JP6782089B2 - Catalyst layer, cathode, electrolytic synthesis cell, membrane electrode assembly, organic compound hydrogenator and method for producing hydrogenated organic compound - Google Patents

Description

The present invention relates to a technique for electrochemically hydrogenating an organic compound, and specifically to a catalyst layer, a cathode, an electrolytic synthesis cell, a membrane electrode assembly, an organic compound hydrogenator, and a method for producing a hydrogenated organic compound. ..

Hydrogen is widely used industrially in petroleum refining, chemically synthesized materials, metal refining, stationary fuel cells, and the like. In recent years, the possibility of use in hydrogen stations for fuel cell vehicles (FCVs), smart communities, hydrogen power plants, etc. has expanded. Furthermore, as the introduction of renewable energy has progressed, it has become necessary to maintain a balance between supply and demand in the power grid, and therefore hydrogen carrier technology for efficiently storing and transporting large volumes of electric power is being developed.

Examples of hydrogen carriers include liquefied hydrogen, ammonia, and hydrogenated organic compounds in which hydrogen is chemically bonded to organic compounds such as benzene, toluene, and naphthalene. Liquefied hydrogen has the advantage of high hydrogen compression density, but it requires low temperature and high pressure for storage and transportation, and the decrease in energy efficiency due to boil-off is a factor that raises costs. Ammonia can store hydrogen at a higher density than liquefied hydrogen, but the establishment of dehydrogenation technology and handling method for removing and using hydrogen is a major issue. On the other hand, methylcyclohexane, which is a type of hydrogenated organic compound in which hydrogen is bound to toluene, is inferior to liquefied hydrogen and ammonia, but can store hydrogen at a higher density than compressed hydrogen, and has the same infrastructure technology as gasoline. It has the advantage of being available. In addition, dehydrogenation catalysts have also been developed, and methylcyclohexane is considered to be the most feasible hydrogen carrier.

The hydrogenated organic compound as a hydrogen carrier is produced by inflowing hydrogen and the gas of the organic compound to be hydrogenated in a high temperature and high pressure state into a fixed bed reactor in which a granular catalyst is supported on a mesh-like bed. However, since the hydrogenation reaction with organic compounds to be hydrogenated such as benzene and toluene is an exothermic reaction, a part of the energy of hydrogen is lost as heat. Further, in order to extract hydrogen from the hydrogenated organic compound, the energy corresponding to this heat loss must be input again, so that there is a problem that the energy cost required for hydrogen utilization increases.

On the other hand, a technique has been developed for directly producing a hydrogenated organic compound without passing through hydrogen by electrochemically reacting water with a hydrogenated organic compound. By this method, the heat loss due to the hydrogenation reaction can be reduced, and the hydrogenation plant becomes unnecessary, so that the equipment can be significantly reduced. As a result, total cost reduction of hydrogen utilization can be expected. Patent Documents 1 to 4 report a method for producing a hydrogenated organic compound using an electrochemical reduction apparatus having a solid polymer electrolyte (PEM) type electrolytic synthesis cell having a structure similar to that of a fuel cell.

Japanese Unexamined Patent Publication No. 2003-45449 Japanese Unexamined Patent Publication No. 2005-126288 Japanese Unexamined Patent Publication No. 2013-11185 International Publication No. 2015/029367

However, there are some points to be improved in the above-mentioned techniques. One is the difficulty of handling an ion-permeable diaphragm (ion exchange membrane, PEM). The PEM type electrolytic synthesis cell contains an ion exchange membrane as a solid electrolyte. In the ion exchange membrane, generally, the ionomer forming the ion exchange membrane has a hydrophilic ion exchange group, and the ion exchange group expresses ion permeability by forming a network of hydrophilic clusters. Based on this principle, the ion exchange membrane generally has a higher voltage loss than the supporting electrolyte aqueous solution, and in order to reduce the voltage loss of the electrolytic synthesis cell, it is necessary to make it as thin as possible. On the other hand, there is a problem that the thinning of the film lowers the mechanical strength and makes it difficult to apply the catalyst layer and handle the cells when assembling the cells.

Further, as the concentration of the hydrogenated product as a product increases in the PEM electrolytic synthesis cell, the ratio of the hydrogen gas generation reaction generated as a side reaction increases, and the Faraday efficiency defined by the following formula 1 decreases. There is. In order to utilize hydrogen as a hydrogen carrier on a large scale, it is necessary to synthesize a high-purity hydrogenated product. For that purpose, it is desirable to realize higher Faraday efficiency even if the concentration of hydrogenated material in the cell is high.
[Equation 1]
Faraday efficiency = number of electrons that contributed to the production of hydrogenated organic compounds / number of electrons energized in the electrolytic synthesis cell

The present invention has been made in view of the above-mentioned problems of the prior art, that the organic compound to be hydrogenated can be hydrogenated without using an ion exchange membrane, and the concentration of the hydride in the cell is high. An object of the present invention is to provide a catalyst layer that realizes high Faraday efficiency even when high, and a cathode, an electrolytic synthesis cell, a membrane electrode assembly, an organic compound hydrogenator, and a method for producing a hydrogenated organic compound using the catalyst layer.

As a result of intensive studies to solve the above problems, the present inventors have a high concentration of hydrides due to a catalyst layer containing an organic polymer and a catalyst metal that absorb a specific amount of an organic compound to be hydrogenated. We have found that the organic compound to be hydrogenated can be selectively supplied from the mixed solution with the organic compound to be hydrogenated to the catalytically active site, and have completed the present invention.

That is, the present invention is as follows.
[1]
A catalyst layer for electrochemically hydrogenating an organic compound to be hydrogenated having an unsaturated bond to obtain a hydride.
Contains catalyst metals and organic polymers
A catalyst layer in which the A is 0.1 kg / kg or more and 100 kg / kg or less, where A is the mass of the hydrogenated organic compound absorbed by the organic polymer per unit mass in the hydrogenated organic compound.
[2]
The swelling coefficient C calculated by A / B is 1.5 or more and 100 or less, where B is the mass of the hydrogenated material absorbed by the organic polymer per unit mass in the hydrogenated material [1]. ]. The catalyst layer.
[3]
The water swelling coefficient E calculated by D / A is 0.7 or less, where D is the mass of water absorbed by the organic polymer per unit mass in water, according to [1] or [2]. Catalyst layer.
[4]
The catalyst layer according to any one of [1] to [3], which contains 0.1 kg or more and 100 kg or less of the organic compound to be hydrogenated with respect to 1 kg of the organic polymer.
[5]
The catalyst layer according to [4], which contains 0.001 kg or more and 33 kg or less of the hydrogenated material with respect to 1 kg of the organic polymer.
[6]
The catalyst layer according to [4] or [5], which contains 33 kg or less of water with respect to 1 kg of the organic polymer.
[7]
The catalyst layer according to any one of [1] to [6], wherein at least a part or all of the organic compound to be hydrogenated is an aromatic compound.
[8]
The aromatic compound is selected from the group consisting of benzene, naphthalene, anthracene, toluene, xylene, diphenylmethane, diphenylethane, triphenylmethane, triphenylethane, dibenzyltoluene, phenol, pyridine, pyrimidine, pyrazine, quinoline and isoquinoline. The catalyst layer according to [7], which is at least one kind of.
[9]
The catalyst layer according to any one of [1] to [8], wherein the organic polymer has a crosslinked structure.
[10]
The catalyst layer according to any one of [1] to [9], wherein the organic polymer has an aromatic ring structure in the main chain skeleton or an aromatic ring structure in the side chain of the repeating unit.
[11]
The catalyst layer according to [10], wherein the organic polymer is a copolymer containing styrene and butadiene as a monomer constituent unit.
[12]
The catalyst layer according to any one of [9] to [11], wherein the gel fraction of the organic polymer measured using toluene as a solvent is 10% by mass or more.
[13]
The catalyst layer according to any one of [1] to [12], which has porosity.
[14]
The catalyst metal comprises at least one selected from the group consisting of platinum, ruthenium, rhodium, palladium, iridium, molybdenum, renium, tungsten, titanium, nickel, copper, zinc, silver, tin, gold, lead and lanthanoids. The catalyst layer according to any one of [1] to [13].
[15]
The catalyst layer according to any one of [1] to [14], which has a structure in which the catalyst metal is supported on a conductive carrier.
[16]
The catalyst layer according to any one of [1] to [15], wherein the catalyst metal and / or the conductive carrier is bound by the organic polymer.
[17]
The catalyst layer according to any one of [1] to [16], wherein the catalyst metal and the conductive carrier have a network structure in contact with each other, and the network structure exhibits conductivity.
[18]
The catalyst layer according to any one of [1] to [17], wherein the ratio of the mass of the catalyst metal to the mass of the organic polymer is in the range of 1: 10 to 16: 1.
[19]
A cathode used in an electrolytic synthesis cell, which has the catalyst layer according to any one of [1] to [18] as an active layer.
[20]
The cathode according to [19], which has the catalyst layer on a conductive substrate.
[21]
An electrolytic synthesis cell comprising the cathode according to [19] or [20] and an anode for oxidizing water to generate oxygen.
[22]
Membrane electrode assembly used in electrolytic synthesis cells
The catalyst layer according to any one of [1] to [18] and
A base film that is non-conductive and porous and is in contact with the catalyst layer,
Membrane electrode assembly having.
[23]
An electrolytic synthesis cell comprising the membrane electrode assembly according to [22] and an anode that oxidizes water to generate oxygen.
[24]
An organic compound hydrogenating apparatus comprising the electrolytic synthesis cell according to [21] or [23], which hydrogenates the organic compound to be hydrogenated.
[25]
A method for producing a hydrogenated organic compound, which comprises a step of hydrogenating the hydrogenated organic compound using the organic compound hydrogenating apparatus according to [24].
[26]
A first hydrogenation step for obtaining a hydrogenated product having a purity of 25% to 75% and a hydrogenated product having a purity of 90% to 99% by using at least two or more organic compound hydrogenators according to [24]. The method for producing a hydrogenated organic compound according to [25], which comprises a second hydrogenation step for obtaining a hydrogenated organic compound.

