Electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane and application of electrochemical carbon dioxide reduction device

Abstract

The invention relates to an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane and application of the electrochemical carbon dioxide reduction device, and belongs to the fields of electrochemistry, carbon dioxide utilization and renewable energy sources. The device comprises an anode for catalyzing an oxygen evolution reaction, a cathode formed by a gas diffusion electrode, an extraction chamber arranged between the anode and the cathode, a cation exchange membrane covering the surface of the anode, a diaphragm covering the surface of the cathode, and ion exchange resin filled in the extraction chamber and used as a solid electrolyte. The device is used for a carbon dioxide reduction reaction, and an extracting solution can be used in an extracting chamber to extract a liquid product solution of carbon dioxide reduction; the components of the liquid product solution only contain the components of the extracting solution and the components of the liquid product. Based on the invention, the use of expensive prefabricated anion exchange membranes with unstable acidic conditions can be avoided, a product with higher purity of a liquid product can be directly obtained, and an additional operation unit for separating the liquid product from metal cations can be omitted.

Description

Technical Field

[0001] The invention belongs to the fields of electrochemistry, carbon dioxide utilization and renewable energy, and particularly relates to an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane and application thereof. Background Art

[0002] Carbon dioxide (CO2) is one of the main greenhouse gases, and its large-scale emission is the main cause of global warming. Through electrochemical carbon dioxide reduction (CO2RR) technology, carbon dioxide can be converted into chemicals or fuels, such as formic acid, methanol, methane, etc. These products are widely used in the fields of chemical industry, medicine, energy, etc., providing a new source of resources for human society. In addition, with the gradual depletion of traditional petrochemical energy, the energy crisis is becoming increasingly severe. CO2RR technology can convert renewable energy (such as solar energy, wind energy, etc.) into fuel and store it, which is conducive to the development and utilization of renewable energy. It can be seen that CO2RR technology is in line with the concept of green, low-carbon and circular economic development.

[0003] Conventional CO2RR technology usually requires the use of high concentrations of alkali metal cations in the cathode liquid to suppress the hydrogen evolution side reaction. However, this will cause the liquid products of CO2RR, such as formic acid, acetic acid, ethanol, etc., to dissolve in the cathode liquid and mix with the high concentration of alkali metal cations. This requires additional, high-energy consumption operating units to separate the liquid products and metal cations to obtain products with higher liquid product purity.

[0004] Electrochemical carbon dioxide reduction devices equipped with solid electrolytes can solve the problem of mixing liquid products with high-concentration alkali metal cations, but their application is limited by the need to use high-cost prefabricated anion exchange membranes (AEMs). A typical electrochemical carbon dioxide reduction device equipped with a solid electrolyte requires an AEM to be covered on the cathode and a cation exchange membrane, CEM, to be covered on the anode. In the extraction chamber formed between the AEM and the CEM, an ion exchange resin is filled as a solid electrolyte layer. On the cathode side, the liquid product produced by the CO2RR reaction will pass through the AEM under the impetus of the electric field or the transmembrane concentration difference; while the protons produced by the oxygen evolution reaction pass through the CEM on the anode side. Pure water or humidified gas is introduced into the extract inlet of the extraction chamber, and a liquid product solution can be obtained at the extract outlet. In the prior art, it is necessary to use expensive prefabricated AEMs in electrochemical carbon dioxide reduction devices equipped with solid electrolytes, the purposes of which include: separating the liquid medium to prevent flooding of the cathode; inhibiting proton migration to improve CO2RR performance; and promoting the passage of charged liquid product ions through the membrane. However, these prefabricated AEMs have the following disadvantages: they are expensive, physically fragile, and do not rely on acidic conditions (while the pH in the solid electrolyte layer is extremely low due to the generation of small molecule organic acids). Therefore, there is an urgent need to develop an electrochemical CO2 reduction device without prefabricated anion exchange membranes. Summary of the invention

