JP7072161B2 - Sith-Alkene manufacturing equipment and manufacturing method - Google Patents

Description

The present invention relates to a cis-alkene manufacturing apparatus and manufacturing method.

Conventionally, some cis-alkenes, in other words, cis-olefins, are known to be useful chemical substances used for fragrances and the like. For example, Patent Document 1 discloses a chemical process for producing a cis-alkene by reducing an alkyne with formic acid.

Japanese Unexamined Patent Publication No. 5-255128

As a result of diligent studies on the above-mentioned production of cis-alkene, the present inventors have come up with a new manufacturing technique for cis-alkene.

The present invention has been made in view of these circumstances, and one of the objects thereof is to provide a novel manufacturing technique for cis-alkene.

One aspect of the invention is a cis-alkene manufacturing device. The manufacturing apparatus includes a solid polymer electrolysis unit and a supply unit for supplying an alkyne to the solid polymer electrolysis unit. The polymer electrolyte electrolysis unit electrolyzes and reduces alkynes to produce cis-alkenes.

Another aspect of the present invention is a method for producing a cis-alkene. The production method comprises electrolyzing and reducing an alkyne using a solid polymer electrolyte unit to produce a cis-alkene.

According to the present invention, it is possible to provide a novel manufacturing technique for cis-alkene.

It is a schematic diagram which shows the schematic structure of the manufacturing apparatus of the cis-alkene which concerns on embodiment. It is sectional drawing which shows the schematic structure of the solid polymer type electrolysis unit.

Hereinafter, the present invention will be described with reference to the drawings based on the preferred embodiments. The embodiments are not limited to the invention, but are exemplary, and all the features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes shown in the drawings shall be designated by the same reference numerals, and duplicate description thereof will be omitted as appropriate. In addition, the scale and shape of each part shown in each figure are set for convenience in order to facilitate explanation, and are not limitedly interpreted unless otherwise specified. In addition, terms such as "first" and "second" used in the present specification or claims do not represent any order or importance unless otherwise specified, and may include one structure and another. It is for distinguishing.

FIG. 1 is a schematic diagram showing a schematic configuration of a Sith-alkene manufacturing apparatus according to an embodiment. Note that FIG. 1 shows a simplified structure of the polymer electrolyte electrolysis unit. The cis-alkene manufacturing apparatus 10 is an apparatus for electrolytically reducing an alkyne to produce a cis-type alkene, and includes a solid polymer electrolyte unit 100, a power control unit 20, a substrate storage tank 30, a hydrogen storage tank 40, and a control. A unit 60 is provided. Hereinafter, the Sith-alkene manufacturing apparatus 10 is simply referred to as “manufacturing apparatus 10”.

The power control unit 20 is, for example, a DC / DC converter that converts the output voltage of a power source into a predetermined voltage. The positive electrode output terminal of the power control unit 20 is connected to the anode 130 of the solid polymer electrolyte electrolysis unit 100. The negative electrode output terminal of the power control unit 20 is connected to the cathode (negative electrode) 120 of the solid polymer electrolyte electrolysis unit 100. As a result, a predetermined voltage is applied between the anode 130 and the cathode 120 of the solid polymer electrolyte unit 100.

The power control unit 20 may be provided with reference electrodes for the purpose of detecting positive and negative potentials. In this case, the reference electrode input terminal is connected to the reference electrode 112 provided on the solid polymer electrolyte membrane 110. The reference electrode 112 is provided in a region of the solid polymer electrolyte membrane 110 separated from the cathode 120 and the anode 130 so as to be in contact with the solid polymer electrolyte membrane 110. The reference electrode 112 is electrically isolated from the cathode 120 and the anode 130. The reference electrode 112 is held at the reference electrode potential. The reference electrode potential in the present application means a potential with respect to a reversible hydrogen electrode (RHE) (reference electrode potential = 0V). The reference electrode potential may be a potential with respect to the Ag / AgCl electrode (reference electrode potential = 0.199V). The reference electrode 112 is preferably installed on the surface of the solid polymer electrolyte membrane 110 on the cathode 120 side.

The current flowing between the cathode 120 and the anode 130 is detected by the current detection unit 113. The current detection unit 113 is composed of, for example, a conventionally known ammeter. The current value detected by the current detection unit 113 is input to the control unit 60 and used for the control of the power control unit 20 by the control unit 60. The potential difference between the reference electrode 112 and the cathode 120 is detected by the voltage detection unit 114. The voltage detection unit 114 is composed of, for example, a conventionally known voltmeter. The value of the potential difference detected by the voltage detection unit 114 is input to the control unit 60 and used for the control of the power control unit 20 by the control unit 60.