According to the present invention, a catalyst layer capable of hydrogenating an organic compound to be hydrogenated without using an ion exchange membrane and achieving high faraday efficiency even when the concentration of the hydride in the cell is high, and a catalyst layer thereof. A cathode, an electrolytic synthesis cell, a membrane electrode assembly, an organic compound hydrogenator, and a method for producing a hydrogenated organic compound can be provided.

FIG. 1 is a partial schematic view of the electrolytic synthesis cell according to the first embodiment. FIG. 2 is a partial schematic view of the electrolytic synthesis cell according to Comparative Example 1. FIG. 3 is a partial schematic view of the electrolytic synthesis cell according to Comparative Example 2. FIG. 4 shows the MCH concentration in the immersion liquid containing toluene (Tol) and methylcyclohexane (MCH), and the amount of the styrene-butadiene copolymer 1 described in Example 1 absorbing Tol or MCH in the immersion liquid. It is a graph which shows the relationship of. FIG. 5 is an explanatory diagram of a three-phase interface of the electrolytic synthesis cell included in one embodiment of the present invention. FIG. 6 is an explanatory diagram of the three-phase interface of the electrolytic synthesis cell according to the prior art.

Hereinafter, embodiments for carrying out the present invention (hereinafter, abbreviated as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiment, and can be modified in various ways within the scope of the gist thereof.

The catalyst layer of the present embodiment is a catalyst layer for electrochemically hydrogenating an organic compound to be hydrogenated having an unsaturated bond to obtain a hydride, and contains a catalyst metal and an organic polymer, and is described above. The mass of the hydrogenated organic compound absorbed by the organic polymer per unit mass in the hydrogenated organic compound is defined as A, and the A is 0.1 kg / kg or more and 100 kg / kg or less. Since it is configured in this way, the catalyst layer of the present embodiment can hydrogenate the organic compound to be hydrogenated without using an ion exchange membrane, and even when the concentration of the hydride in the cell is high. High hydrogenation efficiency can be achieved.

For comparison with electrolysis in this embodiment, the principle of electrolysis using a PEM type cell corresponding to the prior art will be described.

The PEM type cell has an ion exchange membrane as an insulating film between the anode and the cathode. An example of this is a configuration containing a membrane electrode assembly (MEA) having an anode catalyst layer on one side and a cathode catalyst layer on the other side of an ion exchange membrane that allows cations to pass through. The anode catalyst layer contains catalyst particles such as a Pt-supported carbon catalyst in which a Pt catalyst is supported on a carbon carrier, and ionomers having an ion-exchangeable group similar to an ion-exchange membrane. Further, it has a porous network structure in which the Pt-supported carbon particles and the ionomer resin are connected to each other. The cathode catalyst layer on the other side contains an ionomer in which the catalyst particles, such as Pt-supported carbon particles, have an ion exchange group as well as the ion exchange membrane. Further, it has a porous network structure in which the Pt-supported carbon particles and the ionomer resin are connected to each other.

An aqueous solution containing water or an electrochemically stable supporting electrolyte having no oxidation-reduction potential in the voltage region to be applied is supplied to the anode catalyst layer of the PEM type cell. When a voltage is applied so that the potential of the anode catalyst layer with respect to the cathode catalyst layer becomes noble, water is decomposed at the catalytic activity point in the anode catalyst layer at a certain voltage of 1.23 V or more, which is the theoretical decomposition voltage of water, and oxygen molecules are generated. Electrons and hydrogen ions are generated. Of these, oxygen molecules diffuse into the voids of the anode catalyst layer as gas and are discharged to the outside of the system, and electrons are supplied to the electric circuit outside the system via the network of the carbon carrier. On the other hand, hydrogen ions move to the ion exchange membrane via the ionomer network contained in the anode catalyst layer, and are carried to the cathode catalyst layer on the opposite side via the ion exchange membrane. Here, an example of the cathode catalyst layer is shown in FIG. The cathode catalyst layer 60 in FIG. 6 is formed on the ion exchange membrane 68 and contains the catalyst metal particles 62 supported on the conductive carrier 61 and the ion exchange ionomer 63. Further, a diffusion layer 64 is formed on the cathode catalyst layer 60 on the opposite side of the ion exchange membrane 68. In FIG. 6, the electrolytic solution 66 is supplied to the cathode catalyst layer 60. Further, hydrogen ions 69 are supplied from the ion exchange membrane 68 to the active point of the catalyst powder (existing in the catalyst metal particles 62 supported on the conductive carrier 61) via the network of the ion exchange ionomer 63. Further, electrons 65 are carried from the diffusion layer 64 side to the catalytic active site via the network of the catalyst powder contained in the cathode catalyst layer 60 from the electric circuit outside the system. Then, hydrogen ions 69 and electrons 65 react at the catalytic active site to form hydrogen molecules, which diffuse the voids of the cathode catalyst layer 60 and are discharged to the outside of the system.

That is, the catalytically active site in the anodic catalyst layer has a three-phase interface in contact with electrons in the catalyst particles, water in the voids, and an ionomer that receives the generated hydrogen ions, so that the anodic oxidation represented by the following formula 2 is performed. A reaction occurs. On the other hand, the catalytically active point in the cathode catalyst layer has a three-phase interface in contact with electrons in the catalyst particles, hydrogen ions in the ionomer, and voids in which the generated hydrogen is diffused, and is represented by the following formula 3. Cathodic reduction reaction occurs. In PEM type water electrolysis, water electrolysis occurs in this way.
[Equation 2]
_{2H 2 O → O 2 + 4H} + + 4e -
[Equation 3]
2H ^{+ +} 2e ^- → H ₂

For example, in Patent Document 4, in the PEM type cell having the above-mentioned structure, a hydrogenated organic compound molecule 67 (for example, toluene) such as an aromatic hydrocarbon is put on the diffusion layer 64 side in the cathode catalyst layer 60 exemplified in FIG. The hydrocarbon (for example, methylcyclohexane) is produced by supplying from. This is because the voids at the three-phase interface in the cathode catalyst layer 60 are filled with the hydrogenated organic compound molecules 67, so that the hydrogenated organic compound molecules 67, hydrogen ions 69, and electrons 65 are on the catalytic activity point. It is considered that the three-phase interface in contact is formed and the cathode reduction reaction represented by the following formula 4 occurs.
[Equation 4]
_{C 6 H 5 CH 3 + 6H} + + 6e - → C 6 H 11 CH 3

For the above reasons, an ion exchange membrane is indispensable in the PEM type electrolytic synthesis cell. Generally, the ion exchange membrane has a higher voltage loss than the supporting electrolyte aqueous solution, and in order to reduce the voltage loss of the electrolytic synthesis cell, it is preferable to make it as thin as possible. On the other hand, there is a problem that the thin film reduces the mechanical strength and makes it difficult to apply the catalyst layer and handle the cells when assembling them.

