WO2014192089A1

WO2014192089A1 - Device for producing organic hydride

Info

Publication number: WO2014192089A1
Application number: PCT/JP2013/064833
Authority: WO
Inventors: 貴之平重
Original assignee: 株式会社日立製作所
Priority date: 2013-05-29
Filing date: 2013-05-29
Publication date: 2014-12-04

Abstract

Provided is a device that is for producing an organic hydride, electrochemically generates the organic hydride, and has favorable energy efficiency. The device for electrochemically producing an organic hydride is characterized by, as a catalyst that causes a hydrogenation reaction of a hydrogenation subject, disposing a catalyst that causes a chemical hydrogenation reaction in addition to a catalyst that causes an electrochemical hydrogenation reaction.

Description

Organic hydride production equipment

The present invention relates to an organic hydride production apparatus for electrochemically producing organic hydride.

As the global warming due to carbon dioxide becomes serious, hydrogen is attracting attention as an energy source for the next generation instead of fossil fuel. Hydrogen fuel has a low environmental impact because it is the only substance that is discharged when fuel is consumed and does not emit carbon dioxide. On the other hand, since hydrogen is a gas at normal temperature and pressure, transportation, storage, and supply systems are major issues.

In recent years, organic hydride systems using hydrocarbons such as cyclohexane, methylcyclohexane, and decalin have attracted attention as hydrogen storage methods that are excellent in safety, transportability, and storage capacity. Since these hydrocarbons are liquid at room temperature, they are excellent in transportability. For example, toluene and methylcyclohexane are cyclic hydrocarbons having the same carbon number, but toluene is an unsaturated hydrocarbon in which the bonds between hydrocarbons are double bonds, whereas methylcyclohexane has double bonds. It is a saturated hydrocarbon that does not have. Methylcyclohexane is obtained by hydrogenation reaction of toluene, and toluene is obtained by dehydrogenation reaction of methylcyclohexane. That is, hydrogen can be stored and supplied by utilizing the hydrogenation reaction and dehydrogenation reaction of these hydrocarbons.

As a technique for producing an organic hydride such as methylcyclohexane, Patent Document 1 discloses a technique in which hydrogen is first produced and the hydrogen and toluene are reacted on a catalyst. That is, the process disclosed in Patent Document 1 is a two-stage process in which hydrogen is generated in a water electrolysis apparatus and hydrogen and toluene are reacted in a hydrogen addition reaction apparatus to generate organic hydride.

Therefore, a plurality of devices are required until the production of the organic hydride, resulting in a problem that the devices become complicated. Moreover, since it is gaseous hydrogen from hydrogen production to hydrogen addition reaction, a problem arises regarding storage and transportation. If the hydrogen production apparatus and the hydrogen addition reaction apparatus are constructed adjacent to each other, the above problem can be solved, but there is a problem of construction and operation costs, and the overall energy efficiency is also lowered. Moreover, since the apparatus needs to be enlarged, there is a problem that the installation place is limited.

Patent Documents 2 and 3 disclose techniques for producing an organic hydride in a single stage using a single apparatus. These are for electrochemically producing organic hydrides. For example, in Patent Document 3, a metal catalyst is disposed on both sides of a hydrogen ion permeable electrolyte membrane that selectively transmits hydrogen ions, water or water vapor is supplied to one side, and a hydride is supplied to the other side. Organic hydrides are produced by causing hydrogen addition reaction between hydrogen ions generated by electrolysis of water or water vapor on the anode side and hydrides on the cathode side. The reaction formulas of the anode and cathode when toluene is used as the hydride are as follows.

Anode

_{^{... H 2 O → 2H + +}} 1 / 2O 2 + 2e - (1)
Cathode… C ₇ H ₈ + 6H ⁺ + 6e ⁻ → C ₇ H ₁₄ (2)

JP 2008-44851 JP2003-45449 JP 2012-72477

However, the organic hydride manufacturing methods of Patent Documents 2 and 3 have difficulty in obtaining high energy efficiency. One reason is that not only the hydrogen addition reaction of toluene shown in (2) but also the hydrogen generation reaction shown in (3) below occurs as an electrode reaction at the cathode.

^{^{_{2H + + 2e - → H 2}}} (3)
It is thought that the hydrogenation reaction of toluene shown in (2) proceeds at a three-phase interface where three of toluene / electrolyte / catalyst are simultaneously in contact. However, it is considered that the hydrogen generation reaction indicated by (3) instead of (2) occurs on the catalyst to which toluene is not supplied. Examples of the catalyst to which toluene is not supplied include a catalyst deep in the catalyst layer. Another example is that water on the anode side passes through the electrolyte membrane and reaches the cathode side, and the water covers the catalyst. These catalysts to which toluene is not supplied may be able to be reduced to some extent by optimizing the electrode structure such as the electrode thickness. However, it is impossible to make it completely zero, and the hydrogen generation reaction shown in (3) is an unavoidable problem. In a conventional apparatus for electrochemically producing organic hydride, the generated hydrogen gas is treated as exhaust gas. Therefore, there has been a problem that the energy efficiency is reduced by the amount of power consumed in the hydrogen generation reaction shown in (3).

