Organic wastewater electrolysis hydrogen production system and method coupled with hydrogen depolarization process
By adopting a coupled hydrogen depolarization process in the organic wastewater electrolytic hydrogen production system, the alternately arranged anode and cathode remove oxygen impurities, the problem of degradation of hydrogen purity in the membrane-free reactor is solved, and efficient and safe preparation of hydrogen and oxidation of organic matter is achieved.
Patent Information
- Application Number
- CN202510036136.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-09
- Publication Date
- 2025-04-18
AI Technical Summary
The electrolytic hydrogen production efficiency of organic wastewater in existing membrane-free reactors is low, and when the organic substance concentration drops, the purity of hydrogen gas is significantly reduced, making it difficult to take into account both technical and economic indicators.
The organic wastewater electrolytic hydrogen production system adopts a coupled hydrogen depolarization process, by alternately arranging the anode and cathode in the first electrolytic cell, oxygen impurities are removed by alternately passing through the cross-section between the electrodes, and further removal is carried out in the second electrolytic cell through an anion exchange membrane.
The hydrogen depolarization efficiency of the membrane-free reactor is significantly improved, the hydrogen-oxygen mixing problem is avoided, and the low power consumption and high safety are taken into account, while the deep oxidation of organic matter in the wastewater is achieved.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of water electrolysis hydrogen production and wastewater treatment, and specifically relates to an organic wastewater electrolysis hydrogen production system and method coupled with a hydrogen depolarization process. Background Art
[0002] The traditional water electrolysis process includes two half reactions: the cathode hydrogen evolution reaction (HER) and the anode oxygen evolution reaction (OER). OER requires a four-electron transfer process, has slow kinetics, consumes more than 90% of the input energy, and is the rate-controlling step that restricts the efficiency of hydrogen production by water electrolysis. The coupled oxidation technology for hydrogen production by water electrolysis, that is, using the electrochemical oxidation process of organic molecules at the anode end to replace the traditional OER process, can not only reduce the anode oxidation overpotential and improve the cathode hydrogen evolution efficiency, but also achieve the synthesis of high value-added chemicals and the degradation of environmental pollutants, further reducing the cost of hydrogen production, and is expected to provide a new idea for the development of traditional water electrolysis hydrogen production technology. Since the anode does not produce oxygen in principle, the reactor for this technology can be used without a diaphragm to prevent hydrogen and oxygen gas crossover, thereby greatly reducing the processing and manufacturing costs and the maintenance costs caused by the diaphragm being blocked by wastewater impurities. However, in actual applications, the concentration of organic matter in wastewater will decrease as the electrolysis process proceeds, while the competing reaction OER will gradually increase, and the purity of the product hydrogen will decrease significantly without a diaphragm, resulting in the difficulty of taking into account the two technical and economic indicators of the degree of alcohol oxidation conversion and hydrogen purity at the same time. Summary of the invention
[0003] The object of the present invention is to provide a system and method for producing hydrogen by electrolysis of organic wastewater coupled with a hydrogen depolarization process, which solves the defect of low efficiency of producing hydrogen by electrolysis of organic wastewater in existing membraneless reactors.
[0004] In order to achieve the above object, the technical solution adopted by the present invention is: The present invention provides an organic wastewater electrolysis hydrogen production system coupled with a hydrogen depolarization process, comprising a first electrolytic cell and a second electrolytic cell, wherein the anode side of the second electrolytic cell is provided with an electrolyte inlet and an electrolyte outlet, the electrolyte outlet is connected to the electrolyte inlet provided on the first electrolytic cell, the first electrolytic cell is provided with a gas-liquid mixture outlet, the gas-liquid mixture outlet is connected to the gas-liquid inlet provided on the cathode side of the second electrolytic cell, the cathode side of the second electrolytic cell is provided with a gas-liquid outlet, the gas-liquid outlet is connected to an external device; The first electrolytic cell comprises a cell body, in which a plurality of anodes and a plurality of cathodes are alternately arranged, wherein the side at the cell body inlet is the anode, and the side at the cell body outlet is the cathode; an elastic insulating net is arranged between two adjacent anodes and cathodes.
