Electrolysis system

Abstract

The present invention provides an electrolysis system that improves the current efficiency of an electrolytic hydrogenation reaction by reducing the resistance of an electrolyte membrane by supplying water to the electrolyte membrane while suppressing the amount of movement of water to a cathode. An electrolysis system is provided with: an electrolyte membrane having proton conductivity; a cathode comprising a catalyst for an electrochemical reaction in which protons are involved; an anode including a catalyst for oxidizing water to generate protons; and a structure for supplying water vapor to the anode, in which the anode catalyst layer has a proton-conductive ionomer, and the ohmic resistance of the electrolysis system and the ratio of the (002) diffraction peak intensity of carbon in the anode catalyst layer to the (110) diffraction intensity of Ir oxide are within predetermined ranges.

Description

Technical Field

[0001] This invention relates to an electrolysis system capable of electrochemically decomposing water to generate oxygen and protons, and producing hydrides by using the electrochemical reaction of the generated protons to hydrogenate the hydride. Background Technology

[0002] In recent years, there has been a growing interest in renewable energy sources such as solar, wind, hydro, and geothermal power, as these sources offer the potential to reduce carbon dioxide emissions compared to thermal power generation. However, renewable energy sources require measures to mitigate output fluctuations, particularly over medium to long periods. Furthermore, large-scale transmission of renewable energy is challenging. In contrast, converting electricity from renewable sources into chemical energy is an effective method. Electrochemical systems are a prime example of this direct conversion. Secondary batteries, or storage batteries, which convert electricity into chemical energy and store it, are widely used as an example of electrochemical systems.

[0003] As an electrochemical system based on renewable energy, the following system is promising: large-scale solar power generation systems and wind power generation systems are set up in suitable locations around the world, and the resulting renewable energy is used to produce hydrogen through water electrolysis. The hydrogen is then converted into a hydrogen energy carrier suitable for transportation and transported to Japan for energy consumption within Japan.

[0004] Organic hydrides (organochemical hydrides) have attracted attention as a type of energy carrier. Examples of organic hydrides include cyclic organic compounds such as cyclohexane, methylcyclohexane, and decahydronaphthalene. Organic hydrides are typically liquids at room temperature and pressure, making them easy to handle. Furthermore, organic hydrides can undergo electrochemical hydrogenation and chemical dehydrogenation. Therefore, using organic hydrides as an energy carrier allows for simpler transportation and storage compared to liquid hydrogen. Especially when liquids with properties similar to petroleum are chosen as organic hydrides, they exhibit excellent compatibility with large-scale energy supply systems, thus offering the advantage of easy distribution to the end of the energy supply system.

[0005] Previously, methods for producing organic hydrides included: producing hydrogen by water electrolysis using renewable energy sources, and producing organic hydrides by hydrogenation of the hydride (the dehydrogenated form of the organic hydride) in a hydrogenation reactor.

[0006] In contrast, if electrolytic synthesis can be used to directly hydrogenate the hydride, the manufacturing process of organohydrides can be simplified. Furthermore, efficiency loss is minimal regardless of scale, resulting in excellent control over the start-up and shutdown of the organohydride manufacturing apparatus. For example, Patent Document 1 discloses an organohydride manufacturing apparatus comprising an anode that generates protons from water and a cathode that hydrogenates an organic compound with unsaturated bonds. In these organohydride manufacturing apparatuses, oxygen is generated at the anode due to the supply of water or sulfuric acid. The electrode is covered by the generated bubbles, increasing resistance. To avoid this electrode being covered by bubbles while simultaneously promoting the supply of liquid water or sulfuric acid to the anode, porous electrodes such as mesh or foam electrodes are preferred. Patent Documents 2, 3, and 4 disclose electrochemical reduction apparatuses that utilize a water supply method that supplies water or humidifying gas to the anode.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2018-197364

[0010] Patent Document 2: International Publication No. 2015 / 029366

[0011] Patent Document 3: Japanese Patent Application Publication No. 2003-045449

[0012] Patent Document 4: Japanese Patent Application Publication No. 2012-72477 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] In this technology, pure water or sulfuric acid is typically supplied to the anode chamber as disclosed in, for example, Patent Document 1. However, if the electrolyte membrane undergoes ion exchange using impurity cations, it can lead to degradation. Water accompanying protons moving from the anode to the cathode during electrolysis covers the surface of the catalyst components in the cathode, hindering the approach of water-insoluble hydrides such as toluene to the catalyst components. This impedes the desired hydrogenation reaction at the cathode, resulting in a decrease in the formation efficiency of target hydrides such as organic hydrides and the generation of excess hydrogen as a side reaction. Due to the presence of impurity cations, protons in the electrolyte membrane are replaced by cations, leading to an increase in the resistance of the electrolyte membrane and a decrease in electrical efficiency. These are all problems. In particular, there is a problem that in an environment where electrolysis is carried out and toluene hydrogenation (low toluene content) is performed, the contact frequency of toluene on the catalyst decreases, the reaction efficiency decreases, and the performance is significantly degraded.

[0015] Furthermore, during the research of this invention, the following problem was discovered: by supplying steam to the anode, the migration of water moving from the anode to the cathode during electrolysis can be greatly reduced. On the other hand, if the electrolyte membrane has insufficient moisture, the resistance of the electrolyte membrane will increase significantly, thereby increasing the energy consumption and making it impossible to continue electrolysis under certain conditions.

[0016] Patent Document 2 discloses a water supply method for supplying water or humidifying gas to the anode, but since the anode structure has a catalyst component on the aforementioned porous substrate, it does not mention the problems and solutions when supplying water in gas form.

[0017] Patent document 3 discloses a means of supplying water or water vapor to the anode, but does not mention the issue or solution disclosed in this application of controlling the amount of adventitious water to suppress the generation of hydrogen as a side reaction.

[0018] Patent document 4 discloses a means of supplying water or water vapor to the anode, but does not mention the control of the water vapor supplied to the anode, the problem of increased resistance due to condensation, or the solution disclosed in this application.

[0019] The present invention was made in view of the above circumstances, and its object is to provide an electrolysis system that improves the current efficiency of the electrolytic hydrogenation reaction by reducing the resistance of the electrolyte membrane by suppressing the water content that moves to the cathode along with the protons moving from the anode to the cathode during electrolysis, while simultaneously supplying the required water to the electrolyte membrane.

[0020] Methods for solving problems

[0021] Therefore, the inventors discovered that by controlling the humidity while supplying water to the anode in the form of water vapor to remove ionic impurities from the water, and by suppressing excess water present in the electrolyte membrane to allow water to diffuse from the cathode to the anode, it is possible to suppress the water content that moves to the cathode along with protons and improve the current efficiency of the electrolytic hydrogenation reaction, thus completing the present invention.

[0022] That is, the present invention is as follows.

[0023] [1] An electrolysis system comprising: Electrolyte membranes with proton conductivity; The cathode, disposed on one side of the electrolyte membrane, has a cathode catalyst layer comprising a cathode catalyst for electrochemical reactions involving protons. An anode, disposed on the side of the electrolyte membrane opposite to the aforementioned side, includes an anode catalyst layer comprising an anode catalyst for oxidizing water to generate protons; and The structure that supplies water vapor to the anode described above, in, A portion of the aforementioned anolyte catalyst layer contains proton-conductive ionomers. The ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide, as determined by X-ray diffraction, is less than 0.10, with an intensity of 0.6 A / cm. 2 The measured ohmic resistance was 0.400 Ωcm. 2 the following.

[0024] [2] The electrolysis system as described in [1], wherein, at 0.6 A / cm 2 The measured amount of water migrating from the anode to the cathode is greater than 0.00 mg / (cm³). 2 • minutes) and 10.0 mg / (cm) 2 Less than 1 minute.

[0025] [3] An electrolysis system as described in [1] or [2], wherein the electrolysis concentration is 0.6 A / cm 2 The measured amount of water migrating from the anode to the cathode is greater than 0.00 mg / (cm³). 2 • minutes) and 5.0 mg / (cm) 2 Less than 1 minute.

[0026] [4] The electrolysis system as described in any one of [1] to [3], wherein the structure for supplying water vapor to the anode further includes a mechanism for preventing condensation of the vapor.

[0027] [5] An electrolysis system as described in any one of [1] to [4], wherein the anode catalyst layer is formed into a porous layer.

[0028] [6] The electrolysis system as described in any one of [1] to [5], wherein the water vapor supplied to the anode is water vapor in a gas that is inert to the electrochemical reaction.

[0029] [7] The electrolysis system as described in any one of [1] to [5], wherein the water vapor supplied to the anode is water vapor from the air.

[0030] [8] The electrolysis system as described in any one of [1] to [6], wherein the relative humidity of the water vapor supplied at the anode by the structure that supplies water in the form of water vapor described above can be controlled at any value of 70 to 100%.

[0031] [9] The electrolysis system described in [7] wherein the relative humidity of the water vapor supplied at the anode by the structure that supplies water in the form of water vapor described above can be controlled at any value of 70 to 100%.

[0032]

[10] The electrolysis system as described in any one of [1] to [9] further comprises a structure that supplies an aromatic compound to the cathode as a reaction matrix for obtaining the target product by hydrogenation reaction.

[0033]

[11] The electrolysis system as described in

[10] , wherein the aromatic compound is toluene.

[0034]

[12] The electrolysis system as described in any one of [1] to

[11] , wherein the electrolyte membrane and the anode catalyst layer form a membrane electrode assembly, and the mass of the anode catalyst in the anode catalyst layer is 0.1 mg / cm² relative to the electrode area. 2 Above 5.0 mg / cm 2 the following.