The control unit 60 adjusts the potential of the cathode 120 to a predetermined potential. The control unit 60 is realized by an element or a circuit such as a CPU and a memory of a computer as a hardware configuration, and is realized by a computer program or the like as a software configuration. This is of course understood by those skilled in the art. The control unit 60 controls the outputs of the positive electrode output terminal and the negative electrode output terminal of the power control unit 20 so that the potential of the cathode 120 becomes a predetermined potential.

Alkyne as a substrate is stored in the substrate storage tank 30. The alkyne used in this embodiment is not particularly limited, but is represented by, for example, the following formula (1).
R ¹ -C≡C-R ² (1)
[In the formula (1), R ¹ and R ² independently represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, a hydroxyl group, a carboxyl group, an amino group, a nitro group or a halogen atom. Alkyl groups and aryl groups may have functional groups. ]
One type of alkyne as a substrate may be used alone, or a plurality of types may be used in combination.

When the substrate cannot be subjected to the electrolytic reaction as it is, such as when the substrate is solid at room temperature or when the viscosity is high, the substrate may be diluted with a solvent. The solvent is not particularly limited. However, if the solvent adheres to the electrode or is reduced by the electrolytic reaction, the electrolytic reaction of the substrate can be inhibited. Therefore, the solvent is preferably one that can deliver the substrate to the reaction site without inhibiting the electrolytic reaction of the substrate. For example, a suitable solvent includes a solvent having a low polarity. By suppressing the polarity of the solvent, it is possible to prevent the solvent from adhering to the electrode. Therefore, it is possible to prevent the substrate from being excessively adsorbed on the electrode catalyst via the solvent, and thus to prevent the reduction reaction from proceeding too much. As a result, the yield of the target cis-alkene can be increased.

Specific examples of the preferable solvent include methylcyclohexane, toluene, dichlorobenzene and the like. Among these, methylcyclohexane and toluene are more preferable, and methylcyclohexane is most preferable. If the substrate is liquid at room temperature and the viscosity is low enough to be subjected to an electrolytic reaction, the solvent can be omitted.

The alkyne stored in the substrate storage tank 30 is supplied to the cathode 120 of the solid polymer electrolyte unit 100 by the first supply device 32. The substrate storage tank 30 and the first supply device 32 constitute a supply unit 34 that supplies an alkyne to the solid polymer electrolyte unit 100. As the first supply device 32, for example, various pumps such as a gear pump or a cylinder pump, a natural flow type device, or the like can be used.

A circulation path 36 is provided between the substrate storage tank 30 and the cathode 120. The circulation path 36 connects the outbound portion 36a connecting the substrate storage tank 30 and the cathode 120 on the upstream side of the cathode 120 in the flow of the substrate, and the cathode 120 and the substrate storage tank 30 on the downstream side of the cathode 120 in the flow of the substrate. Including the return path portion 36b. A first supply device 32 is provided in the middle of the outward path portion 36a.

The supply unit 34 supplies the alkyne to the cathode 120 via the outward route unit 36a. The reduced product of the alkyne reduced at the cathode 120 and the unreacted alkyne are returned to the substrate storage tank 30 via the return path portion 36b. Although gas is not generated in the main reaction proceeding at the cathode 120, if gas such as hydrogen is by-produced, a gas-liquid separation means may be provided in the middle of the return path portion 36b. Further, the return path portion 36b may not be provided.

For example, humidified hydrogen gas is stored in the hydrogen storage tank 40. Hereinafter, the humidified hydrogen gas is simply referred to as "hydrogen gas". The dew point temperature of the hydrogen gas is, for example, room temperature to 100 ° C, more preferably 50 to 100 ° C. The hydrogen gas stored in the hydrogen storage tank 40 is supplied to the anode 130 of the solid polymer electrolyte electrolysis unit 100 by the second supply device 42. As the second supply device 42, for example, various gas flow controllers, natural flow type devices, or the like can be used.

A circulation path 44 is provided between the hydrogen storage tank 40 and the anode 130. The circulation path 44 includes an outward path portion 44a connecting the hydrogen storage tank 40 and the anode 130 on the upstream side of the anode 130 in the flow of hydrogen gas, and the anode 130 and the hydrogen storage tank 40 on the downstream side of the anode 130 in the flow of hydrogen gas. Including the return path portion 44b connecting the two. A second supply device 42 is provided in the middle of the outward path portion 44a.

