Method for producing ion exchange membrane and ion exchange membrane with catalyst layer

Abstract

To provide a method of producing an ion exchange membrane that is not easily be swollen by an aromatic compound in an environment where an electrolytic hydrogenation device is used.SOLUTION: The method of producing an ion exchange membrane for use in an electrolytic hydrogenation device electrolytically hydrogenating an aromatic compound to produce a hydrogenated organic compound, comprises irradiating a film substrate constituted of a polymer selected from a polyolefin and a fluorocarbon resin with ionizing radiation to generate radicals in the polymer, carrying out graft polymerization using a polymerizable monomer capable of introducing a cation exchange group alone or a polymerizable mixture of the polymerizable monomer and a crosslinking monomer on the polymer in which the radicals are generated, and introducing a sulfonic acid type ion exchange group thereinto subsequently.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing an ion exchange membrane and an ion exchange membrane with a catalyst layer.

Background Art

[0002] As a method for producing a hydrogenated organic substance (for example, cyclohexane, methylcyclohexane, decahydronaphthalene, etc.), a method of adding hydrogen to an aromatic compound (for example, benzene, toluene, naphthalene, etc.) in a hydrogenation reactor is known. In recent years, from the viewpoint of simplifying the production of hydrogenated organic substances, etc., an electrolytic hydrogenation method of an aromatic compound has been studied as an alternative to the above method. The electrolytic hydrogenation of an aromatic compound is carried out using an electrolytic hydrogenation apparatus having a structure in which a cathode chamber and an anode chamber are separated by an ion exchange membrane.

[0003] The ion exchange membrane in the electrolytic hydrogenation apparatus is required to have proton conductivity. Further, since it is used in contact with an aromatic compound such as benzene, chemical resistance is required. Since it has proton conductivity and chemical resistance, perfluorosulfonic acid polymers such as Nafion (registered trademark) and Flemion (registered trademark) have been used as materials for the ion exchange membrane of the electrolytic hydrogenation apparatus (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the performance of the conventional ion exchange membrane is not always sufficient, and there is a demand for a proposal of a new ion exchange membrane that can be used for the electrolytic hydrogenation of aromatic compounds. In view of the above circumstances, an object of the present invention is to provide a method for producing an ion exchange membrane and an ion exchange membrane with a catalyst layer that are less likely to swell due to aromatic compounds even in the usage environment of an electrolytic hydrogenation apparatus.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention employs the following configuration. [1] A method for producing an ion exchange membrane used in an electrolytic hydrogenation apparatus for producing a hydrogenated organic compound by electrolytic hydrogenation of an aromatic compound, comprising irradiating a film substrate composed of a polymer selected from polyolefin and fluororesin with ionizing radiation to generate radicals in the polymer, and then performing graft polymerization on the polymer in which the radicals are generated using a polymerizable monomer alone capable of introducing a cation exchange group or a polymerizable mixture of the polymerizable monomer and a crosslinkable monomer, and then introducing a sulfonic acid type ion exchange group. [2] The method for producing an ion exchange membrane according to [1], wherein a solvent is used when performing graft polymerization using a polymerizable monomer alone or a polymerizable mixture of the polymerizable monomer and a crosslinkable monomer. [3] The method for producing an ion exchange membrane according to [1] or [2], wherein the polymer constituting the film substrate is polyethylene. [4] The method for producing an ion exchange membrane according to [3], wherein the polymer constituting the film substrate is ultra-high molecular weight polyethylene. [5] The method for producing an ion exchange membrane according to [1] or [2], wherein the polymer constituting the film substrate is an ethylene-tetrafluoroethylene copolymer. [6] Further, a method for producing an ion exchange membrane according to any one of [1] to [5], wherein an inorganic particle layer containing inorganic particles and a binder is formed on the first surface. [7] A method for producing an ion exchange membrane with a catalyst layer, comprising producing an ion exchange membrane by the method for producing an ion exchange membrane according to [6], and forming a catalyst layer containing a catalyst on a second surface opposite to the first surface of the obtained ion exchange membrane. [8] A method for manufacturing an electrolytic hydrogenation apparatus, which comprises manufacturing an ion exchange membrane by the method for manufacturing any one of the ion exchange membranes of [1] to [5], and arranging the obtained ion exchange membrane so as to separate a cathode chamber for hydrogenating an aromatic compound to produce a hydrogenated organic substance and an anode chamber for electrolyzing water to produce oxygen. [9] A method for manufacturing an electrolytic hydrogenation apparatus, which comprises manufacturing an ion exchange membrane by the method for manufacturing the ion exchange membrane of [6], and arranging the obtained ion exchange membrane so as to separate a cathode chamber for hydrogenating an aromatic compound to produce a hydrogenated organic substance and an anode chamber for electrolyzing water to produce oxygen, and so that the inorganic particle layer faces the anode chamber.

