Method and device for recovering carbon loss by coupling carbon dioxide electrolysis

Abstract

The invention relates to the technical field of electrocatalytic carbon dioxide reduction, and particularly discloses a method and device for recovering carbon loss by coupling carbon dioxide electrolysis, and the device comprises a carbon dioxide electrolytic tank, a regeneration tank, a circulation system and a carbon dioxide recovery device; the method comprises the steps of cyclic regeneration of a redox medium and reduction and recovery of carbon dioxide. According to the invention, double electrolyzer systems are adopted to operate at the same time, and a carbon dioxide reduction reaction and an oxygen evolution reaction are separated spatially by utilizing a circulating system and an oxidation-reduction medium with electrochemical reversibility, so that carbon dioxide forming bicarbonate radicals or carbonate radicals is prevented from being mixed with oxygen generated by the oxygen evolution reaction again; therefore, the carbon dioxide is conveniently recovered, the carbon loss is reduced, and the energy consumption of system operation is reduced. Meanwhile, the device provided by the invention can maintain the surface environment of the carbon dioxide reduction reaction catalyst to be alkaline, and is beneficial to improving the selectivity of products.

Description

Technical Field

[0001] The present application relates to the technical field of electrocatalytic carbon dioxide reduction, and in particular to a method and device for coupling carbon dioxide electrolysis to recover carbon loss. Background Art

[0002] The consumption of fossil energy causes a large amount of CO2 emissions, which leads to serious greenhouse effects and environmental problems. Therefore, advanced CO2 conversion technologies are urgently needed to be developed. Electrochemical CO2 reduction reaction (CO2RR) uses electricity generated by renewable energy to drive the electrochemical fixation of CO2 and convert CO2 into high value-added chemical products. It is one of the effective ways to achieve comprehensive energy utilization and carbon emission reduction.

[0003] Membrane Electrode Assembly (MEA) is a widely used CO2 electrolyzer structure. The gas diffusion electrode can effectively overcome the limitation of CO2 mass transfer, thereby increasing the reaction rate. In addition, the zero-gap electrolyzer structure can shorten the ion path, reduce ohmic resistance, and effectively improve energy efficiency. Anion exchange membrane (AEM) is considered to be one of the most promising CO2 electrolysis membranes. Its advantage is that it can produce a local alkaline environment at the cathode interface, thereby inhibiting the competitive hydrogen evolution reaction (HER) while maintaining a low and stable operating voltage. However, due to the alkaline environment, most of the input CO2 reacts with OH - The reaction forms bicarbonate or carbonate. These ions can migrate across the AEM to the anode side under the action of the electric field and react with the protons (H + ) to form CO2 gas again. Further, CO2 mixes with O2 generated by the oxygen evolution reaction (OER), reducing the reaction efficiency and raw material utilization. Existing analysis shows that when CO2 is electro-reduced in an alkaline electrolyzer, more than 50% of the energy is used to recover CO2 to form bicarbonate or carbonate, significantly reducing energy efficiency.

[0004] In order to improve the carbon loss of CO2 electroreduction, the existing methods include: (1) using a bipolar membrane composed of a cation exchange layer and an anion exchange layer. Under reverse bias, water dissociation occurs at the interface between the cation exchange layer and the anion exchange layer, and the generated H + and OH -Acting as charge carriers, they are transported to the cathode and anode, respectively. Bipolar membranes can mitigate carbonate formation and CO2 crossover by providing a proton source for the cathode; the disadvantages of this method are low product selectivity, high cell pressure, and difficulty in stable operation of bipolar membrane systems. (2) Using a membrane electrode assembly based on a cation exchange membrane, carbon dioxide reduction is carried out in an acidic medium to reduce carbonate formation; the disadvantage of this method is that the product selectivity is low, and alkaline cations need to be added to the acidic electrolyte to inhibit the main hydrogen evolution competition reaction, but it will induce bicarbonate precipitation in the gas diffusion electrode and cause cathode flooding, thereby limiting the sustainability of the electrolysis system. (3) Using a solid electrolyte system, carbonate ions are internally recovered before they are lost to the anode, thereby reducing CO2 losses; this method still has defects in ionic conductivity, electrochemical and mechanical stability, and interface contact. Summary of the invention

[0005] In order to solve the problem of carbon loss in alkaline carbon dioxide electroreduction, the present application provides a method and apparatus for coupling carbon dioxide electrolysis to recover the carbon loss.