Hydrogen gas is supplied to the anode 130 via the outward path portion 44a. The unreacted hydrogen gas at the anode 130 is returned to the hydrogen storage tank 40 via the return path portion 44b. Further, the return path portion 44b may not be provided.

FIG. 2 is a cross-sectional view showing a schematic configuration of the solid polymer electrolyte unit 100. The solid polymer electrolytic cell 100 of the present embodiment is a solid polymer electrolytic cell having an anode chamber on one side and a cathode chamber on the other side of the film-shaped electrolyte membrane. More specifically, the solid polymer electrolyte unit 100 includes a membrane electrode assembly 102 and a pair of separators 150a and 150b that sandwich the membrane electrode assembly 102. The membrane electrode assembly 102 has a solid polymer electrolyte membrane 110, a cathode 120, and an anode 130.

The solid polymer electrolyte membrane 110 is provided between the anode 130 and the cathode 120. The solid polymer electrolyte membrane 110 is formed of a material having proton conductivity (ionomer). The solid polyelectrolyte membrane 110 selectively conducts protons while suppressing the mixing and diffusion of substances between the cathode 120 and the anode 130. The thickness of the solid polymer electrolyte membrane 110 is, for example, 5 to 300 μm. By setting the thickness of the solid polymer electrolyte membrane 110 to 5 μm or more, the barrier property of the solid polymer electrolyte membrane 110 can be ensured, and the occurrence of cross leaks such as alkynes can be more reliably suppressed. Further, by setting the thickness of the solid polymer electrolyte membrane 110 to 300 μm or less, it is possible to suppress the ion transfer resistance from becoming excessive.

The solid polymer electrolyte membrane 110 preferably contains perfluorosulfonic acid as a material having proton conductivity. For example, the solid polymer electrolyte membrane 110 is composed of a polymer of perfluorosulfonic acid, and examples of the polymer include Nafion (registered trademark) and Flemion (registered trademark). The solid polymer electrolyte membrane 110 may be mixed with a reinforcing material such as porous PTFE (polytetrafluoroethylene). By introducing a reinforcing material, the dimensional stability of the solid polymer electrolyte membrane 110 can be improved. Thereby, the durability of the solid polymer electrolyte membrane 110 can be improved. In addition, crossover of alkynes and the like can be suppressed.

The cathode 120 is an electrode for reducing the alkyne to produce a cis-alkene and is arranged on one side of the solid polymer electrolyte membrane 110. In the present embodiment, the cathode 120 is provided so as to be in contact with one main surface of the solid polymer electrolyte membrane 110. The cathode 120 has a structure in which the cathode catalyst layer 122 and the diffusion layer 124 are laminated. The cathode catalyst layer 122 is arranged closer to the solid polymer electrolyte membrane 110 than the diffusion layer 124.

The cathode catalyst layer 122 is in contact with one main surface of the solid polymer electrolyte membrane 110. The cathode catalyst layer 122 contains a catalyst metal for hydrogenating an alkyne with protons. Preferably, the cathode catalyst layer 122 contains at least one catalyst metal selected from the group consisting of Pd, Ir, Ag and Au. More preferably, the cathode catalyst layer 122 contains Pd. When the cathode catalyst layer 122 contains these catalyst metals, cis-alkene can be produced with high selectivity.

The catalyst metal is supported by a catalyst carrier composed of an electron conductive material. By supporting the catalyst metal on the catalyst carrier, the surface area of the cathode catalyst layer 122 can be expanded. In addition, aggregation of the catalyst metal can be suppressed. The electron conductivity of the electron conductive material used for the catalyst carrier is preferably 1.0 × 10 ⁻² S / cm or more. By setting the electron conductivity of the electron conductive material to 1.0 × 10 ⁻² S / cm or more, it is possible to more reliably impart electron conductivity to the cathode catalyst layer 122.

Examples of the catalyst carrier include an electron conductive material containing any one of porous carbon, porous metal, and porous metal oxide as a main component. Examples of the porous carbon include carbon blacks such as Ketjen Black (registered trademark), acetylene black, furnace black, and Vulcan (registered trademark). Examples of the porous metal include Pt black, Pd black, and Pt metal precipitated in a fractal shape. Examples of the porous metal oxide include oxides of Ti, Zr, Nb, Mo, Hf, Ta, and W. Further, the catalyst carrier includes porous metal compounds such as metal nitrides such as Ti, Zr, Nb, Mo, Hf, Ta, and W, carbides, oxynitrides, carbonitrides, and partially oxidized carbonitrides. Can also be used.