[10] A method for manufacturing a hydrogenated organic substance, which comprises manufacturing an electrolytic hydrogenation apparatus by the method for manufacturing the electrolytic hydrogenation apparatus of [8] or [9], supplying an aromatic compound to the cathode chamber of the obtained electrolytic hydrogenation apparatus, and supplying an electrolyte aqueous solution to the anode chamber to perform electrolysis. [Advantages of the Invention]

[0007] According to the method for manufacturing the ion exchange membrane and the ion exchange membrane with a catalyst layer of the present invention, swelling due to an aromatic compound hardly occurs even in the use environment of the electrolytic hydrogenation apparatus, and stable electrolytic hydrogenation becomes possible. [Brief Description of the Drawings]

[0008]

Figure 1

[0009] The definitions of the following terms in this specification and the claims are as follows. The "ion exchange membrane" is a membrane containing a polymer having an ion exchange group. The "ion exchange group" is a group capable of exchanging at least a part of the ions contained in this group with other ions. The "sulfonic acid type ion exchange group" is a sulfonic acid group (-SO3H) or a sulfonate group (-SO3M 2 . However, M2 is an alkali metal or a quaternary ammonium base.) means.

[0010] "Monomer" means a compound having a polymerizable carbon-carbon double bond. "Unit" means a part derived from a monomer that exists in a polymer and constitutes the polymer. For example, when the unit is formed by addition polymerization of a monomer having a carbon-carbon unsaturated double bond, the unit derived from this monomer is a divalent unit formed by cleavage of this unsaturated double bond. Further, the unit may be a unit obtained by chemically converting this unit, for example, by hydrolysis treatment, after forming a polymer having the structure of a certain unit. In addition, the constituent units derived from individual monomers may be described by a name obtained by attaching "unit" to the monomer name. "Fluororesin" means a resin having fluorine atoms in its molecule. "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0011] <Method for producing an ion exchange membrane> The method for producing an ion exchange membrane of the present invention irradiates a film substrate composed of a polymer with ionizing radiation to generate radicals in the polymer, and graft-polymerizes a monomer-containing liquid to the polymer in which the radicals are generated to form a graft copolymer membrane, and a sulfonic acid type ion exchange group is introduced into the graft copolymer membrane. The ion exchange membrane obtained by the method for producing an ion exchange membrane of the present invention is used in an electrolytic hydrogenation apparatus for electrolytically hydrogenating an aromatic compound to produce a hydrogenated organic substance.

[0012] [Film substrate] The film substrate is obtained by molding a polymer selected from polyolefin and fluororesin into a film shape. The thickness (film thickness) of the film substrate is preferably 20 to 200 μm in terms of excellent durability and swelling suppression properties of the ion exchange membrane. More preferably, it is 20 to 150 μm, and still more preferably, it is 20 to 100 μm.

[0013] Examples of the polyolefin constituting the film base material include homopolymers of olefins such as ethylene, propylene, and butene, or copolymers thereof. Polyethylene is preferred in terms of excellent graft polymerizability and film physical properties, and high-density polyethylene and ultra-high molecular weight polyethylene are more preferred. In particular, ultra-high molecular weight polyethylene is preferred in terms of excellent effects of improving the durability and swelling suppression properties of the ion exchange membrane. The molecular weight of the ultra-high molecular weight polyethylene is preferably 300,000 or more, and more preferably 1,000,000 to 6,300,000. The production method of the ultra-high molecular weight polyethylene film is not particularly limited. For example, an inflation film produced by an inflation method, a skive film produced by a skive method, etc. can be used. Examples of the inflation film include the product name "Saxin New Light Film Innovate" manufactured by Sakushin Kogyo Co., Ltd. Examples of the skive film include the product name "Saxin New Light Film" manufactured by Sakushin Kogyo Co., Ltd. Examples of other commercially available ultra-high molecular weight polyethylene films include the product name "Ultra-High Molecular Weight Polyethylene Film No. 440" manufactured by Nitto Denko Corporation.

[0014] Examples of the fluororesin constituting the film base material include copolymers containing ethylene units and tetrafluoroethylene units, copolymers containing ethylene units and chlorotrifluoroethylene units, copolymers containing tetrafluoroethylene units and perfluoropropyl vinyl ether units, polytetrafluoroethylene, etc. In particular, a copolymer containing ethylene units and tetrafluoroethylene units (also referred to as "ethylene-tetrafluoroethylene copolymer" or "ETFE" in this specification) is preferred. Examples of the ethylene-tetrafluoroethylene copolymer film include the product name "Afflex" manufactured by AGC Inc.

[0015] [Monomer-containing liquid] The monomer-containing liquid used for graft polymerization is either a polymerizable monomer capable of introducing a cation exchange group alone or a polymerizable mixture of the polymerizable monomer and a crosslinkable monomer. It may further contain a solvent. Examples of the polymerizable monomer capable of introducing a cation exchange group (hereinafter also referred to as a monomer for introducing an ion exchange group) that can be used in the present invention are listed below, but are not limited thereto. (1) Monomers having an aromatic ring into which a sulfonic acid group is easily introduced. For example, styrene, vinyl toluene, etc. (2) Monomers having a carboxylic acid group or a nitrile group. For example, acrylic acid esters, methacrylic acid esters, acrylonitrile, etc. The monomer for introducing an ion exchange group is preferably a monomer capable of introducing a sulfonic acid type ion exchange group by reaction with a sulfonating agent after polymerization. For example, styrene, vinyltoluene, etc. are preferable. As the monomer for introducing an ion exchange group, one kind may be used, or two or more kinds may be used in combination.

