Method for in-situ recovery of performance of solid electrolyte CO2 reduction reactor

Abstract

The invention discloses a method for in-situ recovery of performance of a solid electrolyte CO2 reduction reactor. In order to solve the problem of performance degradation caused by water logging of a gas diffusion electrode and saturation of ion exchange resin particles during operation of a solid electrolyte CO2 reduction reactor, in-situ recovery is carried out by periodically introducing inert gas. The method specifically comprises the following steps: operating a reactor in a constant-current or constant-pressure mode, and introducing pure water into an extraction chamber to extract an organic acid product while producing; when the performance degradation index is triggered or the operation is stopped according to a fixed period, emptying the aqueous solution in the extraction chamber, and introducing inert gas for 12-14 hours; and then pure water is introduced again for continuous operation. According to the method, the reactor does not need to be disassembled, the problems of GDE flooding and resin saturation can be synchronously solved, the continuous operation period of the reactor is remarkably prolonged, the maintenance cost is reduced, the method is suitable for different scales of 4-100 cm and constant-current / constant-pressure operation modes, and an efficient solution is provided for industrial application of a CO2 electrochemical reduction technology.

Description

Technical Field

[0001] The present invention belongs to the technical fields of electrochemistry and carbon dioxide utilization, and particularly relates to a method for in-situ restoring the performance of a solid electrolyte CO2 reduction reactor. Background Art

[0002] The solid electrolyte CO2 reduction reactor is a novel electrochemical device. By configuring an extraction chamber filled with a solid electrolyte (such as ion exchange resin particles) and combining pure water as the extraction liquid, the side production and side extraction of organic acid products (such as formic acid and acetic acid) are realized. Its advantages include avoiding high-energy-consuming product separation processes and directly obtaining substrates available for microorganisms, which promotes the application of the electrochemistry-microorganism coupling technology in the high-value utilization of CO2.

[0003] However, in the prior art, the performance of the solid electrolyte reactor is prone to decline during operation. The main reasons include the flooding of the gas diffusion electrode (GDE) and the saturation of the ion exchange resin. The flooding of the gas diffusion electrode means that liquid water penetrates into the pores of the GDE, hindering the mass transfer of CO2, and the saturation of the ion exchange resin means that the ion exchange capacity is exhausted, resulting in a decrease in the product extraction efficiency. The existing restoration methods require disassembling the reactor for off-site treatment (such as replacing the resin and drying the GDE), which is complicated to operate and cannot solve the above two problems simultaneously. For example, the literature reports that the reactor needs to be disassembled 3 times within 7 hours to replace the resin (Wang X, et al. Copper-Bridge-Enhanced p-Band Center Modulation of Carbon-Bismuth Heterojunction for CO2 Electroreduction. Nano Letters 23, 10946-10954 (2023).); Another study needs to disassemble the reactor to dry the GDE to partially restore the performance (Chen S, Ye C, Wang Z, Li P, Jiang W, Zhuang Z, et al. Selective CO(2) Reduction to Ethylene Mediated by Adaptive Small-molecule Engineering of Copper-based Electrocatalysts. Angew Chem Int Ed Engl. 2023;62:e202315621.). Such methods have problems such as low efficiency and inability to meet the requirements of industrial continuous operation. Therefore, there is an urgent need to develop a method for in-situ restoring the performance of a solid electrolyte CO2 reduction reactor. Summary of the Invention

[0004] The object of the present invention is to provide a method for in-situ restoring the performance of a solid electrolyte CO2 reduction reactor, which synchronously solves the problems of GDE flooding and ion exchange resin saturation by introducing an inert gas, significantly prolongs the operation cycle of the reactor and improves the efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for in-situ restoring the performance of a solid electrolyte CO2 reduction reactor, specifically comprising the following steps: (1) Introduce pure water into the extraction chamber of the solid electrolyte CO2 reduction reactor, and operate the reactor to extract formic acid in a constant current or constant pressure mode; (2) Stop operating according to the performance degradation index or fixed cycle, drain the pure water and anolyte in the extraction chamber, and introduce an inert gas; (3) Reintroduce pure water and anolyte into the extraction chamber, and continue to operate the reactor in a constant current / constant pressure mode.

[0006] Further, in step (1), the constant current is 0.2 - 1 A applied per square centimeter of the cathode area; the constant voltage is 3 - 15 V.

[0007] Further, in step (2), the performance degradation index is that the voltage rises > 20% in the constant current mode or the current drops > 20% in the constant pressure mode.

[0008] Further, the fixed cycle in step (2) is 5 - 14 h.

[0009] Further, the inert gas in step (2) is nitrogen or argon.

[0010] Further, the time for introducing the inert gas in step (2) is 12 - 14 h, and the flow rate is 50 - 100 sccm.

[0011] Further, the working area of the solid electrolyte CO2 reduction reactor is 4 - 100 cm 2 .

[0012] The beneficial effects of the present invention are as follows: (1) Synchronous restoration: The inert gas dries the GDE and displaces the organic acids adsorbed on the resin surface, restoring the ion exchange ability; (2) Strong universality: It has an obvious restoration effect on solid electrolyte CO2 reduction reactors with working areas of 4 cm 2 and 100 cm 2 ; it has an obvious restoration effect on solid electrolyte CO2 reduction reactors operating at constant pressure or constant current; (3) Simple operation: In-situ operation, no need to disassemble the equipment, suitable for continuous production. Description of the Drawings

[0013] Figure 1 : In-situ regeneration performance curve when the 4 cm² reactor operates at a constant current of 0.4 A.

[0014] Figure 2 : In-situ regeneration performance curve when the 100 cm² reactor operates at a constant voltage of 6 V.