The catalyst carrier carrying the catalyst metal is coated with an ionomer. This makes it possible to improve the ionic conductivity of the cathode 120. Examples of the ionomer include perfluorosulfonic acid polymers such as Nafion (registered trademark) and Flemion (registered trademark). The ionomer contained in the cathode catalyst layer 122 is preferably partially covered with the catalyst metal. According to this, the three elements (alkyne, proton, electron) necessary for the electrochemical reaction in the cathode catalyst layer 122 can be efficiently supplied to the reaction field.

The thickness of the cathode catalyst layer 122 is, for example, 1 to 100 μm. By setting the thickness of the cathode catalyst layer 122 within the above range, it is possible to suppress an increase in proton transfer resistance and maintain the diffusivity of alkyne.

The cathode catalyst layer 122 is prepared by mixing, for example, a catalyst component powder, a solvent such as water, and an ionomer to prepare a catalyst ink, applying the obtained catalyst ink to the diffusion layer 124, and hot-pressing after drying. Can be made. It is preferable to perform hot pressing after applying the catalyst ink and drying the catalyst ink in a plurality of times. This makes it possible to obtain a more homogeneous cathode catalyst layer 122. Further, the cathode catalyst layer 122 may be formed on the solid polymer electrolyte membrane 110.

The diffusion layer 124 has a function of uniformly diffusing the alkyne supplied from the separator 150a, which will be described later, into the cathode catalyst layer 122. The material constituting the diffusion layer 124 preferably has a high affinity for alkynes. Examples of the material constituting the diffusion layer 124 include carbon woven fabric (carbon cloth), carbon non-woven fabric, and carbon paper. The carbon cloth is made by forming a bundle of hundreds of thin carbon fibers having a diameter of several μm and using this bundle as a woven fabric. Further, carbon paper is obtained by using carbon raw material fiber as a precursor of a thin film by a papermaking method and sintering it. The thickness of the diffusion layer 124 is preferably 50 to 1000 μm.

The cathode 120 may have a dense layer (not shown) between the cathode catalyst layer 122 and the diffusion layer 124. The dense layer has a function of promoting the diffusion of alkyne in the plane direction of the cathode catalyst layer 122. In particular, by providing the dense layer, the alkyne can be diffused directly under the region of the diffusion layer 124 that is in direct contact with the separator 150a.

The separator 150a is laminated on the main surface of the cathode 120 opposite to the solid polymer electrolyte membrane 110. The separator 150a has corrosion resistance to, for example, a carbon resin, Cr-Ni-Fe-based, Cr-Ni-Mo-Fe-based, Cr-Mo-Nb-Ni-based, Cr-Mo-Fe-W-Ni-based, or Ti-based. It can be formed of an alloy. A single or a plurality of groove-shaped flow paths 152a are provided on the surface of the separator 150a on the diffusion layer 124 side. The outward path portion 36a and the return path portion 36b are connected to the flow path 152a. A cathode chamber is defined by the separator 150a, the solid polymer electrolyte membrane 110, and the frame-shaped spacer 126 arranged between them, and the cathode catalyst layer 122 and the diffusion layer 124 are housed in the cathode chamber.

Alkyne flows into the flow path 152a of the cathode chamber via the outward path portion 36a. The alkyne penetrates into the diffusion layer 124 from the flow path 152a. The product of the electrolytic reduction reaction in the cathode catalyst layer 122 and the unreacted alkyne flow out from the cathode chamber via the return path portion 36b and are returned to the substrate storage tank 30. The form of the flow path 152a is not particularly limited, but for example, a linear flow path, a serpentine flow path, or the like may be adopted. Alternatively, the separator 150a may have a porous body layer, and the flow path 152a may be formed by the voids in the porous body layer.

The anode 130 is an electrode for generating protons from hydrogen gas, and is arranged on one side of the solid polymer electrolyte membrane 110, that is, on the side opposite to the side on which the cathode 120 is arranged. The anode 130 has a structure in which the anode catalyst layer 132 and the diffusion layer 134 are laminated. The anode catalyst layer 132 is arranged closer to the solid polymer electrolyte membrane 110 than the diffusion layer 134.