[0016] The crosslinkable monomer is a monomer having two or more polymerizable groups in the molecule and capable of introducing a crosslinked structure into the graft copolymer membrane. Examples of the crosslinkable monomer include divinylbenzene, trivinylbenzene, divinyltoluene, divinylnaphthalene, ethylene glycol dimethacrylate, etc. The amount of the crosslinkable monomer used is preferably 10% by mass or less, more preferably 3% by mass or less, based on the total mass of the monomers. It may be zero.

[0017] The monomer-containing liquid may contain a solvent. The solvent of the monomer-containing liquid is not particularly limited, and examples thereof include hydrocarbons such as benzene, xylene, toluene, and hexane; alcohols such as methanol, ethanol, and isopropyl alcohol; ketones such as acetone, methyl isopropyl ketone, and cyclohexane; ethers such as dioxane and tetrahydrofuran; esters such as ethyl acetate and butyl acetate; nitrogen-containing compounds such as isopropylamine, diethanolamine, N-methylformamide, and N,N-dimethylformamide; and the like. One kind of solvent may be used, or two or more kinds may be used in combination. When the monomer-containing liquid contains a solvent, the total content of the monomers relative to the total mass of the monomer-containing liquid is not particularly limited, but is preferably 20% by mass or more. The upper limit is not particularly limited and can be appropriately set within the range of less than 100% by mass.

[0018] [Formation of graft copolymer film] Irradiate the film substrate with ionizing radiation to generate radicals in the polymer constituting the film substrate, and then graft-polymerize the monomer-containing liquid to form a graft copolymer film. The method of graft polymerization may be a so-called pre-irradiation method in which, after irradiating the film substrate with ionizing radiation, the monomer-containing liquid is supplied for a polymerization reaction, or a so-called simultaneous irradiation method in which the film substrate and the monomer-containing liquid coexist and both are irradiated with ionizing radiation simultaneously for a polymerization reaction. The pre-irradiation method is preferred in terms of the low production amount of homopolymers (by-products) that do not graft-polymerize on the film substrate. As the pre-irradiation method, either a polymer radical method in which the film substrate present in an inert gas is irradiated or a peroxide method in which the film substrate present in an atmosphere containing oxygen is irradiated may be used.

[0019] An example of the pre-irradiation method will be described below. First, irradiate the film substrate with an electron beam, which is one of the ionizing radiations, at -10 to 80°C, preferably around room temperature, and at 10 to 400 kGy, preferably 10 to 100 kGy. When there is a large spatial or temporal difference between the step of irradiating with ionizing radiation and the step of graft polymerization, the following method is preferable. After inserting the substrate into an oxygen-impermeable plastic bag, remove the oxygen inside the bag. For example, replace the oxygen inside the bag with nitrogen to remove the oxygen. In this way, irradiate the plastic bag enclosing the film substrate with ionizing radiation. After irradiation, put the film substrate together with the bag into a dry ice-filled box and perform transportation or storage in a freezer. Thereby, while suppressing the disappearance of radicals generated by the irradiation of ionizing radiation, transportation and storage can be performed. Next, take out the irradiated film substrate inside the bag in the atmosphere, transfer it to a glass container, then fill the glass container with a monomer-containing liquid and perform graft polymerization. As the monomer-containing liquid, one from which oxygen gas has been removed in advance is used. For example, remove oxygen gas by a method of bubbling the monomer-containing liquid with an inert gas in which oxygen does not exist, or a method of freeze-degassing the monomer-containing liquid. The reaction temperature during graft polymerization is preferably from room temperature to 80 °C, more preferably from 40 to 70 °C. In this way, a graft copolymer film in which graft chains are introduced into the film substrate is obtained. The graft ratio of the obtained graft copolymer film (that is, the ratio of graft chains to the film substrate before graft polymerization (by mass)) is preferably 10 to 300% by mass, more preferably 20 to 150% by mass. The graft ratio can be adjusted by changing the irradiation dose, polymerization temperature, polymerization time, etc.

[0020] [Introduction of sulfonic acid type ion exchange group] To the film substrate into which graft chains are introduced (hereinafter also referred to as a graft copolymer film), a sulfonic acid type ion exchange group is introduced as the next step. For the introduction of the sulfonic acid type ion exchange group, a wide range of conventionally used methods can be used without any limitation, and specific examples are shown below.

[0021] The following is a specific example of a method using chlorosulfonic acid as a sulfonating agent. The graft copolymer membrane is immersed in a chlorosulfonic acid solution with a concentration of 0.2 to 1.5 mol / L using 1,2-dichloroethane as a solvent for reaction. The temperature of the chlorosulfonic acid solution is preferably 25 to 80 °C, and the immersion time (reaction time) is preferably 1 to 96 hours. After immersion, the graft copolymer membrane is thoroughly washed. Then, it is immersed in an aqueous sodium hydroxide solution with a concentration of 1 to 10% by mass for 1 to 24 hours to terminate the sulfonation reaction, and the membrane is thoroughly washed with water and further repeatedly treated with an acidic solution such as sulfuric acid and hydrochloric acid to obtain a membrane having a sulfonic acid type ion exchange group. The sulfonating agent is not particularly limited as long as it can introduce a sulfonic acid group, and concentrated sulfuric acid, sulfur trioxide, sodium thiosulfate, etc. can also be used.

[0022] [Formation of inorganic particle layer] It is also preferable to form an inorganic particle layer containing inorganic particles and a binder on the first surface of the ion exchange membrane. Here, the first surface is the surface facing the anode chamber in the electrolytic hydrogenation apparatus.