[0005] The purpose of the present invention is to provide an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane and its application in view of the deficiencies of the prior art. Specifically, the main components of the electrochemical carbon dioxide reduction device include an anode for catalyzing oxygen evolution reaction, a cathode composed of a gas diffusion electrode, an extraction chamber arranged between the anode and the cathode, a cation exchange membrane covering the surface of the anode, a diaphragm covering the surface of the cathode, and an ion exchange resin filled in the extraction chamber as a solid electrolyte. The main features of the electrochemical carbon dioxide reduction device are: no prefabricated anion exchange membrane; the diaphragm is not a prefabricated anion exchange membrane, but a cheap, porous, polymer film that is stable under acidic conditions.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present invention is: an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, comprising an anode for catalyzing an oxygen evolution reaction, a cathode composed of a gas diffusion electrode, an extraction chamber arranged between the anode and the cathode, an anode chamber arranged on the side of the cation exchange membrane away from the extraction chamber and used to assemble the anode, the extraction chamber is composed of a cation exchange membrane covering the surface of the anode and a diaphragm covering the surface of the cathode, the extraction chamber is filled with ion exchange resin as a solid electrolyte, and an extraction liquid is used in the extraction chamber to extract the liquid product of carbon dioxide reduction.

[0007] In one embodiment of the present invention, the membrane covering the cathode surface is not a prefabricated anion exchange membrane.

[0008] In one embodiment of the present invention, the separator covering the cathode surface is a cheap, porous, polymer film that is stable under acidic conditions and includes filter paper, polyvinylidene fluoride (PVDF), and tetrafluoroethylene (PTFE).

[0009] In one embodiment of the present invention, the cathode is modified with a catalyst to catalyze the reduction reaction of carbon dioxide to generate liquid products including formic acid, acetic acid, and ethanol.

[0010] In one embodiment of the present invention, the ion exchange resin is selected from a cation exchange resin or anion exchange resin having a predetermined particle size.

[0011] In one embodiment of the present invention, the extraction liquid is pure water or humidified gas.

[0012] In one embodiment of the present invention, the extraction chamber is provided with an extraction liquid inlet and an extraction liquid outlet.

[0013] In one embodiment of the present invention, anode liquid flows in the anode chamber.

[0014] In one embodiment of the present invention, the anolyte is an inorganic acid solution or pure water.

[0015] The present invention also provides an application of the above-mentioned electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, which is used for carbon dioxide reduction reaction, so that a liquid product solution including formic acid solution, acetic acid solution and ethanol solution is collected at the extraction liquid outlet of the extraction chamber, and the components of the liquid product solution only contain the components of the extraction liquid plus the components of the liquid product.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the electrochemical carbon dioxide reduction device proposed in the present invention can avoid the use of expensive prefabricated anion exchange membranes that are unstable under acidic conditions, can directly obtain products with higher liquid product purity, and can save additional operating units for separating liquid products and metal cations. The electrochemical carbon dioxide reduction device provided by the present invention is applied to carbon dioxide reduction reactions, and liquid product solutions such as formic acid solutions, acetic acid solutions, ethanol solutions, etc. can be collected at the outlet of the extract. The components of the liquid product solution only contain the components of the extract plus the components of the liquid product. For example, when the extract does not contain high-concentration alkali metal cations, the liquid product solution also does not contain high-concentration alkali metal cations. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 For the present invention Figure 1 It is a schematic structural diagram of an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane in a specific embodiment of the present invention.

[0018] Figure 2 It is a schematic diagram of the change of formic acid production when the diaphragm in the electrochemical carbon dioxide reduction device is removed in a specific embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the change of formic acid production when different diaphragms are used in the electrochemical carbon dioxide reduction device in a specific embodiment of the present invention.

[0020] Explanation of the reference numerals: 1 - cathode; 2 - diaphragm; 3 - extraction liquid outlet; 4 - solid electrolyte; 5 - cation exchange membrane; 6 - anode; 7 - anode chamber; 8 - extraction liquid inlet. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0022] The present invention provides an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, comprising an anode for catalyzing an oxygen evolution reaction, a cathode composed of a gas diffusion electrode, an extraction chamber arranged between the anode and the cathode, and an anode chamber arranged on the side of the cation exchange membrane away from the extraction chamber and used for assembling the anode. The extraction chamber is composed of a cation exchange membrane covering the surface of the anode and a diaphragm covering the surface of the cathode. The extraction chamber is filled with an ion exchange resin as a solid electrolyte, and an extraction liquid is used in the extraction chamber to extract a liquid product of carbon dioxide reduction.