[0005] Preferably, a first flow distributor is provided between the electrolyte outlet of the second electrolytic cell and the electrolyte inlet of the first electrolytic cell.
[0006] Preferably, a second flow distributor is provided between the gas-liquid mixture outlet of the first electrolytic cell and the gas-liquid inlet of the second electrolytic cell.
[0007] Preferably, the inter-electrode distance between two adjacent cathodes and anodes in the first electrolytic cell is 0.1 mm to 1 mm.
[0008] Preferably, the first electrolytic cell anode is a nickel-based mesh coated with a nickel-cobalt alloy.
[0009] Preferably, the cathode of the first electrolytic cell is a nickel-based mesh coated with a nickel-molybdenum-iron alloy, and the mesh number of the nickel-based mesh of the cathode of the first electrolytic cell is greater than the mesh number of the nickel-based mesh on the anode side.
[0010] Preferably, the elastic insulating mesh has a thickness of 0.5 mm to 2 mm and a wire diameter of 0.1 mm to 0.4 mm.
[0011] Preferably, a gas diffusion layer is provided on the cathode side of the second electrolytic cell.
[0012] Preferably, a porous transport layer is provided on the anode side in the second electrolytic cell.
[0013] A method for producing hydrogen by electrolysis of organic wastewater coupled with a hydrogen depolarization process, based on the hydrogen production system, comprises the following steps: The alkaline organic wastewater is pre-oxidized on the anode side of the second electrolytic cell; then it is passed into the first electrolytic cell, and the alkaline organic wastewater alternately passes through the anode and cathode of the first electrolytic cell in the form of through-flow, wherein organic matter oxidation reaction and anode oxygen evolution reaction occur at the anode of the first electrolytic cell, and oxygen reduction reaction and cathode hydrogen evolution reaction occur on the cathode side of the first electrolytic cell; finally, it enters the cathode of the second electrolytic cell through the cathode of the first electrolytic cell for final deoxygenation.
[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an organic wastewater electrolysis hydrogen production system coupled with a hydrogen depolarization process. Compared with a membraneless reactor in which the liquid flow direction is parallel to the electrode surface, the system alternately arranges anodes and cathodes in the electrolyzer, realizes the removal of oxygen produced by the competitive reaction of organic oxidation through the cathode ORR reaction by gas alternately passing through the cathode and anode cross-section, and constructs a membraneless electrolysis hydrogen production process with high safety, which can avoid the hydrogen and oxygen mixing problem caused by side reactions when treating wastewater with lower organic concentration; in addition, by adding an anion exchange membrane electrolysis reactor after the membraneless reactor, on the one hand, the oxygen in the hydrogen of the front membraneless reactor is removed by electrochemical reduction reaction, and on the other hand, the oxidation half reaction of the anode on the other side can oxidize the pollutants for pretreatment; further, compared with the traditional membraneless reactor, the zero spacing structure of the diaphragm electrolyzer cannot be constructed due to insulation considerations between the two electrodes. The system adds an elastic insulating net between the cathode and the anode, which can reduce the solution resistance by compressing the distance between the two electrodes, thereby taking into account low power consumption and high safety, while making the equipment more compact. At the same time, the porous elastic insulating net can also improve the distribution uniformity of liquid flow.
[0015] In summary, compared with the traditional hydrogen production by water electrolysis which only produces valuable hydrogen at the cathode, the cathode and anode reactions of this system both achieve product value-added, and at the same time, the cathode reaction is used to remove oxygen from hydrogen without using other process flows, so the energy utilization efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a schematic diagram of the system structure of Example 1 of the present application. DETAILED DESCRIPTION
[0017] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.
[0018] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.
[0019] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.
[0020] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.
[0021] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.
[0022] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.