[0023] In the anode chamber, when oxygen gas generated by electrolysis of the electrolyte aqueous solution adheres to the surface of the ion exchange membrane, the electrolysis voltage increases during electrolytic hydrogenation of the aromatic compound. Forming an inorganic particle layer on the first surface is preferable because it can suppress the adhesion of oxygen gas generated by electrolysis of the electrolyte aqueous solution to the surface of the ion exchange membrane and suppress the increase in the electrolysis voltage.

[0024] The inorganic particles are preferably hydrophilic. Specifically, at least one selected from the group consisting of oxides, nitrides, and carbides of Group 4 elements or Group 14 elements is preferable, SiO2, SiC, ZrO2, and ZrC are more preferable, and ZrO2 is particularly preferable.

[0025] The average particle diameter of the inorganic particles is preferably from 0.01 to 10 μm, more preferably from 0.01 to 5 μm, and even more preferably from 0.5 to 3 μm. When the average particle diameter of the inorganic particles is at least the above lower limit value, a high gas adhesion suppression effect can be obtained. When the average particle diameter of the inorganic particles is at most the above upper limit value, the inorganic particles have excellent resistance to dropping off.

[0026] The average particle diameter of the inorganic particles is the value of the 50% diameter (D 50 ) obtained by calculating the volume average from the particle size distribution when a dispersion liquid in which the inorganic particles are dispersed in a solvent is measured by a known particle size distribution measuring apparatus (a laser diffraction / scattering type particle size distribution measuring apparatus manufactured by Microtrac Bel Co., Ltd. or an apparatus equivalent thereto) based on the laser diffraction / scattering method.

[0027] As the binder, a polymer for a generally used cellulose-based binder can be used. Also, those having hydrophilicity are preferable, a fluorine-containing polymer having a carboxylic acid group or a sulfonic acid group is preferable, and a fluorine-containing polymer having a sulfonic acid group is more preferable. The fluorine-containing polymer may be a homopolymer of a monomer having a carboxylic acid group or a sulfonic acid group, or may be a copolymer of a monomer having a carboxylic acid group or a sulfonic acid group and a monomer copolymerizable with this monomer.

[0028] The mass ratio of the binder to the total mass of the inorganic particles and the binder in the inorganic particle layer (hereinafter, also referred to as "binder ratio") is preferably from 0.1 to 0.5. When the binder ratio in the inorganic particle layer is at least the above lower limit value, the inorganic particles have excellent resistance to dropping off. When the binder ratio in the inorganic particle layer is at most the above upper limit value, a high gas adhesion suppression effect can be obtained. The thickness of the inorganic particle layer is preferably from 1 to 50 μm, more preferably from 1 to 30 μm, and particularly preferably from 1 to 20 μm from the viewpoint of being able to further reduce the electrolytic voltage.

[0029] The method for forming the inorganic particle layer is not particularly limited. For example, a method is provided in which an inorganic particle dispersion containing inorganic particles, a binder, and a solvent is directly applied to the first surface of an ion exchange membrane, and the coating layer of the inorganic particle dispersion is dried. Examples of the coating method include a die coating method and a spray coating method. The coating conditions and drying conditions are not particularly limited, and known conditions can be adopted. Alternatively, after forming an inorganic particle layer on a transfer substrate such as a PET film, it may be transferred to the first surface of the ion exchange membrane while heating as necessary. The inorganic particles and the binder contained in the inorganic particle dispersion are as described above. The solvent contained in the inorganic particle dispersion is not particularly limited, and water or an organic solvent can be used. The formation of the inorganic particle layer may be performed at any stage of manufacturing the ion exchange membrane, such as before or after the step of irradiating the film substrate with ionizing radiation, after graft polymerization, or after the introduction of a sulfonic acid type ion exchange group, but it is preferably after the introduction of the sulfonic acid type ion exchange group. In addition, when forming the inorganic particle layer, it is also preferable to roughen the surface of the ion exchange membrane (or an intermediate during its manufacture) by treating the surface on which the inorganic particle layer is to be formed with a method such as sandpaper or sandblasting.

[0030] <Electrolytic hydrogenation apparatus> An electrolytic hydrogenation apparatus for electrolytically hydrogenating an aromatic compound to produce a hydrogenated organic compound has a cathode chamber for hydrogenating the aromatic compound to produce a hydrogenated organic compound and an anode chamber for electrolyzing water to produce oxygen. By arranging the ion exchange membrane obtained by the method for producing an ion exchange membrane of the present invention so as to separate the cathode chamber and the anode chamber, an electrolytic hydrogenation apparatus can be manufactured.

[0031] FIG. 1 shows a schematic diagram of an electrolytic hydrogenation apparatus using the ion exchange membrane obtained by the method for producing an ion exchange membrane of the present invention. As shown in FIG. 1, the electrolytic hydrogenation apparatus 100 includes a cathode chamber 20 having a cathode 21, an anode chamber 30 having an anode 31, and an ion exchange membrane 10 that separates the cathode chamber 20 and the anode 31.

[0032] The first surface 11 of the ion exchange membrane 10 faces the anode chamber 30, and the second surface 12 on the opposite side of the first surface 11 faces the cathode chamber 20. The ion exchange membrane 10 is an ion exchange membrane obtained by the production method of the present invention, and may have an inorganic particle layer on the first surface 11.