The anode catalyst layer 132 is in contact with the other main surface of the solid polymer electrolyte membrane 110. The anode catalyst layer 132 contains a catalyst metal for producing protons from hydrogen gas. For example, the anode catalyst layer 132 contains at least one catalyst metal selected from the group consisting of Ru, Rh, Pd, Ir, Pt. The catalyst metal may be dispersed and supported or coated on a metal substrate having electron conductivity. Such a metal base material is composed of a metal such as Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ta, W, or an alloy containing these as a main component. Examples thereof include metal fibers (fiber diameter: for example, 10 to 30 μm), meshes (mesh diameter: for example, 500 to 1000 μm), sintered bodies of porous metal bodies, foam molded bodies (foams), expanded metals, and the like. The thickness of the anode catalyst layer 132 is, for example, 0.1 to 10 μm.

The diffusion layer 134 has a function of uniformly diffusing the hydrogen gas supplied from the separator 150b, which will be described later, into the anode catalyst layer 132. Examples of the material constituting the diffusion layer 134 include a carbon woven fabric (carbon cloth), a carbon non-woven fabric, and carbon paper. The thickness of the diffusion layer 134 is preferably 50 to 1000 μm.

The separator 150b is laminated on the main surface of the anode 130 opposite to the solid polymer electrolyte membrane 110. The separator 150b can be made of the same material as the separator 150a. A single or a plurality of groove-shaped flow paths 152b are provided on the surface of the separator 150b on the diffusion layer 134 side. The outward path portion 44a and the return path portion 44b are connected to the flow path 152b. The anode chamber is defined by the separator 150b, the solid polymer electrolyte membrane 110, and the frame-shaped spacer 136 arranged between them, and the anode catalyst layer 132 and the diffusion layer 134 are housed in the anode chamber.

Hydrogen gas flows into the flow path 152b of the anode chamber via the outward path portion 44a. Hydrogen gas permeates into the diffusion layer 134 from the flow path 152b. The unreacted hydrogen gas flows out from the anode chamber via the return path portion 44b and is returned to the hydrogen storage tank 40. The form of the flow path 152b is the same as that of the flow path 152a. In addition, instead of hydrogen gas, ion-exchanged water, pure water, or an aqueous solution obtained by adding an acid such as sulfuric acid, phosphoric acid, nitric acid, or hydrochloric acid to the anode 130 (hereinafter, as appropriate, these are collectively referred to as "anode solution". ") May be supplied. In this case, the anode catalyst layer 132 oxidizes the water in the anode liquid to generate protons. By supplying the anode liquid instead of the hydrogen gas, the manufacturing apparatus 10 can be simplified.

The solid polymer electrolyte unit 100 electrolyzes and reduces alkynes to produce cis-alkene. The reaction in the polymer electrolyte electrolysis unit 100 when diphenylacetylene is used as the alkyne is as follows.
<Electrode reaction at anode 130>
H ₂ → 2H ⁺ + 2e- ^: E ₀ = 0V
<Electrode reaction at cathode 120>
Diphenylacetylene + 2H ⁺ + ^2e- → 1,2-Diphenylacetylene: E ₀ = + 0.05V
<All reactions>
Diphenylacetylene + H ₂ → 1,2-diphenylethane

That is, the electrode reaction at the anode 130 and the electrode reaction at the cathode 120 proceed in parallel. Then, the protons generated at the anode 130 are supplied to the cathode 120 via the solid polymer electrolyte membrane 110. The protons supplied to the cathode 120 are used for the reduction of alkynes at the cathode 120.

In the electrode reaction at the cathode 120, the reduction of diphenylacetylene can produce cis and trans forms of 1,2-diphenylethene. Further, 1,2-diphenylethane can be further reduced to produce 1,2-diphenylethane. Furthermore, 1,2-diphenylethane can be further reduced to produce 1,2-dicyclohexylethane.

On the other hand, as a more preferable embodiment, the control unit 60 adjusts the potential of the cathode 120 to a range of −0.23 V or more and 0 V or less with respect to the theoretical reduction potential of alkyne. The "theoretical reduction potential" means a theoretical value (E ₀ ) of the redox potential (vs. RHE) of alkyne. Further, the above numerical values are values excluding the amount of IR loss. That is, the control unit 60 matches the potential of the cathode 120 with the theoretical reduction potential of the substrate, or shifts it to the minus side within a range of −0.23 V. By adjusting the potential of the cathode 120 to the above range, a cis form of 1,2-diphenylethene can be produced with high selectivity.