In order to solve the above-mentioned problems, the present invention provides a chemical hydrogenation reaction in addition to a catalyst that causes an electrochemical hydrogenation reaction as a catalyst for a hydride in an apparatus for electrochemically producing an organic hydride. An organic hydride manufacturing apparatus in which a catalyst is disposed is provided.

According to the present invention, in an apparatus for electrochemically generating organic hydride, a hydrogen gas generated as a secondary can be subjected to a chemical hydrogenation reaction, and an organic hydride manufacturing apparatus with high energy efficiency is provided. Can do.

It is a figure which shows the membrane electrode assembly of this invention. It is a figure which shows one Example of the organic hydride manufacturing apparatus of this invention. It is a figure which shows the conversion rate of one Example of this invention. It is a figure which shows the yield of one Example of this invention. It is a figure which shows the conversion rate of the organic hydride manufacturing apparatus of a comparative example. It is a figure which shows the yield of the organic hydride manufacturing apparatus of a comparative example. It is a figure which shows one Example of the organic hydride manufacturing system of this invention. It is a figure which shows the conversion rate and yield of a comparative example and Examples 1-3. It is a figure which shows one Example of the cathode catalyst layer of this invention.

First, the outline of the present invention will be described. When an organic hydride is produced by an electrochemical reaction, hydrogen gas is generated. Since this hydrogen gas was treated as exhaust gas, there was a problem of poor energy efficiency. The present invention has a configuration in which hydrogen gas generated as a secondary reaction is chemically reacted with an unsaturated hydrocarbon hydride (one to be hydrogenated) such as toluene to cause a hydrogenation reaction. Thereby, there exists an effect which prevents the fall of energy efficiency.

More specifically, the present invention causes the electrochemical hydrogenation reaction shown in (2) above as a catalyst for causing a hydrogenation reaction on a hydride in an apparatus for electrochemically producing an organic hydride. In addition to the catalyst, a catalyst for causing a chemical hydrogenation reaction as shown in (4) is arranged. Here, C ₇ H ₈ is an example, and any substance that causes a hydrogenation reaction may be used. Unsaturated hydrocarbons can be considered as ones that cause hydrogenation reactions.
C ₇ H ₈ + 3H ₂ → C ₇ H ₁₄ (4)
As an arrangement place of the catalyst that causes a chemical hydrogenation reaction to the hydride, it may be arranged in the cathode catalyst layer that is an electrode. Or it arrange | positions in the gas diffusion layer arrange | positioned between an electrode and a separator. Or arrange | positioning to the flow path of a separator is mentioned. Or arrange | positioning in piping outside a cell is mentioned. Or arrange | positioning to said several places is mentioned.

Hereinafter, the details of the embodiments of the present invention will be described in each example.

FIG. 7 shows the organic hydride system of the present invention. The structure and principle of the organic hydride manufacturing apparatus 31 are described in detail in FIG. 1 and FIG. The control device 34 controls each device to which the arrow is directed. Note that the control device 34 may be a plurality of control devices, or may be provided individually in each device to be controlled. The control device 34 controls the water providing device 35 and the hydride providing device 33 so as to provide the organic hydride manufacturing device 31 with water and hydride. In the organic hydride manufacturing apparatus 31, oxygen and water are discharged to an oxygen and water recovery apparatus. The organic hydride manufacturing apparatus 31 discharges the organic hydride and exhaust gas (such as hydride) to the organic hydride recovery apparatus via the pipe 37.

Here, the heater 38 is a heater for heating the pipe 37. As will be described later, a catalyst that causes a chemical hydrogenation reaction is disposed in the pipe 37, and the chemical hydrogenation reaction is more likely to occur at a higher temperature (about 100 ° C. or higher). Therefore, it is good also as a structure provided with the heater 38. FIG. Note that the catalyst that causes the chemical hydrogenation reaction may not be disposed in the pipe 37, and in this case, the heater 38 is unnecessary.

FIG. 1 shows an electrode portion of an organic hydride manufacturing apparatus 31 of the present embodiment. A plan view of the cathode catalyst layer 12 on the front and back of the solid polymer electrolyte membrane 11, MEA to the anode catalyst layer 13 is formed a (M embrane E lectrode A ssembly) from the cathode side in FIG. 1, DE portion in plan view A cross-sectional view and an enlarged view F are shown.

In the MEA, as shown in the D-E sectional view, the cathode and the anode are formed as dense catalyst layers above and below the solid polymer electrolyte membrane 11. In the cathode catalyst layer 12, a catalyst metal 14 is supported on carbon 15 which is a catalyst carrier, as shown in the enlarged view on the right. The catalyst metal 14 is a catalyst that causes an electrochemical hydrogenation reaction represented by the formula (2), and forms a three-phase interface where the solid polymer electrolyte 18 and a hydride that is a reactant contact. The catalyst metal 16 is also a catalyst that causes an electrochemical hydrogenation reaction, but is a catalyst that is not supplied with a hydride because it is deep in the catalyst layer. The present invention is characterized in that, in addition to the catalyst metal 14 causing an electrochemical hydrogenation reaction, a catalyst 17 causing a chemical hydrogenation reaction is also dispersed in the cathode catalyst layer. A specific embodiment in which a catalyst that causes a chemical hydrogenation reaction in the catalyst layer, that is, in the MEA, is described in Example 3.