[0033] In addition, the cathode chamber 20 is provided with a cathode chamber inlet 22 and a cathode chamber outlet 23, and the cathode liquid flows from the cathode chamber inlet 22 to the cathode chamber outlet 23. In addition, the anode chamber 30 is provided with an anode chamber inlet 32 and an anode chamber outlet 33, and the anode liquid flows from the anode chamber inlet 32 to the anode chamber outlet 33. As the materials constituting the cathode chamber 20 and the anode chamber 30, stainless steel, nickel, etc. are preferable.

[0034] There is no particular limitation on the specific configuration of the cathode 21. As a preferable embodiment, a configuration including a catalyst layer and an electrode substrate in this order from the ion exchange membrane 10 side can be mentioned. The catalyst layer and the electrode substrate may be arranged in contact with each other or with a space therebetween. As the material constituting the electrode substrate, stainless steel, nickel, etc. are preferable. Further, the surface of the electrode substrate is preferably coated with, for example, ruthenium oxide, iridium oxide, etc.

[0035] The catalyst layer is preferably arranged in contact with the second surface 12 of the ion exchange membrane 10. The catalyst layer contains a reduction catalyst for hydrogenating an aromatic compound in the cathode liquid to produce a hydrogenated organic substance. As the reduction catalyst, for example, metal particles selected from the group consisting of Pt, Ru, Pd, Ir, and alloys containing at least one of these can be used.

[0036] The reduction catalyst is preferably supported by a catalyst carrier composed of an electronically conductive material. Examples of the catalyst carrier include electronically conductive materials containing as a main component any one of porous carbon (such as mesoporous carbon), porous metal, and porous metal oxide. Coating the catalyst carrier with an ionomer is preferable as it improves the ionic conductivity of the cathode 21.

[0037] The cathode 21 composed of a catalyst layer and an electrode substrate can be manufactured by applying and drying a catalyst ink obtained by mixing a catalyst component powder, a hydrophobic resin which is a gas-permeable material, water, a solvent, and an ionomer to the electrode substrate.

[0038] Also, the catalyst layer of the cathode 21 may be formed on the ion exchange membrane 10. For example, by applying the catalyst ink to the second surface 12 using a bar coater, an ion exchange membrane with a catalyst layer, which is a composite of the catalyst layer of the cathode and the ion exchange membrane 10, can be produced. Also, by spraying the catalyst ink onto the second surface 12 of the ion exchange membrane 10 and drying the solvent component in the catalyst ink, an ion exchange membrane with a catalyst layer can be produced.

[0039] There is no particular limitation on the specific configuration of the anode 31, but as a preferred embodiment, it is preferably made of an electrode substrate such as stainless steel or nickel. Also, the surface of the electrode substrate is preferably coated with, for example, ruthenium oxide, iridium oxide, etc. The ion exchange membrane 10 and the anode 31 may be arranged in contact with each other or with a gap therebetween. The anode 31 may have a catalyst layer on the side of the ion exchange membrane 10, similar to the cathode side.

[0040] <Method for producing a hydrogenated organic compound> When an aromatic compound is electrohydrogenated by the electrolytic hydrogenation apparatus 100, an electrolytic aqueous solution is supplied as the anolyte to the anode chamber 30 where the anode 31 is arranged, and an aromatic compound is supplied as the catholyte to the cathode chamber 20 where the cathode 21 is arranged. Specific examples of the aromatic compound include benzene, toluene, and naphthalene. An aqueous electrolyte solution is a solution obtained by dissolving an electrolyte in water. Examples of the electrolyte include sulfuric acid and nitric acid. The concentration of the electrolyte is not particularly limited.

[0041] When the electrolytic hydrogenation apparatus 100 is driven, protons (H + ) generated by the electrolysis of the aqueous electrolyte solution in the anode chamber 30 move to the cathode chamber 20 side through the ion exchange membrane 10. Then, hydrogenation of the aromatic compound occurs due to proton addition, and a hydrogenated organic substance is obtained in the cathode chamber 20. Specific examples of the hydrogenated organic substance include cyclohexane, methylcyclohexane, and decahydronaphthalene.

[0042] The cathode liquid flowing out from the cathode chamber outlet 23 of the cathode chamber 20 contains a hydrogenated organic substance. The hydrogenated organic substance can be separated and recovered from the cathode liquid flowing out from the cathode chamber outlet 23. The remaining cathode liquid after separating the hydrogenated organic substance may be circulated so as to flow again into the cathode chamber 20 from the cathode chamber inlet 22.

Example

[0043] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Note that Examples 1 to 5 are examples, and Examples 6 and 7 are comparative examples. The evaluation of the electrolysis voltage and current efficiency of the membrane electrode assembly obtained in each example was performed by the following method.

[0044] <Test for evaluating electrolysis voltage and current efficiency> In a test electrolytic cell with an effective current-carrying area of 1.5 dm 2 (the electrolysis surface size is 150 mm in length and 100 mm in width), the membrane electrode assembly of each example was arranged so that the surface without the catalyst layer was on the anode chamber side. As the diffusion layer of the anode, an electrode obtained by electrodepositing Raney nickel containing ruthenium on a punched metal made of SUS304 (short diameter 5 mm, long diameter 10 mm) was used. Also, the diffusion layer of the anode and the membrane electrode assembly were in direct contact with each other and installed so that no gap was generated. While adjusting the flow rate of toluene supplied to the cathode chamber to 5 mL / min and the flow rate of 1 M sulfuric acid aqueous solution supplied to the anode chamber to 10 mL / min, electrolytic hydrogenation of toluene was carried out under the conditions of a temperature of 65 °C and a current density of 400 mA / cm 2

[0045] The electrolytic voltage (V) was determined by measuring the potential between the cathode and the anode. Also, the current efficiency (%) was determined from the ratio of the actual amount of methylcyclohexane produced to the theoretical amount of methylcyclohexane that should be produced from the amount of coulombs passed.