[0035]

[13] The electrolysis system as described in any one of [1] to

[12] , wherein the electrolyte membrane and the cathode catalyst layer form a membrane electrode assembly, and the mass of the cathode catalyst in the cathode catalyst layer is 0.1 mg / cm² relative to the electrode area. 2 Above 5.0 mg / cm 2 the following.

[0036]

[14] An operating method, which is the operating method of the electrolysis system described in any one of [1] to

[13] , wherein the water vapor in the anode is controlled at any value of relative humidity between 70% and 100%.

[0037] According to the present invention, by controlling the humidity while supplying water to the anode in the form of water vapor, ionic impurities are removed from the water. At the same time, by suppressing the excess water content present in the electrolyte membrane, water is allowed to move from the cathode to the anode by diffusion. Therefore, it is possible to suppress the water content that moves to the cathode along with protons, improve the current efficiency of the electrolytic hydrogenation reaction, and suppress hydrogen production to improve the current efficiency of the desired reaction.

[0038] The effects of the invention

[0039] According to the present invention, an electrolysis system is provided that improves the current efficiency of the electrolytic hydrogenation reaction by reducing the resistance of the electrolyte membrane by suppressing the water content that moves towards the cathode along with the protons moving from the anode to the cathode during electrolysis, while simultaneously supplying the required water to the electrolyte membrane. Attached Figure Description

[0040] Figure 1 This is a schematic diagram illustrating an example of a basic unit of an electrolysis system constituting the electrolysis system of the present invention.

[0041] Figure 2This is a graph showing the relationship between current efficiency (ε) and current density (i) in the embodiments and comparative examples.

[0042] Figure 3 This is a graph showing the relationship between voltage and current density (i) in the embodiments and comparative examples.

[0043] Figure 4 This is a graph showing the relationship between the amount of migrating water discharged from the hydride outlet and the current density (i) in the examples and comparative examples.

[0044] Figure 5 This is a graph showing the relationship between the amount of migrating water discharged from the hydride outlet and the ohmic resistance in the embodiments and comparative examples. Detailed Implementation

[0045] The present invention will now be described based on preferred embodiments with reference to the accompanying drawings. These embodiments are not intended to limit the invention but are illustrative; all features described in the embodiments, and combinations thereof, are not necessarily essential features of the invention. Identical or equivalent structural elements, components, and processes shown in the drawings are indicated by the same symbols, and repeated descriptions are omitted where appropriate. Furthermore, the scales or shapes of the parts shown in the figures have been set for ease of explanation and are not intended to be limiting unless specifically mentioned. Additionally, the use of terms such as "first," "second," etc., in this specification or claims does not indicate any order or importance unless specifically mentioned, but is used to distinguish one configuration from others.

[0046] (Electrolysis system)

[0047] The electrolysis system of the present invention comprises: an electrolyte membrane having proton conductivity; a cathode disposed on one side of the electrolyte membrane and having a cathode catalyst layer comprising a cathode catalyst for an electrochemical reaction involving protons; an anode disposed on the side of the electrolyte membrane opposite to the aforementioned side and having an anode catalyst layer comprising an anode catalyst for oxidizing water to generate protons; and a structure for supplying water vapor to the anode. In the electrolysis system of the present invention, a portion of the anode catalyst layer has a proton-conductive ionomer. Furthermore, in the electrolysis system of the present invention, the ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide, as determined by X-ray diffraction, of the anode catalyst layer is 0.10 or less.

[0048] Figure 1The basic unit 100 of the electrolysis system constituting the electrolysis system of the present invention is shown. The electrolysis system of the present invention can be used as an apparatus for electrochemically decomposing water to generate oxygen and protons, and for producing a reduced substance (e.g., hydride, hydrogen) by reducing a reduced substance (e.g., hydride, proton) through an electrochemical reaction utilizing the generated protons (e.g., hydrogenation, proton reduction). In the electrolysis system of the present invention, since water is supplied to the anode in the form of water vapor, the water content present in the electrolyte membrane and the anode catalyst layer can be suppressed to the minimum required for electrolysis. Water moving towards the cathode in the form of accompanying water returns to the anode side through the electrolyte membrane via diffusion, thus suppressing the water content moving towards the cathode side. By suppressing the amount of water moving toward the cathode side, the approach hindrance of water-insoluble hydrides such as toluene to the catalyst caused by the coverage of the cathode catalyst surface with water can be suppressed. In the case of manufacturing hydrides (organic hydrides, etc.), the generation efficiency of hydrides (organic hydrides, etc.) based on catalytic reactions is improved, and the reasons for the decrease in electrical efficiency, such as the generation of excess hydrogen as a side reaction and the increase in the resistance of the electrolyte membrane caused by the replacement of protons with cations in the electrolyte membrane due to the presence of cations, are suppressed.

[0049] Figure 1 In this context, the proton-conducting electrolyte membrane is equivalent to the solid polymer electrolyte membrane 11. The characteristics of the proton-conducting electrolyte membrane will be described below using the solid polymer electrolyte membrane 11 as an example. The solid polymer electrolyte membrane 11 is formed from a proton-conducting material. The solid polymer electrolyte membrane 11 selectively conducts protons while inhibiting the mixing or diffusion of substances between the cathode 12 and the anode 17. As the proton-conducting material, an ionomer is preferred. As the ionomer, a cation-exchange polymer can be used, for example, a polymer having acidic groups such as sulfonic acid groups or carboxyl groups, or a polymer formed by fluorinating these polymers. Specifically, examples include perfluorosulfonic acid polymers such as Nafion (registered trademark) and Flemion (registered trademark), and (meth)acrylic acid fluoropolymers, among which perfluorosulfonic acid polymers are most preferred. The thickness of the solid polymer electrolyte membrane 11 is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 190 μm or less. By making the thickness of the solid polymer electrolyte membrane 11 5 μm or more, the barrier properties of the solid polymer electrolyte membrane 11 can be ensured, and the cross-leakage of hydrides, hydrides (organic hydrides), and oxygen can be more reliably suppressed. In addition, by making the thickness of the solid polymer electrolyte membrane 11 300 μm or less, excessive ion migration resistance can be prevented.

[0050] The area resistivity (i.e., the resistance to ion movement per unit geometric area) of the solid polymer electrolyte membrane 11 after immersion in distilled water at 25°C for 2 hours is not particularly limited, but is preferably 2000 mΩ·cm. 2 The following, and more preferably, is 1000 mΩ·cm 2 The following, and more preferably, is 500 mΩ·cm 2 The following is an example of achieving an area resistivity of 2000 mΩ·cm for the solid polymer electrolyte membrane 11. 2 The following measures can more reliably avoid concerns about insufficient proton conductivity. The ion exchange capacity (IEC) when using a cation-exchangeable polymer as the ionomer is not particularly limited, but is preferably 0.7 to 2 meq / g, more preferably 1 to 1.3 meq / g. By ensuring the ion exchange capacity of the cation-exchangeable ionomer is 0.7 meq / g or higher, concerns about insufficient ion conductivity can be more reliably avoided. On the other hand, by ensuring the ion exchange capacity is 2 meq / g or less, concerns about insufficient strength of the solid polymer electrolyte membrane 11 due to increased solubility of the ionomer in anolytes, hydrides, organic hydrides, etc., can be more reliably avoided.

[0051] The solid polymer electrolyte membrane 11 can be infused with a reinforcing material composed of corrosion-resistant polymers such as fluoropolymers (e.g., PTFE (polytetrafluoroethylene), Viton (trademark) (fluoroelastomer)). By introducing the reinforcing material, the reduction in the dimensional stability of the electrolyte membrane 11 can be suppressed. This improves the durability of the electrolyte membrane 11. Furthermore, it suppresses the cross-linking of hydrides, organic hydrides, and oxygen. Additionally, the surface of the solid polymer electrolyte membrane 11 can be hydrophilized by coating it with a specified inorganic layer (e.g., platinum, ruthenium, palladium, iridium, or an alloy containing one or more of these). Hydrophilization improves the removal of generated oxygen bubbles and enhances performance.

[0052] The cathode 12 is disposed on one side of the solid polymer electrolyte membrane 11. In this embodiment, the cathode 12 is disposed in contact with one main surface of the electrolyte membrane 11. The space housing the cathode 12 is sometimes referred to as a "cathode chamber." The cathode 12 contains a cathode catalyst for proton-involved electrochemical reactions. The cathode 12 may, for example, have a structure formed by stacking a cathode catalyst layer 12a containing the cathode catalyst with a cathode substrate / porous mass flow path 12b. In this case, the cathode catalyst layer 12a is preferably disposed in contact with one main surface of the electrolyte membrane 11. The main surface of the cathode substrate / porous mass flow path 12b, opposite to the cathode catalyst layer 12a, can be in contact with the cathode-side bipolar plate 16a.

[0053] The cathode catalyst layer 12a contains a cathode catalyst (reduction catalyst) for proton-involved electrochemical reactions. Examples of proton-involved electrochemical reactions include the hydrogenation of a hydride by protons to generate an organohydride. As the cathode catalyst, metal particles selected from the group consisting of Pt, Ru, Pd, Ir, and alloys containing at least one of them can be used. Commercially available cathode catalysts can be used, or cathode catalysts prepared according to known methods can be used. Furthermore, the cathode catalyst can be a metal composition comprising a first catalyst metal (noble metal) composed of at least one of Pt, Ru, Pd, and Ir, and a second catalyst metal selected from Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Sn, W, Re, Pb, and Bi. In this case, examples of the metal composition include alloys of the first and second catalyst metals, or intermetallic compounds composed of the first and second catalyst metals.