[0006] The present application provides a device for coupling carbon dioxide electrolysis to recover carbon loss using the following technical solution: A device for coupling carbon dioxide electrolysis to recover carbon losses, comprising: A carbon dioxide electrolysis cell is divided into an anode chamber and a cathode chamber by an anion exchange membrane; a carbon dioxide reduction reaction occurs at the cathode of the carbon dioxide electrolysis cell, and the electrolyte in the anode chamber of the carbon dioxide electrolysis cell is an electrochemically reversible redox medium, and the redox medium undergoes an oxidation reaction at the anode of the carbon dioxide electrolysis cell; The regeneration tank is divided into an anode chamber and a cathode chamber by an ion exchange membrane; the electrolyte in the cathode chamber of the regeneration tank is an electrochemically reversible redox medium, and the redox medium undergoes a reduction reaction at the cathode of the regeneration tank; A circulation system for driving the redox medium to circulate between the anode chamber of the carbon dioxide electrolysis cell and the cathode chamber of the regeneration cell; A carbon dioxide recovery device is used to recover carbon dioxide from the circulation system.

[0007] Driven by the circulation system, the oxidized redox medium enters the cathode chamber of the regeneration tank from the anode chamber of the carbon dioxide electrolysis cell to be reduced, and the reduced redox medium enters the anode chamber of the carbon dioxide electrolysis cell to be oxidized, completing the cyclic regeneration of the redox medium.

[0008] At the same time, in the cathode chamber of the carbon dioxide electrolysis cell, part of the carbon dioxide is reduced, and another part of the carbon dioxide forms bicarbonate or carbonate under alkaline conditions. The bicarbonate or carbonate passes through the anion exchange membrane into the anode chamber of the carbon dioxide electrolysis cell and combines with protons to regenerate carbon dioxide. Driven by the circulation system, the carbon dioxide in the anode chamber of the carbon dioxide electrolysis cell flows out together with the redox medium and is recovered by the carbon dioxide recovery device.

[0009] Carbon dioxide electrolysis involves two paired half-cell reactions, namely, carbon dioxide reduction reaction and oxygen evolution reaction. The device provided in the present application uses a dual electrolyzer system to operate simultaneously, and uses a redox medium and a circulation system to separate the carbon dioxide reduction reaction and the oxygen evolution reaction in space, so as to avoid the carbon dioxide that forms bicarbonate or carbonate from remixing with the oxygen generated by the oxygen evolution reaction, thereby facilitating the recovery of carbon dioxide to reduce carbon loss and reduce the energy consumption of the system operation. At the same time, the device provided in the present application can also maintain the surface environment of the carbon dioxide reduction reaction catalyst to be alkaline, which is conducive to improving the selectivity of the product.

[0010] Furthermore, the anode material of the carbon dioxide electrolysis cell and the cathode material of the regeneration cell are both porous conductive materials.

[0011] Furthermore, the porous conductive material is selected from one or more of carbon felt, graphite felt and carbon cloth.

[0012] The porous conductive material used as an electrode is capable of absorbing a large amount of redox mediator solution so as to rapidly achieve redox regeneration of the redox mediator.

[0013] Furthermore, the redox medium can undergo a reversible redox reaction within the potential range of the hydrogen evolution reaction and the oxygen evolution reaction.

[0014] Furthermore, the redox mediator is selected from one or more of benzoquinone derivatives, anthraquinone derivatives, phenazine derivatives, and potassium ferrocyanide electrode pairs.

[0015] Furthermore, the circulation system includes a circulation pipeline connected between the anode chamber of the carbon dioxide electrolysis cell and the cathode chamber of the regeneration cell, and also includes a circulation pump arranged on the circulation pipeline.

[0016] Furthermore, the carbon dioxide recovery device comprises a safety bottle arranged in the circulation pipeline, and the gas outlet end of the safety bottle is connected to a detection device.

[0017] The redox medium is driven to circulate between the anode chamber of the carbon dioxide electrolysis cell and the cathode chamber of the regeneration cell by a circulation pump, and the carbon dioxide in the redox medium is recovered by a safety bottle in the circulation pipeline. The detection device can use a mass spectrometer to detect the purity of the recovered carbon dioxide.

[0018] Furthermore, the gas outlet end of the safety bottle is connected to the cathode and / or gas collecting device of the carbon dioxide electrolysis cell.

[0019] In the process of recycling and regenerating the redox medium, no side reaction gas is generated, and the recovered carbon dioxide has high purity and can be reused as a raw material for carbon dioxide reduction, thereby improving the utilization rate of carbon dioxide.

