A low energy consumption electrolytic method for extracting carbon dioxide from aqueous solutions of bicarbonate or carbonate

Abstract

The application discloses an electrolysis method for extracting carbon dioxide from a bicarbonate or carbonate aqueous solution with low energy consumption, adopts a porous electrode as an anode, takes oxidation of hydrogen and bicarbonate or carbonate into carbon dioxide and water as an anode reaction, and takes a reaction of water decomposition into hydrogen and hydroxyl as a cathode reaction. The method has the advantages of easy recovery of generated carbon dioxide, low electrolysis energy consumption, no emission of a large amount of hydrogen in an electrolysis system, and avoidance of use of expensive iridium catalyst in the anode. The purity of generated carbon dioxide is increased from 79% to 98-99%; the electrolysis voltage is decreased by 1.3-1.6 V (compared with an iridium anode); the electrolysis system does not emit a large amount of hydrogen; and the anode does not use iridium catalyst, thereby effectively reducing the cost of noble metal catalyst on the anode (reduced to 1 / 3-1 / 30).

Description

(I) Technical Field

[0001] This invention belongs to the field of electrolytic synthesis and relates to a low-energy electrolytic method for extracting carbon dioxide from aqueous solutions of bicarbonates or carbonates. (II) Background Technology

[0002] Carbon dioxide (approximately 10% carbon dioxide) in industrial flue gas is absorbed by an alkaline aqueous solution to produce bicarbonate or carbonate aqueous solution. Carbon dioxide is then extracted from the bicarbonate or carbonate aqueous solution using electrolysis to prepare an alkaline aqueous solution. Figure 1 This is a method for extracting pure carbon dioxide gas from flue gas with promising industrial applications. The biggest problem with this method is that the following major issues exist during the electrolysis process: (1) CO2 recovery is difficult (CO2 is emitted together with oxygen); (2) Electrolysis energy consumption is relatively high; (3) The electrolysis system emits a large amount of hydrogen gas; (4) The anode catalyst is expensive (~1200 yuan / gram iridium) and used in large quantities (current density ≥1000A / m). 2 Iridium loading ≥10 g / m 2 ). (III) Summary of the Invention

[0003] The purpose of this invention is to provide a low-energy electrolytic method for extracting carbon dioxide from aqueous solutions of bicarbonates or carbonates. The method employs a porous electrode as the anode, with the oxidative reaction of hydrogen and bicarbonate or carbonate ions to carbon dioxide and water as the anodic reaction, and the cathodic reaction of water decomposition into hydrogen and hydroxide ions as the cathode reaction. This method has the advantages of easy recovery of generated carbon dioxide, low electrolytic energy consumption, no emission of large amounts of hydrogen from the electrolytic system, and avoidance of the use of expensive iridium catalysts at the anode.

[0004] The technical solution adopted in this invention is:

[0005] This invention provides a low-energy electrolysis method for extracting carbon dioxide from an aqueous solution of bicarbonate or carbonate. The method uses a three-chamber electrolytic cell as the reactor, which consists of a cathode chamber, an anode chamber, and a gas chamber. The anode chamber is located between the cathode chamber and the gas chamber. A porous electrode is placed between the anode chamber and the gas chamber as the anode, and a diaphragm is placed between the anode chamber and the cathode chamber. The gas chamber has a hydrogen inlet, and the cathode chamber has a hydrogen outlet. An aqueous solution containing bicarbonate or carbonate is used as the anolyte, and an aqueous solution containing alkali metal hydroxide or quaternary ammonium base is used as the catholyte. During electrolysis, water decomposes into hydroxide ions and hydrogen at the cathode. At the anode, hydrogen ions and bicarbonate or carbonate ions are oxidized into carbon dioxide and water. Hydrogen is introduced into the anode from the gas chamber as the anode reaction feedstock. Alkali metal cations or quaternary ammonium cations travel from the anode chamber through the diaphragm to the cathode chamber and combine with hydroxide ions generated at the cathode to form alkali metal hydroxides or quaternary ammonium bases. The carbon dioxide generated at the anode is discharged through the outlet of the anode chamber or the outlet of the gas chamber.