Therefore, the present inventors have conducted intensive studies on a method for forming the above-mentioned three-phase interface without using an ion exchange membrane and an ionomer having an ion exchange group. As a result, the organic compound to be hydrogenated is efficiently supplied to the catalytic active site by adopting a configuration in which the organic polymer that absorbs a specific amount of the organic compound to be hydrogenated and the catalyst metal coexist in the catalyst layer. I found out what I could do.

Among the modes satisfying the above configuration, a particularly preferable mode is illustrated as shown in FIG. In FIG. 5, the cathode catalyst layer 50 is formed on the porous film 58, and includes catalyst metal particles 52 supported on a conductive carrier 51 and an organic polymer 53 that selectively absorbs an organic compound to be hydrogenated. Includes. Further, a diffusion layer 54 is formed on the cathode catalyst layer 50 on the opposite side of the porous membrane 58. Further, in FIG. 5, the electrolytic solution 56 is supplied to the cathode catalyst layer 50. In the embodiment shown in FIG. 5, the cathode catalyst layer 50 has a network structure described later by containing the conductive carrier 51. As described above, by allowing the organic polymer and the catalyst metal to coexist, the organic polymer absorbs the hydrogenated organic compound molecule 57 from the electrolytic solution 56 in the cell, and the hydrogenated organic compound molecule reaches the catalytic activity point. 57 is supplied. As a result, the catalytically active point forms a three-phase interface where the hydrogenated organic compound molecule 57 in the organic polymer, the hydrogen ion 59 in the aqueous solution of water or the electrolyte, and the electron 55 in the catalyst particles meet. By applying a voltage here, the cathode reduction reaction represented by the above formula 4 occurs.

As described above, according to the catalyst layer of the present embodiment, the organic polymer to be hydrogenated is electrochemically hydrogenated by coexisting the organic polymer and the catalyst metal particles without using an ion exchange membrane. This is a great advantage in industrially producing electrolytically synthesized cells.

The mass A of the hydrogenated organic compound absorbed by the organic polymer per unit mass in the hydrogenated organic compound is measured as follows. First, the mass of the dried organic polymer is measured with an electronic balance or the like. This organic polymer is immersed in the organic compound to be hydrogenated (single substance) and allowed to stand under the conditions of an immersion temperature of 25 ° C. and an immersion time of 24 hours. After that, the organic polymer is taken out from the hydrogenated organic compound, the hydrogenated organic compound adhering to the surface is dried, and then the mass of the catalyst layer is measured. The mass increase at this time is defined as the mass A of the hydrogenated organic compound absorbed by the organic compound. Further, since it is sufficient that the mass increase after immersion of the organic compound to be hydrogenated can be quantified, if the member having the catalyst layer or the catalyst layer does not have a member for absorbing the organic compound to be hydrogenated, each member having the catalyst layer There is no problem in measuring the mass before and after immersion.

The mass A must be in the range of 0.1 kg / kg or more and 100 kg / kg or less. In terms of supplying the hydrogenated organic compound to the catalytically active point, it is preferable that the organic polymer absorbs a larger amount of the hydrogenated organic compound, but the organic polymer is the hydrogenated organic. The more the compound is absorbed, the more the organic polymer expands in volume and the organic polymer becomes brittle, so that the structure of the catalyst layer may be destroyed. Therefore, in order to stably maintain high Faraday efficiency for a long period of time, the mass A is in the range of 0.1 kg / kg or more and 100 kg / kg or less, preferably 2 kg / kg or more and 50 kg / kg or less. It is preferably 2.5 kg / kg or more and 30 kg / kg or less.
The above-mentioned A is, for example, molecular design such as selection of a monomer unit constituting an organic polymer (also referred to as a “repeating unit” or a “monomer constituent unit” in the present specification) and selection of a side chain. The above range can be adjusted by adjusting the gel fraction of the organic polymer described later. More specifically, for example, when the organic compound to be hydrogenated is toluene as described later, the value of A tends to increase by increasing the amount of aromatic rings contained in the repeating unit. Since the value of A tends to decrease by reducing the amount of aromatic rings, A can be adjusted to the above range by the amount of aromatic rings.

The catalyst layer of the present embodiment has a swelling coefficient calculated by A / B, where B is the mass of the hydride absorbed by the organic polymer per unit mass in the hydride of the organic compound to be hydrogenated. It is preferable that C is in the range of 1.5 or more and 100 or less.

In the PEM type cell, an increase in the concentration of the hydride in the cell means a decrease in the concentration of the organic compound to be hydrogenated at the three-phase interface in the cathode catalyst layer. For this reason, the number of hydrogenated organic compounds supplied to the cathode catalyst layer is smaller than the number of electrons supplied to the cathode catalyst layer. As a result, the surplus electrons react with the hydrogen ions supplied from the ionomer at the three-phase interface, and the proportion of the reaction represented by the formula 3 which is the competitive reaction of the reaction represented by the formula 4 increases, which is represented by the formula 1. It is thought that Faraday efficiency will decrease.

Therefore, the present inventors have conducted extensive research on a method for selectively supplying the hydrogenated organic compound from a mixed solution of the hydrogenated product and the hydrogenated organic compound to the catalytically active site. As a result, the organic polymer that selectively absorbs the organic compound to be hydrogenated as compared with the hydride and the catalyst metal coexist in the catalyst layer, whereby the organic compound to be hydrogenated is selectively selected at the catalytic activity point. We found that we could supply it.

That is, when the organic compound and the catalyst metal coexist in the catalyst layer, the organic polymer selectively absorbs the hydrogenated organic compound even if the concentration of the hydride in the cell is high. Therefore, the organic polymer is filled with the organic compound to be hydrogenated, and the three-phase interface at the catalytically active point is in the same state as when the hydride concentration is low. As a result, the organic compound to be hydrogenated can be selectively supplied to the catalyst layer, and high Faraday efficiency can be realized even when the hydride is in a high concentration.

The mass B of the hydride absorbed by the organic polymer per unit mass in the hydride of the organic compound to be hydrogenated can be measured in the same manner as in the method for measuring A.

The swelling coefficient C is preferably in the range of 1.5 or more and 100 or less. When the swelling coefficient C is 1.5 or more, the organic compound to be hydrogenated tends to be selectively supplied depending on the catalytic active site. Further, when the swelling coefficient C is 100 or less, the diffusibility of the hydrogenated material produced in the organic polymer in the organic polymer becomes good, and the hydrogenated organic compound becomes a catalytically active point more efficiently. Tends to be supplied to. From the above viewpoint, the swelling coefficient C is more preferably 2 or more and 80 or less, more preferably 3 or more and 50 or less, and more preferably 4 or more and 30 or less. The swelling coefficient C can be adjusted to the above range by, for example, the same method as the method for adjusting A described above.

The catalyst layer of the present embodiment preferably has a water swelling coefficient E calculated by D / A of 0.7 or less, where D is the mass of water absorbed by the organic polymer per unit mass in water. The mass D of water absorbed by the organic polymer in water can be measured in the same manner as the method for measuring A.

From the viewpoint of avoiding an excessive decrease in the amount of the organic compound to be hydrogenated to be supplied to the catalytically active site due to the absorption of water by the organic polymer and more effectively preventing a decrease in Faraday efficiency, the organic The water swelling coefficient E of the polymer is preferably 0.7 or less, more preferably 0.1 or less.
The water swelling coefficient E can be adjusted within the above range, for example, by adjusting the amount of hydrophilic groups and hydrophobic groups contained in the repeating unit.

The catalyst layer of the present embodiment preferably contains 0.1 kg or more and 100 kg or less of the organic compound to be hydrogenated with respect to 1 kg of the organic polymer.

Since the organic polymer contains the hydrogenated organic compound in the catalyst layer, the hydrogenated organic compound is supplied to the catalytically active point. As a result, the catalytically active site forms a three-phase interface where the hydrogenated organic compound in the organic polymer, hydrogen ions in water or an aqueous electrolyte solution, and electrons in the catalyst particles meet. By applying a voltage here, the cathode reduction reaction represented by the formula 4 occurs. As a result, the organic compound to be hydrogenated can be electrochemically hydrogenated without using an ion exchange membrane, which is a great advantage in industrially producing an electrolytic synthesis cell.