When toluene is used as the hydride, the following electrochemical reduction reaction of toluene in the catalyst metal 14 C ₇ H ₈ + 6H ⁺ + 6e ⁻ → C ₇ H ₁₄ (2)
Progresses. On the other hand, in the catalytic metal 16 to which toluene is not supplied, the following reaction occurs to generate hydrogen gas.

^{^{_{2H + + 2e - → H 2}}} (3)
Conventionally, since the hydrogen gas generated here is treated as exhaust gas, the energy efficiency has been low.

In the present invention, the hydrogen gas generated here chemically reacts with toluene in the catalyst 17 causing a chemical hydrogenation reaction as follows.

C ₇ H ₈ + 3H ₂ → C ₇ H ₁₄ (4)
Therefore, hydrogen gas is effectively used, and energy efficiency is higher than in the past.

Note that the catalyst 17 that causes a chemical hydrogenation reaction may be a catalyst that causes not only a reaction between hydrogen and a hydride but also a chemical reaction that increases the yield of organic hydride. For example, a chemical reaction may be considered in which a substance that causes a decrease in yield and a hydride undergo a chemical reaction to generate an organic hydride.

Also, as the electrode structure of the present invention, the carbons 15 are bonded together by a solid polymer electrolyte 18. The catalyst metal 14 has a network structure connected to each other via carbon 15 and forms a path for electrons necessary for the reaction (2). Similarly, the solid polymer electrolyte 18 in the catalyst layer also has a connected network structure, and forms a passage for protons necessary for the reaction (2). In the electrode of this embodiment, since the passage of protons is formed by the solid polymer electrolyte 18, a three-phase interface is also formed on the catalyst metal 14 that is not in direct contact with the solid polymer electrolyte membrane 11. This metal catalyst can contribute to the electrode reaction.

As shown in FIG. 9, the catalyst 14 for causing an electrochemical hydrogenation reaction and the catalyst 17 for causing a chemical hydrogenation reaction are in layers, and the catalyst for causing an electrochemical hydrogenation reaction. A catalyst layer that causes a chemical hydrogenation reaction may be formed on the surface of the layer to form a two-layer structure. Even in this case, the catalyst 14 that causes an electrochemical hydrogenation reaction must form a three-phase interface, and therefore is assumed to be in contact with the carbon 15 and the solid polymer electrolyte 18. Since the layer of the chemical hydrogenation reaction catalyst 17 has a large fine hole diameter, the hydride can pass through the chemical hydrogenation reaction catalyst 17 and reach the catalyst 14 causing the electrochemical hydrogenation reaction. The size of the small hole diameter can be changed by devising the voltage when applying the slurry as will be described later. The catalyst that causes a chemical hydrogenation reaction does not need to form a three-phase interface like the electrochemical hydrogenation reaction catalyst 14, but can be in contact with hydrogen generated by a secondary reaction and a non-hydride. Good.

As a method for producing the catalyst layer, for example, there is a method of spraying (coating) a slurry obtained by mixing a catalyst and a solvent onto an electrolyte membrane using a spray coater. To explain in detail, in the case of two layers, first apply a catalyst slurry that causes an electrochemical hydrogenation reaction to form a catalyst layer, and then apply a catalyst slurry that causes a chemical hydrogenation reaction thereon. And two layers. The solvent is removed by drying after coating.

FIG. 2 shows an example of the organic hydride production apparatus of the present invention. The organic hydride production apparatus of this embodiment is a membrane electrode assembly (MEA: M) in which an anode catalyst layer 13 is joined to one surface of a solid polymer electrolyte membrane 11 and a cathode catalyst layer 12 is joined to the other surface. the embrane E lectrode a ssembly), the gas diffusion layer 25 is constituted by sandwiching separators 21 the gas flow path is formed. Also. A gasket 26 for gas sealing is inserted between the pair of separators 21.

The gas diffusion layer 25 uniformly supplies the reactant (gas or liquid) supplied to the flow path of the separator 21 within the surface of the catalyst layer, and further generates a product or exhaust (gas or liquid) generated in the catalyst layer. ) Is absorbed and discharged. As a material, a substrate having air permeability such as carbon paper or carbon cloth is used. The present embodiment may have a configuration in which a catalyst 27 that causes a chemical hydrogenation reaction is disposed in the gas diffusion layer. A detailed example in which a catalyst 27 that causes a chemical hydrogenation reaction is disposed in the gas diffusion layer is described in Example 2.

On the surface of the separator 21 facing the anode catalyst layer 13 and the cathode catalyst layer 12, a groove serving as a reaction gas or liquid channel is formed. Water or water vapor is supplied to the flow channel of the separator 21 on the anode side. Water or water vapor flowing through the flow channel is supplied to the anode catalyst layer via the gas diffusion layer 25. Further, the cathode-side separator 21 may be provided with a catalyst 27 that causes a chemical hydrogenation reaction. A detailed example in which the hydride is disposed in the cathode-side separator 21 will be described in Example 4. The hydride flowing through the flow channel is supplied to the cathode catalyst via the gas diffusion layer 25.

In addition, the organic hydride manufacturing apparatus 31 is applied with a voltage from an external power source. A voltage can be applied to the separator 21. The separator is a conductive material, and wiring is provided from the separator, and an external power source is connected thereto.