[0006] Furthermore, the porous electrode is composed of a macroporous layer, a microporous layer and a catalytic layer in sequence, with the microporous layer located between the macroporous layer and the catalytic layer; or the porous electrode is composed of a macroporous layer, a microporous layer and a catalytic layer in sequence, with the microporous layer located between the macroporous layer and the catalytic layer, and the catalytic layer located between the microporous layer and the resin layer.

[0007] Furthermore, the macroporous layer is a porous carbon material or a metallic material, the microporous layer is composed of carbon particles and a binder, the catalytic layer is composed of a platinum-carbon catalyst and a binder, the binder is one or more of polytetrafluoroethylene resin (PTFE), polyvinylidene fluoride resin (PVDF), or sulfonic acid resin; the resin layer is a sulfonic acid resin; the sulfonic acid resin includes Nafion resin.

[0008] Furthermore, the carbon material is carbon paper, carbon cloth, graphite felt, carbon felt, or carbon foam, and the metal material is foamed titanium, foamed nickel, or stainless steel.

[0009] Furthermore, the carbon particles are carbon black, acetylene black, activated carbon, or graphite particles.

[0010] Furthermore, the thickness ranges of the macroporous layer, microporous layer, catalytic layer and resin layer in the porous electrode are 100~1000 μm, 5~50 μm, 5~100 μm and 5~500 μm, respectively.

[0011] Furthermore, the mass content of the binder in the microporous layer is 5-30%, and the mass content of the binder in the catalyst layer is 10-25%.

[0012] Furthermore, the platinum loading on the porous electrode is 0.1~1.0 mg / cm³. 2 .

[0013] Furthermore, the anode current density ranges from 1000 to 10000 A / m. 2 The temperature range of the anolyte and catholyte is 10~90℃, and the concentration range of bicarbonate or carbonate in the anolyte is 0.5~5 mol / L.

[0014] Furthermore, the bicarbonate is sodium bicarbonate, potassium bicarbonate, tetramethylammonium bicarbonate, or tetraethylammonium bicarbonate; and the carbonate is sodium carbonate, potassium carbonate, tetramethylammonium carbonate, or tetraethylammonium carbonate.

[0015] Furthermore, the quaternary ammonium base is tetramethylammonium hydroxide or tetraethylammonium hydroxide; the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

[0016] The diaphragm and cathode materials described in this invention can be conventionally selected based on existing knowledge. For example, the diaphragm material can be various cation exchange membranes, including sulfonic acid membranes, carboxylic acid membranes, and sulfonic acid-carboxylic acid composite membranes; the cathode material can be stainless steel, nickel, etc.

[0017] The concentration of the alkali metal hydroxide or quaternary ammonium base in the catholyte, as well as the membrane and cathode current density, can be conventionally selected based on existing electrolytic synthesis expertise. The suitable concentration range for the alkali metal hydroxide or quaternary ammonium base in the catholyte is 0.2–5 mol / L; the suitable range for the membrane and cathode current density is 1000–10000 A / m. 2 The electrolytic extraction method for carbon dioxide can be conventionally designed based on existing knowledge and can be carried out intermittently or continuously.

[0018] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in: (1) the purity of carbon dioxide produced increases from 79% to 98~99%; (2) the electrolysis voltage decreases by 1.3~1.6 V (compared with iridium anode); (3) the electrolysis system does not emit a large amount of hydrogen; (4) the anode does not use iridium catalyst, effectively reducing the cost of precious metal catalyst on the anode (reduced to 1 / 3-1 / 30). (iv) Description of the attached drawings

[0019] Figure 1 A schematic diagram of the principle of extracting carbon dioxide from an aqueous solution of potassium bicarbonate (A) or potassium carbonate (B) using the traditional electrolysis method.

