Integrated system for electrolyte recovery, product separation and co2 capture in alkaline electrochemical synthesis and method of making same

Abstract

The application discloses an integrated system for electrolyte recovery, product separation and CO2 capture in alkaline electrochemical synthesis and a preparation method thereof. The system is provided with an ion separation module (ISM) between an anode and a cathode of an electrolysis system. During the operation of the ERSS system, protons from the anode solution flow into the ISM through a cation exchange membrane (CEM), so that the effluent electrolyte is acidified. K + and the like cations in the ISM flow into the cathode solution through a cathode CEM to balance the OH ‑ produced by the cathode reaction. Compared with a traditional acid-base neutralization recovery separation process (ABNP), the ERSS can save 121.72 dollars and 5.91 GJ of energy per ton of KOH recovered, and is suitable for other alkaline aqueous electrochemical synthesis reactions. Finally, through the integration of technologies, the application can realize the combination of a continuous electrochemical conversion system, a CO2 capture system and an electrochemical recovery separation system (ECS-CCS-ERSS).

Description

Technical Field

[0001] This invention belongs to the fields of CO2 capture and electrochemical synthesis technology, specifically relating to an integrated system for electrolyte recovery, product separation and CO2 capture in alkaline electrochemical synthesis and its preparation method. Background Technology

[0002] Renewable electricity-driven electrosynthesis, such as the electrolysis of CO2, N2, H2O, hydrocarbons, and biomass, offers promising alternatives to traditional industrial reactions and supports carbon emission management and net-zero emission targets. Electrocatalytic CO2R is a key electrosynthetic reaction that can produce high-value fuels and chemicals, facilitate renewable energy storage, and significantly reduce CO2 emissions. Significant efforts have been devoted to developing CO2R catalysts that react with C1 (CO, formate, methanol) or C2O. 2+ (Ethylene, ethanol, n-propanol) products possess high product selectivity (Faraday efficiency, FE), high current density, high energy efficiency (EE), and long-term stability at low overpotentials. Significant progress has been made, but CO2R has not yet been industrialized due to the following challenges:

[0003] First, CO2 capture remains a significant challenge. Traditional wet chemical scrubbing methods using sp3 amines face technical and economic problems such as high energy consumption, corrosion, and adsorbent degradation. The Ca(OH)2 / CaCO3 / CaO+CO2 cycle is energy-intensive and requires temperatures above 900°C to release CO2. Electrochemically mediated carbon capture using redox-active organic compounds (such as quinones) shows promise, but reliable adsorbents with good solubility, processability, and stability to impurities are lacking. Electrochemical solid electrolyte reactors using oxygen / water (O2 / H2O) redox couples also show potential, but are limited by high operating energy consumption.

[0004] Secondly, the CO2 utilization efficiency in CO2R remains very low. Continuous flow electrolyzers, such as zero-gap membrane electrode assemblies (MEAs) and flow cells using highly alkaline electrolytes, can achieve high current densities for the production of CO, ethylene, ethanol, and multi-carbon products. However, high concentrations of OH-... - Ions will pass through 2OH - (aq) + CO2(g) → CO3 2- The reaction (aq) + H2O results in a significant loss of CO2, while CO2 cross-links (CO3). 2- (Migrating into the electrolyte) also reduces the efficiency of CO2R. For example, in the conversion of CO2 to two electrons like CO, the utilization efficiency of CO2 is typically below 50%, while in the production of ethylene and ethanol, it typically does not exceed 25%. Electrocatalytic CO2R in an acidic medium can avoid CO3...2- The formation of [the system] faces some challenges, such as the need for a large number of cations (e.g., K+). + This is used to suppress the instability of HER and anode catalysts under acidic conditions, as well as the severe corrosion of reactor materials.

[0005] Before the reaction products can be applied to the market, they must undergo product separation, purification, and collection. Taking the electrocatalytic CO2R formic acid production reaction as an example, the reaction product solution often needs to be treated with H2O. + Ions acidify formate products to formic acid, which is then purified by extractive distillation or pressure-swing azeotropic distillation. However, electrolyte recovery and product separation are also costly. The article "Acid-base chemistry and the economic implication of electrocatalytic carboxylate production in alkaline electrolytes," Nature Catalysis, 330-337 (2024), presents a techno-economic analysis (TEA) of alkaline CO2 electrolyzers, showing that over 50% of the input energy is used for regenerating the alkaline solution and CO3. 2- The CO2 ions are a significant component of CO2. Furthermore, the recovery of alkaline electrolytes and the separation of products from CO2R effluents further increase costs. For example, chemical neutralization and distillation to separate downstream liquid products from alkaline electrolytes account for over 60% of the cost and 64% of the total energy cost. Most CO2R research tends to focus on catalyst development, electrolyzer design, and mechanism verification, often neglecting product separation and applications, thus delaying the industrialization of CO2R.