[0054] The cathode catalyst is supported on a catalyst support made of an electronically conductive material. By supporting the cathode catalyst on the catalyst support, the surface area of ​​the cathode catalyst layer 12a can be increased. Furthermore, the aggregation of the cathode catalyst can be suppressed. Porous microparticles can be used as the catalyst support; examples include electronically conductive materials containing any of the following as main components: porous carbon (mesoporous carbon, etc.), porous metals, porous metal oxides, metal nitrides, carbides, nitrogen oxides, carbonitrides, and partially oxidized carbonitrides.

[0055] Examples of porous carbon include Ketjen Black (registered trademark), acetylene black, furnace black, and Vulcan (registered trademark). Examples of porous metals include Pt black, Pd black, and Pt metal precipitated in fragments. Examples of metallic elements constituting porous metal oxides or other metal compounds include Ti, Zr, Nb, Mo, Hf, Ta, and W. Furthermore, when using porous metals, the porous metal itself without supported metal particles can be used as the cathode catalyst. The average particle size of the porous particles used as catalyst supports or porous metal catalysts is preferably 0.01 μm to 1 μm.

[0056] The catalyst support or porous metal catalyst loaded with the cathode catalyst can be covered with an ionomer. This improves the ionic conductivity within the cathode catalyst layer 12a. Examples of ionomers that can be used as materials for solid polymer electrolyte membranes 11 include substances that can be used as such. The ionomer contained in the cathode catalyst layer 12a preferably partially covers the cathode catalyst. This allows the three elements required for the electrochemical reaction in the cathode catalyst layer 12a (hydride, proton, and electron) to be efficiently supplied to the reaction field.

[0057] The thickness of the cathode catalyst layer 12a is preferably 1 to 100 μm, more preferably 5 to 30 μm. If the thickness of the cathode catalyst layer 12a increases, not only will the resistance to proton movement increase, but the diffusion of hydrides and organic hydrides will also decrease. Therefore, the thickness of the cathode catalyst layer 12a is preferably adjusted within the above range.

[0058] The cathode catalyst layer 12a can be prepared, for example, by the following method: First, a catalyst component powder, water, a solvent such as 1-propanol, and an ionomer (e.g., Nafion (registered trademark) dispersion DE521 (manufactured by DuPont)) are mixed. The amount of ionomer added is preferably in a ratio of the mass of the dried ionomer to the mass of carbon in the catalyst component powder of 1:10 to 10:1. Optionally, a solvent is appropriately added to the resulting mixture to prepare a catalyst ink.

[0059] Next, the obtained catalyst ink is coated onto the cathode substrate / porous mass flow path 12b, dried, and then hot-pressed to fix the cathode catalyst layer 12a onto the cathode substrate / porous mass flow path 12b. Preferably, the hot pressing is performed after the above coating and drying are repeated several times. This results in a more homogeneous cathode catalyst layer 12a. The cathode catalyst layer 12a can be fabricated using the above steps. It should be noted that the cathode catalyst layer 12a can be formed on the solid polymer electrolyte membrane 11. For example, by using a blade coater to coat the catalyst ink onto one main surface of the solid polymer electrolyte membrane 11, a composite of the cathode catalyst layer 12a and the solid polymer electrolyte membrane 11 can be fabricated. Alternatively, by spraying the catalyst ink onto one main surface of the solid polymer electrolyte membrane 11 and drying the solvent components in the catalyst ink, the cathode catalyst layer 12a and the solid polymer electrolyte membrane 11 can be fabricated. Alternatively, catalyst ink can be blown onto a PTFE substrate and then transferred to a solid polymer electrolyte membrane 11 under heating conditions via pressing or other methods, thereby fabricating a cathode catalyst layer 12a and a solid polymer electrolyte membrane 11. It should be noted that in these cases, the solid polymer electrolyte membrane 11 and the cathode catalyst layer 12a can be considered to form a membrane electrode assembly. The mass of the cathode catalyst (reduction catalyst, such as a catalyst metal) in the cathode catalyst layer 12a is preferably 0.1 mg / cm² relative to the electrode area. 2 The above, and more preferably, is 0.2 mg / cm³ 2 The above, and more preferably, is 0.3 mg / cm³. 2 The above, preferably 5.0 mg / cm³ 2 The following, or more preferably, is 3.0 mg / cm³ 2 The following, and more preferably, is 1.0 mg / cm³. 2 The catalyst ink is applied in the following manner. If the mass of the cathode catalyst in the cathode catalyst layer 12a is above the lower limit mentioned above, the reaction resistance can be reduced, which helps to improve the electrolysis performance. If the mass of the cathode catalyst in the cathode catalyst layer 12a is below the upper limit mentioned above, the catalyst layer thickness can be reduced, and the resistance to ion movement can be suppressed.

[0060] The cathode substrate / porous flow path 12b functions to uniformly distribute liquid hydrides supplied from the outside into the surface of the cathode catalyst layer 12a. The material constituting the cathode substrate / porous flow path 12b preferably has high affinity for hydrides and hydrides (organic hydrides). Examples of materials constituting the cathode substrate / porous flow path 12b include porous conductive substrates and sintered fiber bodies. These materials are preferred because they possess porosity suitable for supplying liquid hydrides, removing liquid hydrides and byproducts, and maintaining sufficient electrical conductivity. The thickness of the cathode substrate / porous flow path 12b is selected to optimize the pressure loss within the cathode substrate / porous flow path 12b associated with the supply of liquid hydrides to the cathode catalyst layer 12a and the removal of liquid hydrides and byproducts; it is preferably 10 to 5000 μm.

[0061] More specific examples of materials constituting the cathode substrate and porous flow path 12b include carbon fabric (carbon cloth), carbon nonwoven fabric, and carbon paper. Carbon cloth is made by weaving hundreds of fine carbon fibers with a fiber diameter of several μm into a bundle. Carbon paper is made by sintering carbon raw material fibers into a film precursor using a papermaking process.

[0062] The cathode substrate, which is also a porous flow path 12b, is provided with a hydride inlet 13 and a hydride outlet 14 that connect the interior and exterior of the cathode substrate, which is also a porous flow path 12b.

[0063] Preferably, a hydride inlet 13 is provided on the cathode 12 as a means of supplying hydrides to the cathode 12, and a hydride outlet 14 as a means of recovering hydrides generated at the cathode 12. For example, the hydride inlet 13 can be disposed below the cathode 12, and the hydride outlet 14 can be disposed above the cathode 12 and above the hydride inlet 13 in the vertical direction. One end of the hydride inlet 13 and the hydride outlet 14 can be connected to the cathode substrate and porous mass flow path 12b. In addition, the other end of one or both of the hydride inlet 13 and the hydride outlet 14 can be connected to a catholyte storage tank (not shown) for storing catholyte (a general term for liquid containing hydrides supplied to the cathode 12 and liquid containing hydrides discharged from the cathode 12). A catholy transfer device (not shown), consisting of various pumps such as gear pumps, cylinder pumps, or natural flow devices, can be installed between the hydride inlet 13 and / or the hydride outlet 14 and the catholy liquid storage tank. When both the hydride inlet 13 and the hydride outlet 14 are connected to the catholy liquid storage tank, the catholy liquid is gradually hydrogenated at the cathode 12 through an electrochemical reduction reaction while circulating within the system.

[0064] The cathode liquid storage tank contains: a liquid containing a hydride that will be hydrogenated through the electrochemical reduction reaction in this electrolysis system, a liquid containing a hydrogenated hydride, or a circulating liquid that is gradually hydrogenated. The combination system of the dehydrogenator (hydride) and the organic hydride (hydride) used in this embodiment is not particularly limited as long as it is a combination system of organic compounds capable of hydrogen addition / desorption through reversible hydrogenation / dehydrogenation reactions. However, a combination system in which both the hydride and the hydride are liquids is preferred; for example, acetone-isopropanol systems, benzoquinone-hydroquinone systems, and aromatic hydrocarbon-aromatic hydrocarbon hydride systems are widely used. The aromatic hydrocarbon compound used as the dehydrogenator of the organic hydride is a compound containing at least one aromatic ring, such as benzene and alkylbenzenes. Alkylbenzenes are compounds in which 1 to 4 hydrogen atoms of the aromatic ring are replaced by straight-chain or branched alkyl groups having 1 to 2 carbon atoms, such as toluene and xylene. They can be used alone or in combination. The aromatic hydrocarbon compound is preferably at least one of toluene and benzene. It should be noted that nitrogen-containing heterocyclic aromatic compounds such as pyridine, pyrimidine, and pyrazine can also be used as dehydrogenators. Organohydrides are formed by hydrogenating the above-mentioned dehydrogenators; examples include methylcyclohexane, dimethylcyclohexane, and piperidine.

[0065] The dehydrogenated form of the organic hydride, i.e., the hydride itself, is preferably liquid at room temperature. Furthermore, when using a mixture of two or more of the aforementioned aromatic hydrocarbon compounds and / or nitrogen-containing heterocyclic aromatic compounds, it is acceptable as long as the mixture is liquid. When the hydride is liquid at room temperature, it can be supplied to the cathode 12 in a liquid state without heating, pressurization, or other treatments. This simplifies the structure of the electrolysis system.