[0020] Figure 2 The schematic diagram of the electrolytic extraction of carbon dioxide of the present invention is as follows: A. A porous electrode composed of a macroporous layer, a microporous layer and a catalyst layer in sequence is the anode, and an aqueous solution containing bicarbonate is the anolyte; B. A porous electrode composed of a macroporous layer, a microporous layer and a catalyst layer in sequence is the anode, and an aqueous solution containing carbonate is the anolyte; C. A porous electrode composed of a macroporous layer, a microporous layer, a catalyst layer and a resin layer in sequence is the anode, and an aqueous solution containing bicarbonate is the anolyte; D. A porous electrode composed of a macroporous layer, a microporous layer, a catalyst layer and a resin layer in sequence is the anode, and an aqueous solution containing carbonate is the anolyte.

[0021] Figure 3 A schematic diagram of the porous electrode of the present invention.

[0022] Figure 4 , three A schematic diagram of the structure of a chamber electrolytic cell. (V) Detailed Implementation Methods

[0023] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0024] In the following comparative examples and embodiments, both the porous electrode and the titanium-plated iridium oxide electrode were purchased from Hangzhou Sai'ao Electrochemical Instrument Co., Ltd.

[0025] The current efficiency (CE, %) of the electrolytic synthesis is defined as follows:

[0026]

[0027] Where V is the volume of the catholyte at the end of electrolysis (L), C is the concentration of the newly generated alkali in the catholyte at the end of electrolysis (mol / L), I is the electrolysis current (A), and t is the electrolysis time (h).

[0028] Comparative Example 1: Extraction of carbon dioxide from potassium bicarbonate aqueous solution—the anode uses a titanium-plated iridium oxide electrode.

[0029] by Figure 4 The three-chamber electrolytic cell shown is an electrolytic reactor, consisting of a gas chamber, an anode chamber, and a cathode chamber. The anode chamber is located between the cathode chamber and the gas chamber, with the anode placed between them. A diaphragm is placed between the anode chamber and the cathode chamber. The gas chamber has a hydrogen inlet and an outlet Y, the anode chamber has an outlet X, and the cathode chamber has a hydrogen outlet. The anode has an area of ​​3 cm². 2 Titanium plate coated with iridium oxide electrode (iridium loading 1 mg / cm³) 2 The cathode has an area of ​​6 cm². 2 The stainless steel sheet electrode is used; the Nafion 324 membrane is used as the diaphragm.

[0030] An electrolysis reaction was carried out using 100 mL of a 2 mol / L potassium bicarbonate aqueous solution as the anolyte and 80 mL of a 0.2 mol / L potassium hydroxide aqueous solution as the catholyte. The electrolysis current was 0.3 A, and the temperatures of the anolyte and catholyte were controlled between 50 and 60 °C. No hydrogen gas was introduced during the electrolysis process. At the cathode, water decomposed to form hydroxide ions and hydrogen gas, while at the anode, bicarbonate decomposed to produce carbon dioxide, oxygen, and water. Potassium ions traveled from the anode chamber through the diaphragm to the cathode chamber and combined with the hydroxide ions generated at the cathode to form new potassium hydroxide. Carbon dioxide and oxygen were discharged from the outlet X of the anode chamber. Electrolysis was stopped after 15 hours. At this point, the concentration of potassium bicarbonate in the anolyte had decreased to 0.49 mol / L, and the concentration of potassium hydroxide in the catholyte had increased to 2.0 mol / L. The average voltage of the electrolysis process was 5.0 V, and the current efficiency was 86.0%. During electrolysis, the gas flow rate discharged from outlet X of the anode chamber was 0.32 L / h, and the contents of carbon dioxide and oxygen in the gas were 79% and 21%, respectively. The results show that the electrolytic extraction of carbon dioxide using titanium-plated iridium oxide electrode technology not only requires high voltage and expensive electrodes, but also results in carbon dioxide gas with too low purity, necessitating secondary separation.

[0031] Comparative Example 2: Extraction of carbon dioxide from potassium bicarbonate aqueous solution—anode using porous electrode #1

[0032] In Comparative Example 1 Figure 4 The three-chamber electrolytic cell shown is an electrolytic reactor, in which the anode has an area of ​​3 cm². 2 The porous electrode is designated as porous electrode 1#; the cathode has an area of ​​6 cm². 2 The stainless steel sheet electrode is used; the Nafion 324 membrane is used as the diaphragm.