[0006] Regarding electrolyte purification, most researchers currently focus on lithium-ion batteries in the field of electrolyte separation and recovery. For example, Chinese patent CN114747065 A involves contacting the used electrolyte with a polar aprotic solvent to produce a solution containing lithium electrolyte salt, electrolyte solvent, and polar aprotic solvent, which is then separated and recovered. However, in the field of molecular alkaline electrocatalysis, it is relatively difficult to generate electrolyte precipitates by introducing external solutions.

[0007] Using electricity to drive the movement of electrolytes for separation and purification is a promising field, such as capacitive deionization technology. This technology applies a DC voltage to generate an electrostatic field, forcing ions to penetrate the ion exchange membrane and move towards the electrode with the opposite charge. This technique often requires the introduction of electrode materials with good conductivity and large specific surface area, such as activated carbon and carbon aerogel, to form a strong electrical double layer at the electrolyte solution interface. This allows the electrolyte to be extracted from the mother solution and adsorbed for storage. Finally, removing the electric field releases the attracted ions, achieving the separation of the electrolyte from the mother solution. However, this technology heavily relies on the research and development of high-performance electrode materials, and its widespread industrial application still has considerable room for improvement.

[0008] The industrialization of CO2R requires a systematic engineering approach to optimize catalyst production, electrolyzer manufacturing, CO2 capture, CO2 utilization efficiency, electrolyte recovery, and product separation costs. Such a comprehensive approach has not yet been reported. Therefore, there is an urgent need to develop a new technology to advance the industrialization of CO2R. Summary of the Invention

[0009] The purpose of this invention is to address the current research situation: a large amount of research focuses only on the design and preparation of catalysts in continuous electrochemical synthesis systems, often neglecting practical problems such as product separation, electrolyte recovery, and CO2 capture that hinder its industrial application. This invention proposes and designs an integrated system for electrolyte recovery, product separation, and CO2 capture in alkaline electrochemical synthesis (hereinafter referred to as the ECS-CCS-ERSS combined system) and its preparation method. The ECS-CCS-ERSS combined system designed in this invention achieves high electrolyte recovery, product separation, and high-purity CO2 capture.

[0010] This invention first constructs an electrochemical recovery and separation system (ERSS) at the back end of an electrochemical conversion system (ECS) based on fundamental electrochemical principles. Then, it simulates a KOH electrolyte containing common liquid products (methanol, ethanol, propanol, formic acid, acetic acid, etc.) and runs the ERSS, demonstrating the system's successful operation. Secondly, considering CO2 capture (CCS), the alkaline solution adsorbs CO2 from air or flue gas. After adsorption saturation, it is then run through the ERSS, again achieving the integrated application of product separation, electrolyte recovery, and CO2 capture. Finally, an ECS-CCS-ERSS combined system is constructed.

[0011] The primary objective of this invention is to provide a substrate separation device that addresses the problem of product purification in the field of molecular alkaline electrocatalysis. This device aims to rapidly and efficiently separate the electrolyte and the reaction substrate into two chambers, each producing a high-purity solution that flows out. Compared to current industrial purification methods, this separation method achieves lower energy consumption.

[0012] The second objective of this invention is to provide an ECS-CCS-ERSS combined system to address the challenges of existing carbon dioxide capture and utilization methods, aiming to achieve a closed-loop chemical process encompassing carbon dioxide capture, reaction, substrate purification, and electrolyte regeneration.

[0013] The objective of this invention is achieved through the following technical solution.

[0014] This invention provides an integrated system for electrolyte recovery, product separation, and CO2 capture in alkaline electrochemical synthesis, the main components of which are:

[0015] The core of an ECS-CCS-ERSS combined system is the back-end ERSS, whose regenerated electrolyte can be used to support CO2 capture and reaction.