[0066] Furthermore, when producing hydrogen instead of liquid hydrides, there is no need for means to supply hydrogen from the cathode liquid storage tank to the hydride inlet 13 and the hydride outlet 14. Among these, when the purpose is to transport energy using ships or vehicles, considering factors such as transportability, toxicity, safety, and storage stability, and considering energy conversion efficiency such as the amount of hydrogen that can be transported per unit volume or mass, the ease of hydrogenation and dehydrogenation reactions, and the minimal increase in Gibbs free energy change, aromatic hydrocarbon-aromatic hydrocarbon hydride systems, represented by the toluene-methylcyclohexane system, are preferred. The hydride can be supplied to the cathode 12 in its original (i.e., 100%) state, or it can be supplied to the cathode 12 in the form of a solution dissolved in a solvent (e.g., using common organic solvents such as cyclohexane and methylcyclohexane. Organic solvents without double bonds have weak adsorption and are not easily reduced, so they are preferred). In the case of a solution, the concentration of the hydride can be, for example, 1 to 100% vol / vol.

[0067] To seal the area below and above the cathode 12 and to protect the hydride inlet 13 and hydride outlet 14, a cathode-side spacer 15 is preferably provided. The cathode-side spacer 15 may be provided below and above the cathode 12 in a manner that surrounds the hydride inlet 13 and hydride outlet 14, thus sealing them tightly. The cathode-side spacer 15 also serves as a sealing material to prevent leakage of organic matter containing hydrides and hydrides to the cathode substrate and porous flow path 12b, and preferably has electronic insulation properties. Examples of materials constituting the cathode-side spacer 15 include corrosion-resistant polymers such as fluoropolymers (e.g., PTFE (polytetrafluoroethylene), Viton (trademark) (fluoroelastomer)).

[0068] The cathode-side bipolar plate 16a can be grounded to the cathode substrate / porous mass flow path 12b. In this embodiment, the cathode-side bipolar plate 16a is stacked on the main surface of the cathode substrate / porous mass flow path 12b opposite to the cathode catalyst layer 12a. The cathode-side bipolar plate 16a has electronic conductivity and also functions as a power supply plate. Examples of materials constituting the cathode-side bipolar plate 16a include metals such as SUS and Ti.

[0069] The anode 17 is disposed on the other side of the solid polymer electrolyte membrane 11. In this embodiment, the cathode 12 is disposed in contact with one main surface of the solid polymer electrolyte membrane 11, therefore the anode 17 is disposed on the main surface opposite to the solid polymer electrolyte membrane 11. The anode 17 may be composed of a porous anode catalyst layer 17a, or it may have a structure in which the anode catalyst layer 17a and the anode substrate 17b are laminated. The anode 17 may be disposed between the solid polymer electrolyte membrane 11 and the anode flow path structure 18. When the anode 17 is composed of the anode catalyst layer 17a, it may be disposed in such a way that one main surface of the anode catalyst layer 17a is in contact with the solid polymer electrolyte membrane 11 and the other main surface of the anode catalyst layer 17a is in contact with the anode flow path structure 18. It should be noted that in these cases, the solid polymer electrolyte membrane 11 and the anode catalyst layer 17a can be regarded as forming a membrane electrode assembly. When the anode 17 has a structure formed by stacking an anode catalyst layer 17a and an anode substrate 17b, it can be arranged such that the anode catalyst layer 17a is in contact with one main surface of the solid polymer electrolyte membrane 11, and the main surface of the anode substrate 17b on the side opposite to the anode catalyst layer 17a is in contact with the anode flow path structure 18. The anode-side bipolar plate 16b can be disposed in contact with the anode flow path structure 18 on the main surface of the anode flow path structure 18 on the side opposite to the anode 17. As a material constituting the anode-side bipolar plate 16b, examples of materials constituting the cathode-side bipolar plate 16a can be cited. The electrolysis system of the present invention consists of... Figure 1When the basic unit 100 of the electrolysis system shown is configured as a repeating structure of repeating units, in addition to the basic unit of the electrolysis system at the end, the anode-side bipolar plate 16b also serves as the cathode-side bipolar plate 16a of the basic unit of the electrolysis system adjacent to the anode side.

[0070] The anode catalyst layer 17a contains an anode catalyst (oxidation catalyst) for oxidizing water to generate protons. Examples of reactions that oxidize water to generate protons include the decomposition of water into oxygen and protons. As the anode catalyst, particles composed of Ir or Ru oxides and composite oxides containing at least one of them can be used, for example. Commercially available anode catalysts can be used, or products manufactured according to known methods can be used. The mass of the anode catalyst (oxidation catalyst, such as a catalyst metal oxide) in the anode catalyst layer 17a is preferably 0.1 mg / cm² relative to the electrode area. 2 The above, and more preferably 0.2 mg / cm 2 The above, and further preferred, is 0.3 mg / cm³. 2 The above can be considered as an optimal 5.0 mg / cm³. 2 The following, more preferably 3.0 mg / cm 2 The following, a further preferred 1.0 mg / cm 2 The following applies: If the mass of the anode catalyst in the anode catalyst layer 17a is above the lower limit mentioned above, the reaction resistance can be reduced, which helps to improve electrolysis performance. If the mass of the anode catalyst in the anode catalyst layer 17a is below the upper limit mentioned above, the catalyst layer thickness can be reduced, which suppresses ion migration resistance.

[0071] The anode catalyst can be supported on a catalyst carrier. Examples of catalyst carriers include carbon materials and non-carbon materials, with non-carbon materials being preferred. If carbon materials are present in the anode, there is a concern that they may be oxidized, leading to a decrease in current efficiency. The carbon content present in the anode catalyst layer 17a is preferably 30 wt% or less, more preferably 10 wt% or less, further preferably 1 wt% or less, and most preferably approximately 0 wt%.

[0072] The carbon content in the anode catalyst layer 17a can be qualitatively determined, for example, by the ratio of the diffraction intensity of carbon to the diffraction intensity of Ir oxide, as determined by wide-angle X-ray diffraction. Specifically, it can be determined by the ratio of the intensity of (002) diffraction of carbon appearing near a diffraction angle of 26° based on CuKα rays to the intensity of (110) diffraction of Ir oxide appearing near a diffraction angle of 28° ((002)...). C / (110) IrO2The value can be determined in the form of (). In cases where two diffraction peaks overlap and cannot be clearly separated, the value can also be determined as the ratio of the intensity of the (10) diffraction of carbon appearing near a diffraction angle of 42-43 degrees to the intensity of the (200) diffraction of Ir oxide appearing near a diffraction angle of 39 degrees ((10)). C / (200) IrO2 The result is obtained in the form of (002). From the perspective of suppressing the reduction in current efficiency, (002) C / (110) IrO2 and (10) C / (200) IrO2 The preferred values ​​are 0.1 or less and 0.2 or less, respectively.

[0073] A portion of the anode catalyst layer 17a contains an ionomer with proton conductivity. In this embodiment, "containing an ionomer" means that the ionomer exists in the voids of the porous layer, for example, it can be "coated with an ionomer". This improves the ionic conductivity within the anode catalyst layer 17a. Examples of ionomers include substances that can be used as materials for solid polymer electrolyte membranes 11. The ionomer contained in the anode catalyst layer 17a preferably partially coats the anode catalyst. This allows water required for the electrochemical reaction in the anode catalyst layer 17a to be supplied to the reaction field, and protons, electrons, and oxygen to be removed from the reaction field.

[0074] The types of ionomers present in the anode catalyst layer 17a can be identified by known methods, such as micro Fourier transform infrared spectroscopy and solid-state 19F NMR, or analyzed by X-ray photoelectron spectroscopy (XPS).

[0075] From the perspective of capturing moisture supplied to the anode and improving the proton conductivity of the electrolyte membrane, the mass fraction of ionomers present in the anode catalyst layer 17a is 1 wt% or more, preferably 5 wt% or more, and more preferably 10 wt% or more. Furthermore, from the perspective of maintaining the catalytic reaction well and reducing ion resistance, it is preferably 50 wt% or less, more preferably 40 wt% or less, and even more preferably 30 wt% or less. The mass fraction of ionomers present in the anode catalyst layer can be determined, for example, using a scanning electron microscope-energy dispersive X-ray fluorescence analysis (SEM-EDX). The scanning electron microscope can be a Hitachi SU8010 manufactured by Hitachi Advanced Technology, and the EDX can be an EMAX Evolution manufactured by Horiba. The accelerating voltage can be set to 10 kV and the magnification to 1 k. For any part of the anode catalyst layer, the target elements, C, O, F, S, and Ir are measured. If ionomers are present in the anode catalyst layer, the elemental peaks of all target elements are observed. The proportion of ionomers in the anode catalyst layer, as determined by EDX, can be measured using the ratio of the mass percentage of the F element peak to the mass percentage of the Ir element peak. From the perspective of water capture and improved proton conductivity of the electrolyte membrane, a mass percentage of 0.01 or more, more preferably 0.03 or more, and even more preferably 0.05 or more is preferred. From the perspective of maintaining the catalytic reaction well and reducing ion resistance, a mass percentage of 1.00 or less is preferred, more preferably 0.80 or less, and even more preferably 0.70 or less is preferred.

[0076] The thickness of the anode catalyst layer 17a is preferably 1 to 100 μm, more preferably 5 to 30 μm. If the thickness of the anode catalyst layer 17a increases, not only will the resistance to proton movement increase, but the diffusivity of water and oxygen will also decrease. Therefore, the thickness of the anode catalyst layer 17a is preferably adjusted within the above-mentioned range.

[0077] The ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide in the anode catalyst layer 17a needs to be 0.10 or less, preferably 0.05 or less, and more preferably no (002) diffraction peak of carbon is detected (i.e., the ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide is approximately 0). The magnitude of the ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide in the anode catalyst layer 17a reflects the carbon content in the anode catalyst layer. For example, if no (002) diffraction peak of carbon is detected (i.e., the ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide is approximately 0), it reflects that the carbon content present in the anode catalyst layer 17a is approximately 0 wt%. By setting the ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide in the anode catalyst layer 17a to the above-mentioned upper limit, the current consumption caused by carbon oxidation can be suppressed.