[0033] Porous electrode #1 is composed of a macroporous layer, a microporous layer, and a catalyst layer sequentially (the thicknesses of the three layers are 200 μm, 15 μm, and 35 μm, respectively), with the microporous layer located between the macroporous layer and the catalyst layer (e.g., ...). Figure 3 (As shown in Figure A); the macroporous layer is porous carbon paper; the microporous layer is composed of carbon black and polyvinylidene fluoride (PVDF) resin in a mass ratio of 7:3; the catalyst layer is composed of platinum-carbon catalyst (Pt / C) and Nafion resin in a mass ratio of 8:2; the platinum loading on the porous electrode is 0.1 mg / cm³. 2 .

[0034] Using 100 mL of 2 mol / L potassium bicarbonate aqueous solution as the anolyte and 80 mL of 0.2 mol / L potassium hydroxide aqueous solution as the catholyte, electrolysis was carried out after hydrogen gas was introduced through the hydrogen inlet of the gas chamber (flow rate of 0.25 L / h). The electrolysis current was 0.3 A, and the temperatures of the anolyte and catholyte were controlled at 50–60 °C. Electrolysis was stopped after 15 hours. At this point, the concentration of potassium bicarbonate in the anolyte had decreased to 0.48 mol / L, and the concentration of potassium hydroxide in the catholyte had increased to 2.0 mol / L. The average voltage during the electrolysis process was 3.3 V, and the current efficiency was 86.0%. During electrolysis, almost no gas was discharged from the outlet X of the anolyte; the flow rate of the gas discharged from the outlet Y of the gas chamber was 0.37 L / h, of which the concentration of carbon dioxide was 69.5%, and the remainder was hydrogen.

[0035] The results show that the porous electrode composed of macroporous layer, microporous layer and catalyst layer can significantly reduce the voltage of carbon dioxide electrolysis (by 1.7V), but the purity of the generated carbon dioxide gas is still not ideal and requires secondary separation.

[0036] Example 1: Extraction of carbon dioxide from potassium bicarbonate aqueous solution—anode using porous electrode #2

[0037] In Comparative Example 1 Figure 4 The three-chamber electrolytic cell shown is an electrolytic reactor, in which the anode has an area of ​​3 cm². 2 Porous electrode #2; cathode with an area of ​​6 cm² 2The stainless steel sheet electrode is used; the Nafion 324 membrane (sulfonic acid membrane) is used as the diaphragm.

[0038] The porous electrode #2 used in the experiment was composed of a macroporous layer, a microporous layer, a catalytic layer, and a resin layer (with thicknesses of 200 μm, 15 μm, 35 μm, and 50 μm, respectively). The microporous layer was located between the macroporous layer and the catalytic layer, and the catalytic layer was located between the microporous layer and the resin layer (e.g., ...). Figure 3 (As shown in B); the porous layer is porous carbon paper; the microporous layer is composed of carbon black and polytetrafluoroethylene (PTFE) resin in a mass ratio of 7:3; the catalyst layer is composed of platinum-carbon catalyst (Pt / C) and Nafion resin in a mass ratio of 8:2; the resin layer is Nafion resin; the platinum loading on the porous electrode is 0.1 mg / cm³. 2 .

[0039] Using 100 mL of 2 mol / L potassium bicarbonate aqueous solution as the anolyte and 80 mL of 0.2 mol / L potassium hydroxide aqueous solution as the catholyte, hydrogen gas was introduced through the hydrogen inlet of the gas chamber (flow rate of 0.25 L / h) for electrolysis. The hydrogen gas produced in the cathode chamber was not reused and was discharged through the hydrogen outlet of the cathode chamber. The electrolysis current was 0.3 A, and the temperatures of the anolyte and catholyte were controlled at 50–60 °C. Electrolysis was stopped after 15 hours. At this point, the concentration of potassium bicarbonate in the anolyte had decreased to 0.49 mol / L, and the concentration of potassium hydroxide in the catholyte had increased to 2.0 mol / L. The average voltage during the electrolysis process was 3.7 V, and the current efficiency was 86.0%. During electrolysis, the gas flow rate discharged from outlet X of the anolyte was 0.25 L / h, with a carbon dioxide concentration of 99%; the gas flow rate discharged from outlet Y of the gas chamber was 0.12 L / h, with a hydrogen concentration of 99%.