[0016] The construction of the front-end ECS and CCS includes the following steps:

[0017] (1) Common CO2 catalysts are placed at the cathode end, and in order to reduce energy consumption, common molecular catalytic oxidation catalysts are placed at the anode end to construct membrane electrode devices.

[0018] (2) Pass a solution purified and recovered from the ERSS system or a fresh MOH solution as an electrolyte solution and apply a certain potential to carry out the reaction;

[0019] (3) Use the electrolyte solution after ECS reaction as a CO2 capture carrier to fully adsorb CO2 in the air or flue gas and monitor the pH change of the solution in real time until pH≤9.

[0020] The construction of the backend ERSS includes the following steps:

[0021] (4) Design a three-chamber electrolytic cell and build a membrane electrode reactor in the order of cathode chamber, proton exchange membrane, separation chamber, proton exchange membrane and anode chamber.

[0022] (5) Pass the ECS reaction solution that has adsorbed CO2 into the separation chamber, and at the same time pass pure water into both ends of the cathode chamber and the anode chamber. The amount of pure water can be adjusted according to actual needs.

[0023] (6) A constant current electrolysis method is used, and a certain potential is applied across the membrane electrode to make H + OH from the anode chamber passes through the proton exchange membrane and reacts with OH from the separation chamber. - And the reaction substrate, which may exist as an anion, undergoes coordination, while the cation in the separation chamber (called M) + ) through the proton exchange membrane and OH in the cathode chamber -Coordination occurs to form an MOH solution (electrolyte solution).

[0024] After completing the above steps, you will obtain the ECS-CCS-ERSS combined system.

[0025] Preferably, in step (1), the CO2 catalyst used at the cathode is one of the metals such as Cu, Bi, Ag, Au, Co and their corresponding metal oxides or metal alloys; the molecular catalytic oxidation catalyst used at the anode is one of the metals such as Cu, Pt, Pd, Bi, Ag, Au, Co and their corresponding metal oxides or metal alloys.

[0026] Preferably, the anode in step (1) can be a reaction system for the electrocatalytic oxidation of methanol, ethanol, ethylene glycol, glycerol, glucose, 5-hydroxyfurfural, etc.

[0027] Preferably, in step (2), when there is no recovered solution at the beginning, fresh electrolyte can be used, and then it passes through CCS and ERSS in sequence. The electrolyte solution that has passed through ERSS can be recycled to ECS, and the recovered electrolyte solution is used as the subsequent electrolyte.

[0028] Preferably, the potential applied in step (2) is 1-10V.

[0029] Preferably, the flow rate of the air or flue gas in step (3) is 1-10000 sccm.

[0030] Preferably, in step (4), the cathode chamber is filled with a catalyst for the hydrogen evolution reaction, such as platinum carbon, ruthenium dioxide, etc.; the separation chamber is filled with a membrane support material, such as carbon felt, porous polyethylene block, solid electrolyte, etc.; the cation exchange membrane is any kind of exchange membrane that allows cations to shuttle freely, such as sulfonic acid type ion exchange membrane, carboxylic acid type ion exchange membrane, phosphoric acid type ion exchange membrane, etc.; the anode chamber is filled with a catalyst for the oxygen evolution reaction, such as iridium, iridium oxide, ruthenium, etc.

[0031] Preferably, the solution after the ECS reaction and adsorbed CO2 in step (5) can be one or more common alkaline electrolytes containing liquid products such as methanol, ethanol, propanol, formic acid, and acetic acid, such as LiOH, NaOH, KOH, and CsOH, or one or more of the carbonate and bicarbonate solutions corresponding to the above metal cations (such as Li, Na, K, and Cs), with a concentration of 0.05-10 mol / L.

[0032] Preferably, step (6) uses a constant current electrolysis method with a current range of 0.01-10A and a potential range of 2-20V. The continuous separation mode can be designed by adjusting the electrolyte concentration (0.05-10mol / L) and electrolyte flow rate (0.01-1000mL / min).