When 0.1 kg or more of the hydrogenated organic compound is contained in 1 kg of the organic polymer, the hydrogenated organic compound tends to be more efficiently supplied to the catalytically active site. Further, when 100 kg or less of the organic compound to be hydrogenated is contained in 1 kg of the organic polymer, excessive volume expansion of the organic polymer can be prevented, the structure of the catalyst layer can be easily maintained, and as a result, a longer period of time can be maintained. There is a tendency for stable and high polymer efficiency to be maintained. From the above viewpoint, the content of the hydrogenated organic compound with respect to 1 kg of the organic polymer is more preferably 2 kg / kg or more and 50 kg / kg or less, still more preferably 3 kg / kg or more and 30 kg / kg or less, and further. It is preferably 4 kg / kg or more and 20 kg / kg or less.
The content can be adjusted to the above range by, for example, the same method as the method for adjusting A described above.

The catalyst layer of the present embodiment preferably contains 0.001 kg or more and 33 kg or less of the hydrogenated material with respect to 1 kg of the organic polymer.

That is, when the organic polymer and the catalyst metal coexist in the catalyst layer, the organic polymer selectively absorbs the hydrogenated organic compound even if the concentration of the hydride in the cell is high. .. Therefore, the organic polymer to be hydrogenated tends to be present in a larger amount in the organic polymer, and the three-phase interface at the catalytically active point tends to be in the same state as when the concentration of the hydride is low. As a result, the organic compound to be hydrogenated can be selectively supplied to the catalyst layer, and high Faraday efficiency can be realized even when the hydride is in a high concentration.

When 33 kg or less of a hydrogenated substance is contained in 1 kg of the organic polymer, the organic compound to be hydrogenated tends to be selectively supplied depending on the catalytic active site. Further, when 0.001 kg or more of the hydrogenated compound is contained with respect to 1 kg of the organic polymer, the diffusibility of the hydrogenated compound produced in the organic polymer in the organic polymer becomes good, and the efficiency becomes higher. Often, the hydrogenated organic compound tends to be supplied to the catalytically active site. From the above viewpoint, the content of the hydrogenated product is more preferably 0.001 kg or more and 50 kg or less, further preferably 0.002 kg or more and 33 kg or less, and even more preferably 0.003 kg or more and 25 kg or less.

The catalyst layer of the present embodiment preferably contains 33 kg or less of water with respect to 1 kg of the organic polymer. When the water content is 33 kg / kg or less, the organic polymer tends to absorb a larger amount of the organic compound to be hydrogenated, and a decrease in Faraday efficiency tends to be more effectively prevented. From the above viewpoint, the content of the water is more preferably 5 kg / kg or less.
The content can be adjusted to the above range by, for example, the same method as the method for adjusting A described above.

(Organic compound to be hydrogenated)
In the catalyst layer of the present embodiment, it is preferable that at least a part or all of the organic compound to be hydrogenated is an aromatic compound. Further, in the catalyst layer of the present embodiment, the aromatic compound is benzene, naphthalene, anthracene, toluene, xylene, diphenylmethane, diphenylethane, triphenylmethane, triphenylethane, dibenzyltoluene, phenol, pyridine, pyrimidine, pyrazine, It is preferably at least one selected from the group consisting of quinoline and isoquinoline. Further, these aromatic compounds may be contained alone or as a mixture of two or more kinds. Further, it is more preferable that the organic compound to be hydrogenated is a liquid at normal temperature and pressure. By using a liquid as an electrolytic solution, electrochemical hydrogenation by an electrolytic synthesis cell becomes possible without using a temperature raising and boosting facility, and it tends to be easy to handle as a hydrogen carrier. From this point of view, the organic compound to be hydrogenated is more preferably benzene, toluene, xylene, diphenylethane or quinoline.

(Organic polymer)
In the catalyst layer of the present embodiment, it is preferable that the organic polymer has a crosslinked structure.
When it has a crosslinked structure, it is possible to effectively prevent the dissolution of the organic polymer that may occur when the catalyst layer is immersed in the hydrogenated organic compound, and the structure of the catalyst layer tends to be more stable. The method of the cross-linking treatment is not particularly limited, but for example, a polyfunctional monomer can be polymerized and cross-linked. In addition to the polymerization, the cross-linking method is not limited to the following, and examples thereof include cross-linking by irradiation with an electron beam or γ-ray, thermal cross-linking with a cross-linking agent, and the like.

The catalyst layer of the present embodiment preferably has a structure derived from a vinyl-based monomer having an aryl group in the side chain as a repeating unit of the organic polymer. In order for the organic polymer to selectively absorb the hydrogenated organic compound, it is preferable that the organic polymer has a structure similar to the hydrogenated organic compound. For example, when an aromatic compound is used as the organic compound to be hydrogenated, it is preferable that the organic polymer contains an aromatic ring as a repeating unit. From this point of view, the polymer of a vinyl compound containing an aryl group such as styrene is more preferable as the organic polymer.

In the catalyst layer of the present embodiment, it is preferable that the organic polymer has a structure derived from a conjugated diene-based monomer. Since the organic polymer has a structure derived from a conjugated diene-based monomer, the molecular chain expands and contracts elastically, and there is a tendency that more organic compounds to be hydrogenated can be absorbed even at a high degree of cross-linking. It tends to be easily crosslinked. From this point of view, as the monomer of the organic polymer, organic compounds containing at least two double bonds, for example, 1,3-butadiene, isoprene, 2,3-dimethyl 1,3-butadiene, 2- More preferably, ethyl-1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, chloroprene, 2-chloro-1,3-butadiene, cyclopentadiene and the like.

In order to selectively absorb the hydrogenated organic compound, it is preferable that the organic polymer contains a large amount of a portion having a structure similar to the hydrogenated organic compound. Therefore, the aromatic compound is hydrogenated. In the case of a hydrogenated organic compound, it is preferable that the structure derived from a vinyl-based monomer having a double bond in the main chain and an aryl group in the side chain has a large mass. From this point of view, it is preferable that the organic polymer has a structure derived from a vinyl-based monomer having an aryl group in the side chain and a structure derived from a conjugated diene-based monomer as a repeating unit. Further, in the catalyst layer of the present embodiment, the organic polymer has a single amount of a structure derived from a vinyl-based monomer having an aryl group in the side chain and a structure derived from a conjugated diene-based monomer as a repeating unit. The molar ratio of the body unit is preferably a copolymer having a molar ratio in the range of 99.1: 0.9 to 0.3: 99.7, and the molar ratio is more preferably 99.1: 0.9 to 99.1: 0.9 to 99.7. It is 2.9: 97.1, more preferably 99.1: 0.9 to 36.0: 64.0.

From the above viewpoint, the catalyst layer of the present embodiment has a structure derived from styrene and a structure derived from butadiene as an example of the organic polymer when the aromatic compound is the organic compound to be hydrogenated. It is a copolymer. That is, it is particularly preferable that the copolymer contains styrene and butadiene as the monomer constituent unit.

When the aromatic compound is the hydrogenated organic compound in the catalyst layer of the present embodiment, another preferable example of the organic polymer is an organic polymer having an aromatic ring structure in the main chain skeleton. Examples of such an organic polymer include polyphenylene ether, polyphenylene sulfide, polysulphon, polyethersulphon, polyetherketone, polyphenylene, aromatic polyester, aromatic polyether, aromatic polyamide, aromatic polyimide, and aromatic epoxy resin. And at least one selected from the group consisting of melamine resin is more preferable.

In the catalyst layer of the present embodiment, the gel content of the organic polymer measured using toluene as a solvent is preferably 10% by mass or more, more preferably 10% by mass or more and 99.9% by mass or less, and further. It is preferably 30% by mass or more and 99% by mass or less, and even more preferably 50% by mass or more and 90% by mass or less. When the gel fraction is 10% by mass or more, the structure of the catalyst layer tends to be more stable even when the organic polymer absorbs the hydrogenated organic compound. When the gel fraction is 99.9% by mass or less, more organic compounds to be hydrogenated tend to be supplied to the catalytic active site. The gel fraction can be adjusted to the above range by controlling the degree of crosslinking in the above-mentioned crosslinking method. For example, in the polymerization method, a method of controlling the concentration of a polyfunctional monomer can be mentioned, in the radiation irradiation method, a method of controlling the radiation intensity and the irradiation time can be mentioned, and in the thermal cross-linking method, a cross-linking agent can be added. There is a method of controlling the amount.