[0040] Compared with Comparative Example 1, the concentration of carbon dioxide produced in the anode chamber increased from 79% to 99%, the average voltage of the electrolysis process decreased by 1.3 V, the amount of precious metal used decreased to 1 / 10, and the cost of precious metals decreased to 1 / 30 (based on the price of platinum of 400 yuan / gram).

[0041] Compared with Comparative Example 2, the purity of carbon dioxide gas produced by the reactor increased from 69.5% to 99%.

[0042] Example 2: Extraction of carbon dioxide from potassium bicarbonate aqueous solution — Anode: porous electrode #2 — Sealed gas chamber outlet Y — Cathode: hydrogen gas introduced into the gas chamber

[0043] In Comparative Example 1 Figure 4 The three-chamber electrolytic cell shown is an electrolytic reactor (with the gas outlet Y of the sealed gas chamber and hydrogen generated in the cathode chamber introduced into the gas chamber), wherein the anode has an area of ​​3 cm². 2Porous electrode #2 (same as Example 1); cathode with an area of ​​6 cm² 2 The stainless steel sheet electrode is used; the Nafion 324 membrane (sulfonic acid membrane) is used as the diaphragm.

[0044] Using 100 mL of 2 mol / L potassium bicarbonate aqueous solution as the anolyte and 80 mL of 0.2 mol / L potassium hydroxide aqueous solution as the catholyte, hydrogen gas (flow rate of 0.125 L / h) was introduced through the hydrogen inlet of the gas chamber for electrolysis. The gas chamber outlet Y was sealed, and the hydrogen gas generated in the cathode chamber was recycled into the gas chamber. The electrolysis current was 0.3 A, and the temperatures of the anolyte and catholyte were controlled at 50–60 °C. Electrolysis was stopped after 15 hours. At this point, the concentration of potassium bicarbonate in the anolyte had decreased to 0.49 mol / L, and the concentration of potassium hydroxide in the catholyte had increased to 2.0 mol / L. The average voltage during the electrolysis process was 3.8 V, and the current efficiency was 86.0%. During electrolysis, the gas flow rate discharged from the anolyte outlet X was 0.25 L / h, with a carbon dioxide concentration of 99%.

[0045] Compared with Comparative Example 1, the concentration of carbon dioxide produced in the anode chamber increased from 79% to 99%, the average voltage of the electrolysis process decreased by 1.2 V, the amount of precious metal used decreased to 1 / 10, the cost of precious metals decreased to 1 / 30 (the price of platinum is 400 yuan / gram), and no hydrogen was produced in the electrolysis system.

[0046] Compared with Comparative Example 2, the purity of carbon dioxide gas produced by the reactor increased from 69.5% to 99%.

[0047] Example 3: Extraction of carbon dioxide from potassium bicarbonate aqueous solution—anode using porous electrode #1

[0048] In Comparative Example 1 Figure 4 The three-chamber electrolytic cell shown is an electrolytic reactor, in which the anode has an area of ​​3 cm². 2 Porous electrode 1# (same as comparative example 2); cathode with an area of ​​6 cm² 2 The stainless steel sheet electrode is used; the Nafion 324 membrane is used as the diaphragm.

[0049] Using 100 mL of 2 mol / L potassium bicarbonate aqueous solution as the anolyte and 80 mL of 0.2 mol / L potassium hydroxide aqueous solution as the catholyte, electrolysis was carried out after hydrogen gas was introduced through the hydrogen inlet of the gas chamber (flow rate of 0.13 L / h). The electrolysis current was 0.3 A, and the temperatures of the anolyte and catholyte were controlled at 50–60 °C. Electrolysis was stopped after 15 hours. At this time, the concentration of potassium bicarbonate in the anolyte decreased to 0.48 mol / L, and the concentration of potassium hydroxide in the catholyte increased to 2.0 mol / L. The average voltage of the electrolysis process was 3.4 V, and the current efficiency was 86.0%. During electrolysis, almost no gas was discharged from the outlet X of the anolyte; the flow rate of the gas discharged from the outlet Y of the gas chamber was 0.25 L / h, of which the concentration of carbon dioxide was 98%, and the remainder was hydrogen.