[0033] This invention proposes an integrated electrochemical recovery and separation system (ERSS) based on the principle of electrodialysis. This system incorporates an ion separation module (ISM) between the anode and cathode of the electrolysis system, enabling CO2 capture and alkaline electrolyte recovery through electrochemical methods. The ERSS can promote the acidification of the ISM (CO3). 2- (aq) / HCO3 - The recovery of CO2 adsorbed by electrolyte in the CO2(aq)→CO2(g) process achieves a KOH recovery rate of over 90% and a CO2R product separation efficiency of over 80%. The KOH recovered by the ERSS can capture CO2 from air or flue gas, or be directly used for CO2R, thus supporting continuous CO2 capture, conversion, and utilization. This invention's ECS-CCS-ERSS combined system provides a feasible solution for the industrialization of CO2R using renewable energy.

[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0035] (1) Traditional electrolyte recovery and separation uses ABNP, which consumes a large amount of sulfuric acid and produces sulfate as a byproduct. This invention not only eliminates the need for sulfuric acid but also recovers alkaline electrolytes for reuse. Economic, technical, and energy consumption analyses demonstrate that this invention offers better cost-effectiveness in terms of both economy and energy consumption.

[0036] (2) The CO2 capture technology of the present invention has excellent cycle stability. Compared with the traditional CO2 capture technology, which requires a high temperature of up to 900°C for regeneration, the present invention does not require high temperature for regeneration and can be done at room temperature.

[0037] (3) With the rapid development of CEM process and catalyst, the present invention can further reduce energy consumption and economic costs, and only requires renewable electric energy to drive it.

[0038] (4) This invention promotes the industrialization of CO2 capture, conversion and utilization. The technical process of successfully connecting ECS ​​and CCS around the ERSS device provides an application reference for significantly reducing the high cost and energy consumption faced by industrial CO2R implementation. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the ECS-CCS-ERSS combined system of the present invention.

[0040] Figure 2 This is a schematic diagram of an ERSS device.

[0041] Figure 3 The Faraday efficiency (FE) of Bi-based catalysts for electrocatalyzing CO2R products under different current densities is given.

[0042] Figure 4 The pH change curve of the cathode solution after electrocatalytic CO2R adsorption of simulated flue gas (10% CO2, 100 sccm).

[0043] Figure 5 This is a schematic diagram of an ERSS system used to recover KOH, capture CO2, and separate organic molecules from carbonate / bicarbonate electrolytes.

[0044] Figure 6 The yields of formic acid, potassium ions, and carbon dioxide in a simulated ERSS with 10 μL formic acid and 10 mL K2CO3 (0.5 mol / L) electrolyte.

[0045] Figure 7 The yields of formic acid, potassium ions, and carbon dioxide in a simulated ERSS with 10 μL formic acid and 10 mL KHCO3 (1 mol / L) electrolyte.

[0046] Figure 8 The yields of each substrate and potassium ions were calculated when 1 mL of formic acid or acetic acid was mixed with 10 mL of KOH (0.1 mol / L) solution in a simulated ERSS.

[0047] Figure 9 The yields of each substrate and potassium ions were calculated when 1 mL of methanol, ethanol, or propanol was mixed with 10 mL of KOH (0.1 mol / L) solution in a simulated ERSS.

[0048] Figure 10 The ET curve is shown for the ECS-CCS-ERSS system during continuous operation of the ERSS under constant current. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. However, the implementation and protection of this invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0050] Please see Figure 1The ECS-CCS-ERSS combined system of this invention mainly consists of three parts: an ECS device, a CCS device, and an ERSS device. The ECS device is a common membrane electrode device coupled with CO2R and small molecule oxidation. Its structure and mechanism are not key elements of this invention and will not be elaborated upon here. In this region, the electrolyte solution purified and separated by the ERSS system flows through the anode and cathode. The ECS electrolyte solution proposed in this invention includes, but is not limited to, common alkaline electrolytes such as LiOH, NaOH, KOH, and CsOH. In specific embodiments, KOH is used as the reaction electrolyte for analysis and explanation. The CCS device mainly introduces CO2 from air or flue gas into the excess electrolyte solution after the ECS reaction, causing it to generate carbonates and bicarbonates corresponding to the electrolyte cations. Then, the ERSS is introduced, where CO2 desorption and purification of the CO2R reaction products occur. Simultaneously, the electrolyte solution flowing into the ECS can be regenerated here. The ERSS device includes a membrane electrode reactor (e.g., a cathode chamber, a proton exchange membrane, a separation chamber, another proton exchange membrane, and an anode chamber) constructed in that order. Figure 2 (As shown). During implementation, the hydrogen evolution reaction catalyst in the cathode chamber can be any type of hydrogen evolution catalyst, such as platinum-carbon or ruthenium dioxide; the oxygen evolution reaction catalyst in the anode chamber can be any type of oxygen evolution catalyst, such as iridium, iridium oxide, or ruthenium; the cation exchange membrane can be any type of exchange membrane that allows cations to shuttle freely, such as sulfonic acid type ion exchange membranes, carboxylic acid type ion exchange membranes, or phosphoric acid type ion exchange membranes; the packing layer in the separation chamber can be any type of alkali-resistant solid porous material, such as carbon felt, porous polyethylene blocks, or solid electrolytes. For normal system operation, the electrolyte solution must first fill the entire flow channel of the combined system device. Then, the reaction substrate is introduced into the ECS and CCS devices, and the corresponding voltage is applied to the ECS and ERSS devices. This enables the continuous application of electrolyte recovery, product separation, and CO2 capture reactions in alkaline electrochemical synthesis.