[Manufacturing method of Sith-Alkene]
The method for producing a cis-alkene according to the present embodiment includes electrolyzing and reducing an alkyne using a solid polymer electrolyte unit 100 to produce a cis-alkene. More specifically, hydrogen gas is supplied to the anode catalyst layer 132 of the anode 130. Alkyne is also supplied to the cathode catalyst layer 122 of the cathode 120. Then, a predetermined voltage is applied between the anode 130 and the cathode 120 of the solid polymer electrolyte electrolysis unit 100 by the power control unit 20.

As a result, protons are generated in the anode catalyst layer 132. The generated protons pass through the solid polymer electrolyte membrane 110 and move to the cathode 120 side. In the cathode catalyst layer 122, alkynes are hydrogenated by protons that have passed through the solid polymer electrolyte membrane 110 to generate cis-alkene. The process of producing a proton and the process of producing a cis-alkene by an electrolytic reduction reaction occur in parallel at least at one time.

Preferably, the potential of the cathode 120 is adjusted to be in the range of −0.23 V or more and 0 V or less with respect to the theoretical reduction potential of alkyne. Thereby, the cis-alkene can be produced with high selectivity.

As described above, the cis-alkene manufacturing apparatus 10 and the cis-alkene manufacturing method according to the present embodiment are to electrolyze and reduce the alkyne with the solid polymer electrolyte electrolytic unit 100 to manufacture the cis-alkene. including. Therefore, according to the present embodiment, it is possible to obtain a novel technique for producing a cis-alkene.

In the conventional chemical process, it is common to mix an alkyne as a substrate in a solution in which a catalyst is dispersed to produce a cis-alkene. Therefore, it is necessary to provide a step of separating the catalyst in the solution. On the other hand, since the solid polymer electrolyte unit 100 is used in this embodiment, the catalyst separation step can be omitted. Therefore, the manufacturing process of the cis-alkene can be simplified.

Further, in the conventional chemical process, a complex catalyst may be used in order to realize the production of cis-alkene under mild conditions. However, since the complex catalyst is expensive, the manufacturing cost increases. On the other hand, when a conventionally known Lindlar catalyst or the like is used instead of the complex catalyst in order to reduce the production cost, the reaction temperature rises (for example, about 200 ° C.). On the other hand, since the solid polymer electrolysis unit 100 is used in the present embodiment, it is possible to achieve both the manufacturing cost and the mild reaction conditions. Therefore, according to the present embodiment, it is possible to obtain an industrially excellent manufacturing technique for cis-alkene.

Further, by using the solid polymer type electrolysis unit 100, the size of the electrolytic cell can be reduced as compared with the conventional liquid type electrolysis. In addition, the overvoltage at the cathode 120 can be reduced. Therefore, simpler potential control becomes possible. Since the potential control becomes easy, more accurate potential control becomes possible.

Further, the cathode catalyst layer 122 of the solid polymer electrolyte unit 100 preferably contains at least one catalyst metal selected from the group consisting of Pd, Ir, Ag, and Au, and more preferably contains Pd. As a result, the cis-alkene can be produced with high selectivity as compared with the trans-alkene and the alkane produced by further reducing the cis / trans-alkene.

Further, the control unit 60 preferably adjusts the potential of the cathode 120 to a range of −0.23 V or more and 0 V or less with respect to the theoretical reduction potential of alkyne. This makes it possible to produce cis-alkene with high selectivity as compared with trans-alkene and alkane. That is, by adjusting the potential of the cathode 120 to a range of −0.23 V or more and 0 V or less with respect to the theoretical reduction potential, by-products such as trans-alkene and alkane while considering the progress rate of the reaction at the cathode 120. The occurrence can be suppressed.

Further, in the present embodiment, hydrogen gas is supplied to the anode 130. Therefore, the potential of the anode 130 is 0 V (vs. RHE). Therefore, the anode 130 can be used in place of the reference electrode 112. Therefore, the reference electrode 112 can be omitted.

Hereinafter, examples of the present invention will be described, but the examples are merely examples for suitably explaining the present invention, and do not limit the present invention in any way.

(Example 1)
<Manufacturing of anode>
Nafion (registered trademark) dispersion DE2020 (manufactured by DuPont) in powder of Pt / C catalyst (product number: TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) in which platinum as a catalyst metal is supported on porous carbon as a catalyst carrier. Was added, and a catalyst ink for the anode catalyst layer was prepared by using an appropriate solvent. The amount of the Nafion (registered trademark) dispersion liquid added was such that the mass ratio of the dried Nafion (registered trademark) to carbon in the catalyst was 0.8: 1.

