Method for preparing acetic acid from CO

Abstract

The invention relates to a method for preparing acetic acid from CO. The cathode takes carbon monoxide (CO) as a raw material, acetate is prepared by adopting an electrolytic method, and the anode is subjected to water electrolysis reaction. Acetate prepared through electrolysis is further subjected to bipolar membrane electrodialysis to prepare pure acetic acid and KOH, KOH is recycled, and almost no KOH is consumed in the reaction. The novel pure acetic acid preparation method is provided, only CO and water are consumed in the reaction process, and almost no other consumption exists.

Description

Technical Field

[0001] The present invention mainly relates to the field of electrochemistry, and in particular to the technical field of electrochemical utilization of carbon monoxide. Background Art

[0002] In the field of chemical engineering and technology, electrolysis is an important chemical process, which is widely used in the preparation and purification of various substances. Among them, CO electrolysis is an important reaction that can produce a variety of useful chemicals, such as acetic acid. In the electrolysis process, the choice of electrodes and catalysts has an important influence on the efficiency of the reaction and the purity of the product. In addition, acetic acid in the field of organic chemistry is an important chemical raw material, which is widely used in various chemical reactions and industrial production.

[0003] At present, most of the production of acetic acid by CO electrolysis adopts the cationic membrane electrolysis process, and the electrolysis product is acetate, and acetic acid cannot be directly obtained. And there is no industrial report on the production of acetic acid by CO electrolysis.

[0004] In the existing technology, the main method for preparing acetic acid by CO electrolysis is to prepare potassium acetate by cathode electrolysis, and then obtain acetic acid by sulfuric acid acidification. The advantage of this method is that CO can be effectively converted into acetic acid, but its disadvantage is that the purity of the product is not high, often containing a large amount of potassium sulfate, and the device occupies a large area and has high energy consumption. Another means is anion membrane electrolysis or solid electrolyte + cation membrane + anion membrane electrolysis process. The electrolysis product can be a pure acetic acid aqueous solution, but the low life of the anion membrane limits its industrialization possibility.

[0005] Invention patent CN113913932B provides a polycrystalline copper nanomaterial and its preparation method and application. The polycrystalline copper nanomaterial has grain boundaries and can be highly selectively converted into acetic acid during the electrocatalytic carbon monoxide reduction process. It uses a membrane electrode solid electrolyte battery and can maintain stable performance for 140 hours at a current of 250mA to prepare acetic acid aqueous solution. However, the problem caused by the use of a solid electrolyte structure is that the cathode liquid chamber OH - The concentration is three times that of acetic acid. The life span of the anion membrane limits its stable operation, and the strong alkaline environment affects the chemical stability of the electrode.

[0006] Invention patent CN113881955B provides a novel copper-palladium alloy nano-electrocatalyst that can efficiently convert carbon monoxide into acetate. Although it uses a membrane electrode electrolysis device, its product is acetate, and acetic acid is not produced.

[0007] Invention patent CN116970962A provides a method for preparing multi-carbon products by high-voltage electrocatalytic conversion of carbon monoxide, the product of which is a C2 product. However, it uses CO to be pressurized and dissolved in an electrolyte to prepare the C2 product in a KOH electrolyte, wherein the acetic acid selectivity is less than 50%, and the product is acetate, and no acetic acid is prepared.

[0008] The existing technology for preparing acetic acid by CO electrolysis has the following major problems: First, acetic acid prepared by solid electrolyte structure has a short anion membrane life due to the strong alkaline environment in the cathode chamber, making it difficult to operate stably; second, most of the existing processes prepare acetate rather than acetic acid, and there is no mature acetic acid preparation process. Finally, in the existing technology, the Faraday efficiency of CO electrolysis to prepare acetic acid / acetate is not high, and most of the products are C2 mixtures rather than pure acetic acid / acetate. Summary of the invention

[0009] The present invention provides a method for preparing acetic acid from CO. The cathode uses carbon monoxide (CO) as a raw material to prepare acetate by electrolysis, and the anode performs a water electrolysis reaction. The acetate prepared by electrolysis is further prepared into acetic acid and KOH by electrodialysis, and the KOH is recycled, and the reaction hardly consumes KOH.

[0010] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing acetic acid from CO, comprising the following steps:

[0012] (1) CO electrolysis to produce potassium acetate, using KOH to adjust the pH of the cathode liquid to alkaline during the reaction;

[0013] (2) Potassium acetate is treated by an electrodialysis device to produce acetic acid and KOH.