The separator is in contact with the catalyst layer, which is an electrode, through a gas diffusion layer (also conductive material), allowing electrons to pass through. The electrons transmitted from the separator are transmitted to the carbon carrier. The carbon carrier may not be carbon as long as it is a conductor that allows electrons to pass in addition to carbon.

The organic hydride production apparatus 31 is also connected to a pipe 28 connected to an external organic hydride recovery apparatus (FIG. 7, 32). A catalyst 27 that causes a chemical hydrogenation reaction may be disposed in the pipe 28. In the present embodiment, the pipe 28 is not included in the organic hydride manufacturing apparatus, and may be configured outside. Further, as described above, the heater 38 may be provided in the pipe as shown in FIG. The catalyst 27 that causes the chemical hydrogenation reaction may not be disposed in the MEA or the like, and the catalyst 27 that causes the chemical hydrogenation reaction may be disposed only in the pipe 28.

Although the above shows an example of a flow path such as a gas diffusion layer, a separator, and a pipe, a catalyst that causes a chemical hydrogenation reaction is disposed in a flow path that discharges a product generated in the cathode catalyst layer. What is necessary is just to have, and it is not limited to a gas diffusion layer, a separator, and piping. Further, a catalyst that causes a chemical hydrogenation reaction may not be disposed in the cathode catalyst layer, but may be disposed only in the flow path.

The heater 29 warms the organic hydride manufacturing apparatus, and may be provided inside or outside the organic hydride manufacturing apparatus. The higher the temperature, the easier the electrochemical reaction and chemical reaction proceed, so the MEA, gas diffusion layer, and separator are heated by the heater 29. In addition, all may be heated and the structure which heats any one of the above-mentioned may be sufficient.

The reaction mechanism will be described with reference to FIG. When water or water vapor is supplied to the anode side via the separator 21 and toluene is supplied as a hydride to the cathode side, when a voltage is applied between the anode and the cathode, electrolysis of water of formula (1) is performed at the anode. A reaction takes place. Protons generated by the electrolysis reaction of the formula (1) move to the cathode 24 through the solid polymer electrolyte membrane 22, and the hydrogen addition reaction of the formula (2) occurs at the cathode to generate methylcyclohexane as an organic hydride.

H ₂ O → 2H ⁺ + 1 / 2O ₂ + 2e ⁻ (1)
C ₇ H ₈ + 6H ⁺ + 6e ⁻ → C ₇ H ₁₄ (2)
On the other hand, hydrogen gas is partially generated at the cathode by the following reaction.

^{^{_{2H + + 2e - → H 2}}} (3)
Conventionally, the generated hydrogen gas is treated as exhaust gas, so that the energy efficiency is low. Therefore, in the present invention, the following reaction is caused by a catalyst that causes a chemical hydrogenation reaction.

As a method for supplying the hydride, a liquid hydride may be supplied as it is, or a vapor hydride using He gas, N ₂ gas or the like as a carrier may be supplied.

The separator 21 has conductivity, and the material is preferably a dense graphite plate, a carbon plate formed by molding a carbon material such as graphite or carbon black with a resin, or a metal material having excellent corrosion resistance such as stainless steel or titanium. It is also desirable to plate the surface of the separator 21 with a noble metal, or to apply a surface treatment by applying a conductive paint having excellent corrosion resistance and heat resistance.

The gasket 26 is insulative, in particular, resistant to hydrogen or hydride, organic hydride, and can be any material that has little permeation and maintains confidentiality. For example, butyl rubber, viton rubber, EPDM rubber, etc. Can be mentioned.

As a condition required for a catalyst that causes an electrochemical hydrogen addition reaction, since the reaction requires movement of electrons, electrical conductivity is required. Moreover, since it contacts with the proton conductive solid polymer electrolyte in the catalyst layer, it must be a stable catalyst even with a strong acid.

On the other hand, as a condition required for a catalyst that causes a chemical hydrogenation reaction, electrical conductivity is not necessary, and non-noble metals are used because they do not contact solid polymer electrolytes when placed outside the catalyst layer. Is possible.

As the catalyst metal used in the present invention, a catalyst material having a hydrogen addition action on a hydride is used, for example, Ni, Pd, Pt, Rh, Ir, Re, Ru, Mo, W, V, Os, Cr, Co Metals such as Fe and alloy catalysts thereof can be used. Among them, as a catalyst metal that causes an electrochemical hydrogen addition reaction, a noble metal that is stable even with a strong acid is desirable because it contacts a proton conductive solid polymer electrolyte in the catalyst layer. On the other hand, a catalyst other than a noble metal can be used as a catalyst metal that causes a chemical hydrogenation reaction. In that case, Ni or the like is particularly desirable in terms of cost.

In addition, the hydrogenation catalyst, either a catalytic metal that causes an electrochemical hydrogenation reaction or a catalytic metal that undergoes an electrochemical hydrogenation reaction, is made finer to reduce the cost and increase the reaction surface area by reducing the catalytic metal. It is preferable to do. For fine particle formation, it is desirable to support a catalyst metal on a support.

As the catalyst carrier that causes the electrochemical hydrogenation reaction, any material may be used as long as it is an electrically conductive material. In particular, carbon is desirable because it can disperse and can easily carry a catalytic metal. Examples of the carbon include furnace black, channel black, acetylene black, amorphous black, carbon nanotube, carbon nanohorn, carbon black, activated carbon, and graphite. These can be used alone or in combination.