[0020] The present application also provides a method for recovering carbon loss by coupling carbon dioxide electrolysis, using the above-mentioned device for recovering carbon loss by coupling carbon dioxide electrolysis, the method comprises the following steps: Circulation and regeneration of redox media: Driven by the circulation system, the oxidized redox media enters the cathode chamber of the regeneration tank from the anode chamber of the carbon dioxide electrolysis cell to be reduced, and the reduced redox media returns to the anode chamber of the carbon dioxide electrolysis cell to be oxidized, completing the circulation and regeneration of the redox media; Carbon dioxide reduction and recovery: In the cathode chamber of the carbon dioxide electrolytic cell, part of the carbon dioxide is reduced, and another part of the carbon dioxide forms bicarbonate or carbonate under alkaline conditions. The bicarbonate or carbonate passes through the anion exchange membrane into the anode chamber of the carbon dioxide electrolytic cell and combines with protons to regenerate carbon dioxide. Driven by the circulation system, the carbon dioxide in the anode chamber of the carbon dioxide electrolytic cell flows out together with the redox medium and is recovered by the carbon dioxide recovery device.

[0021] Furthermore, the method further comprises the following steps: reintroducing the carbon dioxide recovered by the carbon dioxide recovery device into the cathode of the carbon dioxide electrolysis cell for reduction.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. The device provided in the present application uses a dual electrolyzer system to operate simultaneously, and uses a redox medium and a circulation system to separate the carbon dioxide reduction reaction and the oxygen evolution reaction in space, so as to avoid the carbon dioxide that forms bicarbonate or carbonate from remixing with the oxygen generated by the oxygen evolution reaction, thereby facilitating the recovery of carbon dioxide, thereby reducing carbon loss and reducing the energy consumption of the system operation; 2. In the process of recycling the redox medium, no side reaction gas is generated, and the recovered carbon dioxide has high purity and can be reused as a raw material for carbon dioxide reduction, thereby improving the utilization rate of carbon dioxide; 3. The method adopted in the present application can maintain the surface environment of the carbon dioxide reduction reaction catalyst to be alkaline, which is beneficial to improving the selectivity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a schematic diagram of the overall structure of a device for coupling carbon dioxide electrolysis to recover carbon loss according to an embodiment of the present application; Figure 2 It is 100 mA / cm in the embodiment of this application 2 Faradaic efficiency and cell pressure diagram for system operation at current density; Figure 3 It is 100 mA / cm in the embodiment of this application 2 Real-time mass spectrometry detection results of the system running under current density; Figure 4 It is 200 mA / cm in the embodiment of this application 2 CO2 flow diagram for system operation at current density.

[0024] Reference numerals: 1. carbon dioxide electrolysis cell; 2. regeneration cell; 3. circulation system; 4. circulation pump; 5. safety bottle. DETAILED DESCRIPTION

[0025] The English abbreviations in the attached drawings are as follows: AEM: anion exchange membrane; CEM: cation exchange membrane; CF: carbon felt; AQDSH2: anthracenol-2,7-disulfonic acid (reduced); AQDS: Anthraquinone-2,7-disulfonic acid (oxidized state).

[0026] The following is combined with Figure 1-4 This application is described in further detail.

[0027] The present application embodiment discloses a device for coupling carbon dioxide electrolysis to recover carbon loss. Figure 1 , a device for coupling carbon dioxide electrolysis to recover carbon loss includes a carbon dioxide electrolysis cell 1, a regeneration cell 2, a circulation system 3 and a carbon dioxide recovery device.

[0028] Reference Figure 1 The carbon dioxide electrolysis cell 1 is divided into an anode chamber and a cathode chamber by an anion exchange membrane. The anode material of the carbon dioxide electrolysis cell 1 is a carbon felt with a thickness of 3-5 mm, and the electrolyte in the anode chamber is a saturated anthraquinone-2,7-disulfonic acid solution. The cathode material of the carbon dioxide electrolysis cell 1 is a hydrophobic carbon paper sprayed with Ag nanoparticles, and the carbon dioxide flow rate of the cathode is 100 sccm.

[0029] In the cathode chamber of the carbon dioxide electrolysis cell 1, carbon dioxide is electrocatalytically reduced to carbon monoxide; in the anode chamber of the carbon dioxide electrolysis cell 1, anthracenol-2,7-disulfonic acid solution undergoes an oxidation reaction.