[0078] The anode catalyst layer 17a can form a porous layer. Furthermore, when the anode catalyst layer 17a forms a porous layer, it can also contain proton-conducting ionomers within a portion of the voids in the porous layer. The porosity and other properties of the porous layer that can be formed by the anode catalyst layer 17a can be analyzed, for example, by the method shown below.

[0079] Regarding the porosity (V) of the anode catalyst layer 17a formed on the PTFE sheet or the anode catalyst layer 17a in the membrane electrode assembly p,CL According to the packing density (ρ) of the individual anode catalyst layer 17a bulk,CL ) and true density (ρ real,CL The value can be obtained using the following formula.

[0080] V p,CL =1-ρ bulk,CL / ρ real,CL

[0081] Regarding the anode catalyst layer 17a formed on the PTFE sheet or the anode catalyst layer 17a in the membrane electrode assembly, when measuring their density, the cathode catalyst layer 12a is removed, and the laminate composed of the PTFE sheet and the anode catalyst layer 17a, or the laminate composed of the solid polymer electrolyte membrane 11 and the anode catalyst layer 17a, is provided for measurement.

[0082] The packing density (ρ) of the anode catalyst layer 17a alone bulk,CLThe following procedure is followed to determine the mass of the anode catalyst layer 17a. First, the mass of the individual anode catalyst layer 17a is calculated by subtracting the mass of the PTFE sheet or solid polymer electrolyte membrane 11 of the same size from the mass of the laminate consisting of a PTFE sheet and an anode catalyst layer 17a cut to a specified size, or the laminate consisting of a solid polymer electrolyte membrane 11 and an anode catalyst layer 17a. Next, the thickness of the individual anode catalyst layer 17a is determined based on cross-sectional observations using a scanning electron microscope. Finally, the bulk density (ρ) of the individual anode catalyst layer 17a is calculated by dividing its mass by its size and thickness. bulk,CL ).

[0083] True density (ρ) of a single anode catalyst layer 17a real,CL The density can be measured using a densitometer (e.g., the Accyc II 1345 dry automatic densitometer (Shimadzu Corporation)). First, the mass (M) of a laminate consisting of a PTFE sheet and an anode catalyst layer 17a, or a laminate consisting of a solid polymer electrolyte membrane 11 and an anode catalyst layer 17a, cut to a specified size, is measured. c Subtract the mass (M) of the same size PTFE sheet or solid polymer electrolyte membrane 11. s From this, the mass (M) of the individual anode catalyst layer 17a can be determined. CL Next, a densitometer is used to determine the true density (ρ) of the cut-out laminate composed of PTFE sheets and anode catalyst layer 17a or the laminate composed of solid polymer electrolyte membrane 11 and anode catalyst layer 17a. real,c The measurement was then performed. Next, the true density (ρ) of the PTFE sheet or solid polymer electrolyte membrane 11 was similarly determined. real,s Finally, the true density (ρ) of the individual anode catalyst layer 17a was calculated according to the following formula. real,CL ).

[0084] ρ real,CL =M CL / (M c / ρ real,c -M s / ρ real,s )

[0085] If the anode catalyst layer is porous, this can also be confirmed by cutting a cross-section of the anode catalyst layer using, for example, low-temperature slicing, and then observing the voids present in the cross-section using a scanning electron microscope.

[0086] The anode substrate 17b functions to uniformly diffuse water from the outside into the anode catalyst layer 17a. The material constituting the anode substrate 17b is stable in the strongly oxidizing environment of the anode catalyst layer 17a and also facilitates electron conduction between the anode catalyst layer 17a and the anode flow path structure 18; therefore, high electron conductivity is preferred. Examples of materials constituting the anode substrate 17b include porous conductive substrates and sintered fiber bodies. These are preferred because they possess porosity suitable for the supply and removal of gases and liquids and can maintain sufficient electrical conductivity. The thickness of the anode substrate 17b is preferably 10–5000 μm.

[0087] More specific examples of materials constituting the anode substrate 17b include materials formed by depositing electron conductors such as Pt, Ir, and Ru, which are used to improve the electron conduction of the surface, onto titanium fiber sintered bodies or titanium porous sintered bodies.

[0088] The electrolysis system of the present invention further includes a structure for supplying water vapor to the anode (hereinafter referred to as the "water vapor supply structure"). The water vapor supplied to the anode can be water vapor in an inert gas (i.e., a mixture of water vapor and an inert gas). The water vapor supply structure can, for example, be a means of generating a mixture of water vapor and an inert gas (equivalent to...). Figure 1 The humidifier body 23), a means of allowing the mixed gas to flow into the anode (equivalent to Figure 1 The humidifying gas inlet 20) and the space for storing the mixed gas in the anode (equivalent to) Figure 1 Anode chamber 19), means of venting residual gas (equivalent to) Figure 1The anode is configured with a humidified gas outlet 21. To form a region (anode chamber 19) for storing the mixed gas in the anode, an anode flow path structure 18 can be provided between the anode 17 and the anode-side bipolar plate 16b (i.e., between the anode catalyst layer 17a and the anode-side bipolar plate 16b when the anode substrate 17b is absent; or between the anode substrate 17b and the bipolar plate 16b when the anode substrate 17b is present). The anode flow path structure 18 facilitates electron conduction between the anode 17 and the anode-side bipolar plate 16b and forms a space for supplying the gas containing the supply water 25 to the anode 17 in the anode chamber 19. The anode flow path structure 18 can be, for example, a cylindrical structure formed by a skeleton made of a rigid conductive material (e.g., metal). The thickness of the anode flow path structure 18 is preferably 0.2–1.0 mm, more preferably 0.4–0.7 mm. The humidifying gas inlet 20 can be configured such that one end is connected to the lower part of the anode chamber 19 and the other end is connected to the humidifier body 23. A gas that does not participate in the reaction in the anode catalyst layer 17a is introduced into the humidifier body 23 through the inert gas inlet 24, and water 25 is supplied to the anode chamber 19 in the form of steam from the humidifying gas inlet 20. As the inert gas, not only electrochemically inert gases such as nitrogen and rare gases (e.g., helium, neon, argon, krypton, xenon, etc.) can be used, but air can also be used. Air is preferred as the inert gas for simplicity. Furthermore, the humidifying gas outlet 21 can be configured above the humidifying gas inlet 20 in the vertical direction.

[0089] The steam supply structure can have a structure that prevents steam condensation. For example, known methods such as covering with insulating material or heating with a heater can be used. In the electrolysis system of the present invention, since electrolysis is performed by supplying the minimum required amount of water to the anode catalyst layer and the electrolyte membrane, the control of the water supply in a vapor state is important. By preventing the condensation of the supplied steam and suppressing the loss of water supply, the water content supplied to the anode catalyst layer and the electrolyte membrane is controlled, thereby preventing the increase in resistance due to insufficient water and achieving high current efficiency due to the suppression of migrating water. Furthermore, by preventing condensation, it helps to prevent flow path blockage in the anode chamber caused by condensate water and prevent local swelling of the electrolyte membrane, thus improving durability during long-term use.

[0090] To seal the area below and above the anode 17 and to protect the humidifying gas inlet 20 and the humidifying gas outlet 21, an anode-side spacer 22 is preferably provided. The anode-side spacer 22 may be provided, for example, to tightly seal against the anode 17 from below and above, surrounding the humidifying gas inlet 20 and the humidifying gas outlet 21. The anode-side spacer 22 also serves as a sealing material to prevent leakage of the mixture of water vapor and inert gas to the outside of the anode chamber 19, and preferably has electronic insulation properties. Examples of materials constituting the anode-side spacer 22 include corrosion-resistant polymers such as fluoropolymers (e.g., PTFE (polytetrafluoroethylene)).

[0091] In the electrolysis system of the present invention, the relative humidity of the water vapor supplied by the water vapor supply structure at the anode is preferably controlled at any value of 70-100%, more preferably 80-100%, and even more preferably 90-100%. The relative humidity of the water vapor can be controlled, for example, by adjusting the heating temperature of the humidifier body 23, the mixing amount of inert gas, and optionally by measuring the humidity at the anode and providing feedback.

[0092] In the electrolysis system of the present invention, the water content of the electrolyte membrane varies depending on the amount of water vapor supplied to the anode, and therefore the ohmic resistance also varies. For example, when the supplied water vapor is insufficient, the water content of the electrolyte membrane is insufficient, thus maintaining a low amount of water migrating towards the cathode; on the other hand, the resistance of the electrolyte membrane increases. When the supplied water vapor is excessive, the following problems occur: the electrolyte membrane becomes sufficiently humidified, the resistance decreases, and condensation occurs in the anode chamber and along the path of the supplied water vapor. It is important to control the resistance and the amount of water migrating in the electrolysis system within appropriate ranges.

[0093] In the electrolysis system of this invention, from the aspects of reducing the electrolysis potential, reducing energy consumption, and reducing hydrogen generation due to side reactions, a current of 0.6 A / cm is achieved. 2 The measured ohmic resistance can preferably be 0.400 Ωcm. 2 The preferred value is 0.350 Ωcm. 2 The preferred value is 0.300 Ωcm. 2 The preferred value is 0.280 Ωcm. 2 the following.