[0051] Example 1

[0052] Bi-based catalyst was sprayed onto hydrophobic carbon paper and packed into the cathode of the membrane electrode reactor. A commercially available oxygen evolution catalyst (IrTa-Ti catalyst was used here) was packed into the anode. 1M KOH solution and CO2 were then introduced, and different current densities (25, 50, 100, 150, 200 mA / cm²) were applied. 2 This allows it to produce formic acid products with high Faradaic efficiency. For example... Figure 3 As shown, at 25, 50, 100, 150, and 200 mA / cm 2 The corresponding Faraday efficiencies at the given current densities are 87.4%, 95.7%, 92%, 88.7%, and 90.7%, respectively.

[0053] Example 2

[0054] The electrolyte from the reaction in Example 1 was used as a CO2 adsorption carrier. Simulated flue gas was bubbled with 10% CO2 at 100 sccm and allowed to fully adsorb, thereby generating potassium carbonate and potassium bicarbonate. The reaction process could be monitored by pH (e.g., ...). Figure 4 (As shown).

[0055] Example 3

[0056] like Figure 2 As shown, a three-chamber electrolytic cell was designed, and the ERSS system was constructed in the following order: cathode chamber, proton exchange membrane, separation chamber, and proton exchange membrane and anode chamber. The cathode chamber, separation chamber, and anode chamber were filled with Pt-Ti catalyst, carbon felt, and IrTa-Ti catalyst, respectively. 10 μL of formic acid was added to 10 mL of K₂CO₃ (0.5 mol / L) or 10 mL of KHCO₃ (1 mol / L) and introduced into the separation chamber. Pure water was introduced through both sides. Then, a constant potential of 4 V was applied to electrolyze the ERSS (e.g., ...). Figure 5 (As shown).

[0057] Example 4

[0058] like Figure 2 As shown, a three-chamber electrolytic cell was designed, and the ERSS system was constructed in the following order: cathode chamber, proton exchange membrane, separation chamber, and proton exchange membrane and anode chamber. The cathode chamber, separation chamber, and anode chamber were filled with Pt-Ti catalyst, carbon felt, and IrTa-Ti catalyst, respectively. 1 mL of formic acid and 10 mL of KOH (0.1 mol / L) solution were mixed and introduced into the separation chamber, while pure water was introduced into both sides. Then, a constant potential of 3 V was applied to electrolyze the ERSS.

[0059] Example 5

[0060] like Figure 2 As shown, a three-chamber electrolytic cell was designed, and the ERSS system was constructed in the following order: cathode chamber, proton exchange membrane, separation chamber, and proton exchange membrane and anode chamber. The cathode chamber, separation chamber, and anode chamber were filled with Pt-Ti catalyst, carbon felt, and IrTa-Ti catalyst, respectively. 1 mL of acetic acid and 10 mL of KOH (0.1 mol / L) solution were mixed and introduced into the separation chamber, while pure water was introduced into both sides. Then, a constant potential of 3 V was applied to electrolyze the ERSS.

[0061] Example 6

[0062] like Figure 2As shown, a three-chamber electrolytic cell was designed, and the ERSS system was constructed in the following order: cathode chamber, proton exchange membrane, separation chamber, and proton exchange membrane and anode chamber. The cathode chamber, separation chamber, and anode chamber were filled with Pt-Ti catalyst, carbon felt, and IrTa-Ti catalyst, respectively. 1 mL of methanol and 10 mL of KOH (0.1 mol / L) solution were mixed and introduced into the separation chamber, while pure water was introduced into both sides. Then, a constant potential of 3 V was applied to electrolyze the ERSS.

