Step 1: Prepare a bifunctional composite membrane by solution casting using a 190-micron-thick sulfonated polyarylethersulfone cation exchange layer and a 200-micron-thick polytetrafluoroethylene porous layer as a hydrophobic porous layer. Use this composite membrane to separate the electrolytic cell into a cathode chamber and an anode chamber, with the cation exchange layer facing the anode chamber and the hydrophobic porous layer facing the cathode chamber.

[0097] Step 2: A silver / nickel alloy electrode containing 60% silver was used as the cathode, a graphite electrode was used as the anode, a 2.5 mol / L tetrabutylammonium trifluoromethanesulfonate solution containing carbon dioxide was used as the cathode electrolyte (the solvent was an acetonitrile solution containing 20% ​​ethylene carbonate), an additive water concentration of 300 mmol / L, and a 45% lithium chloride aqueous solution was used as the anode electrolyte;

[0098] Step 3: Power on to start the electrolysis process, controlling the cell voltage to 4.6V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide electroreduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. Lithium ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate lithium carbonate. The results of the 24-hour long-cycle electrolysis experiment show that the current efficiency of carbon monoxide generation reaches 92.8%, and the current density is maintained at 96.8 mA / cm 2 ;

[0099] Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the lithium carbonate precipitate is separated by filtration. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing lithium chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

[0100] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide and a method for using the same, characterized by: The bifunctional composite membrane is composed of a cation exchange layer and a hydrophobic porous layer stacked and composited. The cation exchange layer has the function of selectively passing cations, and the hydrophobic porous layer has the function of inhibiting the passage of water molecules. The two functional layers are prepared into an integrated bifunctional composite membrane by methods such as hot pressing composite, solution casting, interface grafting and cross-linking, electrostatic layer self-assembly, blended membrane pulling, composite membrane pulling or in-situ polymerization.

2. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to claim 1, and the method for using the same, are characterized by: The cation exchange layer of the bifunctional composite membrane is a polystyrene sulfonic acid layer, a sulfonated polyethylene layer, a sulfonated polyetheretherketone layer, a sulfonated polyvinylidene fluoride layer, a perfluorosulfonic acid type cation exchange layer, and one of sulfonated polybenzimidazole, sulfonated polysulfone, sulfonated polyarylethersulfone, sulfonated polyaryletherketone and chitosan modified layer. The thickness of the cation exchange layer is 20 to 200 microns.

3. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to claim 1 and the method for using the same are characterized by: The hydrophobic porous layer of the bifunctional composite membrane is one of a polytetrafluoroethylene porous layer, a polyethylene porous layer, a polyvinylidene fluoride porous layer, a polypropylene porous layer, a polysulfone porous layer, a polyimide porous layer or a polyetherimide porous layer, and the thickness of the hydrophobic porous layer is 10 to 200 microns.

4. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to claim 1 and the method for using the same are characterized by: The electrolytic cell is divided into a cathode chamber and an anode chamber by a bifunctional composite membrane, wherein the cation exchange layer faces the anode chamber, and the hydrophobic porous layer faces the cathode chamber. An aqueous solution containing metal chloride is injected into the anode chamber, and an organic electrolyte containing carbon dioxide is injected into the cathode chamber. During the electrolysis reaction, the chloride ions in the anode chamber undergo an oxidation reaction to generate chlorine gas, and the carbon dioxide in the cathode chamber undergoes a reduction reaction to generate carbon monoxide and carbonate ions. The metal cations in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with the carbonate ions to generate carbonates.

5. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to claim 1 and the method for using the same are characterized by: The diaphragm electrolytic cell constructed based on a bifunctional composite membrane has an organic electrolyte in the cathode chamber, which is composed of three functional components: an organic solvent, a supporting electrolyte and an additive. The organic solvent that meets the technical requirements is one of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, tetrahydrofuran, 1,2-dimethoxyethane, acetonitrile, dimethyl sulfoxide, thioacetamide, N,N-dimethylformamide, and N-methylpyrrolidone, or a mixed solvent composed of the above solvents in any proportion. The supporting electrolyte that meets the technical requirements is a quaternary ammonium salt, an imidazole ionic liquid or a pyridine ionic liquid, or a mixture of the above electrolytes in any proportion. The additive that meets the technical requirements is one of imidazole, pyridine, triethylamine, metal porphyrin, metal phthalocyanine, and water, or a mixture of the above additives in any proportion.

6. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to claim 1 and the method for using the same are characterized by: The diaphragm electrolytic cell constructed based on a bifunctional composite membrane has an anode chamber electrolyte that is a metal chloride aqueous solution. The metal chloride that meets the technical requirements is one of sodium chloride, potassium chloride, lithium chloride, and rubidium chloride, or a mixture of the above metal chlorides in any proportion.

7. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to claim 1 and the method for using the same are characterized by: The diaphragm electrolytic cell constructed based on a bifunctional composite membrane has a cathode that is one of copper, silver, gold, zinc, gallium, indium, and nickel electrodes, or an alloy electrode composed of the above metals in any proportion, and an anode that is any of a coated titanium electrode, a graphite electrode, and a conductive ceramic electrode.

8. The dual-function composite membrane for producing carbon monoxide and chlorine and carbonate by electrolysis of carbon dioxide according to any one of claims 1 to 7 and the method for using the same, characterized in that The specific implementation steps are as follows: Step 1: preparing an integrated dual-functional composite membrane by methods such as hot pressing, solution casting, interface grafting and cross-linking, electrostatic layer self-assembly, blending and drawing, composite drawing or in-situ polymerization; Step 2: Using a bifunctional composite membrane to separate the electrolytic cell into a cathode chamber and an anode chamber, the cation exchange layer of the bifunctional composite membrane faces the anode chamber, and the hydrophobic porous layer faces the cathode chamber. An anode and a cathode are set in the electrolytic cell, and an organic electrolyte containing carbon dioxide is injected into the cathode chamber. The organic electrolyte contains a supporting electrolyte and an additive, wherein the concentration of the supporting electrolyte is 0.1 to 5.0 mol / L and the concentration of the additive is 1 to 300 mmol / L. The electrolyte in the anode chamber is a metal chloride aqueous solution with a concentration of 5% to 81%; Step 3: Power on to start the electrolysis process, controlling the cell voltage to 3.9-8.0V. Chloride ion oxidation reaction occurs on the anode to generate chlorine gas, and carbon dioxide reduction reaction occurs on the cathode to generate carbon monoxide and carbonate ions. The metal ions in the anode chamber pass through the bifunctional composite membrane and enter the cathode chamber, where they combine with carbonate ions to generate carbonates. Step 4: During the electrolysis reaction, the organic electrolyte flows out from the upper part of the cathode chamber, and the carbonate precipitate is separated by filtration or water washing extraction. The organic electrolyte after separation and precipitation enters the gas absorption tower to dissolve and absorb carbon dioxide. The organic electrolyte dissolved in carbon dioxide is introduced from the gas absorption tower into the bottom of the cathode chamber to form a cathode electrolyte cycle. At the same time, the electrolyte discharged from the upper part of the anode chamber is collected in a liquid storage tank, and after replenishing the metal chloride, it is introduced into the bottom of the anode chamber again to form an anode electrolyte cycle.

Images