[0014] In the present invention, in step (1), the electrolysis uses a CO electrolyzer, which includes a cathode chamber, an anode chamber, a gas chamber, a gas diffusion electrode, and an anode membrane electrode containing an ion membrane. The electrode in the cathode chamber is a gas diffusion electrode, which separates the electrolyte side and the CO gas. CO diffuses from the gas chamber of the gas diffusion electrode to the cathode chamber to electrolyze potassium acetate and KOH; the anode chamber undergoes a water electrolysis reaction to generate H + and O2, H + Cross the membrane into the cathode compartment and mix with OH - Generates water.

[0015] In the present invention, the electrolyte in the anode chamber of the CO electrolyzer is pure water.

[0016] In the present invention, the anode membrane electrode containing the ion membrane is a membrane electrode with an iridium oxide catalyst coated on the surface of the Nafion115 membrane, and an electrochemical oxidation reaction is performed to prepare H +and O2.

[0017] As a preferred solution, in the present invention, the cathode liquid in the cathode chamber of the CO electrolyzer contains potassium acetate, and during the electrolysis process, 5-20 wt % of KOH needs to be added to the cathode liquid in the cathode chamber to adjust the pH of the cathode liquid.

[0018] As a preferred solution, in the present invention, the cathode liquid concentration in the cathode chamber of the CO electrolyzer is 0.1-5 mol / L, preferably 0.5-2 mol / L, and the pH value of the cathode liquid in the electrolyzer is adjusted to 7-9 by using KOH.

[0019] In the present invention, the gas diffusion electrode of the cathode chamber comprises an electrode substrate and a catalyst slurry supported on the substrate.

[0020] As a preferred solution, in the present invention, the electrode substrate of the gas diffusion electrode is carbon felt or carbon cloth.

[0021] As a preferred solution, in the present invention, the substrate thickness is 110-500 μm, preferably 330-500 μm.

[0022] In the present invention, the catalyst slurry supported on the substrate comprises the following components: catalyst, ion polymer Nafion, alcohol and water.

[0023] As a preferred embodiment, in the catalyst slurry, the mass ratio of the catalyst to the ionic polymer Nafion, alcohol and water is 1:(0.01-0.05):(0.3-1):(1-2), preferably 1:(0.01-0.02):(0.3-0.6):(1-1.5).

[0024] As a preferred embodiment, the catalyst of the present invention comprises a main catalyst and a sub-catalyst, wherein the active metal of the main catalyst is Cu; the active metal of the sub-catalyst contains Re, and preferably also contains Fe and / or CeO.

[0025] As a preferred solution, the main catalyst and the sub-catalyst are metal composite structures, wherein the mass ratio of Cu in the catalyst is 50-70%, the mass ratio of Re is 19-39%, and the mass ratio of Fe and / or CeO is 1-21%.

[0026] As a preferred solution, the method for preparing the catalyst of the present invention comprises the following steps: mixing Cu powder, Re powder, Fe powder and / or CeO powder, and putting them into an ultrasonic planetary ball mill for ultrasonic grinding.

[0027] As a preferred solution, in the present invention, the rotation speed of the ultrasonic planetary ball mill is 200-500 rpm, the ultrasonic power is 20-40 KHz, and the processing time is 1-4 hours.

[0028] As a preferred embodiment, in the present invention, the alcohol in the catalyst slurry is ethanol and / or isopropanol.

[0029] As a preferred solution, in the present invention, the gas diffusion electrode substrate in the catalyst cathode chamber is coated with catalyst slurry near the cathode liquid side; and the PTFE membrane is near the gas side.

[0030] As a preferred solution, in the present invention, the method for preparing the gas diffusion electrode comprises the following steps: according to the ratio,

[0031] (1) mixing the catalyst with ionic polymer Nafion, alcohol and water to prepare a slurry;

[0032] (2) applying the slurry on the electrode substrate by scraping and drying at 60-99°C;

[0033] (3) The electrode precursor obtained in step (2) is hot-pressed and bonded to the PTFE membrane at 100-150°C.

[0034] As a preferred solution, in the method for preparing the gas diffusion electrode, the thickness of the scraped electrode is 500-1000 μm.