The gel fraction of the organic polymer is evaluated as follows. First, the mass of the organic polymer contained in the catalyst layer is measured with an electronic balance or the like. Subsequently, the organic polymer is immersed in toluene to extract the non-crosslinked component of the hydrogenated organic compound. After immersing the organic polymer in toluene for a sufficient time (for example, 24 hours), the organic polymer is taken out from toluene and held at 40 ° C. to 60 ° C. for a sufficient time (for example, 24 hours), and the resin is prepared. Toluene absorbed in the resin is dried. After that, the mass of the organic polymer is measured again, and the ratio of this mass to the mass measured before immersion of the resin in toluene is defined as the gel fraction.

The catalyst layer of the present embodiment preferably has porosity. By having porosity, there is a tendency that catalytic active sites forming a three-phase interface can be produced more efficiently. The method for making the porous material is not particularly limited, but for example, a method of supporting the organic polymer and the catalyst metal on a conductive porous base material such as a metal mesh, a metal foam, or an expanded metal, or an organic polymer. A method of supporting the organic polymer and the catalyst metal on a non-conductive porous base material such as a resin mesh or a non-woven material of an organic polymer resin, and a film containing an ink containing the organic polymer and the catalyst metal, which will be described later. Examples include a method of applying on top. The method for confirming porosity is not particularly limited, and examples thereof include measurement of specific surface area / pore distribution by a gas adsorption method.

(Catalyst metal)
In the catalyst layer of the present embodiment, from the viewpoint of catalytic activity, the catalyst metal is platinum, ruthenium, rhodium, palladium, iridium, molybdenum, renium, tungsten, titanium, nickel, copper, zinc, silver, tin, gold, lead. And at least one selected from the group consisting of lanthanoids.

The catalyst layer of the present embodiment preferably has a structure in which the catalyst metal is supported on a conductive carrier. The carrier is not particularly limited, and examples thereof include carbon particles, alumina, silica, zeolite, and mesoporous materials. By supporting the fine particles of the catalyst metal on the carrier, the amount of the catalyst metal used is reduced, and the specific surface area per volume of the catalyst metal tends to be large, so that the catalytic activity tends to be further improved.

The conductive carrier in the catalyst layer of the present embodiment has physical stability when supporting the catalyst metal, conductivity at the contact point with the catalyst metal, chemical stability to an electrolytic solution, and electrochemical under an electrolytic environment. From the viewpoint of stability and economy, a carbon material is preferable. Further, the conductive carrier is preferably in the form of particles from the viewpoint of forming the network structure, which is a more preferable form of the present embodiment, which will be described later, by the catalyst ink coating method. From the above viewpoint, it is more preferable that the conductive carrier is carbon particles.

In the catalyst layer of the present embodiment, it is preferable that the catalyst metal and / or the conductive carrier is bound to the organic polymer. Since the catalyst metal and / or the conductive carrier is bound by the organic polymer, the three-phase interface tends to be formed more efficiently.
The method for binding the catalyst metal and / or the conductive carrier with the organic polymer is not particularly limited, but for example, a method for forming a catalyst layer by a catalyst ink coating method described later, the catalyst metal and /. Alternatively, a method of polymerizing the organic polymer in the presence of the conductive carrier and the like can be mentioned.

The catalyst layer of the present embodiment has a structure in which the catalyst metal and the conductive carrier are in contact with each other, and the structure is referred to as a network structure. The network structure preferably exhibits conductivity. Since the catalyst metal and the conductive carrier have a network structure in which they are in contact with each other, they tend to have conductivity, so that electrons can be more efficiently supplied from the external circuit to the catalytic active site.
The method for obtaining the network structure is not particularly limited, and examples thereof include a catalyst ink coating method described later.
The method of confirming the conductivity by the network structure is not particularly limited, but for example, a method of simply contacting the electrode of the tester with the catalyst layer to measure the resistance value, or more strictly, a sheet resistance measuring machine or the like is used. A method of measuring the sheet resistance value and the volume resistivity can be mentioned.

In the catalyst layer of the present embodiment, the ratio of the mass of the catalyst metal to the mass of the organic polymer is preferably in the range of 1: 10 to 16: 1. Due to this mass ratio, the ratio of the volume occupied by each of the catalyst metal powder, the organic polymer, and the voids in the catalyst layer tends to be in the range where higher Faraday efficiency can be obtained.

The method for forming the catalyst layer of the present embodiment is not particularly limited, and examples thereof include a catalyst ink coating method described later. In the catalyst ink coating method, first, the organic polymer and the catalyst metal and / or the conductive carrier are contained, and the organic polymer and the catalyst metal and / or the conductive carrier are mixed with water. / Or prepare a catalytic ink uniformly dispersed in an organic solvent. When preparing the catalyst ink, a dispersant may be used in order to uniformly disperse the organic polymer and the catalyst metal and / or the conductive carrier. The method for uniformly dispersing the organic polymer, the catalyst metal and / or the conductive carrier in water and / or an organic solvent is not particularly limited, but is dispersed by, for example, an ultrasonic cleaner. Examples thereof include a method of dispersing with a magnetic stirrer and a method of dispersing with a homogenizer. The catalyst ink prepared as described above is applied onto a substrate to form a wet film. The method for applying the catalyst ink is not particularly limited, and examples thereof include a screen printing method using a squeegee and a coating method using an applicator. The water and / or the organic solvent contained in the wet film is dried at room temperature and then heated to bind the organic polymer and the catalyst metal and / or the conductive carrier. The heating temperature is preferably equal to or higher than the glass transition point of the organic polymer, more preferably equal to or lower than the decomposition temperature of the organic polymer, and further higher than the range in which the organic polymer is not oxidized. More preferred. Further, when an appropriate load is applied in the direction perpendicular to the wet film during heating, the organic polymer and the catalyst metal and / or the conductive carrier are more firmly bound to each other, and the heated film is formed. It is preferable because it tends to be stable. The catalyst layer of the present embodiment can be obtained by heating the wet film for a sufficient time (for example, 30 minutes) as described above and then removing heat at room temperature.

(Cathode)
The cathode used in the electrolytic synthesis cell of the present embodiment has the catalyst layer of the present embodiment as an active layer. Further, the cathode used in the electrolytic synthesis cell of the present embodiment preferably has the catalyst layer of the present embodiment on a conductive base material. The conductive base material is not particularly limited, and examples thereof include carbon paper, metal foil, metal plate, carbon molded body, expanded metal, metal mesh, porous metal, conductive oxide sintered body, and the like. .. By forming the catalyst layer on the conductive base material, it becomes possible to manufacture an electrolytically synthesized cell without a septum.

In the membrane electrode assembly used in the electrolytic synthesis cell of the present embodiment, the catalyst layer of the present embodiment is placed on a non-conductive and porous base film (hereinafter, also referred to as “non-conductive porous membrane”). Have. That is, the membrane electrode assembly of the present embodiment has the catalyst layer of the present embodiment and a base film that is non-conductive and porous and is in contact with the catalyst layer. The non-conductive porous membrane is not particularly limited, and as an example thereof, a fluororesin such as polytetrafluoroethylene (PTFE) is preferable, and a porous membrane thereof, a mesh, a non-woven fabric, and the like can be mentioned. By forming the catalyst layer on the non-conductive porous membrane, it becomes possible to manufacture an electrolytic synthesis cell that does not use an ion exchange membrane. In the above, the non-conductive property can be confirmed by, for example, a method of measuring the sheet resistance value or the volume resistivity using a sheet resistance measuring machine or the like. Further, the porosity can be confirmed by measuring the specific surface area / pore distribution by the gas adsorption method or the like.

(Electrolytic synthesis cell)
The electrolytic synthesis cell of the present embodiment includes a cathode of the present embodiment and an anode for oxidizing water to generate oxygen. The configuration of the electrolytic synthesis cell is not particularly limited, and an example thereof includes the following configuration. A catalyst layer containing the catalyst metal particles in which the catalyst metal in the present embodiment is supported on the carrier in the present embodiment and the organic polymer in the present embodiment is formed on the conductive substrate in the present embodiment. Has a catalyst. Further, for connecting the current collector for connecting the conductive base material and the external circuit, the anode in which the porous catalyst layer is formed on the surface of the conductive base material in the present embodiment, and the anode and the external circuit. It contains a current collector and an insulating spacer having a frame shape for insulating the anode and the cathode and filling the electrolytic solution inside. An example of the present embodiment is a diaphragmless electrolytic synthesis cell in which these are stacked in the order of a cathode current collector / cathode / spacer / anode / anode current collector. By using a diaphragmless electrolytic synthesis cell, it is possible to supply an energetically highly efficient electrolytic synthesis cell with reduced voltage loss derived from the diaphragm.