[0046] [Evaluation Criteria for Electrolytic Voltage] ◎: 2.3 V or less. ○: More than 2.3 V and 2.4 V or less. △: More than 2.4 V and 2.5 V or less. ×: More than 2.5 V.

[0047] [Evaluation Criteria for Current Efficiency] ◎: 98% or more. ○: 96% or more and less than 98%. ×: Less than 96%.

[0048] [Example 1] [Manufacture of Ion Exchange Membrane] As the film substrate, a ultra-high molecular weight polyethylene substrate (product name "Saxin Newlite Film" manufactured by Sakushin Kogyo Co., Ltd.) with a molecular weight of 2 million and a film thickness of 50 μm produced by the skive method was used. As the monomer-containing solution, a mixed solution of styrene, which is a monomer for introducing an ion exchange group, and xylene, which is a solvent, was used after bubbling with high-purity nitrogen in advance to remove oxygen gas. The content of styrene in the total mass of the monomer-containing solution was 40% by mass.

[0049] ​First, the film substrate was placed in an oxygen-impermeable polyethylene bag, purged with nitrogen to remove the oxygen inside the bag, and then sealed. Next, the bag containing the film substrate was irradiated with an electron beam at 25°C, an acceleration voltage of 250 keV, and an electron beam current of 32.7 mA at 100 kGy. Then, the irradiated film substrate inside the bag was taken out into the atmosphere and transferred to a glass container. This glass container was filled with a monomer-containing liquid and subjected to graft polymerization at 50°C for 180 minutes. The obtained graft copolymer film was taken out from the glass container, washed with methanol, and air-dried. The grafting rate was 85% by mass.

[0050] For the obtained graft copolymer film, a sulfonic acid type ion exchange group was introduced using chlorosulfonic acid as a sulfonating agent. First, the graft copolymer film was immersed in a 1% by mass chlorosulfonic acid solution with 1,2-dichloroethane as a solvent at room temperature for 72 hours, and then the film was thoroughly washed with water. Next, it was immersed in a 1% by mass aqueous sodium hydroxide solution for 24 hours for neutralization, and then repeatedly washed with 1N hydrochloric acid aqueous solution to obtain a sulfonic acid type cation exchange membrane I.

[0051] [Preparation of Dispersion Liquid] Tetrafluoroethylene (hereinafter also referred to as "TFE") and a monomer represented by the following formula 1 were copolymerized, and after hydrolysis and acid treatment, a polymer in acid form (ion exchange capacity: 1.10 meq / g dry resin) was dispersed in a solvent of water / ethanol = 40 / 60 (mass%) at a solid content concentration of 25.8% by mass to obtain a dispersion liquid (hereinafter also referred to as "dispersion liquid 1"). CF2=CF-O-CF2CF(CF3)-O-CF2CF2-SO2F ··· Formula 1

[0052] [Formation of Cathode Catalyst Layer] The obtained dispersion liquid 1 (20.1 g), ethanol (11 g), and Zeolora-H (manufactured by Nippon Zeon) (6.3 g) were mixed and kneaded to obtain a mixed liquid 1. Also, water (59.4 g) and ethanol (39.6 g) were added to 11 g of a supported catalyst in which 46 mass% of platinum was supported on carbon powder (TEC10E50E manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), and the mixture was pulverized by mixing using an ultrasonic homogenizer to obtain a dispersion of the catalyst.

[0053] To the dispersion of the catalyst, 29.2 g of the mixture 1 was added. Further, 3.66 g of water and 7.63 g of ethanol were added and mixed for 60 minutes using a paint conditioner to adjust the solid content concentration to 10.0 mass%, thereby obtaining a cathode catalyst ink (catalyst dispersion). The cathode catalyst ink was applied onto an ETFE sheet using a die coater, dried at 80°C, and further heat-treated at 150°C for 15 minutes to obtain a decal A having a cathode catalyst layer with a platinum amount of 0.4 mg / cm 2 formed thereon.

[0054] [Manufacture of Membrane Electrode Assembly] The cation exchange membrane I obtained above was heated and pressed under the conditions of a pressing temperature of 150°C, a pressing time of 2 minutes, and a pressure of 3 MPa with the surface of the decal A having the cathode catalyst layer facing each other, thereby joining the cation exchange membrane I and the cathode catalyst layer. After lowering the temperature to 70°C, the pressure was released and the product was taken out. The ETFE sheet of the decal A was peeled off to obtain an ion exchange membrane I with a catalyst layer having a catalyst layer on the surface of the cation exchange membrane I. A carbon felt was joined to the surface of the catalyst layer of the obtained ion exchange membrane I with a catalyst layer to obtain a membrane electrode assembly I. The cathode area of the membrane electrode assembly I was 25 cm 2 .