[0063] Example 7

[0064] like Figure 2 As shown, a three-chamber electrolytic cell was designed, and the ERSS system was constructed in the following order: cathode chamber, proton exchange membrane, separation chamber, and proton exchange membrane and anode chamber. The cathode chamber, separation chamber, and anode chamber were filled with Pt-Ti catalyst, carbon felt, and IrTa-Ti catalyst, respectively. 1 mL of ethanol and 10 mL of KOH (0.1 mol / L) solution were mixed and introduced into the separation chamber, while pure water was introduced into both sides. Then, a constant potential of 3 V was applied to electrolyze the ERSS.

[0065] Example 8

[0066] like Figure 2 As shown, a three-chamber electrolytic cell was designed, and the ERSS system was constructed in the following order: cathode chamber, proton exchange membrane, separation chamber, and proton exchange membrane and anode chamber. The cathode chamber, separation chamber, and anode chamber were filled with Pt-Ti catalyst, carbon felt, and IrTa-Ti catalyst, respectively. 1 mL of propanol and 10 mL of KOH (0.1 mol / L) solution were mixed and introduced into the separation chamber, while pure water was introduced into both sides. Then, a constant potential of 3 V was applied to electrolyze the ERSS.

[0067] Example 9

[0068] according to Figure 1 An ECS-CCS-ERSS combined system was constructed. The ECS device used Bi-based catalyst and IrTa_Ti catalyst to construct the cathode and anode, respectively, for the CO2R and OER reactions. Then, in the CCS device, CO2 was bubbled into the electrolyte after the reaction, and then flowed into the ERSS device, which was constructed in the following order: cathode chamber (filled with Pt_Ti catalyst), proton exchange membrane, separation chamber (filled with carbon felt), proton exchange membrane and anode chamber (filled with IrTa_Ti catalyst) for ionization. Initially, the electrolyte flow rate was adjusted to 1.1 mL / min and a constant current of 2 A was applied. Then, the flow rate was adjusted to 2.2 mL / min and a constant current of 4 A was applied.

[0069] ECS, CCS, and ERSS devices were constructed separately, and simulated electrolytes were introduced to test the feasibility of individual operation of each device. The simulated ECS device (Example 1) was tested under different current densities (25–200 mA / cm²). 2 It can produce formic acid products with high Faraday efficiency (such as...) Figure 3 As shown); the CCS device under simulated conditions (Example 2) can effectively absorb CO2 and form carbonates or bicarbonates that lower the pH of the solution (e.g. Figure 4 (As shown); the simulated ERSS device (Example 3) can extract and recover approximately 90% of KOH, with formic acid yield reaching approximately 82% and carbon dioxide yield reaching approximately 80% (as shown). Figure 6 , Figure 7 (As shown).

[0070] In the field of CO2R, different catalyst elements, structures, and other characteristics can affect product selectivity. Currently, the main products are formic acid (Example 4), acetic acid (Example 5), methanol (Example 6), ethanol (Example 7), and propanol (Example 8). By simulating a 0.1 mol / L reaction product solution, the ERSS system also exhibits high K0 for other reaction products. + Recovery rate and low product loss rate (e.g.) Figure 8 , Figure 9 (As shown).

[0071] Finally, the ECS, CCS, and ERSS units were connected in series, and the electrical signal of the ERSS, formic acid yield, and KOH recovery rate were analyzed (e.g., Figure 10 As can be seen, the yields of both KOH electrolyte and formic acid reached over 80%, indicating that the series-connected device can operate stably and continuously for a long time, and can effectively separate the electrolyte from the CO2R product with high efficiency. This invention enables a closed-loop, sustainable application of CO2 reaction utilization, adsorption-desorption, and electrolyte purification. It avoids the need for large amounts of sulfuric acid in current electrochemical separation and purification systems, significantly reducing energy consumption and costs in product acquisition. Furthermore, the pure electrolyte can be recycled and reused, further supporting the resource input for electrocatalytic reactions, demonstrating excellent economic and market value.

[0072] The above embodiments are merely preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any changes, substitutions, modifications, etc., made by those skilled in the art without departing from the spirit and essence of the present invention should be within the protection scope of the present invention.