Further, the electrolytic synthesis cell of the present embodiment preferably includes the membrane electrode assembly of the present embodiment and an anode that oxidizes water to generate oxygen. The configuration of the electrolytic synthesis cell is not particularly limited, and an example thereof includes the following configuration. The catalyst layer containing the catalyst metal particles in which the catalyst metal in the present embodiment is supported on the carrier in the present embodiment and the organic polymer in the present embodiment is formed on the non-conductive porous membrane in the present embodiment. It has a formed membrane electrode assembly. Further, in order to electrically and efficiently connect the catalyst layer and the current collector by being sandwiched between the current collector for connecting the catalyst layer and the external circuit and the catalyst layer and the current collector on the membrane electrode assembly. It contains a carbon paper, an anode in which a porous catalyst layer is formed on the surface of the conductive base material in the present embodiment, and a current collector for connecting the anode and an external circuit, and is a cathode current collector / carbon. Examples thereof include a configuration in which a paper / membrane electrode assembly / anode / anode current collector is stacked in this order. By manufacturing an electrolytic synthesis cell that does not use an ion exchange membrane, energization is generated by the electrolytic solution in the pore, and it becomes possible to reduce the voltage loss as compared with the ion exchange membrane.

(Organic compound hydrogenator)
The organic compound hydrogenation apparatus for hydrogenating the hydrogenated organic compound of the present embodiment includes the electrolytic synthesis cell of the present embodiment. With this apparatus, electrolytic hydrogenation with high Faraday efficiency becomes possible even when a mixed solution with a hydrogenated material having a high hydrogenated material concentration is used as a raw material.

(Hydrogenation method)
The method for producing a hydrogenated organic compound according to the present embodiment includes a step of hydrogenating the hydrogenated organic compound using the organic compound hydrogenating apparatus of the present embodiment. According to this method, electrolytic hydrogenation with high Faraday efficiency becomes possible even when a mixed solution with a hydrogenated material having a high hydrogenated material concentration is used as a raw material.

(Manufacturing method of hydrogenated organic compound)
The method for producing a hydrogenated organic compound of the present embodiment includes a first hydrogenation step for obtaining a hydrogenated product having a purity of 25% to 75% by using at least two or more organic compound hydrogenating devices of the present embodiment. It is preferable to have a second hydrogenation step for obtaining a hydrogenated product having a purity of 90% to 99%. This method makes it possible to efficiently produce hydrogenated organic compounds on an industrial scale.

Hereinafter, the present embodiment will be described in more detail with reference to Examples and Comparative Examples, but the present embodiment is not limited to the following Examples. The evaluation method and measurement method used in this example are as follows.

[Example 1]
Platinum-ruthenium-supported carbon catalyst particles (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., standard catalyst for solid polymer fuel cells, carbon monoxide poisoning catalyst standard product TEC61E54-Pt and Ru content 54% by mass (Pt: Ru = 1) : 1.5) Support catalyst (carrier Ketjenblack EC), hereinafter also referred to as "Pt / Ru-C catalyst"), put 1.21 g into a screw tube bottle with a capacity of 30 mL, and distilled water (manufactured by Hayashi Junyaku) 17.76 mL. Was dropped. 0.83 g of sodium carboxymethyl cellulose (manufactured by Kanto Chemical Co., Inc., hereinafter also referred to as "CMC") was added to this sample. Using a homogenizer (manufactured by AS ONE Corporation, HOMOGENIZER Model AHG-160D, shaft generator manufactured by AS ONE Corporation, HT1008), this sample was stirred at 2000 rpm for 2 minutes, 12000 rpm for 5 minutes, and 27000 rpm for 5 minutes. The / C catalyst was uniformly dispersed (hereinafter, this dispersion method is also referred to as "standard dispersion method") to obtain a catalyst dispersion liquid 1. On the other hand, the styrene-butadiene copolymer (hereinafter, also referred to as “SB”) latex 1 to be added to the catalyst dispersion 1 was prepared as follows. First, 63 parts by mass of water was placed in a pressure-resistant reaction vessel equipped with a stirrer and a jacket for temperature control. Further, 0.2 parts by mass of sodium dodecylbenzenesulfonate was charged, and the internal temperature was raised to 90 ° C. Then
Styrene: 57.0 parts by mass Butadiene: 41.0 parts by mass Acrylic acid: 2.0 parts by mass t-dodecyl mercaptan: 0.2 parts by mass of a monomer composition mixed with
Water: 20 parts by mass Sodium peroxodisulfate: 1.2 parts by mass Sodium lauryl sulfate: 0.1 parts by mass Sodium hydroxide: 0.2 parts by mass of an initiator-based aqueous solution mixed over 4 hours and 5 hours, respectively. Was added at a constant flow rate. After the addition was completed, the temperature of 90 ° C. was maintained for 1 hour and then cooled. Then, sodium hydroxide was added to adjust the pH to 8. Next, the unreacted monomer was removed by the steam stripping method and filtered through a 200 mesh wire mesh. Water was added to this latex dispersion to adjust the solid content concentration to 50% by mass to obtain SB latex 1. The particle size of SB dispersed in this SB latex 1 was measured by a laser diffraction / scattering type particle size distribution measuring device ( When measured with LA-920) manufactured by HORIBA, Ltd., it was 170 nm. Then, 0.74 g of SB latex 1 was added dropwise to the catalyst dispersion liquid 1 and dispersed again using a homogenizer by the standard dispersion method to produce a catalyst ink 1 having the following composition.
Pt-Ru / C catalyst: 6.1% by mass
SB Latex 1: 3.8% by mass
CMC: 0.61% by mass
Water: 89.5% by mass

Hydrophilic PTFE porous membrane (Omnipore TM, model number JGWP04700, heat resistant temperature: 130 ° C., pore diameter: 0.2 μm, thickness: 80 μm, porosity: 80%, bubble point: 93.8 kPa (13.6 psi), diameter: 47 mm ) Was suction-fixed with a vacuum chuck stand under a mask having a circular hole with a diameter of 2 mm. Immediately after producing the catalyst ink 1, a few mL of the catalyst ink 1 is dropped onto the mask, and the mask is used with an applicator (manufactured by Tester Sangyo Co., Ltd., SA-201 Baker type applicator, effective width 150 mm) so that the wet thickness is 90 μm. The catalyst ink 1 was applied to the hydrophilic PTFE porous membrane through the film. After drying this coating film in the air for 30 minutes, it is sandwiched between 1 mm thick PTFE sheets (manufactured by Sampler Tech) and then placed in an oven (manufactured by Advantech, dryer, FC-410) heated to 80 degrees. It was put in, a weight of 5 kg was put on it, and it was heated and compressed. After 45 minutes, it was taken out and cooled in air to prepare a membrane electrode assembly A1 coated with a catalyst layer having a dry thickness of about 30 μm.

The electrolytic synthesis cell 1 using the membrane electrode assembly A1 was manufactured as follows. A cell is manufactured from a SUS316 plate (thickness 1 mm) and a PTFE cell (thickness 5 mm), and a PTFE gasket (manufactured by Nippon Gore Co., Ltd., Gore (registered trademark) hypersheet (registered trademark) gasket, model number: SG05X-J, A gasket with a thickness of 500 um) and a shape suitable for the cell was manufactured. For the cathode current collector, the hydrogen electrode carbon separator (with O-ring) used in the small polymer electrolyte fuel cell assembly kit Pem Master (registered trademark) (model number: PEM-004) manufactured by Chemix Co., Ltd. was adopted. .. A carbon sheet (thickness 300 μm) purchased from Chemix Co., Ltd. was used as the cathode diffusion layer. For the gasket for fixing the carbon sheet, the silicon gasket used in Pem Master (registered trademark) manufactured by Chemix Co., Ltd. was adopted. The anode current collector was manufactured using a Ti plate (manufactured by Niraco, model number: TI-453511, thickness 1.0 mm). A DSE (registered trademark) electrode manufactured by Denora Permelek Co., Ltd. was used as the anode catalyst electrode. Each of the above members was stacked in the following order and tightened with bolts to produce an electrolytic synthesis cell 1. A partial schematic diagram of the electrolytic synthesis cell 1 is shown in FIG. In FIG. 1, for convenience, the members are shown separately from each other, but as described above, the members are in contact with each other in the assembled state of the electrolytic synthesis cell 1.
(Cathode side) SUS316 plate / PTFE cell / PTFE gasket / cathode current collector 11 / silicone gasket + diffusion layer 12 / membrane electrode assembly A1 (catalyst layer 13 coating side is cathode side) / 3 PTFE gaskets + anode catalyst electrode 15 / Electrode current collector 16 / PTFE gasket / PTFE cell / SUS316 plate (electrode side)