[0035] As a preferred solution, in the method for preparing the gas diffusion electrode, the thickness of the PTFE membrane is 500-1000 μm.

[0036] As a preferred solution, in the method for preparing the gas diffusion electrode, the CO raw gas pressure in the gas chamber is 2-20 kPa higher than the cathode liquid pressure, and the CO raw gas pressure is 0.1-1 MpaG.

[0037] As a preferred solution, in the present invention, the electrolytic cell adopts a plate-and-frame electrolytic cell.

[0038] The electrolysis device used in the present invention performs CO electrolysis, uses a DC power supply, and adopts a constant current method to perform electrolysis reaction on the electrolyte, with a current density of 1000A / m 2 -5000A / m 2 The voltage was controlled below 5 V to prepare potassium acetate.

[0039] As a preferred solution, in the present invention, the voltage applied to the electrolytic cell is 3-5V, and the temperature of the electrolytic cell is 40-80°C.

[0040] In step (2) of the present invention, the potassium acetate is separated by an electrodialysis device to prepare acetic acid and KOH, and the prepared KOH is circulated back to the electrolytic cell to adjust the pH of the cathode liquid.

[0041] In the present invention, the electrodialysis device is a three-cell two-membrane electrodialysis device, including an anode chamber, an anion membrane, an intermediate chamber, a cation membrane, and a cathode chamber.

[0042] In the present invention, in the electrodialysis device, potassium acetate enters the electrodialysis device through the intermediate chamber, wherein K + The OH generated by electrolysis enters the cathode chamber through the cation membrane - Generate KOH, CH3COO - The H generated by electrolysis enters the anode chamber through the anion membrane + This produces acetic acid.

[0043] Compared with the existing technology, the beneficial effects of this technical solution are as follows:

[0044] (1) Improving product purity: The present invention converts potassium acetate into acetic acid and KOH through bipolar membrane electrodialysis, which can effectively prepare pure acetic acid and reduce energy consumption and three wastes.

[0045] (2) Optimizing electrodes and catalysts: The present invention uses a gas diffusion electrode prepared by a copper-based catalyst doped with Re, optionally Fe and / or CeO, thereby reducing the cell voltage and improving the reaction efficiency.

[0046] (3) Improving CO utilization: The preparation method of the present invention can effectively improve the utilization rate of CO, making it more widely used in industrial production. It also improves the utilization efficiency of resources, which is in line with the development trend of green chemistry.

[0047] (4) Improving electrolysis life and stability: The CO electrolyzer of the present invention does not contain anionic membranes, and there is no problem of low anionic membrane life caused by strong alkali. The electrolysis reaction can ensure stable operation for 1000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the whole process of producing acetic acid by CO electrolysis. 1 is a CO electrolyzer, 2 is a gas diffusion electrode, 3 is an anode membrane electrode containing an ion membrane, 4 is an electrodialysis device, 5 is an anion membrane, and 6 is a cation membrane. DETAILED DESCRIPTION

[0049] The following is a detailed description of the embodiments of the present invention. The embodiments are implemented based on the technical solution of the present invention. Although it is impossible to list them all, representative detailed implementation methods and specific operation processes are given based on experimental results. The protection scope of the present invention is not limited to the following embodiments.

[0050] Example 1

[0051] Catalyst and electrode preparation:

[0052] Weigh 10g of Cu powder, and weigh Re powder and Fe powder according to the mass ratio of Cu to Re to Fe of 70%:19%:1%. After weighing, the materials are ground in an ultrasonic planetary ball mill at a speed of 200rpm, an ultrasonic power of 40KHz, and a grinding time of 3h to obtain the target catalyst.

[0053] Weigh 10g of catalyst, and mix the materials according to the mass ratio of catalyst to ion polymer DuPont 5wt% Nafion solution, isopropanol, and water of 1:0.01:0.3:1 to prepare slurry. Scrape the prepared slurry on a carbon felt with a thickness of 300μm, and the coating thickness is 500μm. After scraping, the substrate is dried in an oven at 60℃ for 4h. After drying, a PTFE film with a thickness of 1000μm is attached to the material-free side of the substrate, and the electrode is hot-pressed at 150℃ to prepare the electrode.