[0094] Regarding the method for measuring ohmic resistance, after stabilizing the operating temperature, the liquid delivery rate to the cathode chamber, and the supply rate to the anode chamber, the method described in the examples can be used to measure 0.6 A / cm. 2The ohmic resistance under the specified conditions. Specifically, the organic hydride manufacturing apparatus was connected to an electrochemical characteristic evaluation device (VSP300, manufactured by BioLogic). After adjusting the organic hydride manufacturing apparatus to the operating conditions, the ohmic resistance was measured at 0.60 A / cm. 2 Hold the condition for 30 seconds, then perform impedance measurement under the following conditions. Calculate the ohmic resistance (Ω·cm) by multiplying the intersection of the high-frequency curve with the real axis by the electrode area, based on the obtained Nyquist plot. 2 ).

[0095] Current density: 0.60 A / cm 2

[0096] Amplitude: 40mA

[0097] Frequency: 100.0kHz~10.0mHz

[0098] Number of measurement points: 6 / decade

[0099] In addition, in the case of single-tank or stacked tanks, the value can be determined by subsequent measurements after stabilizing the operating temperature, the liquid feed rate to the cathode, and the supply rate to the anode chamber. The value will be expressed as 0.6 A / cm. 2 If the voltage stabilized by the applied current is set to V1, the current density will just change to 0.7 A / cm². 2 Let the voltage after that be V2, and let the magnitude of the voltage change at this point be ΔV. 12 Again at 0.6 A / cm 2 Apply current, set the stable voltage to V3, and adjust the current density to just 0.6 A / cm². 2 Let the voltage after that be V4, and let the voltage change at this point be ΔV. 34 The obtained value can be used to calculate the ohmic resistance using the following formula.

[0100] Ohm resistance (Ωcm) 2 )={ΔV 12 (V) / 0.1(A / cm 2 )+ΔV 34 (V) / 0.1(A / cm 2 )} / 2

[0101] Furthermore, by appropriately changing the current density that is being measured as the target, the ohmic resistance at the target current density can be determined.

[0102] In the electrolysis system of the present invention, from the perspective of reducing the amount of water present in the cathode catalyst layer and improving current efficiency by promoting the supply of hydrides to the catalyst, the amount of water migrating from the anode to the cathode is preferably 10.0 mg / (cm³). 2(min) or less, preferably 5.0 mg / (cm³) 2 ·min) or less, preferably 3.0 mg / (cm) 2 ·min) or less, preferably 2.7mg / (cm) 2 (minutes) or less. From the perspective of ensuring the water content of the electrolyte membrane and reducing resistance, a concentration greater than 0.00 mg / (cm³) is preferred. 2 • minutes), preferably 0.01 mg / (cm³) 2 (minutes) or more, preferably 0.05 mg / (cm³) 2 (minutes or more)

[0103] In the electrolysis system of the present invention, after stabilizing the operating temperature, the liquid delivery rate to the cathode chamber, and the supply rate to the anode chamber, the method described in the embodiments can be used to determine the flow rate at 0.6 A / cm. 2 The amount of water that migrates from the anode to the cathode was measured.

[0104] Regarding the temperature when using the electrolysis system of the present invention, there is no particular limitation as long as the hydrogenation reaction can be carried out and the supplied water can be maintained at a state of water vapor with a specified relative humidity. The temperature when using the electrolysis system of the present invention is preferably 50 to 100°C, more preferably 70 to 90°C.

[0105] The electrolysis system of the present invention can consist of a single... Figure 1 The electrolysis system shown is composed of a basic unit 100, which can also be composed of... Figure 1 The basic unit 100 of the electrolysis system shown is configured as a repeating structure of repeating units. As an example of an electrolysis system configured with a repeating structure, an electrolysis system having the following repeating structure can be described, in which the basic units 100 of the electrolysis system are connected in series with each other by bipolar plates (cathode-side bipolar plate 16a and anode-side bipolar plate 16b) in such a way that, in addition to the basic units of the electrolysis system at the ends, the anode-side bipolar plate 16b also serves as the cathode-side bipolar plate 16a of the basic units of the electrolysis system adjacent to the anode side.

[0106] The hydride, inert gas, and water supply 25 are supplied, and DC power is input into the electrolysis system, which is composed of a single electrolysis system basic unit 100 or multiple electrolysis system basic units 100 stacked together, and then operated. Therefore, a power control unit and a drive control unit (not shown) can be connected to the electrolysis system. The power control unit is, for example, a DC / DC converter that converts the output voltage of the power source into a specified voltage. The positive output terminal of the power control unit is connected to the anode-side bipolar plate 16b located at one end of the electrolysis system. The negative output terminal of the power control unit is connected to the cathode-side bipolar plate 16a located at the opposite end of the electrolysis system. Thus, a specified voltage is applied between the anode 17 and cathode 12 of the electrolysis system basic unit 100.

[0107] In an electrochemical system with the above structure, the reaction that occurs, for example, when toluene (TL) is used as the hydride, is as follows. When toluene is used as the hydride, the resulting organic hydride is methylcyclohexane (MCH).

[0108] <Electrode reaction at the anode>

[0109] 2H₂O → O₂ + 4H + +4e -

[0110] <Electrode reaction at the cathode>

[0111] TL + 6H + + 6e - → MCH

[0112] <Overall Reaction>

[0113] 2TL + 6H2O → 2MCH + 3O2

[0114] That is, the electrode reaction at the anode 17 proceeds in parallel with the electrode reaction at the cathode 12. Furthermore, the protons (H+) generated at the anode 17 through the electrolysis of water... + The protons supplied to the cathode 12 are via a solid polymer electrolyte membrane 11. The protons supplied to the cathode 12 are used for the hydrogenation of the hydride in the cathode 12. Thus, toluene is hydrogenated to produce methylcyclohexane. Therefore, according to the electrolysis system of this embodiment, the electrolysis of water and the hydrogenation reaction of the hydride can be carried out in one step. The same electrode reaction is also carried out when a compound other than toluene is used as the hydride.

[0115] (Method for manufacturing the reduced form)

[0116] The electrolysis system of the present invention can be used in methods for manufacturing reducing agents (e.g., hydrides such as organic hydrides, hydrogen). The method for manufacturing reducing agents disclosed herein includes: (i) Water is supplied to the anode of an electrolysis system in the form of water vapor in a gas that is inert to the electrochemical reaction at the anode, the electrolysis system comprising: an electrolyte membrane having proton conductivity; a cathode disposed on one side of the electrolyte membrane, comprising a cathode catalyst for an electrochemical reaction involving protons; and an anode disposed on the side of the electrolyte membrane opposite to the aforementioned side, comprising an anode catalyst for oxidizing water to generate protons, wherein the anode catalyst forms a porous layer, and a portion of the pores of the porous layer has a proton-conductive ionomer; (ii) In the case of manufacturing hydrides, the hydride that serves as a precursor of the hydride (e.g., an organic hydride) is supplied to the cathode of the electrolysis system. (iii) Powering the aforementioned electrolysis system; and (iv) By simultaneously performing (i) to (iii), the reduced substance (e.g., hydride, proton) at the cathode of the above electrolysis system is reduced by an electrochemical reaction (e.g., hydride, proton reduction) to generate a reduced form of the reduced substance (e.g., hydride, proton) (e.g., organic hydride, etc., hydride, hydrogen).

[0117] The method for producing organic hydrides disclosed herein can be carried out by operating the electrolysis system of the present invention described above. The components of the electrolysis system, the applicable combinations of hydrides and hydrides, the conditions for steam supply, etc., can be described using the information presented in the electrolysis system of the present invention.

[0118] This invention is not limited to the above-described embodiments. Various design changes and modifications can be made based on the knowledge of those skilled in the art, and embodiments with such modifications can also be included within the scope of this invention.

[0119] Example

[0120] The following describes embodiments of the present invention, but these embodiments are merely examples for appropriately illustrating the present invention and do not limit the present invention in any way.

[0121] (Fabrication of the membrane-anodide junction)

[0122] Catalyst ink for the anode catalyst layer was prepared by adding Nafion (registered trademark) dispersion DE521 (manufactured by DuPont) to IrOx catalyst ELC-0110 (manufactured by Tanaka Precious Metals Industry Co., Ltd.) powder. The Nafion (registered trademark) dispersion was added in such a manner that the mass of the dried Nafion was 22 wt% relative to the mass of the catalyst.

[0123] Additionally, Nafion 117 (183 μm thick, manufactured by DuPont) was prepared as a solid polymer electrolyte membrane. The obtained catalyst ink was spray-coated onto one main surface of the solid polymer electrolyte membrane. The catalyst ink was prepared at a mass ratio of Ir to electrode area of ​​1.0 mg / cm². 2 The coating was applied in a specific manner. The coating was then dried at 50°C to remove the solvent from the catalyst ink, forming an anode composed of a porous anode catalyst layer on the surface of the solid high-molecular electrolyte membrane, thus obtaining a membrane-anode junction. The ratio of the (002) diffraction intensity of carbon to the (110) diffraction intensity of Ir oxide based on X-ray diffraction of the anode catalyst layer was measured, and no (002) peak of carbon was detected. The anode catalyst layer used in the examples did not use carbon materials and had a carbon content of 0 wt%.

[0124] In addition, the At.% values ​​of C1s, O1s, F1s, and S2p elements in the anolyte catalyst layer were determined using X-ray photoelectron spectroscopy (XPS) (manufactured by Thermo Fisher Scientific, ESCALAB250), with results of 30.21 At.%, 8.21 At.%, 60.24 At.%, and 1.34 At.%, respectively. A mono-AlKα excitation source of 15 kV × 10 mA was used, with an analysis size of 1 mm (ellipse) and a photoelectron incident angle of 0°. A full scan (0–1100 eV) and a narrow scan (C1s, O1s, F1s, S2p) were performed. The relative elemental concentrations were derived using the following formula.