[0030] Reference Figure 1, the regeneration tank 2 is divided into an anode chamber and a cathode chamber by a cation exchange membrane. The cathode material of the regeneration tank 2 is a carbon felt with a thickness of 3-5 mm, and the electrolyte in the cathode chamber is a saturated anthraquinone-2,7-disulfonic acid solution. The anode material of the regeneration tank 2 is a titanium plate loaded with iridium oxide, and the electrolyte in the anode chamber is ultrapure water.

[0031] An oxygen evolution reaction occurs in the anode chamber of the regeneration tank 2; and a reduction reaction occurs in the anthraquinone-2,7-disulfonic acid solution in the cathode chamber of the regeneration tank 2.

[0032] Reference Figure 1 The circulation system 3 includes a circulation pipeline connected between the anode chamber of the carbon dioxide electrolysis cell 1 and the cathode chamber of the regeneration cell 2, and also includes a circulation pump 4 arranged on the circulation pipeline, and the circulation pump 4 can be a peristaltic pump. The carbon dioxide recovery device is a safety bottle 5 arranged in the circulation pipeline for recovering carbon dioxide, and the gas outlet end of the safety bottle 5 is connected to a mass spectrometer. In order to realize the reuse of the recovered carbon dioxide, the gas outlet end of the safety bottle 5 can be connected to the cathode of the carbon dioxide electrolysis cell 1, and the gas outlet end of the safety bottle 5 can also be connected to a gas collection device such as a balloon or an air bag to realize carbon dioxide collection.

[0033] A method for recovering carbon loss by coupling carbon dioxide electrolysis using the above device comprises the following steps: When the system is running, the recycling process of the redox medium and the carbon dioxide reduction and recovery process are carried out simultaneously, as follows: Circular regeneration of redox media: driven by the circulation system 3, the oxidized anthraquinone-2,7-disulfonic acid (AQDS) enters the cathode chamber of the regeneration cell 2 from the anode chamber of the carbon dioxide electrolysis cell 1 to be reduced to generate reduced anthraquinone-2,7-disulfonic acid (AQDSH2); at the same time, driven by the circulation system 3, the reduced anthraquinone-2,7-disulfonic acid (AQDSH2) returns to the anode chamber of the carbon dioxide electrolysis cell 1 to be oxidized to generate oxidized anthraquinone-2,7-disulfonic acid (AQDS), thus completing the circular regeneration of the redox media.

[0034] Carbon dioxide reduction and recovery: In the cathode chamber of the carbon dioxide electrolysis cell 1, part of the carbon dioxide is reduced, and another part of the carbon dioxide forms bicarbonate or carbonate under alkaline conditions. The bicarbonate or carbonate enters the anode chamber of the carbon dioxide electrolysis cell 1 through the anion exchange membrane and combines with protons to regenerate carbon dioxide. Driven by the circulation system, the carbon dioxide in the anode chamber of the carbon dioxide electrolysis cell 1 flows out together with the anthraquinone-2,7-disulfonic acid solution and is recovered by the safety bottle 5.

[0035] like Figure 2 As shown, 100 mA / cm 2 The Faradaic efficiency (FE) of the system under the current density CO) is around 90%, and the tank pressure is low and stable. Figure 3 The mass spectrometry results shown in real time confirm the pure recovery of carbon dioxide. Figure 4 As shown, carbon dioxide can be stably recovered through the membrane.

[0036] In order to realize the reuse of recovered carbon dioxide, the carbon dioxide recovered by the carbon dioxide recovery device can be reintroduced as a raw material into the cathode of the carbon dioxide electrolysis cell for reduction, thereby improving the utilization rate of carbon dioxide.

[0037] Carbon dioxide electrolysis involves two paired half-cell reactions, namely, carbon dioxide reduction reaction and oxygen evolution reaction. The device provided in the present application uses a dual electrolyzer system to operate simultaneously, and uses a redox medium and a circulation system to separate the carbon dioxide reduction reaction and the oxygen evolution reaction in space, so as to avoid the carbon dioxide that forms bicarbonate or carbonate from remixing with the oxygen generated by the oxygen evolution reaction, so as to facilitate the recovery of pure and stable carbon dioxide, reduce carbon loss and reduce the energy consumption of system operation. At the same time, the method provided in the present application can also maintain the alkaline environment of the surface of the carbon dioxide reduction reaction catalyst, which is conducive to improving the selectivity of the product.