Further, a diffusion layer having a size of 4 cm ² (product name: SGL35BC, manufactured by SGL Carbon Co., Ltd.) was prepared. Then, the prepared catalyst ink was spray-coated on one main surface of the diffusion layer. The catalyst ink was applied so that the mass of Pt was 0.5 mg / cm ² per electrode area. Then, the diffusion layer coated with the catalyst ink was dried at 80 ° C. to remove the solvent component in the catalyst ink. Subsequently, thermal bonding was performed at 120 ° C. and 0.4 MPa for 1 minute to obtain a first laminated body composed of an anode catalyst layer and a diffusion layer.

<Cathode preparation>
PdCl ₂ and carbon black (CB) were dispersed in pure water, and the obtained solution was subjected to ultrasonic treatment at 60 ° C. for 30 minutes. Then the solution was dried up. The obtained sample was dried at 60 ° C. overnight and then hydrogenated (hydrogenated) at 350 ° C. The obtained sample will be referred to as "Pd / CB" below. The concentration of Pd in Pd / CB was 28% by weight as measured by thermogravimetric analysis. A catalyst ink for a cathode catalyst layer containing Pd / CB is prepared by the same procedure as the preparation of the anode, the catalyst ink is spray-applied to the diffusion layer, thermal bonding is performed, and the cathode catalyst layer and the diffusion layer are separated. A second laminated body was obtained.

<Making a membrane electrode assembly>
A solid polymer electrolyte membrane with a thickness of 50 μm (product name: Nafion (registered trademark) 212, manufactured by DuPont) was prepared. Then, this electrolyte membrane was sandwiched between the first laminated body and the second laminated body, and heat-bonded for 1 minute under the conditions of 120 ° C. and 0.4 MPa. As a result, a membrane electrode assembly (MEA) composed of a diffusion layer, a cathode catalyst layer, a solid polymer electrolyte membrane, an anode catalyst layer and a diffusion layer was obtained.

<Measurement of product>
Humidified nitrogen was circulated on the cathode side of the MEA and humidified hydrogen was circulated on the anode side at a flow rate of 100 mL / min for 1 hour, respectively, and the MEA was pretreated. The dew points of humidified nitrogen and humidified hydrogen were set to 50 ° C., respectively. After the pretreatment, a cathode solution prepared by mixing diphenylacetylene as a substrate and methylcyclohexane as a solvent was circulated on the cathode side of MEA. The substrate concentration of the cathode solution was 1 mol / L. The cathode solution was circulated using a syringe at a flow rate of 0.25 mL / min. In addition, humidified hydrogen was continuously circulated on the anode side at a flow rate of 100 mL / min. Then, a predetermined voltage was applied to the MEA, and constant potential electrolysis was carried out for 20 minutes. The voltage was set so that the difference in the potential of the cathode (potential difference ΔV) with respect to the theoretical reduction potential of diphenylacetylene was the value shown in Table 1. The potential difference ΔV shown in Table 1 is a value excluding the IR loss. The IR loss is a voltage loss based on the internal resistance of the cell.

After constant potential electrolysis, the reaction product contained in the cathode solution was quantified using a high performance liquid chromatograph (HPLC) (product name: LC-10AD VP, manufactured by Shimadzu Corporation, detector UV / VIS). From the molar ratio of each product obtained, the ratio of the current used to generate each product to the current applied by constant potential electrolysis was calculated as the current efficiency (%) of the product. The results are shown in Table 1.

(Example 2)
The current efficiency (%) of the product was calculated in the same manner as in Example 1 except that the solvent of the cathode solution was toluene instead of methylcyclohexane. The results are shown in Table 1.

(Example 3)
The current efficiency (%) of the product was calculated in the same manner as in Example 1 except that the solvent of the cathode solution was dichlorobenzene instead of methylcyclohexane. The results are shown in Table 1.

(Example 4)
The current efficiency (%) of the product was calculated in the same manner as in Example 1 except that the substrate of the cathode solution was 1-phenyl-1-propyne instead of diphenylacetylene. The results are shown in Table 1. The theoretical reduction potential of 1-phenyl-1-propine is +0.04V.