[0054] Electrolysis reaction:

[0055] In the three-chamber plate-frame electrolyzer, the material of the electrolyzer is corrosion-resistant titanium alloy, the above-prepared electrode is used as the cathode, the anode is the N115 membrane electrode coated with iridium oxide, the cathode electrolyte is 0.5 mol / L potassium acetate, 20 wt% KOH is added to adjust the pH to 7-9, and the anode is 1 mol / L H2SO4. The reaction temperature of the electrolyzer is controlled at 75°C, the CO pressure is 0.1 MPaG, the pressure difference between CO and the cathode is 10 kPa, and the reaction is started. The current density is 1000 A / m 2 , the cell voltage is 3V, and the current efficiency of the product potassium acetate is 85%.

[0056] Electrodialysis process:

[0057] The cathode liquid at the outlet of the electrolyzer is separated by a three-grid two-membrane electrodialysis device, and potassium acetate enters the electrodialysis device through the intermediate chamber, where K + The OH generated by electrolysis enters the cathode chamber through the cation membrane - Generate KOH, CH3COO - The H generated by electrolysis enters the anode chamber through the anion membrane + Produce acetic acid. Current density 1000A / m 2 The KOH generated at the cathode returns to the cathode of the electrolytic cell; the anode obtains an aqueous solution of acetic acid.

[0058] Example 2

[0059] Catalyst and electrode preparation:

[0060] Weigh 10g of Cu powder, and weigh Re powder and Fe powder according to the mass ratio of Cu to Re to Fe of 50%:39%:11%. After weighing, the materials are ground in an ultrasonic planetary ball mill at a speed of 500rpm, an ultrasonic power of 40KHz, and a grinding time of 1h to obtain the target catalyst.

[0061] Weigh 10g of catalyst, and mix the materials according to the mass ratio of catalyst to ion polymer DuPont 5wt% Nafion solution, isopropanol, and water of 1:0.02:0.6:1.5 to prepare slurry. Scrape the prepared slurry on a carbon felt with a thickness of 500μm, and the scraping thickness is 1000μm. After scraping, the substrate is dried in an oven at 80℃ for 2h. After drying, a PTFE film with a thickness of 500μm is attached to the material-free side of the substrate, and the electrode is hot-pressed at 120℃ to prepare the electrode.

[0062] Electrolysis reaction:

[0063] In the three-chamber plate-frame electrolyzer, the material of the electrolyzer is corrosion-resistant titanium alloy, the above-prepared electrode is used as the cathode, the anode is the N115 membrane electrode coated with iridium oxide, the cathode electrolyte is 2 mol / L potassium acetate, 5 wt% KOH is added to adjust the pH to 7-9, and the anode is 1 mol / L H2SO4. The reaction temperature of the electrolyzer is controlled at 60°C, the CO pressure is 1 MPaG, the pressure difference between CO and the cathode is 2 kPa, and the reaction is started. The current density is 3000 A / m 2 , the cell voltage is 4V, and the current efficiency of the product potassium acetate is 83%.

[0064] Electrodialysis process:

[0065] The cathode liquid at the outlet of the electrolyzer is separated by a three-grid two-membrane electrodialysis device, and potassium acetate enters the electrodialysis device through the intermediate chamber, where K + The OH generated by electrolysis enters the cathode chamber through the cation membrane - Generate KOH, CH3COO - The H generated by electrolysis enters the anode chamber through the anion membrane + Produce acetic acid. Current density 1000A / m 2 The KOH generated at the cathode returns to the cathode of the electrolytic cell; the anode obtains an aqueous solution of acetic acid.

[0066] Example 3

[0067] Catalyst and electrode preparation:

[0068] Weigh 10g of Cu powder, and weigh Re powder, Fe powder and CeO powder according to the mass ratio of Cu to Re to Fe to CeO of 60%:19%:20%:1%. After weighing, the materials are ground in an ultrasonic planetary ball mill at a speed of 200rpm, an ultrasonic power of 20KHz, and a grinding time of 4h to obtain the target catalyst.

[0069] Weigh 10g of catalyst, and mix the materials according to the mass ratio of catalyst to ion polymer DuPont 5wt% Nafion solution, ethanol, and water of 1:0.02:0.5:1.3 to prepare slurry. Scrape the prepared slurry on a carbon cloth with a thickness of 400μm, and the scraping thickness is 600μm. After scraping, the substrate is dried in an oven at 99℃ for 1h. After drying, a PTFE film with a thickness of 800μm is attached to the material-free side of the substrate, and the electrode is hot-pressed at 100℃ to prepare the electrode.