[0038] It should be noted that the electrochemically reversible redox medium used in this method is not limited to AQDS, and the catalyst used in the carbon dioxide reduction reaction and the oxygen evolution reaction is not limited to the catalyst used in this embodiment. Whether the anode of the carbon dioxide electrolysis cell and the cathode of the regeneration cell need a catalyst and what catalyst to use depends on the type of redox medium selected; when AQDS is used as the redox medium in this embodiment, no catalyst is required for the anode of the carbon dioxide electrolysis cell and the cathode of the regeneration cell.

[0039] Furthermore, the application of the coupling method provided by the present method is not limited to carbon dioxide electrolysis devices, and can also be promoted and used in flow cells, H cells and other devices. In the present method, the anode reaction of the regeneration cell is not limited to the oxygen evolution reaction, and other oxidation reactions (such as ammonia oxidation to generate nitrates, etc.) do not affect the recovery of carbon dioxide.

[0040] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A device for coupling carbon dioxide electrolysis to recover carbon losses, characterized in that: include: A carbon dioxide electrolysis cell is divided into an anode chamber and a cathode chamber by an anion exchange membrane; a carbon dioxide reduction reaction occurs at the cathode of the carbon dioxide electrolysis cell, and the electrolyte in the anode chamber of the carbon dioxide electrolysis cell is an electrochemically reversible redox medium, and the redox medium undergoes an oxidation reaction at the anode of the carbon dioxide electrolysis cell; The regeneration tank is divided into an anode chamber and a cathode chamber by an ion exchange membrane; the electrolyte in the cathode chamber of the regeneration tank is an electrochemically reversible redox medium, and the redox medium undergoes a reduction reaction at the cathode of the regeneration tank; A circulation system for driving the redox medium to circulate between the anode chamber of the carbon dioxide electrolysis cell and the cathode chamber of the regeneration cell; A carbon dioxide recovery device is used to recover carbon dioxide from the circulation system.

2. A device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 1, characterized in that: The anode material of the carbon dioxide electrolysis cell and the cathode material of the regeneration cell are both porous conductive materials.

3. A device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 2, characterized in that: The porous conductive material is selected from one or more of carbon felt, graphite felt and carbon cloth.

4. The device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 1, characterized in that: The redox mediator can undergo a reversible redox reaction within a potential range of a hydrogen evolution reaction and an oxygen evolution reaction.

5. The device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 4, characterized in that: The redox mediator is selected from one or more of p-benzoquinone derivatives, anthraquinone derivatives, phenazine derivatives, and potassium ferrocyanide electrode pairs.

6. The device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 1, characterized in that: The circulation system comprises a circulation pipeline connected between the anode chamber of the carbon dioxide electrolysis cell and the cathode chamber of the regeneration cell, and also comprises a circulation pump arranged on the circulation pipeline.

7. The device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 6, characterized in that: The carbon dioxide recovery device comprises a safety bottle arranged in the circulation pipeline, and a detection device is connected to the gas outlet end of the safety bottle.

8. The device for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 7, characterized in that: The gas outlet end of the safety bottle is connected to the cathode and / or the gas collecting device of the carbon dioxide electrolysis cell.

9. A method for recovering carbon loss by coupling carbon dioxide electrolysis, using a device for recovering carbon loss by coupling carbon dioxide electrolysis according to any one of claims 1 to 8, characterized in that: The following steps are involved: Circulation and regeneration of redox media: Driven by the circulation system, the oxidized redox media enters the cathode chamber of the regeneration tank from the anode chamber of the carbon dioxide electrolysis cell to be reduced, and the reduced redox media returns to the anode chamber of the carbon dioxide electrolysis cell to be oxidized, completing the circulation and regeneration of the redox media; Carbon dioxide reduction and recovery: In the cathode chamber of the carbon dioxide electrolytic cell, part of the carbon dioxide is reduced, and another part of the carbon dioxide forms bicarbonate or carbonate under alkaline conditions. The bicarbonate or carbonate passes through the anion exchange membrane into the anode chamber of the carbon dioxide electrolytic cell and combines with protons to regenerate carbon dioxide. Driven by the circulation system, the carbon dioxide in the anode chamber of the carbon dioxide electrolytic cell flows out together with the redox medium and is recovered by the carbon dioxide recovery device.

10. A method for recovering carbon loss by coupling carbon dioxide electrolysis according to claim 9, characterized in that: The following steps are also included: The carbon dioxide recovered by the carbon dioxide recovery device is reintroduced into the cathode of the carbon dioxide electrolysis cell for reduction.

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