Claims

1. A method of preparation of an integrated system for electrolyte recovery, product separation and CO2 capture in alkaline electrochemical synthesis, characterized in that, It comprises the following steps: S1, construction of ECS and CCS (1) placing CO2 catalyst at the cathode end and molecular catalytic oxidation catalyst at the anode end to construct a membrane electrode device; (2) introducing the solution purified and recovered from the ERSS system or fresh electrolyte as an electrolyte solution and applying a potential for reaction; (3) using the electrolyte solution remaining after the ECS reaction as a CO2 capture carrier to fully adsorb CO2 in air or flue gas and monitoring the pH change of the solution in real time until pH≤9; S2, construction of ERSS (4) designing a three-chamber electrolytic cell and building a membrane electrode reactor in the order of cathode chamber, proton exchange membrane, separation chamber, proton exchange membrane and anode chamber; (5) introducing the solution after the ECS reaction and adsorbing CO2 into the separation chamber, and introducing pure water into the cathode chamber and the anode chamber at both ends; (6) A constant current electrolysis method is used to apply a potential across the membrane electrode so that H + OH from the anode chamber passes through the proton exchange membrane and reacts with OH from the separation chamber. - And the reaction substrate, present as an anion, undergoes coordination, while simultaneously, the cation M in the separation chamber... + OH- through the proton exchange membrane and the cathode chamber - When coordination occurs to form an MOH solution, it becomes an electrolyte solution. The above steps are completed to obtain the ECS-CCS-ERSS combined system. Wherein, ECS is an electrochemical conversion system, ERSS is an electrochemical recovery and separation system, and CCS is a CO2 capture system. The cation M + M in the MOH solution represents Li, Na, K, Cs.

2. The production method according to claim 1, characterized by, In step (1), the CO2 catalyst used at the cathode end is one of Cu, Bi, Ag, Au, Co and corresponding metal oxides or metal alloy materials; and the molecular catalytic oxidation catalyst used at the anode end is one of Cu, Pt, Pd, Bi, Ag, Au, Co and corresponding metal oxides or metal alloy materials.

3. The preparation method according to claim 1, characterized in that, The potential applied in step (2) is 1-10V.

4. The preparation method according to claim 1, characterized in that, The flow rate of air or flue gas in step (3) is 1-10000sccm.

5. The preparation method according to claim 1, characterized in that, In step (4), the substance filled in the cathode chamber is a catalyst for hydrogen evolution reaction; the filling layer of the separation chamber is an alkali-resistant solid porous material; the cation exchange membrane is any exchange membrane allowing free shuttling of cations; and the substance filled in the anode chamber is a catalyst for oxygen evolution reaction.

6. The production method according to claim 5, wherein In step (4), the hydrogen evolution reaction catalyst filled in the cathode chamber is one of platinum carbon and ruthenium dioxide; the filling layer of the separation chamber is one of carbon felt, porous polyethylene block and solid electrolyte; the cation exchange membrane is one of sulfonic acid type ion exchange membrane, carboxylic acid type ion exchange membrane and phosphoric acid type ion exchange membrane; and the oxygen evolution reaction catalyst filled in the anode chamber is one of iridium, iridium oxide and ruthenium.

7. The preparation method according to claim 1, characterized in that, The solution after the ECS reaction and adsorbing CO2 in step (5) is a basic electrolyte containing one or more of methanol, ethanol, propanol, formic acid, acetic acid corresponding to LiOH, NaOH, KOH, CsOH, or is a solution of one or more of the cations M + one or more of the corresponding carbonate and bicarbonate solutions, the concentration of which is 0.05-10 mol / L.

8. The method of claim 1, wherein, In step (6), the constant current electrolysis mode is adopted, the current range is 0.01-10A, the potential range is 2-20V, and the continuous separation mode is adjusted and designed according to the electrolyte concentration and electrolyte flow rate.

9. An integrated electrolyte recovery, product separation and CO2 capture system for alkaline electrochemical synthesis obtained by the preparation method of any one of claims 1-8.

10. An integrated system for electrolyte recovery, product separation, and CO2 capture in an alkaline electrochemical synthesis according to claim 9, characterized in that, More than 90% of KOH recovery rate and more than 80% of CO2R product separation efficiency can be achieved.

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