[0023] The present invention also provides an application of the above-mentioned electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, which is used for carbon dioxide reduction reaction, so that a liquid product solution including formic acid solution, acetic acid solution and ethanol solution is collected at the extraction liquid outlet of the extraction chamber, and the components of the liquid product solution only contain the components of the extraction liquid plus the components of the liquid product.

[0024] The following are specific implementation examples of the present invention.

[0025] Example 1 In this embodiment, combined with Figure 1 , the structure of an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane in a specific embodiment of the present invention is described, which includes: Electrochemical carbon dioxide reduction device; The main components include an anode 6 for catalyzing the oxygen evolution reaction, a cathode 1 composed of a gas diffusion electrode, an extraction chamber arranged between the anode and the cathode, an extraction liquid outlet 3 and an extraction liquid inlet 8 arranged in the extraction chamber, a cation exchange membrane 5 covering the surface of the anode, a diaphragm 2 covering the surface of the cathode, an ion exchange resin filled in the extraction chamber as a solid electrolyte 4, and an anode chamber 7 for assembling the anode, which can be used to pass the anode liquid. The main feature of the electrochemical carbon dioxide reduction device is that there is no prefabricated anion exchange membrane. In addition, the diaphragm is not a prefabricated anion exchange membrane, but a cheap, porous, polymer film that is stable under acidic conditions. In the present invention, the preferred diaphragm is filter paper. In the present invention, the preferred solid electrolyte is a strongly acidic cation exchange resin.

[0026] The present invention discloses an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, which is applied to the carbon dioxide reduction reaction. On the cathode side, the liquid product produced by the CO2RR reaction will pass through the diaphragm under the impetus of the electric field or the concentration difference; while the protons produced by the oxygen evolution reaction pass through the CEM on the anode side. Since the anolyte is an inorganic acid solution or pure water, theoretically, only protons can cross the CEM to reach the extraction chamber. The preferred anolyte is 0.5 M H2SO4, which can provide more ions than pure water and reduce the internal resistance of the anode reaction. Pure water or humidified gas is introduced into the extraction liquid inlet of the extraction chamber, and a liquid product solution can be obtained at the extraction liquid outlet; the components of the liquid product solution only contain the components of the extraction liquid plus the components of the liquid product. In the present invention, pure water is used as the extractant.

[0027] Example 2 In this embodiment, combined with Figure 2 , the change in formic acid production when the diaphragm in the electrochemical carbon dioxide reduction device is removed in a specific embodiment of the present invention is described. When there is no diaphragm, the cathode is in direct contact with the solid electrolyte. The cathode is made by spraying a bismuth nanoparticle catalyst on a SGL carbon paper gas diffusion layer (39 BB). The anode is a platinum-plated titanium felt. The anode liquid is 100 ml of 0.5 M H2SO4 solution. Pure water enters the extraction chamber as the extraction liquid, flowing in one direction. The flow rate of CO2 supplied to the cathode is controlled to 50 mL min -1 ; Anolyte flow rate was 2 mL min -1 ; Extraction flow rate: 0.26 mLmin -1 The battery test system was used to power the electrochemical carbon dioxide reduction device to drive the CO2 reduction reaction. The currents were constant at 60 mA, 120 mA, 240 mA, 360 mA, 480 mA, 600 mA, and 720 mA, respectively. Considering the electrode area of ​​4 cm 2 , the current density can be calculated to be 15-180 mA cm -2 The samples at the outlet of the extract were collected and analyzed for formic acid concentration. The results showed that the formic acid concentration was 720 mA (current density mA cm -2 ), only 150 mM can be achieved, which is lower than the case in Example 3 below. Therefore, in an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, a diaphragm is very necessary.