[0050] Compared with Comparative Example 1, the concentration of carbon dioxide produced in the anode chamber increased from 79% to 98%, the average voltage of the electrolysis process decreased by 1.6 V, the amount of precious metal used decreased to 1 / 10, and the cost of precious metals decreased to 1 / 30 (based on the price of platinum of 400 yuan / gram).

[0051] Examples 4-10: Extraction of carbon dioxide from tetramethylammonium bicarbonate aqueous solution—anode using porous electrode #2

[0052] Unless otherwise specified, the reaction conditions were the same as in Example 1. The experimental conditions and results are shown in Table 1. It can be seen that the porous electrode used met the following conditions: the porous electrode was composed of a macroporous layer, a microporous layer, a catalytic layer, and a resin layer (the thicknesses of the four layers ranged from 100 to 1000 μm, 5 to 50 μm, 5 to 100 μm, and 5 to 500 μm, respectively). The microporous layer was located between the macroporous layer and the catalytic layer, and the catalytic layer was located between the microporous layer and the resin layer (e.g., ...). Figure 3 As shown in Figure B), the macroporous layer is composed of porous carbon cloth, graphite felt, carbon felt, carbon foam, titanium, nickel, or stainless steel. The microporous layer consists of carbon black, acetylene black, activated carbon, or graphite particles and PTFE resin, PVDF resin, sulfonic acid resin, or a mixture of both or all three. The resin content in the microporous layer is 5-30%. The catalyst layer consists of a platinum-carbon catalyst and PTFE resin, sulfonic acid resin, or a mixture of both. The resin content in the catalyst layer is 10-25%. The resin layer is formed by hot pressing a sulfonic acid film or by coating with sulfonic acid resin. The platinum content in the porous electrode is 0.1-1 mg / cm³. 2 The temperatures of the anolyte and catholyte are controlled at 10~90℃, and the anolyte current density is 1000~10000 A / m. 2 Both can achieve excellent electrolysis results.

[0053] Table 1. Effect of different reaction conditions on carbon dioxide extraction from potassium bicarbonate aqueous solution.

[0054]

[0055] Remark:

[0056] a During the electrolysis process, the gas flow rate discharged from reactor outlet X is 0.25 L / h, with a carbon dioxide concentration of 99%.

[0057] b During electrolysis, the flow rate of hydrogen gas is 2.5 L / h, and the flow rate of gas discharged from reactor outlet X is 2.5 L / h, with a carbon dioxide concentration of 99%.

[0058] c During electrolysis, the flow rate of hydrogen gas is 0.5 L / h, and the flow rate of gas discharged from reactor outlet X is 0.5 L / h, with a carbon dioxide concentration of 99%.

[0059] Examples 11-14: Electrolytic extraction of carbon dioxide with different anolytes and catholytes—Anode using porous electrode #2

[0060] Unless otherwise specified, the reaction conditions were the same as in Example 1. The experimental conditions and results are shown in Table 2. It can be seen that excellent electrolysis results can be obtained when the anolyte is an aqueous solution of tetramethylammonium bicarbonate, tetraethylammonium carbonate, potassium bicarbonate, and sodium carbonate at a concentration of 0.5~5 mol / L; and the catholyte is an aqueous solution of sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide.

[0061] Table 2 Effects of Electrolytic Carbon Dioxide Extraction—Different Anodic and Cathode Solutions

[0062]

[0063] Remark:

[0064] a During electrolysis, the gas flow rate at reactor outlet X is 0.25 L / h, with a carbon dioxide concentration of 99%; the gas flow rate at reactor outlet Y is 0.12 L / h, with a hydrogen concentration of 99%; at the end of electrolysis, the concentration of tetramethylammonium bicarbonate aqueous solution in the anolyte is 0.5 mol / L.