[0055] [Example 2] [Manufacture of Ion Exchange Membrane] A sulfonic acid type cation exchange membrane II was obtained in the same manner as in Example 1, except that the irradiation dose of the electron beam on the bag enclosing the film substrate was changed to 25 kGy. The graft ratio of the graft copolymer membrane was 42 mass%. [Manufacture of Membrane Electrode Assembly] A membrane electrode assembly II was obtained in the same manner as in Example 1, except that a cation exchange membrane II was used instead of the cation exchange membrane I. The cathode area of the membrane electrode assembly II was 25 cm 2 .

[0056] <Example 3> [Manufacture of Ion Exchange Membrane] An ethylene-tetrafluoroethylene copolymer film with a thickness of 50 μm was used as the film substrate. As the monomer-containing solution, a mixed solution of styrene, which is a monomer for introducing an ion exchange group, divinylbenzene, which is a crosslinkable monomer, and xylene, which is a solvent, was used after being bubbled with high-purity nitrogen in advance to remove oxygen gas. The total content of the monomers was 75% by mass based on the total mass of the monomer-containing solution. The ratio of the crosslinkable monomer to the total mass of the monomers was 3% by mass.

[0057] First, the film substrate was put into an oxygen-impermeable polyethylene bag, purged with nitrogen to remove oxygen inside the bag, and sealed. Next, the bag containing the film substrate was irradiated with an electron beam at 25 °C, an acceleration voltage of 250 keV, and an electron beam current of 10 mA at 25 kGy. Then, the irradiated film substrate inside the bag was taken out in the air and transferred to a glass container. This glass container was filled with the monomer-containing solution and graft polymerized at 50 °C for 120 minutes. The obtained graft copolymer membrane was taken out from the glass container, washed in the order of acetone and methanol, and vacuum dried to measure the mass. The grafting rate was 58% by mass.

[0058] Sulfonic acid type ion exchange groups were introduced into the obtained graft copolymer membrane using chlorosulfonic acid as a sulfonating agent. First, the graft copolymer membrane was immersed in a 10% by mass chlorosulfonic acid solution using 1,2-dichloroethane as a solvent at room temperature for 24 hours, and then the membrane was thoroughly washed with water. Next, it was immersed in a 1% by mass aqueous sodium hydroxide solution for 24 hours for neutralization, and then repeatedly washed with a 1N hydrochloric acid aqueous solution to obtain a sulfonic acid type cation exchange membrane III. [Manufacture of Membrane Electrode Assembly] A membrane electrode assembly III was obtained in the same manner as in Example 1, except that a cation exchange membrane III was used instead of the cation exchange membrane I. The cathode area of the membrane electrode assembly III was 25 cm 2 .

[0059] <Example 4> [Manufacture of Ion Exchange Membrane] An ethylene-tetrafluoroethylene copolymer film with a thickness of 100 μm was used as the film substrate. As the monomer-containing solution, a mixed solution of styrene, which is a monomer for introducing an ion exchange group, and xylene, which is a diluting solvent, was used. The mixed solution was previously bubbled with high-purity nitrogen to remove oxygen gas. The content of styrene in the total mass of the monomer-containing solution was 50% by mass. In the same manner as in Example 3, the film substrate was irradiated with an electron beam for graft polymerization to obtain a graft copolymer film. The grafting rate of the graft copolymer film was 47% by mass. A sulfonic acid type cation exchange membrane IV was obtained by introducing a sulfonic acid type ion exchange group into the obtained graft copolymer film in the same manner as in Example 3. [Manufacture of Membrane Electrode Assembly] A membrane electrode assembly IV was obtained in the same manner as in Example 1, except that a cation exchange membrane IV was used instead of the cation exchange membrane I. The cathode area of the membrane electrode assembly IV was 25 cm 2 .

[0060] <Example 5> [Preparation of Inorganic Particle Dispersion] TFE and the monomer represented by the above formula (1) were copolymerized, subjected to a hydrolysis treatment, and then subjected to an acid form treatment to obtain a sulfonic acid type fluoropolymer (ion exchange capacity: 1.1 meq / g dry resin). The obtained fluoropolymer was dissolved in ethanol to prepare an ethanol solution with a concentration of 9.5% by mass. 10.8% by mass of zirconium oxide (average particle diameter: 0.4 μm) was added to the obtained ethanol solution, and the mixture was uniformly stirred using a ball mill so that the binder ratio became 0.2 to obtain a coating solution (Q1).

[0061] [Manufacture of Ion Exchange Membrane] In the same manner as in Example 3, a sulfonic acid type cation exchange membrane III was obtained. After roughening the surface shape of one side of the cation exchange membrane III with sandpaper, a coating solution (Q1) containing inorganic particles was spray-coated so that the adhesion amount of zirconium oxide was 20 g / m 2 and dried at 80 °C to obtain an ion exchange membrane V having an inorganic particle layer formed on one side (the first surface).