[0023] Example 1 This embodiment provides a system for producing hydrogen by electrolysis of organic wastewater coupled with a hydrogen depolarization process, and a method for improving the efficiency and safety of producing hydrogen by electrolysis of organic wastewater in a membraneless reactor by using a cathode hydrogen depolarization process. Figure 1 As shown, it includes a first electrolytic cell 1 and a second electrolytic cell 2, wherein: An electrolyte inlet is provided on the anode side of the second electrolytic cell 2, the electrolyte outlet of the second electrolytic cell 2 is connected to the electrolyte inlet of the first electrolytic cell 1 through a first flow distributor 3, the gas-liquid mixture outlet of the first electrolytic cell 1 is connected to the gas-liquid inlet of the second electrolytic cell 2 through a second flow distributor 4, and the gas-liquid outlet of the second electrolytic cell 2 is connected to a gas-liquid separation unit 5.
[0024] The first electrolytic cell 1 comprises a cell body, in which a plurality of anodes 21 and a plurality of cathodes 22 are alternately arranged, wherein the anode 21 is disposed at the inlet of the cell body, and the cathode 22 is disposed at the outlet of the cell body; an elastic insulating net 23 is disposed between two adjacent anodes and cathodes.
[0025] The second electrolytic cell 2 comprises a cell body, wherein the cell body is provided with an anode 11 and a cathode 12 , and an anion exchange membrane 13 is provided between the anode and the cathode.
[0026] The working process of this embodiment: The alkaline organic wastewater is pre-oxidized on the anode side of the second electrolytic cell 2 and then introduced into the first electrolytic cell 1. The alkaline organic wastewater alternately passes through the anode and cathode of the first electrolytic cell 1 in the form of through-flow, and finally enters the cathode of the second electrolytic cell 2 through the cathode of the first electrolytic cell 1 for final deoxygenation.
[0027] In the above process, the byproduct oxygen generated at the anode in the first electrolytic cell 1 undergoes an oxygen reduction reaction (ORR) when passing through the porous cathode. The thermodynamic potential of this reaction (0.401 V) is higher than that of the hydrogen evolution reaction (0 V), so O2 can more easily replace H + A reduction reaction occurs on the electrode surface, thereby weakening the electrochemical polarization process of hydrogen. + The depolarization effect of reduction can effectively remove oxygen impurities on the one hand; on the other hand, the ORR product is OH - , thereby reducing the alkali consumption caused by OER and organic oxidation reactions and improving the process economy; then, the gas-liquid mixture is passed into the cathode side of the second electrolytic cell 2, and the oxygen impurities in the hydrogen are reduced to OH- through the ORR on the cathode side of the second electrolytic cell 2, and the gas is purified again, while forming a complete electrochemical reaction with the oxidation of organic matter at the other side of the anode; finally, the gas-liquid mixture is passed into the gas-liquid separator to recover the gaseous product hydrogen and the oxidation value-added products in the liquid product.
[0028] The present application realizes the electrochemical purification of hydrogen by coupling the hydrogen depolarization process, which can significantly reduce the oxygen impurities in the gas-liquid mixture produced by the membraneless electrolyzer and avoid the formation of an explosive gas mixture in the gas-liquid separator. Compared with the hydrogen purification achieved by hydrogen-oxygen recombination based on precious metal catalysts, this method uses electrochemical reduction method in the case of high oxygen content in hydrogen, which is safer. Based on the above advantages, deep oxidation of organic matter in wastewater can be achieved, and at the same time, the safety problem of decreased hydrogen purity caused by OER when the organic concentration is low can be effectively controlled, thereby taking into account the economic efficiency of cathode and anode products, and effectively overcoming the industry problem that hydrogen energy preparation and organic value-added conversion cannot be effectively coordinated in the traditional membraneless electrolysis hydrogen production process.
[0029] Example 2 This embodiment provides an organic wastewater electrolysis hydrogen production system coupled with a hydrogen depolarization process, and a method for improving the efficiency and safety of organic wastewater electrolysis hydrogen production in a membraneless reactor through a cathode hydrogen depolarization process. It includes a first electrolytic cell 1 and a second electrolytic cell 2, wherein: An electrolyte inlet is provided on the anode side of the second electrolytic cell 2, the electrolyte outlet of the second electrolytic cell 2 is connected to the electrolyte inlet of the first electrolytic cell 1 through a first flow distributor 3, the gas-liquid mixture outlet of the first electrolytic cell 1 is connected to the gas-liquid inlet of the second electrolytic cell 2 through a second flow distributor 4, and the gas-liquid outlet of the second electrolytic cell 2 is connected to a gas-liquid separation unit 5.