[0028] Example 3 In this embodiment, combined with Figure 3, in a specific embodiment of the present invention, the change in formic acid production when different diaphragms are used in the electrochemical carbon dioxide reduction device is described. Different types of filter papers, including Whatman No. 1, No. 2, No. 4, No. 6, and No. 43 filter papers, are used as diaphragms and placed between the cathode and the solid electrolyte. The cathode is made by spraying bismuth nanoparticle catalyst on the SGL carbon paper gas diffusion layer (39 BB). The anode is platinum-plated titanium felt. The anode liquid is 100 ml of 0.5 M H2SO4 solution. The extraction chamber uses pure water as the extraction liquid, which flows in one direction. The flow rate of CO2 supplied to the cathode is controlled to 50 mL min -1 ; Anolyte flow rate was 2 mL min -1 ; Extraction flow rate: 0.26 mL min -1 The battery test system was used to power the electrochemical carbon dioxide reduction device to drive the CO2 reduction reaction. The currents were constant at 60 mA, 120 mA, 240 mA, 360 mA, 480 mA, 600 mA, and 720 mA, respectively. Considering the electrode area of ​​4 cm 2 , the current density can be calculated to be 15-180 mA cm -2 . Samples from the outlet of the extract were collected and analyzed for formic acid concentration. The results showed that when Whatman No. 1, No. 2, and No. 6 filter papers were used as diaphragms, their formic acid production performance was good and close, and the formic acid concentration increased with the increase of the current intensity applied in the electrochemical carbon dioxide reduction device, and could reach 380 mM. However, when Whatman No. 4 filter paper was used as a diaphragm, its performance was poor; when Whatman No. 43 filter paper was used as a diaphragm, its performance was poor at high current density. This result tells us that the performance of the electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane is affected by different diaphragm materials.

[0029] Although the present invention has been described in detail, modifications within the spirit and scope of the present invention will be apparent to those skilled in the art, and the above description is intended only as an example and is not intended to limit the present invention.

[0030] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions do not exceed the scope of the technical solution of the present invention, belong to the protection scope of the present invention.

Claims

1. An electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane, characterized in that: The invention comprises an anode for catalyzing oxygen evolution reaction, a cathode composed of a gas diffusion electrode, an extraction chamber arranged between the anode and the cathode, and an anode chamber arranged on the side of the cation exchange membrane away from the extraction chamber and used for assembling the anode. The extraction chamber is composed of a cation exchange membrane covering the surface of the anode and a diaphragm covering the surface of the cathode. The extraction chamber is filled with ion exchange resin as a solid electrolyte, and an extraction liquid is used in the extraction chamber to extract the liquid product of carbon dioxide reduction.

2. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 1, characterized in that: The diaphragm covering the cathode surface is not a prefabricated anion exchange membrane.

3. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 2, characterized in that: The diaphragm covering the cathode surface is a cheap, porous, polymer film that is stable under acidic conditions, including filter paper, polyvinylidene fluoride (PVDF), and tetrafluoroethylene (PTFE).

4. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 1, characterized in that: The cathode is modified with a catalyst to catalyze the reduction reaction of carbon dioxide to generate liquid products including formic acid, acetic acid and ethanol.

5. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 1, characterized in that: The ion exchange resin is selected from a cation exchange resin or anion exchange resin having a predetermined particle size.

6. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 1, characterized in that: The extraction liquid is pure water or humidified gas.

7. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 1, characterized in that: The extraction chamber is provided with an extraction liquid inlet and an extraction liquid outlet.

8. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 1, characterized in that: Anode liquid flows in the anode chamber.

9. The electrochemical carbon dioxide reduction device without prefabricated anion exchange membrane according to claim 8, characterized in that: The anolyte is an inorganic acid solution or pure water.

10. An application of an electrochemical carbon dioxide reduction device without a prefabricated anion exchange membrane according to any one of claims 1 to 9, characterized in that: Used for carbon dioxide reduction reaction, a liquid product solution including formic acid solution, acetic acid solution and ethanol solution is collected at the extraction liquid outlet of the extraction chamber, and the components of the liquid product solution only contain the components of the extraction liquid plus the components of the liquid product.

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