[Comparative Example 1]
A cathode cell was made using a SUS316 plate, and an anode cell was made using an acrylic plate. The membrane electrode joint (both positive and negative) used in the small SPE electrolysis assembly kit Pem Master (registered trademark) (model number: PEM-004H2O) manufactured by Chemix Co., Ltd., which is a standard PEM type electrolytic synthesis cell configuration. A platinum-supported carbon catalyst to which a platinum-supported carbon catalyst is bound by a Nafion ionomer) was adopted as an ion exchange membrane and a positron catalyst layer to form a film electrode junction B2. For the anode current collector, a hydrogen electrode carbon separator (with an O-ring) used in Pem Master (registered trademark) (model number: PEM-004) manufactured by Chemix Co., Ltd. was adopted. As the anode diffusion layer, a carbon sheet (thickness 300 μm) purchased from Chemix Co., Ltd. was used.
Using the above members, as in Example 1, the cells were stacked in the following order and tightened with bolts to produce an electrolytic synthesis cell 2. A partial schematic diagram of the electrolytic synthesis cell 2 is shown in FIG. In FIG. 2, for convenience, the members are shown separately from each other, but as described above, the members are in contact with each other in the assembled state of the electrolytic synthesis cell 2.
(Cathode side) SUS316 cell / Cathode current collector 21 / Silicone gasket + Diffusion layer 22 / Membrane electrode assembly B2 / Silicone gasket + Diffusion layer 26 / Anoden current collector 27 / Acrylic cell (Adenode side)

[Comparative Example 2]
A 1.48 g Pt / Ru-C catalyst was placed in a screw tube bottle having a capacity of 30 mL, and a mixed solution of 4.26 mL of distilled water (manufactured by Hayashi Junyaku) and 21.47 mL of ethanol (Kanto Chemical Co., Inc.) was added dropwise. 2.27 mL of ionomer dispersion (manufactured by DuPont, model number: Nafion (registered trademark) DE2020, component composition ionomer: water: normal propanol = 22.5% by mass: 40% by mass: 37.5% by mass) was added dropwise to this sample. After that, the mixture was dispersed by a standard dispersion method to produce a catalyst ink 2 having the following composition.
Pt-Ru / C catalyst: 5.9% by mass
Ionomer dispersion: 9.3% by mass
Water: 17.0% by mass
Ethanol: 67.8% by mass

The catalyst ink 2 was applied to the hydrophilic PTFE porous membrane in the same manner as in Example 1. This coating film is dried in air for 30 minutes, sandwiched between 1 mm thick PTFE sheets (manufactured by Sampler Tech), placed in an oven heated to 110 degrees, and heated and compressed with a weight of 5 kg. After 45 minutes, it was taken out and cooled in air to prepare a membrane electrode assembly C3 coated with a catalyst layer having a dry thickness of about 30 μm.
In the electrolytic synthesis cell 3 using the membrane electrode assembly C3, the above members were stacked in the following order and tightened with bolts to produce the electrolytic synthesis cell 3 in the same manner as in Example 1. A partial schematic diagram of the electrolytic synthesis cell 3 is shown in FIG. In FIG. 3, for convenience, the members are shown separately from each other, but as described above, the members are in contact with each other in the assembled state of the electrolytic synthesis cell 3.
(Cathode side) SUS316 plate / PTFE cell / PTFE gasket / cathode current collector 31 / silicone gasket + diffusion layer 32 / membrane electrode assembly C3 (catalyst layer 33 coating side is cathode side) / 3 PTFE gaskets + anode catalyst electrode 35 / Electrode collector 36 / PTFE gasket / PTFE cell / SUS316 plate (electrode side)

In both Examples and Comparative Examples, the organic compound to be hydrogenated was toluene, and the hydride was methylcyclohexane (hereinafter, also referred to as “MCH”).

The concentration of the mixed solution of toluene and MCH is gas chromatography (GC-14B and chromatopack C-R6A manufactured by Shimadzu Corporation, detector FID, packed column: DB-1 manufactured by Agilent (length 30 m, inner diameter 0.32 mm, inner diameter 0.32 mm, The film thickness was 0.25 μm), hereinafter also referred to as “GC”), and the quantification was performed by the following method. When preparing the measurement sample, the solvent was N-methylpyrrolidone (hereinafter, also referred to as “NMP”), and the internal standard was isopropanol (hereinafter, also referred to as “IPA”). First, the added masses of toluene and MCH are measured, and the mixed solution having a known concentration is adjusted with different concentrations (MCH concentration 0% by mass, 25% by mass, 50% by mass, 75% by mass, 100% by mass). A calibration curve sample was used (hereinafter, adjusting the sample for GC measurement at this volume ratio is referred to as a standard GC sample preparation method). NMP: IPA: Calibration curve sample = 98 vol%: 1 vol%: 1 vol% was mixed, and the mixed mass of each was measured and used as a measurement sample. GC measurement was performed on these measurement samples, and a calibration curve was prepared from the correlation between the detection peak area of GC and the known concentration of the calibration curve sample. When quantifying the concentration of the toluene and MCH mixed solution of unknown concentration, the sample prepared according to the standard GC sample preparation method was measured by the same temperature raising program as when the calibration curve was prepared.

The resin SB1 obtained by drying the SB latex 1 used in Example 1 and the naphthion membrane (manufactured by DuPont, NR212) used as an ion exchange membrane in the membrane electrode assembly B2 of Comparative Example 1 absorbed each other. The masses A, B, and D of toluene, MCH, and water were measured by the following methods. First, about several mL of SB latex 1 was dropped onto the PTFE sheet. This SB latex 1 was placed in an oven heated to 50 ° C. and dried for 24 hours or more. The dried resin SB1 was taken out from the oven, peeled off from the PTFE sheet, and cut into pieces of about 0.1 to 0.2 g. The mass of each of the carved SB1s was measured. Each of these SB1s was immersed in about 50 mL of toluene, about 50 mL of MCH, or about 50 mL of water (immersion temperature 25 ° C.), and allowed to stand for 24 hours or more. After that, each SB1 was taken out from each immersion liquid, and each immersion liquid adhering to the surface was wiped off with a Kimwipe and dried for several seconds. After that, the mass of each SB1 was measured, and the mass difference of each SB1 before and after immersion in the immersion liquid was defined as A, B, and D. Further, in the Nafion film, A, B, and D were calculated by the same method as described above except for the step of drying the SB latex. Further, the swelling coefficient C and the water swelling coefficient E were calculated from these A, B, and D. The results are shown in Table 1. It can be seen that in Example 1, toluene was selectively absorbed as compared with methylcyclohexane and water. On the other hand, in Comparative Example 1, it can be seen that toluene and methylcyclohexane were not absorbed, but only water was absorbed. Further, each of the toluene-absorbed SB1s produced here was allowed to stand in an oven heated to 50 ° C. for 24 hours to dry the toluene absorbed by SB1. After that, the respective masses were measured, and the ratio to the mass before immersion in toluene was calculated as the gel fraction. As a result, the gel fraction of SB1 was 93% by mass.

After immersing SB1 in a mixed solution having a known concentration of toluene and MCH for 24 hours or more, the mass increase of each was quantified. The concentration of the mixed solution before and after immersion was quantified by GC. FIG. 4 shows the result of calculating how much SB1 absorbs toluene and MCH from these values. From these results, it can be seen that SB1 of Example 1 selectively absorbs toluene even when immersed in a mixed solution having a high MCH concentration.