[0030] The first electrolytic cell 1 comprises a cell body, in which a plurality of anodes 21 and a plurality of cathodes 22 are alternately arranged, wherein the anode 21 is disposed at the inlet of the cell body, and the cathode 22 is disposed at the outlet of the cell body; an elastic insulating net 23 is disposed between two adjacent anodes and cathodes.
[0031] The second electrolytic cell 2 comprises a cell body, wherein the cell body is provided with an anode 11 and a cathode 12 , and an anion exchange membrane 13 is provided between the anode and the cathode.
[0032] The inter-electrode distance between two adjacent cathodes and anodes in the first electrolytic cell 1 is 0.1 mm to 1 mm.
[0033] The working temperature of the first electrolytic cell 1 is 85-95%, and the working pressure is 1.6-3.0Mpa.
[0034] The anode of the first electrolytic cell 1 is a nickel-based mesh coated with a nickel-cobalt alloy, with a mesh size of 46 to 60, and the coating process is a thermal spraying method such as plasma thermal spraying, supersonic flame spraying, and supersonic arc.
[0035] The cathode of the first electrolytic cell 1 is a nickel-based mesh coated with a nickel-molybdenum-iron alloy with a mesh size of 60-100 meshes, and the coating process is a thermal spraying method such as plasma thermal spraying, supersonic flame spraying, and supersonic arc.
[0036] The mesh number of the cathode nickel mesh in the first electrolytic cell 1 is higher than that of the anode, so as to better trap oxygen bubbles.
[0037] The elastic insulator is made of one of polytetrafluoroethylene, tetrafluoroethylene-ethylene copolymer, polyperfluoroethylene propylene, polyvinylidene fluoride, polyetheretherketone, polyetherketoneketone, polyetherketone, polyetherketoneetherketoneketone, etc., with a thickness of 0.5 mm ~ 2 mm, a wire diameter of 0.1 mm ~ 0.4 mm, and a weaving method of single wire or double wire.
[0038] The second electrolytic cell 2 is an AEM electrolytic cell, and the AEM is a structurally reinforced membrane with a supporting mesh, and the pressure on both sides of the membrane is equal.
[0039] The surface of the AEM placed on the cathode side is coated with a catalyst, which is in powder form and can be a commercial Pt / C catalyst or a transition metal (Co, Fe, Zn, etc.) single atom catalyst supported on porous nitrogen-doped carbon material. The catalyst is coated on the surface of the AEM on the cathode side by ultrasonic spraying, slit coating, etc.
[0040] The surface of the AEM placed on the anode side is coated with a catalyst, which is a hydrophilic nickel-cobalt hydroxide. The catalyst can be first synthesized in the form of powder and then coated on the porous transport layer or anion exchange membrane (AEM) on the anode side, or it can be directly grown on the surface of the porous transport layer by hydrothermal, electrodeposition, etc.
[0041] A gas diffusion layer is provided on the cathode side of the second electrolytic cell 2. The gas diffusion layer is a hydrophobic carbon paper with a thickness of 0.4-0.8 mm.
[0042] A porous transmission layer is provided on the anode side of the second electrolytic cell 2, and the porous transmission layer is foamed nickel, nickel felt, woven nickel mesh, stamped nickel mesh or stretched nickel mesh.
[0043] The operating temperature of the second electrolytic cell 2 is 60-80%, and the operating pressure is 1.6-3MPa; The membrane electrode size of the second electrolytic cell 2 is 600-6000 cm 2 The number of chambers should be such that the purity of hydrogen after leaving the electrolyzer is ≥99.8%.