[0062] [Manufacture of Membrane Electrode Assembly] In the same manner as in Example 1, a decal A having a cathode catalyst layer formed on an ETFE sheet was obtained. The surface of the cathode catalyst layer of the decal A was opposed to the surface of the ion exchange membrane V obtained above where the inorganic particle layer was not formed (the second surface), and heat-pressed at a press temperature of 150 °C for a press time of 2 minutes and a pressure of 3 MPa to bond the ion exchange membrane V and the cathode catalyst layer. After lowering the temperature to 70 °C, the pressure was released and taken out, and the ETFE sheet of the decal A was peeled off. Thus, an ion exchange membrane V with a catalyst layer having an inorganic particle layer in contact with one surface (the first surface) of the cation exchange membrane III and a catalyst layer in contact with the other surface (the second surface) was obtained. A carbon felt was bonded to the surface of the catalyst layer of the obtained ion exchange membrane V with a catalyst layer to obtain a membrane electrode assembly V. The cathode area of the membrane electrode assembly V was 25 cm 2 at that time.

[0063] <Example 6> 50 g of polyphenylsulfone having the structure of the following formula 2 with a melt flow rate of 19.5 g / 10 min as measured according to ASTM method D1328 was dissolved in 1000 g of tetrachloroethane, and chlorosulfonic acid was added thereto so that the ion exchange capacity became 2.0 mmol / g, and the reaction was carried out at room temperature for 24 hours. After adding water to the obtained reaction product, trimethylamine gas was bubbled until the pH of the aqueous layer became weakly alkaline. Subsequently, water and the solvent were distilled off by distillation under reduced pressure, and the obtained polymer was dissolved in N,N-dimethylformamide to obtain a polymer solution A1 with a solid content concentration of 10% by mass. In Formula 2, n is the number of repetitions.

[0064] [Chemical formula]

[0065] A non-woven fabric (thickness 100 μm, basis weight 60 g / m 2 ) made of short fibers with a polyethylene coating on a polypropylene core material was corona-treated, and the above polymer solution A1 was coated thereon, and filling and drying were repeated a plurality of times in the voids to completely fill the voids with the polymer, obtaining a film-like body with a thickness of 150 μm. Subsequently, the obtained film-like body was repeatedly treated with a 1N hydrochloric acid aqueous solution to obtain a sulfonic acid type cation exchange membrane VI.

[0066] [Manufacture of membrane electrode assembly] A membrane electrode assembly VI was obtained in the same manner as in Example 1, except that the cation exchange membrane VI obtained above was used instead of the cation exchange membrane I. The cathode area of the membrane electrode assembly VI was 25 cm 2 .

[0067] [Example 7] A polymer solution A1 was obtained in the same manner as in Example 6. To this polymer solution A1, a 10% dimethylformamide solution of polyphenylsulfone having the same structure as Formula 2 used in Example 6 was added in an amount equivalent to 1 / 2 of the polymer solid content in the polymer solution A1 to obtain a polymer solution A2. A sulfonic acid type cation exchange membrane VII was obtained in the same manner as in Example 6, except that the polymer solution A2 was used instead of the polymer solution A1.

[0068] [Manufacture of membrane electrode assembly] A membrane electrode assembly VII was obtained in the same manner as in Example 1, except that the cation exchange membrane VII obtained above was used instead of the cation exchange membrane I. The cathode area of the membrane electrode assembly VII was 25 cm 2 was.

[0069] The evaluation results of the electrolysis voltage and current efficiency of the membrane electrode assemblies of each example are shown in Table 1. As shown in Table 1, it was found that the membrane electrode assembly using the ion exchange membrane of the present invention not only has resistance to toluene but also has good characteristics. On the other hand, in Examples 6 and 7, membrane leakage occurred.

[0070]

Table 1

Explanation of symbols

[0071] 10 Ion exchange membrane 11 First surface 12 Second surface 20 Cathode chamber 21 Cathode 22 Cathode chamber inlet 23 Cathode chamber outlet 30 Anode chamber 31 Anode 32 Anode chamber inlet 33 Anode chamber outlet 100 Electrolytic hydrogenation device

Claims

1. A method for producing an ion exchange membrane used in an electrolytic hydrogenation apparatus for producing a hydrogenated organic substance by electrolytic hydrogenation of an aromatic compound, A film substrate composed of a polymer selected from polyolefin and fluororesin is irradiated with ionizing radiation to generate radicals in the polymer, and a polymerizable monomer capable of introducing a cation exchange group alone, or a polymerizable mixture of the polymerizable monomer and a crosslinkable monomer is used for graft polymerization, and then a sulfonic acid type ion exchange group is introduced. A method for producing an ion exchange membrane.

2. The method for producing an ion exchange membrane according to claim 1, wherein a solvent is used when performing graft polymerization using a polymerizable monomer alone or a polymerizable mixture of the polymerizable monomer and a crosslinkable monomer.

3. The method for producing an ion exchange membrane according to claim 1 or 2, wherein the polymer constituting the film substrate is polyethylene.

4. The method for producing an ion exchange membrane according to claim 3, wherein the polymer constituting the film substrate is ultra-high molecular weight polyethylene.

5. The method for producing an ion exchange membrane according to claim 1 or 2, wherein the polymer constituting the film substrate is an ethylene-tetrafluoroethylene copolymer.

6. Further, an inorganic particle layer containing inorganic particles and a binder is formed on the first surface of the ion exchange membrane. The method for producing an ion exchange membrane according to any one of claims 1 to 5.

7. An ion exchange membrane is produced by the method for producing an ion exchange membrane according to claim 6, and a catalyst layer containing a catalyst is formed on the second surface opposite to the first surface of the obtained ion exchange membrane. A method for producing an ion exchange membrane with a catalyst layer.

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