The electrolysis test was carried out by the following method. A diaphragm pump (MGI-25N-TTT-6, manufactured by Kyoritsu Kiko Co., Ltd.) sucked up the liquid from each electrolyte tank of the positive cathode and let it flow into the inlet of the electrolyte of each positive cathode of the cell. The electrolytic solution discharged from the electrolytic solution outlet of each positive cathode of the cell was refluxed to the electrolytic solution tank of each positive cathode. The anodic electrolyte was a 0.5 MH ₂ SO ₄ aqueous solution. The cathode electrolytic solution was a mixed solution of toluene and MCH having an arbitrary concentration. The gas generated by electrolysis was discharged together with the electrolytic solution from the electrolytic solution outlet, and then transferred to the electrolytic solution tank. Exhaust lines from each of the positive cathode electrolyte tanks were provided, they were gathered in one path, passed through the same cooling capacitor, and exhausted to the outside of the system. At this time, the vaporized electrolyte was arranged so as to fall from the cooling condenser into the cathode electrolyte tank. Further, a power source (manufactured by Matsusada Precision Co., Ltd., PK36-11) and a current collector of each of the positive and cathode were connected in series, and a voltage was applied to perform constant current electrolysis. A data logger (TR-V550 manufactured by KEYENCE CORPORATION) was connected in parallel with the cell to monitor the cell voltage in the electrolytic solution.

The Faraday efficiency was calculated as follows. After performing constant current electrolysis and energizing for an arbitrary time, electrolysis was stopped, the cathode electrolytic solution was sampled, and then the component compositions of toluene and MCH were quantified by GC measurement. This operation was repeated to quantify the MCH produced by electrolysis from the change in the concentration of MCH in the cathode electrolyte. On the other hand, the number of electrons energized in the cell was calculated from the current value at the time of constant current electrolysis and the energization time. From these values, the Faraday efficiency was calculated using Equation 1 according to the quantitative ratio of Equation 4.

Table 2 shows the cell configurations of Example 1, Comparative Example 1 and Comparative Example 2, and the Faraday efficiency (at the time of constant current electrolysis with a current density of 1.0 kA / m ² ) at the MCH concentration of the cathode solution. In Example 1, MCH was produced by electrolysis without the ion exchange membrane. Further, in the general PEM type cell of Comparative Example 1, the Faraday efficiency decreased as the MCH concentration of the cathode solution increased, whereas in Example 1, the high Faraday efficiency was maintained even when the MCH concentration increased. Further, Comparative Example 2 is an electrolytic cell in which only the cathode catalyst binding material of Example 1 is changed from SB1 to Nafion ionomer. The Faraday efficiency when MCH was around 1% by mass was higher than that of Comparative Example 1, which is considered to be because the cathode catalyst was changed from Pt / C to Pt-Ru / C. In Comparative Example 2, as in Comparative Example 1, the Faraday efficiency decreased as the MCH concentration increased.

From the results of Examples and Comparative Examples, the concentration of hydrogenated material in the electrolytic solution is increased by binding the catalyst powder with an organic polymer that selectively absorbs the organic compound to be hydrogenated to form a catalyst layer. However, it was found that high hydrogenation efficiency was maintained. It was also found that by using the catalyst layer, the organic compound to be hydrogenated can be electrochemically hydrogenated without using an ion exchange membrane.

According to the present invention, high Faraday efficiency can be realized even when a high-concentration hydrogenated organic compound / hydrogenated organic compound mixed solution is used as a raw material. Therefore, the cost of industrial hydrogen energy utilization can be significantly reduced, and it is possible to contribute to the realization of a hydrogen society.

1: Membrane electrode junction A, 11: Cathode current collector, 12: Diffusion layer, 13: Catalyst layer, 14: Porous membrane, 15: Anocatalyst electrode, 16: Anoelectric current collector 2: Membrane electrode junction B, 21: Cathode current collector, 22: Diffusion layer, 23: Catalyst layer, 14: Ion exchange membrane, 25: Catalyst layer, 26: Diffusion layer, 27: Anoden current collector 3: Membrane electrode junction C, 31: Cathode Collector, 32: Diffusion layer, 33: Catalyst layer, 34: Porous membrane, 35: Anocatalyst electrode, 36: Anostate current collector 50: Cathode catalyst layer, 51: Conductive carrier, 52: Catalyst metal particles, 53 : Organic polymer that selectively absorbs the organic compound to be hydrogenated, 54: Diffusion layer, 55: Electron, 56: Electrolyte, 57: Organic compound molecule to be hydrogenated, 58: Porous membrane, 59: Hydrogen ion 60: Cathode catalyst layer, 61: conductive carrier, 62: catalyst metal particles, 63: ion exchangeable ionomer, 64: diffusion layer, 65: electrons, 66: electrolytic solution, 67: hydrogenated organic compound molecule, 68: ion exchange Membrane, 69: Hydrogen ion

Claims (23)

A catalyst layer for electrochemically hydrogenating an organic compound to be hydrogenated having an unsaturated bond to obtain a hydride.
Contains catalyst metals and organic polymers
The mass of the object to be hydrogenated organic compounds wherein the organic polymer is absorbed per unit mass in the object to be hydrogenated organic compound as A, Ri said A is 0.1 kg / kg or 100 kg / kg der less,
The organic compound to be hydrogenated contains toluene and contains
A catalyst layer in which the organic polymer contains a copolymer having a structure derived from styrene and a structure derived from a conjugated diene-based monomer . The claim that the swelling coefficient C calculated by A / B is 1.5 or more and 100 or less, where B is the mass of the hydrogenated material absorbed by the organic polymer per unit mass in the hydrogenated material. The catalyst layer according to 1. The first or second claim, wherein the water swelling coefficient E calculated by D / A is 0.7 or less, where D is the mass of water absorbed by the organic polymer per unit mass in water. Catalyst layer. The catalyst layer according to any one of claims 1 to 3, which contains 0.1 kg or more and 100 kg or less of the organic compound to be hydrogenated with respect to 1 kg of the organic polymer. The catalyst layer according to claim 4, which contains 0.001 kg or more and 33 kg or less of the hydrogenated material with respect to 1 kg of the organic polymer. The catalyst layer according to claim 4 or 5, which contains 33 kg or less of water with respect to 1 kg of the organic polymer. The catalyst layer according to any one of claims 1 to 6 , wherein the organic polymer has a crosslinked structure. The conjugated diene monomer is a butadiene emissions, the catalyst layer according to any one of claims 1-7. The catalyst layer according to claim 7 or 8 , wherein the gel fraction of the organic polymer measured using toluene as a solvent is 10% by mass or more. The catalyst layer according to any one of claims 1 to 9 , which has porosity. The catalyst metal comprises at least one selected from the group consisting of platinum, ruthenium, rhodium, palladium, iridium, molybdenum, renium, tungsten, titanium, nickel, copper, zinc, silver, tin, gold, lead and lanthanoids. The catalyst layer according to any one of claims 1 to 10 . The catalyst layer according to any one of claims 1 to 11 , wherein the catalyst metal has a structure supported on a conductive carrier. The catalyst layer according to any one of claims 1 to 12 , wherein the catalyst metal and / or the conductive carrier is bound to the organic polymer. The catalyst layer according to any one of claims 1 to 13 , wherein the catalyst metal and the conductive carrier have a network structure in contact with each other, and the network structure exhibits conductivity. The catalyst layer according to any one of claims 1 to 14 , wherein the ratio of the mass of the catalyst metal to the mass of the organic polymer is in the range of 1: 10 to 16: 1. A cathode used in an electrolytic synthesis cell, wherein the cathode has the catalyst layer according to any one of claims 1 to 15 as an active layer. The cathode according to claim 16 , wherein the catalyst layer is provided on a conductive substrate. An electrolytically synthesized cell comprising the cathode according to claim 16 or 17 and an anode for oxidizing water to generate oxygen. Membrane electrode assembly used in electrolytic synthesis cells
The catalyst layer according to any one of claims 1 to 15 .
A base film that is non-conductive and porous and is in contact with the catalyst layer,
Membrane electrode assembly having. An electrolytic synthesis cell comprising the membrane electrode assembly according to claim 19 and an anode that oxidizes water to generate oxygen. An organic compound hydrogenating apparatus comprising the electrolytic synthesis cell according to claim 18 or 20 , which hydrogenates the hydrogenated organic compound. A method for producing a hydrogenated organic compound, which comprises a step of hydrogenating the hydrogenated organic compound using the organic compound hydrogenating apparatus according to claim 21 . A first hydrogenation step for obtaining a hydrogenated product having a purity of 25% to 75% and a hydrogenated product having a purity of 90% to 99% by using at least two or more organic compound hydrogenators according to claim 21. The method for producing a hydrogenated organic compound according to claim 22 , which comprises a second hydrogenation step for obtaining a hydrogenated organic compound.