[0065] b During electrolysis, the gas flow rate discharged from reactor outlet X is 0.12 L / h, with a carbon dioxide concentration of 99%; the gas flow rate discharged from reactor outlet Y is 0.12 L / h, with a hydrogen concentration of 99%.

[0066] cDuring electrolysis, the gas flow rate discharged from reactor outlet X is 0.25 L / h, with a carbon dioxide concentration of 99%; the gas flow rate discharged from reactor outlet Y is 0.12 L / h, with a hydrogen concentration of 99%.

Claims

1. A low-energy electrolysis method for extracting carbon dioxide from an aqueous solution of bicarbonate or carbonate, characterized in that, The method employs a three-chamber electrolytic cell as the reactor, which consists of a cathode chamber, an anode chamber, and a gas chamber. The anode chamber is located between the cathode chamber and the gas chamber, with a porous electrode placed between them as the anode. A diaphragm is placed between the anode chamber and the cathode chamber. The gas chamber has a hydrogen inlet, and the cathode chamber has a hydrogen outlet. An aqueous solution containing bicarbonate or carbonate is used as the anolyte, and an aqueous solution containing alkali metal hydroxide or quaternary ammonium base is used as the catholyte. During electrolysis, water decomposes into hydroxide and hydrogen at the cathode. At the anode, hydrogen reacts with bicarbonate or carbonate to oxidize into carbon dioxide and water. Hydrogen is introduced into the anode from the gas chamber as the anode reaction feedstock. Alkali metal cations or quaternary ammonium cations travel from the anode chamber through the diaphragm to the cathode chamber and combine with hydroxide generated at the cathode to form alkali metal hydroxide or quaternary ammonium base. Carbon dioxide generated at the anode is discharged through the outlet of the anode chamber or the outlet of the gas chamber.

2. The electrolysis method as described in claim 1, characterized in that, The porous electrode is one of the following: (1) composed of a macroporous layer, a microporous layer and a catalytic layer in sequence, with the microporous layer located between the macroporous layer and the catalytic layer; (2) composed of a macroporous layer, a microporous layer, a catalytic layer and a resin layer in sequence, with the microporous layer located between the macroporous layer and the catalytic layer, and the catalytic layer located between the microporous layer and the resin layer.

3. The electrolysis method as described in claim 2, characterized in that, The macroporous layer is a porous carbon material or metal material, the microporous layer is composed of carbon particles and a binder, the catalytic layer is composed of a platinum-carbon catalyst and a binder, the binder is one or more of polytetrafluoroethylene resin, polyvinylidene fluoride resin or sulfonic acid resin; the resin layer is sulfonic acid resin.

4. The electrolysis method as described in claim 3, characterized in that, The carbon material is carbon paper, carbon cloth, graphite felt, carbon felt, or carbon foam; the metal material is titanium, nickel, or stainless steel; and the carbon particles are carbon black, acetylene black, activated carbon, or graphite particles.

5. The electrolysis method as described in claim 3, characterized in that, The thickness ranges of the macroporous layer, microporous layer, catalyst layer and resin layer are 100~1000 μm, 5~50 μm, 5~100 μm and 5~500 μm, respectively.

6. The electrolysis method as described in claim 3, characterized in that, The binder content in the microporous layer is 5-30% by mass, and the binder content in the catalyst layer is 10-25% by mass.

7. The electrolysis method as described in claim 3, characterized in that, The platinum loading on the porous electrode is 0.1~1.0 mg / cm³. 2 .

8. The electrolysis method as described in claim 1, characterized in that, The anode current density ranges from 1000 to 10000 A / m 2 The temperature range of the anolyte and catholyte is 10~90℃, and the concentration range of bicarbonate or carbonate in the anolyte is 0.5~5mol / L.

9. The electrolysis method as described in claim 1, characterized in that, The bicarbonate is sodium bicarbonate, potassium bicarbonate, tetramethylammonium bicarbonate, or tetraethylammonium bicarbonate; the carbonate is sodium carbonate, potassium carbonate, tetramethylammonium carbonate, or tetraethylammonium carbonate.

10. The electrolysis method as described in claim 1, characterized in that, The quaternary ammonium base is tetramethylammonium hydroxide or tetraethylammonium hydroxide; the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

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