[0070] Electrolysis reaction:

[0071] In the three-chamber plate-frame electrolyzer, the material of the electrolyzer is corrosion-resistant titanium alloy, the above-prepared electrode is used as the cathode, the anode is the N115 membrane electrode coated with iridium oxide, the cathode electrolyte is 5 mol / L potassium acetate, 10 wt% KOH is added to adjust the pH to 7-9, and the anode is 1 mol / L H2SO4. The reaction temperature of the electrolyzer is controlled at 80°C, the CO pressure is 0.5 MPaG, the CO and cathode fluid pressure difference is 20 kPa, and the reaction is started. The current density is 5000 A / m 2 , the cell voltage is 5V, and the current efficiency of the product potassium acetate is 80%.

[0072] Electrodialysis process:

[0073] The cathode liquid at the outlet of the electrolyzer is separated by a three-grid two-membrane electrodialysis device, and potassium acetate enters the electrodialysis device through the intermediate chamber, where K + The OH generated by electrolysis enters the cathode chamber through the cation membrane - Generate KOH, CH3COO - The H generated by electrolysis enters the anode chamber through the anion membrane + Produce acetic acid. Current density 1000A / m 2 The KOH generated at the cathode returns to the cathode of the electrolytic cell; the anode obtains acetic acid aqueous solution

[0074] Example 4

[0075] Catalyst and electrode preparation:

[0076] Weigh 10g of Cu powder, and weigh Re powder, Fe powder and CeO powder according to the mass ratio of Cu to Re to Fe to CeO of 60%:20%:10%:10%. After weighing, the materials are ground in an ultrasonic planetary ball mill at a speed of 300rpm, an ultrasonic power of 30KHz, and a grinding time of 2h to obtain the target catalyst.

[0077] Weigh 10g of catalyst, and mix and slurry the catalyst, ion polymer DuPont 5wt% Nafion solution, isopropanol, and water in a mass ratio of 1:0.05:1:2. Slurry is scraped on a carbon cloth with a thickness of 110μm, and the scraping thickness is 600μm. After scraping, the substrate is dried in an oven at 99℃ for 2h. After drying, a PTFE film with a thickness of 800μm is attached to the material-free side of the substrate, and the electrode is hot-pressed at 100℃ to prepare the electrode.

[0078] Electrolysis reaction:

[0079] In the three-chamber plate-frame electrolyzer, the material of the electrolyzer is corrosion-resistant titanium alloy, the above-prepared electrode is used as the cathode, the anode is the N115 membrane electrode coated with iridium oxide, the cathode electrolyte is 0.1 mol / L potassium acetate, 15wt% KOH is added to adjust the pH to 7-9, and the anode is 1 mol / L H2SO4. The reaction temperature of the electrolyzer is controlled at 40°C, the CO pressure is 0.8MPaG, the pressure difference between CO and the cathode is 15kPa, and the reaction is started. The current density is 1000A / m 2 , the cell voltage is 3.5V, and the current efficiency of the product potassium acetate is 80%.

[0080] Electrodialysis process:

[0081] The cathode liquid at the outlet of the electrolyzer is separated by a three-grid two-membrane electrodialysis device, and potassium acetate enters the electrodialysis device through the intermediate chamber, where K + The OH generated by electrolysis enters the cathode chamber through the cation membrane - Generate KOH, CH3COO - The H generated by electrolysis enters the anode chamber through the anion membrane + Produce acetic acid. Current density 1000A / m 2 , the KOH generated at the cathode returns to the cathode of the electrolytic cell; the anode obtains an acetic acid aqueous solution.

[0082] Comparative Example 1 differs from Example 1 only in the catalyst preparation process, where the catalyst contains only Cu powder and no other raw materials. The electrode preparation and reaction process parameters are the same.

[0083] Electrolysis reaction:

[0084] In the three-chamber plate-frame electrolyzer, the material of the electrolyzer is corrosion-resistant titanium alloy, the above-prepared electrode is used as the cathode, the anode is the N115 membrane electrode coated with iridium oxide, the cathode electrolyte is 0.1 mol / L potassium acetate, 15wt% KOH is added to adjust the pH to 7-9, and the anode is 1 mol / L H2SO4. The reaction temperature of the electrolyzer is controlled at 40°C, the CO pressure is 0.8MPaG, the pressure difference between CO and the cathode is 15kPa, and the reaction is started. The current density is 1000A / m2 , the cell voltage is 3.2V, and the current efficiency of the product potassium acetate is 50%.