The carrier for the catalyst that causes a chemical hydrogenation reaction is not necessarily an electrically conductive material. For example, a metal oxide can be used as a support. As the metal oxide, Al ₂ O ₃ , ZrO ₂ , Nb ₂ O ₅ , SiO ₂ , P ₂ O ₅ —Al ₂ O ₃ or the like can be used.

Further, the method for supporting the catalyst metal on the carrier is not particularly limited, such as a coprecipitation method, a thermal decomposition method, and an electroless plating method.

FIG. 1 shows an example in which the chemical hydrogenation reaction is placed in the catalyst layer, but as described above, in the gas diffusion layer, in the separator channel, in the pipe outside the cell. It can also be placed at other locations. Each location has its advantages. When arranged in the catalyst layer, a merit is that the generated hydrogen gas can be immediately hydrogenated to the hydride, and an increase in pressure due to gas generation can be prevented. However, the catalyst layer is limited to noble metals because of the presence of a strong acid proton-conducting solid polymer electrolyte.

The advantage of dispersing in the gas diffusion layer is that the generated hydrogen gas can be immediately hydrogenated to the hydride as in the case of dispersing in the catalyst layer, and the pressure increase due to gas generation can be prevented. Is mentioned. Further, since it is not in direct contact with the strong acid proton-conducting solid polymer electrolyte, a non-noble metal catalyst can be used, and the cost can be reduced.

As an advantage of installing in the separator flow path, the total amount of surface area in the separator flow path is large, so the amount of catalyst can be increased compared to other installation locations. For this reason, it is considered that the chance of contact between the hydrogen gas and the unreacted hydride increases, and the reaction amount increases accordingly. Also, in the separator flow path, a non-noble metal catalyst can be used because it is not in direct contact with the strong acid proton-conducting solid polymer electrolyte, and the cost can be reduced.

An advantage of installing in piping outside the cell is that the temperature can be set freely independently of the cell temperature. The temperature inside the cell is about 100 ° C. at most, but the temperature can be raised to 100 ° C. or more outside the cell. The higher the temperature, the easier the hydrogen addition reaction proceeds. Here, the reason why the temperature in the cell cannot be increased as compared with the piping is that it cannot be raised so much because of the nature of the solid polymer electrolyte membrane 22. Solid polymer electrolyte membranes exhibit proton conductivity when humidified (wet with water). When the temperature is raised (especially at 100 ° C. or higher), water evaporates and water in the solid polymer electrolyte membrane decreases, which is not preferable because proton conductivity decreases and resistance increases. Since piping does not cause such a problem, it can be set to a high temperature. Further, a non-noble metal catalyst can be used also in the piping, and the cost can be reduced.

The catalyst that causes a chemical hydrogenation reaction must be installed at any one or more of the above installation locations (in the catalyst layer, gas diffusion layer, separator, and piping). Can do. It is desirable to determine in consideration of conditions such as the scale and installation location of the electrolytic hydrogenation reactor.

The MEA of the present invention can be produced by the following method. First, a catalyst that causes an electrochemical hydrogenation reaction, a catalyst that causes a chemical hydrogenation reaction, a solid polymer electrolyte, and a cathode catalyst paste that is mixed well with a solvent that dissolves the solid polymer electrolyte, platinum black, a solid An anode catalyst paste in which a polymer electrolyte and a solvent for dissolving the solid polymer electrolyte are added and mixed well is prepared. Each of these pastes is sprayed onto a release film such as a polyfluoroethylene (PTFE) film by a spray drying method or the like, dried at 80 ° C. to evaporate the solvent, and a cathode and an anode catalyst layer are formed. Next, the MEA of the present invention can be produced by joining the cathode and anode catalyst layers by hot pressing with the solid polymer electrolyte membrane in the middle and peeling the release film (PTFE).

Further, as another example of MEA production of the present invention, a catalyst for causing an electrochemical hydrogen addition reaction, a catalyst for causing a chemical hydrogen addition reaction, a solid polymer electrolyte, and a solvent for dissolving the solid polymer electrolyte are sufficiently added. Spray the mixed cathode catalyst paste and platinum black, solid polymer electrolyte, and anode catalyst paste mixed well by adding a solvent that dissolves the solid polymer electrolyte directly onto the solid polymer electrolyte membrane by spray drying method, etc. Can also be produced.

Examples of the organic polymer constituting the solid polymer electrolyte membrane include perfluorocarbon sulfonic acid, polystyrene, polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, other engineering plastic materials, sulfonic acid groups, phosphones. A proton donor such as an acid group or a carboxyl group doped or chemically bonded and immobilized can be used. It is also desirable to improve the material stability by forming a crosslinked structure or partially fluorinating the material.

For the solid polymer electrolyte contained in the catalyst layer, a polymer material exhibiting proton conductivity is used. For example, sulfonated or alkylenesulfonated typified by perfluorocarbon sulfonic acid resin or polyperfluorostyrene sulfonic acid resin is used. Fluoropolymers and polystyrenes can be mentioned. Other examples include polysulfones, polyether sulfones, polyether ether sulfones, polyether ether ketones, and materials obtained by introducing a proton donor such as a sulfonic acid group into a hydrocarbon polymer.