[0125] C j (%) = 100×(I j / RSF j ) / Σ(I j / RSF j )

[0126] C j Relative elemental concentration (atomic%)

[0127] I j Area intensity (in cps·eV) of each spectrum obtained by setting the background to a straight line.

[0128] RSF j Relative sensitivity coefficients of Li 1s, O 1s, and C 1s

[0129] (S 2p:1.98, C 1s:1.00, O 1s:2.72, F 1s:4.67)

[0130] (Fabrication of cathode substrate that also serves as porous flow path)

[0131] In addition, Pt particles were loaded onto carbon paper to create a cathode substrate that also functions as a porous flow path. The Pt particles in this cathode substrate / porous flow path promote the chemical reaction between hydrogen, a byproduct at the cathode, and unreacted hydrides. First, a mixed solution was prepared by mixing H₂PtCl₆·6H₂O with 1-propanol. The amount of H₂PtCl₆·6H₂O added was adjusted to achieve a Pt loading of 0.02 mg / cm³ on the carbon paper. 2 Carbon paper GDL38BC (manufactured by SGL Carbon) was immersed in the resulting mixed solution. The carbon paper was then completely dried at room temperature. Next, the carbon paper was immersed in a 1 mg NaBH4 aqueous solution for a reduction treatment of 2 hours. After the reduction treatment, the carbon paper was rinsed in pure water. The carbon paper was then dried to obtain a cathode substrate that also functions as a porous flow path.

[0132] (Fabrication of the cathode and the cathode-film-anode junction)

[0133] PtRu / C catalyst (TEC61E54, manufactured by Tanaka Precious Metals Industry Co., Ltd.), pure water, 5 wt% Nafion (registered trademark) solution (manufactured by DuPont), and 1-propanol (manufactured by Wako) were mixed in a ball mill container to prepare the catalyst ink for the cathode catalyst layer. The Nafion / carbon mass ratio of the catalyst ink was 0.8. The catalyst ink was then coated using a bar coater to achieve a precious metal content (PtRu content) of 0.5 mg / cm³. 2 The catalyst ink was adjusted and coated onto GDL38BC carbon paper (manufactured by SGLCarbon). Then, it was heated to 50°C to dry the solvent components in the catalyst ink, resulting in a cathode catalyst layer. The obtained cathode substrate / porous flow path, cathode catalyst layer, and membrane-anode junction were sequentially stacked with the cathode catalyst layer and the membrane-anode junction's membrane side surface (the non-coated side of the catalyst ink) in the direction of contact. Hot pressing was then performed at 120°C and 1 MPa for 3 minutes. This yielded the cathode-membrane-anode junction.

[0134] (Fabrication of an organohydride manufacturing apparatus)

[0135] Prepare cathode-side bipolar plates and anode-side bipolar plates, cathode-side spacers and anode-side spacers, and an anode flow path structure. The cathode and anode bipolar plates are made of titanium. The cathode and anode-side spacers are made of Viton (trademark). The anode flow path structure is made of Pt-plated Ti fiber sintered body. The thickness of the anode flow path structure is 0.55 mm. Stack the cathode bipolar plates, the cathode-membrane-anode junction (a laminate of cathode substrate / porous mass flow path, cathode catalyst layer, electrolyte membrane, and anode), the anode flow path structure, and the anode-side bipolar plates sequentially. The cathode-side spacers are positioned between the cathode-side bipolar plates and the electrolyte membrane, and are tightly fitted to the cathode (cathode substrate / porous mass flow path and cathode catalyst layer). The anode-side spacers are positioned between the electrolyte membrane and the anode-side bipolar plates, and are tightly fitted to the anode (anode catalyst layer) and the anode flow path structure. All components are then secured with bolts and nuts. The layers are pressed together by the elastic force of the anolyte flow path structure, thus creating a tight seal between the layers. These laminates are assembled under a pressure of 0.93 MPa. This results in an organohydride manufacturing apparatus (electrolyzer, electrolysis system) with various membrane electrode junctions. The effective electrode area of ​​the organohydride manufacturing apparatus is 16 cm². 2 .

[0136] (Example 1)

[0137] Using the aforementioned organic hydride manufacturing apparatus, a hydride supply path is connected to the hydride inlet on the cathode side. A hydride discharge path is connected to the hydride outlet on the cathode side. Additionally, a humidifying air supply path is connected to the humidifying gas inlet on the anode side. A humidifying air discharge path is connected to the humidifying gas outlet on the anode side. The anode-side humidifying air supply path is covered with insulation material and heated using a belt heater to prevent condensation due to temperature drop. 10% v / v (ratio relative to methylcyclohexane) toluene, serving as the initial cathode liquid (liquid containing the hydride), is circulated in the cathode chamber (the space housing the cathode) at a flow rate of 5 mL / min. Furthermore, humidifying air at 80°C and 100% RH is circulated in the anode chamber at a flow rate of 0.8 L / min. The electrolytic cell temperature is adjusted to 80°C using a rod heater.

[0138] [Table 1]

[0139] (IV test)

[0140] An organic hydride manufacturing apparatus was connected to an electrochemical characterization evaluation apparatus (VSP300, manufactured by BioLogic), and the electrolytic reduction reaction (electrolytic hydrogenation reaction) of toluene was carried out under the conditions listed in Table 1. The current density was increased from 0.1 A / cm². 2The current is increased sequentially, and the potential is measured after holding for 30 seconds. The potential is measured at various current densities within a range not exceeding 2.2V. The current density is 0.6A / cm². 2 The measured potentials are recorded in Table 2.

[0141] (Current efficiency measurement)

[0142] A PP hydrogen recovery tube, approximately 120 cm long, with a three-way valve branch, is installed at the front end of the discharge path of the hydride outlet on the cathode side. With no voltage applied, the catholyte flows until the hydrogen recovery tube is full. The weight of the solution in the hydrogen recovery tube is recorded as the initial weight. Next, electrolysis begins at a specified current density, and the moment when the catholyte begins to be recovered into the hydrogen recovery tube is recorded as 0 (sec), and electrolysis is performed for a certain period (electrolysis time (sec)). The electrolysis time is adjusted so that the hydrogen recovery tube is not completely filled with hydrogen, and the generated hydrogen is recovered. The weight of the solution in the hydrogen recovery tube is recorded as the post-electrolysis weight (g). At this point, it is confirmed that the catholyte in the hydrogen recovery tube has been cooled to room temperature.

[0143] The current efficiency is calculated by determining the volume of hydrogen produced based on the initial weight (g) and the weight after electrolysis (g) using the following formula. It is assumed that no reactions other than the electrolytic hydrogenation of toluene and the hydrogen generation reaction occur at the cathode.

[0144] The density of the catholyte was taken as 0.77915 (g / cm³). 3 ) to perform calculations.

[0145] F was calculated as 96485 (sec·A / mol).

[0146] Hydrogen volume (cm) 3 = (Initial weight (g) - Weight after electrolysis (g)) / Density of cathode solution (g / cm³) 3 )

[0147] Hydrogen quantity (mol) = Hydrogen volume (cm³) 3 )×101.3(kPa) / 8.31(kPa·L / K·mol) / temperature (K)

[0148] Current efficiency (%) = {1 - hydrogen content (mol) × 2 × F (A·sec / mol) / [(electrolysis current density (A / cm)]} 2 ) × Effective electrode area (cm²) 2 [(electrolysis time (sec))]×100

[0149] (Ohmic resistance measurement)

[0150] The organic hydride manufacturing apparatus was connected to the electrochemical performance evaluation apparatus (VSP300, manufactured by BioLogic), and after adjusting to the conditions listed in Table 1, an A / cm² flow rate was applied. 2 Hold for 30 seconds, then perform impedance measurement under the following conditions. Calculate the ohmic resistance (Ω·cm) by multiplying the intersection of the high-frequency curve with the real axis by the electrode area, based on the obtained Nyquist plot. 2 ).

[0151] Current density: 0.60 A / cm 2

[0152] Amplitude: 40mA

[0153] Frequency: 100.0kHz~10.0mHz

[0154] Number of measurement points: 6 / decade

[0155] (Measurement of Migrating Water Volume)

[0156] The organic hydride manufacturing apparatus was connected to the electrochemical performance evaluation apparatus (VSP300, manufactured by BioLogic), and after adjusting to the conditions listed in Table 1, an A / cm² flow rate was applied. 2 Electrolytic reduction of toluene was carried out. To recover the migrating water discharged from the cathode chamber without leaving residue on the vessel walls, a Teflon tube was connected to the cathode chamber outlet, and the catholyte was recovered into a PP bottle. The start time for recovery into the empty PP bottle was set to 0 minutes, and the catholyte discharged after 30 minutes of electrolysis was recovered. The separated migrating water was identified at the bottom of the bottle. Using a PP dropper, the entire amount of migrating water was recovered into a pre-measured empty PP test tube, and the weight of the recovered migrating water (mg) was measured. It should be noted that, for accurate measurement, the electrolysis time was adjusted so that more than 1g of migrating water could be recovered. At 0.60 A / cm... 2 At different current densities, the electrolysis time was also extended to determine the amount of migrated water. The results are shown in Table 2. Figure 4 .