[0044] The working process of this embodiment: The byproduct oxygen generated at the anode in the first electrolytic cell 1 undergoes an oxygen reduction reaction (ORR) when passing through the porous cathode. The thermodynamic potential of this reaction (0.401 V) is higher than that of the hydrogen evolution reaction (0 V), so O2 can more easily replace H + A reduction reaction occurs on the electrode surface, thereby weakening the electrochemical polarization process of hydrogen. + The depolarization effect of reduction can effectively remove oxygen impurities on the one hand; on the other hand, the ORR product is OH - , thereby reducing the alkali consumption caused by OER and organic oxidation reactions and improving the process economy; then, the gas-liquid mixture is passed into the cathode side of the second electrolytic cell 2, and the oxygen impurities in the hydrogen are reduced to OH- through the ORR on the cathode side of the second electrolytic cell 2, and the gas is purified again, while forming a complete electrochemical reaction with the oxidation of organic matter at the other side of the anode; finally, the gas-liquid mixture is passed into the gas-liquid separator to recover the gaseous product hydrogen and the oxidation value-added products in the liquid product.
[0045] Example 3 The present embodiment provides a method for producing hydrogen by electrolysis of organic wastewater coupled with a hydrogen depolarization process, comprising the following steps: Step 1, mixing organic wastewater with potassium hydroxide to prepare an electrolyte solution, and introducing the electrolyte solution into the anode side of the second electrolytic cell 2, where an organic oxidation reaction (reaction 1) occurs to obtain a reactant; Step 2, the obtained reactant enters the first electrolytic cell 1 through the first flow distributor 3 at the liquid inlet of the first electrolytic cell 1, and the flow distributor is arranged so that the liquid passes through the electrode evenly in the reactor cross section, and an organic oxidation reaction (reaction 1) and an OER side reaction (reaction 2) occur on the anode side of the first electrolytic cell 1 to obtain a reactant; Step 3, the reactants obtained in step 2 enter the cathode side of the first electrolytic cell 1 through the elastic insulator, and HER reaction (reaction 3) and ORR reaction (reaction 4) occur on the cathode side to form a gas-liquid mixer; Step 4, the obtained gas-liquid mixture enters the cathode side of the second electrolytic cell 2, where mainly ORR reaction (reaction 4) and a small amount of HER reaction (reaction 3) occur to obtain gas-liquid products; Step 5, the obtained gas-liquid product enters the gas-liquid separator, and the hydrogen product then enters the purification unit. This part is the same as conventional alkaline water electrolysis and will not be repeated here. The organic solution can be extracted by precipitation, distillation, exchange membrane and other methods according to the composition.
[0046] In this embodiment, reactions 1 to 4 are respectively: Organic matter (alcohols, aldehydes, phenols, etc.) → oxidation products + ne - (Reaction 1) 4OH - → O2(g) + 2H2O (l) + 4e - (Reaction 2) 4H2O (l) + 4e - → 2H2(g) + 4OH - (Reaction 3) O2(g) + 2H2O (l) + 4e - → 4OH - (Reaction 4) In this embodiment, the molar concentration of potassium hydroxide in the electrolyte solution in step 1 is 1-7 M.
[0047] The working process of this embodiment: The alkaline organic wastewater is pre-oxidized on the anode side of the second electrolytic cell 2 and then introduced into the first electrolytic cell 1. The alkaline organic wastewater alternately passes through the anode and cathode of the first electrolytic cell 1 in the form of through-flow, and finally enters the cathode of the second electrolytic cell 2 through the cathode of the first electrolytic cell 1 for final deoxygenation.
[0048] The byproduct oxygen generated at the anode in the first electrolytic cell 1 undergoes an oxygen reduction reaction (ORR) when passing through the porous cathode. The thermodynamic potential of this reaction (0.401 V) is higher than that of the hydrogen evolution reaction (0 V), so O2 can more easily replace H + A reduction reaction occurs on the electrode surface, thereby weakening the electrochemical polarization process of hydrogen. + The depolarization effect of reduction can effectively remove oxygen impurities on the one hand; on the other hand, the ORR product is OH - , thereby reducing the alkali consumption caused by OER and organic oxidation reactions and improving the process economy; then, the gas-liquid mixture is passed into the cathode side of the second electrolytic cell 2, and the oxygen impurities in the hydrogen are reduced to OH- through the ORR on the cathode side of the second electrolytic cell 2, and the gas is purified again, while forming a complete electrochemical reaction with the oxidation of organic matter at the other side of the anode; finally, the gas-liquid mixture is passed into the gas-liquid separator to recover the gaseous product hydrogen and the oxidation value-added products in the liquid product.