Unsaturated hydrocarbon is used as the hydride. For example, benzene, toluene, xylene, mesitylene, naphthalene, methylnaphthalene, anthracene, biphenyl, phenanthroline, and alkyl substitution products thereof or a mixture thereof can be used. Hydrogen can be stored by adding hydrogen to the double bond between these carbon atoms.

Also, the following method can be considered as an example of a method for dispersing the catalyst that causes a chemical hydrogenation reaction in the gas diffusion layer. A catalyst that causes a chemical hydrogenation reaction is mixed with a solution of ethanol: water = 1: 1. A gas diffusion layer in which a catalyst for causing a chemical hydrogenation reaction is dispersed can be obtained by immersing the gas diffusion layer therein and drying it at 80 ° C. with hot air.

The following method can be considered as an example of a method for dispersing the catalyst that causes a chemical hydrogenation reaction in the separator channel. A catalyst that causes a chemical hydrogenation reaction is mixed with a solution of ethanol: water = 1: 1. By applying the solution to the separator channel and drying with hot air at 80 ° C., a separator channel in which a catalyst causing a chemical hydrogenation reaction is dispersed can be obtained.

The following method can be considered as an example of a method for dispersing the catalyst that causes a chemical hydrogenation reaction in the pipe. A catalyst that causes a chemical hydrogenation reaction is mixed with a solution of ethanol: water = 1: 1. The solution is applied to the inside of the pipe and dried with hot air at 80 ° C., whereby the inside of the pipe in which the catalyst for causing the chemical hydrogenation reaction is dispersed can be obtained.

Hereinafter, the details of the present invention will be described with reference to the following examples. In the following examples, the present invention is not limited to the following examples with respect to conditions such as substances, weight, and temperature. In each embodiment, the description of the configuration in FIGS. 1, 2, and 7 that is common to the first embodiment is omitted.

MEA was prepared using a catalyst in which 30 wt% of Pt fine particles were dispersed and supported on carbon black as a catalyst for causing an electrochemical hydrogenation reaction at the cathode. An ion exchange membrane was used as the electrolyte membrane. The cathode catalyst layer was formed by directly applying the catalyst slurry to the ion exchange membrane using a spray coater. The cathode catalyst layer was applied to the ion exchange membrane in the following order.

First, the ion exchange membrane was placed on a hot plate of the substrate and fixed by suction. The temperature of the hot plate was 50 ° C. Next, a mask was applied from above, and the cathode catalyst slurry was applied with a spray coater. As the cathode catalyst slurry, the catalyst prepared in Example 2 and water, 5 wt% ion exchange membrane solution, 221 solution (1-propanol: 2-propanol: water = 2: 2: 1 solution) 2: 1.2: 5.4: What was mixed by the weight ratio of 10.6 was used. The application conditions were as follows: liquid pressure 0.01 MPa, swirl pressure 0.15 MPa, atomization pressure 0.15 MPa, gun / substrate distance 60 mm, and substrate temperature 50 ° C. The amount of the cathode catalyst was 0.4 mg Pt · cm ⁻² .

After the cathode catalyst layer was formed on the surface of the ion exchange membrane, an anode catalyst layer was formed on the back surface thereof. The anode catalyst layer was formed by a transfer method. First, an anode catalyst slurry was prepared. As the anode catalyst slurry, a mixture of platinum black, 5 wt% ion exchange membrane solution, and 221 solution in a weight ratio of 1: 1.11: 2.22 was used. It was applied onto a polytetrafluoroethylene sheet with an applicator. The anode catalyst layer coated on the polytetrafluoroethylene sheet was formed on the surface of the ion exchange membrane by thermal transfer using hot pressing. The hot press pressure was 37.2 kgf · cm ⁻² , the hot press temperature was 120 ° C., and the hot press time was 2 minutes. The anode catalyst amount was 4.8 mg Pt · cm ⁻² .

Then, a catalyst that causes a chemical hydrogenation reaction was dispersed in the gas diffusion layer. Carbon cloth was used as the gas diffusion layer. Alumina-supported nickel was used as a catalyst for causing a chemical hydrogenation reaction.

Alumina Al ₂ O ₃ was placed in an electric furnace and baked at 650 ° C. for 3 hours. Then, nickel nitrate hexahydrate Ni (NO ₃ ) ₂ · 6H ₂ O was dissolved in pure water, and the calcined alumina was immersed therein and impregnated at room temperature for 1 hour. Thereafter, moisture was removed by vacuum drying at 80 ° C. Thereafter, the catalyst was activated by calcination in an electric furnace at 650 ° C. in a hydrogen atmosphere. The alumina-supported nickel produced as described above was dispersed in a solution of ethanol: pure water = 1: 1 and impregnated with carbon cloth. The solution was removed by vacuum drying at 80 ° C. to obtain a carbon cloth having alumina-supported nickel dispersed therein.