[0015] Figure 3 : In-situ regeneration performance curve when the 100 cm² reactor operates at a constant current of 6 A. Specific embodiments

[0016] To make the content of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0017] In the following embodiments, the solid electrolyte CO2 reduction reactor can be built with commercially available materials directly purchased. The anode plate, cathode plate, solid electrolyte chamber, cation exchange membrane, and anion exchange membrane of the reactor are all purchased from Suzhou Shengnuoke Technology Co., Ltd., and the solid electrolyte chamber is filled with strongly acidic cation exchange resin particles.

[0018] Example 1 Constant current operation of 4 cm² reactor (1) Initial operation: Pure water is introduced into the extraction chamber at a rate of 0.26 mL / min, and the solid electrolyte CO2 reduction reactor is operated at a constant current of 400 mA for 100 hours to extract formic acid, where the cathode area is 4 cm²; (2) First recovery: Stop the operation of the solid electrolyte CO2 reduction reactor, drain the aqueous solution in the extraction chamber, stop the anolyte circulation, and then introduce 50 sccm of nitrogen into the extraction chamber for 14 hours; (3) Secondary operation: Reintroduce pure water and anolyte, and resume operation at a constant current of 400 mA for 35 hours; (4) Second recovery: Stop the operation of the solid electrolyte CO2 reduction reactor, drain the aqueous solution in the extraction chamber, stop the anolyte circulation, and introduce 50 sccm of nitrogen into the extraction chamber for 14 hours; (5) Tertiary operation: Reintroduce pure water and anolyte, continue to operate for 11 hours, and the total cumulative operation time reaches 146 hours, and the performance remains stable.

[0019] Figure 1 It is the in-situ regeneration performance curve when the 4 cm² reactor operates at a constant current of 0.4 A. The results show that during the constant current operation of the 4 cm² reactor, through in-situ recovery operations, the key indicator of Faraday efficiency can be effectively restored, especially during the first recovery, but during the second recovery, the recovery effect decreases slightly.

[0020] Example 2: Constant-pressure operation of a 100 cm² reactor (1) First batch of operation: Inject 1 ml / min of pure water into the extraction chamber, operate the solid electrolyte CO₂ reduction reactor at a constant pressure of 6 V for 5 hours, then stop the operation of the solid electrolyte CO₂ reduction reactor, drain the aqueous solution in the extraction chamber, stop the anolyte circulation, and inject 50 sccm of nitrogen into the extraction chamber for 12 hours; (2) Second batch of operation: Re-inject pure water and anolyte, then operate at a constant pressure of 6 V for 5 hours, stop the operation of the solid electrolyte CO₂ reduction reactor, drain the aqueous solution in the extraction chamber, stop the anolyte circulation, and inject 50 sccm of nitrogen into the extraction chamber for 12 hours; (3) Third batch of operation: Re-inject pure water and anolyte, then operate at a constant pressure of 6 V for 5 hours.

[0021] Figure 2 is the in-situ regeneration performance curve when the 100 cm² reactor operates at a constant pressure of 6 V. The results show that during the constant-pressure operation of the 100 cm² reactor, through the in-situ recovery operation, the reactor current can be increased, and the reaction rate can be improved.

[0022] Example 3: Constant-current operation of a 100 cm² reactor (1) First batch of operation: Inject 1 ml / min of pure water into the extraction chamber, operate the solid electrolyte CO₂ reduction reactor at a constant current of 6 A (with a cathode area of 100 cm²) for 5 hours, then stop the operation of the solid electrolyte CO₂ reduction reactor, drain the aqueous solution in the extraction chamber, stop the anolyte circulation, and inject 50 sccm of nitrogen into the extraction chamber for 12 hours; (2) Second batch of operation: Re-inject pure water and anolyte, then operate at a constant current of 6 A for 5 hours, stop the operation of the solid electrolyte CO₂ reduction reactor, drain the aqueous solution in the extraction chamber, stop the anolyte circulation, and inject 50 sccm of nitrogen into the extraction chamber for 12 hours; (3) Third batch of operation: Re-inject pure water and anolyte, then operate at a constant current of 6 A for 5 hours.

[0023] Figure 3 is the in-situ regeneration performance curve when the 100 cm² reactor operates at a constant current of 6 A. The results show that during the constant-current operation of the 100 cm² reactor, through the in-situ recovery operation, the reactor voltage can be decreased, and the energy consumption can be reduced.

[0024] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. A method for in-situ restoring the performance of a solid electrolyte CO2 reduction reactor, characterized in that: Specifically, it includes the following steps: (1) Introduce pure water into the extraction chamber of the solid electrolyte CO2 reduction reactor, and operate the reactor to extract formic acid in a constant current or constant pressure mode; (2) Stop the operation according to the performance degradation index or fixed cycle, evacuate the pure water and anolyte in the extraction chamber, and introduce an inert gas; (3) Reintroduce pure water and anolyte into the extraction chamber, and continue to operate the reactor in a constant current / constant pressure mode.

2. The method according to claim 1, wherein: In step (1), the constant current is 0.2 - 1 A applied per square centimeter of the cathode area; the constant voltage is 3 - 15 V.

3. The method according to claim 1, wherein: In step (2), the performance degradation index is that the voltage rises > 20% in the constant current mode or the current drops > 20% in the constant pressure mode.

4. The method according to claim 1, wherein: In step (2), the fixed cycle is 5 - 14 h.

5. The method according to claim 1, wherein: In step (2), the inert gas is nitrogen or argon.

6. The method according to claim 1, wherein: In step (2), the time for introducing the inert gas is 12 - 14 h, and the flow rate is 50 - 100 sccm.

7. The method according to claim 1, characterized in that: The working area of the solid electrolyte CO2 reduction reactor is 4 to 100 cm 2 .

Images