[0049] The present application realizes the electrochemical purification of hydrogen by coupling the hydrogen depolarization process, which can significantly reduce the oxygen impurities in the gas-liquid mixture produced by the membraneless electrolyzer and avoid the formation of an explosive gas mixture in the gas-liquid separator. Compared with the hydrogen purification achieved by hydrogen-oxygen recombination based on precious metal catalysts, this method uses electrochemical reduction method in the case of high oxygen content in hydrogen, which is safer. Based on the above advantages, deep oxidation of organic matter in wastewater can be achieved, and at the same time, the safety problem of decreased hydrogen purity caused by OER when the organic concentration is low can be effectively controlled, thereby taking into account the economic efficiency of cathode and anode products, and effectively overcoming the industry problem that hydrogen energy preparation and organic value-added conversion cannot be effectively coordinated in the traditional membraneless electrolysis hydrogen production process.
[0050] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.
Claims
1. An organic wastewater electrolysis hydrogen production system coupled with a hydrogen depolarization process, characterized in that: The invention comprises a first electrolytic cell and a second electrolytic cell, wherein the anode side of the second electrolytic cell is provided with an electrolyte inlet and an electrolyte outlet, the electrolyte outlet is connected to the electrolyte inlet provided on the first electrolytic cell, the first electrolytic cell is provided with a gas-liquid mixture outlet, the gas-liquid mixture outlet is connected to the gas-liquid inlet provided on the cathode side of the second electrolytic cell, and the cathode side of the second electrolytic cell is provided with a gas-liquid outlet, the gas-liquid outlet is connected to an external device; The first electrolytic cell comprises a cell body, in which a plurality of anodes and a plurality of cathodes are alternately arranged, wherein the side at the cell body inlet is the anode, and the side at the cell body outlet is the cathode; an elastic insulating net is arranged between two adjacent anodes and cathodes.
2. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1 is characterized in that: A first flow distributor is arranged between the electrolyte outlet of the second electrolytic cell and the electrolyte inlet of the first electrolytic cell.
3. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1 is characterized in that: A second flow distributor is provided between the gas-liquid mixture outlet of the first electrolytic cell and the gas-liquid inlet of the second electrolytic cell.
4. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1 is characterized in that: The inter-electrode distance between two adjacent cathodes and anodes in the first electrolytic cell is 0.1 mm to 1 mm.
5. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1 is characterized in that: The first electrolytic cell anode is a nickel-based mesh coated with a nickel-cobalt alloy.
6. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 5 is characterized in that: The cathode of the first electrolytic cell is a nickel-based mesh coated with a nickel-molybdenum-iron alloy, and the mesh number of the nickel-based mesh of the cathode of the first electrolytic cell is greater than the mesh number of the nickel-based mesh on the anode side.
7. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1 is characterized in that: The thickness of the elastic insulating net is 0.5 mm to 2 mm, and the wire diameter is 0.1 mm to 0.4 mm.
8. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1 is characterized in that: A gas diffusion layer is provided on the cathode side of the second electrolytic cell.
9. The organic wastewater electrolysis hydrogen production system coupled with hydrogen depolarization process according to claim 1, characterized in that: A porous transport layer is provided on the anode side of the second electrolytic cell.
10. A method for producing hydrogen by electrolysis of organic wastewater coupled with a hydrogen depolarization process, characterized in that: The following steps are involved: The alkaline organic wastewater is pre-oxidized on the anode side of the second electrolytic cell; then it is passed into the first electrolytic cell, and the alkaline organic wastewater alternately passes through the anode and cathode of the first electrolytic cell in the form of through-flow, wherein organic matter oxidation reaction and anode oxygen evolution reaction occur at the anode of the first electrolytic cell, and oxygen reduction reaction and cathode hydrogen evolution reaction occur on the cathode side of the first electrolytic cell; finally, it enters the cathode of the second electrolytic cell through the cathode of the first electrolytic cell for final deoxygenation.