The fabricated MEA and the carbon cloth in which the alumina-carrying nickel was dispersed were incorporated into the organic hydride manufacturing apparatus shown in FIG. Here, no treatment was performed in the flow path of the separator, and the separator was used as it was. Toluene was used as the hydride. A voltage was applied between the anode and cathode while toluene was supplied to the cathode at 10 cc / min and pure water was supplied to the anode at 5 cc / min. The cell temperature was 80 ° C. As a result, when a load of 1.6 V or higher was applied, current flowed and the reaction proceeded. The voltage was applied to 2.2V, but the current increased as the voltage was increased, and the reaction proceeded. When the cathode exhaust gas was analyzed by gas chromatography, toluene and methylcyclohexane were detected. Thereby, it was confirmed that methylcyclohexane was produced by the hydrogenation reaction of toluene. FIG. 3 shows the conversion rate from toluene to methylcyclohexane calculated from the peak intensity of gas chromatography. The higher the voltage, the better the conversion, and the maximum value under this condition was 70% when 2.2V was applied. FIG. 4 shows the yield of produced methylcyclohexane relative to the total amount of electricity added. The higher the voltage, the better the yield, and the maximum value under this condition was 88% with a 2.2V load.

<Comparative Example 1>
An MEA was produced by the same production method and conditions as in Example 1. Carbon cloth was used for the gas diffusion layer, but unlike Example 2, it was used as it was without being treated.

The fabricated MEA and gas diffusion layer were incorporated into the organic hydride production apparatus of FIG. 2 and a hydrogen addition reaction test to toluene was performed under the same conditions as in Example 2. FIG. 5 shows the conversion of toluene to methylcyclohexane. The highest value under this condition was 60.3% with a load of 2.2V. Compared to Example 1, the conversion rate was low. The reason is considered as follows. In the catalyst to which toluene is not supplied, it is considered that hydrogen generation occurs not by the hydrogenation reaction of toluene but by the reaction of the following formula (3).

^{^{_{2H + + 2e - → H 2}}} (3)
In Example 2, the generated hydrogen gas chemically reacted with toluene to produce methylcyclohexane. In Comparative Example 1, it is considered that the generated hydrogen gas was discharged as exhaust gas without chemically reacting. Actually, when the gas flow rate at the outlet was measured using a gas flow meter, the gas flow rate increased in Comparative Example 1 compared to Example 2. Therefore, it is thought that the conversion rate was low.

FIG. 6 shows the yield of produced methylcyclohexane relative to the total amount of electricity added. The higher the voltage, the better the yield, but it was lower than in Example 1 and was 78.4% at 2.2 V at the maximum. Since the generated hydrogen gas was discharged without chemically reacting, the energy efficiency for producing methylcyclohexane was lowered accordingly.

As a catalyst for causing an electrochemical hydrogenation reaction at the cathode, a catalyst in which 30 wt% of Pt fine particles were dispersedly supported on carbon black was used. In addition, platinum supported on alumina was mixed as a catalyst for causing a chemical hydrogenation reaction at the cathode.

The method for synthesizing the alumina-supported platinum was as follows. Alumina Al ₂ O ₃ was placed in an electric furnace and baked at 650 ° C. for 3 hours. The calcined alumina was immersed in a platinum colloid solution and impregnated at room temperature for 1 hour. Thereafter, the solution was removed by vacuum drying at 80 ° C. Thereafter, the catalyst was activated by calcination in an electric furnace at 650 ° C. in a hydrogen atmosphere.

An MEA including a catalyst that causes the electrochemical hydrogenation reaction and a catalyst that causes the chemical hydrogenation reaction was prepared. As a cathode catalyst slurry, a catalyst that causes an electrochemical hydrogen addition reaction and a catalyst that causes a chemical hydrogen addition reaction, water, 5 wt% ion exchange membrane solution, 221 solution (1-propanol: 2-propanol: water = 2: 2: 1) was mixed at a weight ratio of 1: 1: 1.2: 5.4: 10.6. Other MEA production conditions and methods were the same as in Example 1.

The fabricated MEA was incorporated into the organic hydride production apparatus shown in FIG. 2, and a hydrogen addition reaction test on toluene was performed under the same conditions as in Example 1. Here, the gas diffusion layer and the separator flow path were used without any treatment. The result is shown in FIG. FIG. 8 shows the conversion rate and yield when 2.2 V is applied between the anode and the cathode. Compared to Comparative Example 1, both the conversion rate and the yield increased, and the effect of introducing a catalyst that causes a chemical hydrogenation reaction into the cathode catalyst layer was recognized.

A catalyst that causes a chemical hydrogenation reaction was placed in the separator channel. Alumina-supported nickel was used as a catalyst for causing a chemical hydrogenation reaction.

Alumina Al ₂ O ₃ was placed in an electric furnace and baked at 650 ° C. for 3 hours. Then, nickel nitrate hexahydrate Ni (NO ₃ ) ₂ · 6H ₂ O was dissolved in pure water, and the calcined alumina was immersed therein and impregnated at room temperature for 1 hour. Thereafter, moisture was removed by vacuum drying at 80 ° C. Thereafter, the catalyst was activated by calcination in an electric furnace at 650 ° C. in a hydrogen atmosphere. This alumina-supported nickel was dispersed in a solution of ethanol: pure water = 1: 1 and applied to the separator flow path. The solution was removed by vacuum drying at 80 ° C.