[0085] Comparative Example 2

[0086] Comparative Example 2 Catalyst and electrode preparation, the electrolysis reaction process is consistent, but there is no electrodialysis process. The reaction process consumes KOH, and no pure acetic acid is produced.

[0087] Through the technical solution of the present invention, carbon monoxide can be effectively utilized to prepare potassium hydroxide and acetate, thus realizing the resource utilization of carbon monoxide and also reducing energy consumption and carbon monoxide emissions.

Claims

1. A method for preparing acetic acid from CO, comprising the following steps: (1) CO electrolysis to produce potassium acetate, using KOH to adjust the pH of the cathode liquid to alkaline during the reaction; (2) Potassium acetate is treated by an electrodialysis device to produce acetic acid and KOH.

2. The method according to claim 1, characterized in that The electrolytic cell used in step (1) comprises a cathode chamber, an anode chamber, a gas chamber, a gas diffusion electrode, and an anode membrane electrode containing an ion membrane, wherein the electrode in the cathode chamber is a gas diffusion electrode, which separates the electrolyte side and the CO gas, and CO diffuses from the gas chamber of the gas diffusion electrode to the cathode chamber for electrolysis to produce potassium acetate and KOH; the anode chamber undergoes a water electrolysis reaction to produce H + and O2, H + Cross the membrane into the cathode compartment and mix with OH - Generates water.

3. The method according to claim 1 or 2, characterized in that: The electrolyte in the anode chamber of the CO electrolyzer is pure water; and / or, the cathode liquid in the cathode chamber of the CO electrolyzer contains potassium acetate, and 5-20wt% of KOH is added to the cathode liquid in the cathode chamber to adjust the pH of the cathode liquid during the electrolysis process; preferably, the concentration of the cathode liquid in the cathode chamber of the CO electrolyzer is 0.1-5mol / L, preferably 0.5-2mol / L, and the pH value of the cathode liquid in the electrolyzer is adjusted to 7-9 by using KOH.

4. The method according to any one of claims 1 to 3, characterized in that: The anode membrane electrode containing the ion membrane is a membrane electrode with an iridium oxide catalyst coated on the surface of a Nafion115 membrane.

5. The method according to any one of claims 1 to 4, characterized in that: The gas diffusion electrode of the cathode chamber comprises an electrode substrate and a catalyst slurry loaded on the substrate; preferably, the catalyst slurry loaded on the substrate comprises the following components: catalyst, ionic polymer Nafion, alcohol, and water; preferably, in the catalyst slurry, the mass ratio of the catalyst to the ionic polymer Nafion, alcohol, and water is 1:(0.01-0.05):(0.3-1):(1-2), preferably 1:(0.01-0.02):(0.3-0.6):(1-1.5).

6. The method according to any one of claims 1 to 5, characterized in that: The catalyst comprises a main catalyst and a sub-catalyst, wherein the active metal of the main catalyst is Cu; the active metal of the sub-catalyst contains Re, preferably Fe and / or Ce; preferably, in the catalyst, Cu is 50-70wt%, Re is 19-39wt%, and Fe and / or Ce is 1-21wt%.

7. The method according to any one of claims 1 to 6, characterized in that: The method for preparing the gas diffusion electrode comprises the following steps: according to the ratio, (1) mixing the catalyst with ionic polymer Nafion, alcohol and water to prepare a slurry; (2) applying the slurry on the electrode substrate by scraping and drying at 60-99°C; (3) The electrode precursor obtained in step (2) is hot-pressed and bonded to the PTFE membrane at 100-150°C.

8. The method according to claim 7, characterized in that In the preparation method of the gas diffusion electrode, the thickness of the scraped electrode is 500-1000 μm; the thickness of the PTFE membrane is 500-1000 μm.

9. The method according to any one of claims 1 to 8, characterized in that: The electrodialysis device is a three-cell two-membrane electrodialysis device, comprising an anode chamber, an anion membrane, an intermediate chamber, a cation membrane, and a cathode chamber.

10. The method according to claims 1-9, characterized in that The electrolyte was electrolyzed using a DC power supply and a constant current method with a current density of 1000 A / m 2 -5000A / m 2 , the voltage is below 5V.

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