(Example 5)
The current efficiency (%) of the product was calculated in the same manner as in Example 1 except that a Pt / C catalyst (product number: TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was used for the cathode catalyst layer instead of Pd / CB. bottom. The results are shown in Table 1.

(Example 6)
The current efficiency (%) of the product was calculated in the same manner as in Example 1 except that Rh / CB was used instead of Pd / CB for the cathode catalyst layer. The results are shown in Table 1. Rh / CB was prepared by the following procedure. That is, first, RhCl ₂ and carbon black (CB) were dispersed in pure water, and the obtained solution was subjected to ultrasonic treatment at 60 ° C. for 30 minutes. Then the solution was dried up. The obtained sample was dried at 60 ° C. overnight and then hydrogenated at 350 ° C. to obtain Rh / CB. The concentration of Rh in Rh / CB was 29% by mass as measured by thermogravimetric analysis.

(Example 7)
The current efficiency (%) of the product was calculated in the same manner as in Example 1 except that the substrate of the cathode solution was 3-hexyne-1-ol instead of diphenylacetylene. The results are shown in Table 1. The theoretical reduction potential of 3-hexyne-1-ol is +0.20V.

As shown in Table 1, it was confirmed from Examples 1 to 7 that cis-alkene can be produced by electrolytic reduction of alkyne. Further, from the comparison of Examples 1, 5 and 6, it was confirmed that when Pd is contained as the catalyst metal of the cathode, the selectivity of cis-alkene is higher than that when Pt and Rh are contained. Those skilled in the art can understand that the selectivity of cis-alkene is high for Ir, Ag, and Au from this result showing the superiority of Pd over Pt and Rh.

Further, from the results of Examples 1 to 4, 7 and the like, when the potential of the cathode is in the range of −0.23 V or more and 0 V or less with respect to the theoretical reduction potential of the substrate, the selectivity of cis-alkene tends to increase. It was confirmed that there was. Further, from the results of Examples 1 to 3, it was confirmed that the lower the polarity of the solvent, the higher the selectivity of the cis-alkene. In Table 1, the total current efficiency of each product is not 100% because a part of the current was used to generate hydrogen gas.

The present invention is not limited to the above-described embodiment, and various modifications such as design changes can be added based on the knowledge of those skilled in the art, and the embodiment to which such modifications are added. Can also be included in the scope of the present invention.

Arbitrary combinations of components described in the embodiments, conversions of the representations of the invention between methods, devices, systems, etc. are also valid embodiments of the invention.

10 Sys-Arken manufacturing equipment, 34 supply unit, 60 control unit, 100 solid polymer electrolyte unit, 110 solid polymer electrolyte membrane, 120 cathode, 122 cathode catalyst layer, 130 anode, 132 anode catalyst layer.

Claims (5)

An anode including an anode catalyst layer, a cathode including a cathode catalyst layer, and a solid polymer electrolytic unit having a solid polymer electrolyte film provided between the anode and the cathode .
A supply unit that supplies an alkyne to the cathode of the solid polymer electrolyte unit,
A control unit for adjusting the potential of the cathode is provided.
The polymer electrolyte electrolysis unit electrolyzes and reduces the alkyne to produce a cis-alkene.
The cathode catalyst layer contains at least one catalyst metal selected from the group consisting of Pd, Ir, Ag and Au.
The control unit is a cis-alkene manufacturing apparatus characterized in that the potential of the cathode is adjusted to a range of −0.23 V or more and 0 V or less with respect to the theoretical reduction potential of the alkyne . The cis-alkene manufacturing apparatus according to claim 1 , wherein the cathode catalyst layer contains Pd. The cis-alkene manufacturing apparatus according to claim 1 or 2 , wherein the control unit adjusts the potential of the cathode to a range of −0.14 V or more and 0 V or less with respect to the theoretical reduction potential of the alkyne. The apparatus for producing a cis-alkene according to any one of claims 1 to 3 , wherein the solid polyelectrolyte membrane contains perfluorosulfonic acid. An anode including an anode catalyst layer, a cathode containing a cathode catalyst layer containing at least one catalyst metal selected from the group consisting of Pd, Ir, Ag, and Au, and a solid polymer provided between the anode and the cathode. Using a solid polymer type electrolytic unit having an electrolyte membrane, the cathode potential is adjusted to a range of -0.23 V or more and 0 V or less with respect to the theoretical reduction potential of the alkyne, and the alkyne is electrolytically reduced to produce a cis-alkene. A method for producing a cis-alkene, which comprises:

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