MEA was produced by the same method and conditions as in Example 1. This MEA was incorporated into the organic hydride production apparatus shown in FIG. 2 using a separator in which a catalyst for causing a chemical hydrogenation reaction was placed in the flow path, and a hydrogen addition reaction test for toluene was performed under the same conditions as in Example 2. I did it. Here, the gas diffusion layer was used without any treatment. The result is shown in FIG. Compared with Comparative Example 1, both the conversion rate and the yield increased, and the effect of arranging a catalyst for causing a chemical hydrogenation reaction in the separator channel was recognized.

11 ----- Solid polymer electrolyte membrane, 12 ----- Cathode catalyst layer, 13 ----- Anode catalyst layer, 14 ----- Catalyst causing electrochemical hydrogenation reaction, 15- ---- Support, 16 ----- Catalyst metal without three-phase interface, 17 ----- Catalyst metal causing chemical hydrogenation reaction, 18 ----- Solid polymer electrolyte
21 ----- Separator, 22 ----- Solid polymer electrolyte membrane, 23 ----- Anode catalyst layer, 24 ----- Cathode catalyst layer, 25 ----- Gas diffusion layer, 26 ----- Gasket, 27 ----- Catalyst causing chemical hydrogenation reaction,

Claims

A cathode catalyst layer for producing organic hydride from the hydride,
A first catalyst disposed within the cathode catalyst layer and causing an electrochemical hydrogenation reaction to the hydride;
An anode catalyst layer that generates protons, oxygen, and electrons from water;
A solid polymer electrolyte membrane provided between the cathode catalyst layer and the anode catalyst layer and capable of transferring the protons from the anode catalyst layer to the cathode catalyst layer;
An organic hydride manufacturing apparatus, comprising: a second catalyst that causes a chemical hydrogen addition reaction to the hydrogen gas generated in the cathode catalyst layer and the hydride.
The organic hydride manufacturing apparatus according to claim 1, wherein the second catalyst is disposed in the cathode catalyst layer.
The organic hydride manufacturing apparatus according to claim 2, wherein the second catalyst is a noble metal.
A supply unit for supplying the hydride to the cathode catalyst layer;
The cathode catalyst layer includes a carrier of the first catalyst that is a path for electrons and an electrolyte that is a path for protons;
The first catalyst is disposed on a flow path to which the hydride is supplied and in a position in contact with the support of the first catalyst and the electrolyte,
4. The second catalyst is disposed on a flow path supplied by the hydride, and is disposed at a position that does not contact at least either the carrier of the first catalyst or the electrolyte. The organic hydride manufacturing apparatus described in 1.
The catalyst for causing the electrochemical hydrogenation reaction in the cathode catalyst layer and the catalyst for causing the chemical hydrogenation reaction are respectively in a layer state,
3. The organic hydride manufacturing apparatus according to claim 2, wherein the second catalyst is disposed at a position distant from the first catalyst with respect to the solid polymer electrolyte membrane.
A cathode catalyst layer for producing organic hydride from the hydride,
A first catalyst disposed within the cathode catalyst layer and causing an electrochemical hydrogenation reaction to the hydride;
An anode catalyst layer that generates protons, oxygen, and electrons from water;
A solid polymer electrolyte membrane provided between the cathode catalyst layer and the anode catalyst layer and capable of transferring the protons from the anode catalyst layer to the cathode catalyst layer;
A flow path for discharging the product produced in the cathode catalyst layer;
An organic hydride manufacturing apparatus comprising a second catalyst that causes a chemical reaction in the flow path.
The organic hydride manufacturing apparatus according to claim 6, wherein the chemical reaction is a chemical reaction that causes a chemical hydrogenation reaction to the hydride.
The flow path is
A gas diffusion layer disposed on a surface of each of the cathode catalyst layer and the anode catalyst layer and discharging a product from the cathode catalyst layer and the anode catalyst layer;
The organic hydride according to claim 6, wherein the organic hydride is a separator that is disposed on a surface of each of the gas diffusion layers, has a channel groove formed on a surface in contact with the gas diffusion layer, and discharges the product to the outside. Manufacturing equipment.
9. The organic hydride manufacturing apparatus according to claim 8, wherein the catalyst that causes the chemical hydrogenation reaction is disposed at least in either the gas diffusion layer or the flow channel of the separator.
The flow path includes a pipe for discharging the organic hydride to the outside,
The organic hydride manufacturing apparatus according to claim 6, wherein a catalyst that causes the chemical hydrogenation reaction is disposed in the pipe.
Furthermore, a pipe connected to the separator and discharging the organic hydride to the outside is provided.
The organic hydride manufacturing apparatus according to claim 6, wherein a catalyst that causes the chemical hydrogenation reaction is disposed in the pipe.
The catalyst that causes the chemical hydrogenation reaction is made of Ni, Pd, Pt, Rh, Ir, Re, Ru, Mo, W, V, Os, Cr, Co, Fe, or an alloy containing at least a part thereof. The organic hydride manufacturing apparatus according to claim 6.
The organic hydride manufacturing apparatus according to claim 10, wherein the pipe is provided with a heater for raising a temperature.
The organic hydride manufacturing apparatus according to claim 8, wherein the second catalyst is disposed on the cathode catalyst layer.
The organic hydride manufacturing apparatus according to claim 14, further comprising a heater that increases a temperature of at least one of the cathode catalyst layer, the gas diffusion layer, or the separator.