[0157] Migrating water volume (mg / (cm³)) 2 • minutes) = Recovered migrating water (mg) / (Electrode effective area (cm²) 2 (× Electrolysis time (minutes))

[0158] [Table 2]

[0159] (Examples 2-8)

[0160] The humidification conditions for supplying moisture to the anode side and the humidification airflow rate to the anode side were as described in Table 1, and the above-described characteristic evaluation was performed in the same manner as in Example 1. The results are recorded in Table 2. Figures 2-4 .

[0161] In Examples 7 and 8, a small amount of condensate was discharged at the anode-side outlet.

[0162] (Comparative Example 1)

[0163] Using the above-described organic hydride manufacturing apparatus, a hydride supply path is connected to the hydride inlet on the cathode side. A hydride discharge path is connected to the hydride outlet on the cathode side. Additionally, a water supply path is connected to the humidifying gas inlet on the anode side. A water discharge path is connected to the humidifying gas outlet on the anode side. 10% v / v (ratio relative to methylcyclohexane) of toluene, used as the initial cathode liquid (liquid containing the hydride), is circulated in the cathode chamber at a flow rate of 5 mL / min. Water heated to 60°C is circulated in the anode chamber at a flow rate of 5 mL / min. The electrolytic cell temperature is adjusted to 80°C using a rod heater. The results are recorded in Table 2. Figures 2-4 middle.

[0164] (Comparative Example 2)

[0165] The water supplied to the anode chamber was heated to 80°C and circulated at a rate of 10 mL / min, otherwise the procedure was the same as in Comparative Example 1. The results are recorded in Table 2. Figures 2-4 .

[0166] (Comparative Example 3)

[0167] Except that the humidifying airflow on the anode side was maintained at a rate of 0.5 L / min, the procedure was the same as in Example 1. The electrolyte membrane was not adequately humidified, resulting in a high voltage that could only be measured up to 0.4 A / cm. 2 Therefore, regarding ohmic resistance, it will be expressed as 0.4 A / cm. 2 The measured ohmic resistance values ​​are recorded as reference values ​​in Table 2. Due to the high resistance, inability to perform stable electrolysis, and very small amount of migrated water, the amount of migrated water was not measured. The results are recorded in Table 2. Figure 2 , 3 .

[0168] (Comparative Example 4)

[0169] Except that a 1M dilute sulfuric acid aqueous solution heated to 60°C was used as the water supplied to the anode chamber, the procedure was the same as in Comparative Example 1. The potential was high, and measurements could only be made up to 0.4 A / cm. 2 Therefore, regarding ohmic resistance, it will be expressed as 0.4 A / cm. 2The measured ohmic resistance values ​​are recorded as reference values ​​in Table 2. Despite the high potential, more water migration occurred, therefore, for 0.1 A / cm... 2 ~0.4A / cm 2 The amount of migrating water was measured. Since the amount of migrating water increases proportionally with current density, it was determined based on 0.1 A / cm². 2 ~0.4A / cm 2 The estimated value is 0.6 A / cm. 2 The migration volume under the given conditions is recorded as a reference value in Table 2. The results are recorded in Table 2. Figures 2-4 .

[0170] (Evaluation of the relationship between anode-side supply method and migrating water volume)

[0171] Figure 4 This is a graph showing the relationship between the amount of migrating water discharged from the hydride outlet and the current density (i) (comparison of Examples 1-6 and Comparative Examples 1, 2, and 4). Regarding the amount of migrating water, it was confirmed that in the humidified air anolyte supply method, the amount of migrating water is reduced to less than 1 / 3 compared to the water anolyte supply method. This can be understood as follows: in the humidified air anolyte supply method, a minimum amount of water is supplied while ensuring the amount of water used for oxygen generation reaction at the anode and swelling of the solid polymer electrolyte membrane, thus reducing the amount of migrating water to the cathode.

[0172] (Evaluation of the relationship between anode-side supply method and current efficiency)

[0173] Figure 2 This is a graph showing the relationship between current efficiency (ε) and current density (i). Regarding current efficiency, compared to the significant decrease in current efficiency in the water-based anode supply method, in the humidified air-based anode supply method, with appropriate adjustments to the swelling of the electrolyte membrane, it was confirmed that the decrease in current efficiency was significantly suppressed in an embodiment. The main reason for the decrease in current efficiency is that the migration water retained in the cathode catalyst layer hinders the diffusion of toluene to the cathode catalyst, leading to hydrogen production. The improvement in current efficiency based on the humidified air-based anode supply method is attributed to the reduction of retained water in the cathode catalyst layer as the migration water from the anode to the cathode decreases, thereby improving catalyst utilization.

[0174] (Evaluation of the relationship between water migration volume and ohmic resistance)

[0175] Figure 5 This shows 0.6A / cm 2A graph showing the relationship between the measured amount of migrated water and ohmic resistance. In the anolyte supply method using water or sulfuric acid solution, the amount of migrated water reaches a high level. Although decreasing the temperature and adding sulfuric acid can reduce the amount of migrated water to some extent, it cannot reach the range where current efficiency is improved. In the anolyte supply method using humidified air, the amount of migrated water is significantly reduced compared to the water supply method. When the supply of humidified air is insufficient, the ohmic resistance increases due to insufficient moisture in the electrolyte membrane; however, increasing the supply reduces the ohmic resistance.

[0176] Industrial applicability

[0177] According to the present invention, an electrolysis system is provided that improves the current efficiency of the electrolytic hydrogenation reaction by reducing the resistance of the electrolyte membrane by suppressing the water content that moves towards the cathode along with the protons moving from the anode to the cathode during electrolysis, while simultaneously supplying the required water to the electrolyte membrane.

[0178] Explanation of symbols

[0179] 11 Solid polymer electrolyte membrane

[0180] 12 Cathode

[0181] 12a Cathode catalyst layer

[0182] 12b cathode substrate also serves as a porous mass flow path

[0183] 13 Hydrogenated Inlet

[0184] 14. Hydrogen export

[0185] 15. Cathode-side spacer

[0186] 16a Cathode-side bipolar plate

[0187] 16b Anode-side bipolar plate

[0188] 17 Anode

[0189] 17a Anode catalyst layer

[0190] 17b Anode substrate

[0191] 18 Anode Flow Path Structure

[0192] 19 Anode Chamber

[0193] 20 Humidifying gas inlet

[0194] 21 Humidifying gas outlet

[0195] 22 Anode-side spacer

[0196] 23 Humidifier body

[0197] 24 Inert gas inlet

[0198] 25. Water supply

[0199] 100 Basic Units of Electrolysis System

Claims

1. An electrolysis system comprising: Electrolyte membranes with proton conductivity; A cathode, disposed on one side of the electrolyte membrane, has a cathode catalyst layer comprising a cathode catalyst for proton-involved electrochemical reactions. An anode, disposed on the side of the electrolyte membrane opposite to the stated side, includes an anode catalyst layer comprising an anode catalyst for oxidizing water to generate protons; and The structure that supplies water vapor to the anode in, A portion of the anode catalyst layer contains a proton-conductive ionomer, wherein the ratio of the (002) diffraction peak intensity of carbon to the (110) diffraction intensity of Ir oxide, as determined by X-ray diffraction, is less than 0.10, at 0.6 A / cm. 2 The measured ohmic resistance was 0.400 Ωcm. 2 the following.

2. The electrolysis system as described in claim 1, wherein, At 0.6A / cm 2 The measured amount of water migrating from the anode to the cathode is greater than 0.00 mg / (cm³). 2 • minutes) and 10.0 mg / (cm) 2 Less than 1 minute.

3. The electrolysis system as described in claim 1 or 2, wherein, At 0.6A / cm 2 The measured amount of water migrating from the anode to the cathode is greater than 0.00 mg / (cm³). 2 • minutes) and 5.0 mg / (cm) 2 Less than 1 minute.

4. The electrolysis system as described in claim 1 or 2, wherein, The structure for supplying water vapor to the anode further includes a mechanism to prevent condensation of the vapor.

5. The electrolysis system as described in claim 1 or 2, wherein, The anode catalyst layer is formed into a porous layer.

6. The electrolysis system as described in claim 1 or 2, wherein, The water vapor supplied to the anode is water vapor from a gas that is inert to the electrochemical reaction.

7. The electrolysis system as described in claim 1 or 2, wherein, The water vapor supplied to the anode is water vapor from the air.

8. The electrolysis system as described in claim 1 or 2, wherein, The relative humidity of the water vapor supplied at the anode through the structure that supplies water in the form of water vapor can be controlled to any value between 70% and 100%.

9. The electrolysis system as described in claim 6, wherein, The relative humidity of the water vapor supplied at the anode through the structure that supplies water in the form of water vapor can be controlled to any value between 70% and 100%.

10. The electrolysis system of claim 1 or 2, further comprising a structure for supplying an aromatic compound to the cathode as a reaction matrix for obtaining the target product by hydrogenation.

11. The electrolysis system of claim 10, wherein, The aromatic compound is toluene.

12. The electrolysis system as described in claim 1 or 2, wherein, The electrolyte membrane and the anode catalyst layer form a membrane electrode assembly, wherein the mass of the anode catalyst in the anode catalyst layer is 0.1 mg / cm² relative to the electrode area. 2 Above 5.0 mg / cm 2 the following.

13. The electrolysis system as described in claim 1 or 2, wherein, The electrolyte membrane and the cathode catalyst layer form a membrane electrode assembly, wherein the mass of the cathode catalyst in the cathode catalyst layer is 0.1 mg / cm² relative to the electrode area. 2 Above 5.0 mg / cm 2 the following.

14. An operating method, which is the operating method of the electrolysis system according to claim 1 or 2, wherein, The water vapor in the anode is controlled at any value between 70% and 100% relative humidity.

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