Hydrogen gas production apparatus and hydrogen gas production method

Abstract

We provide an apparatus capable of producing high-purity hydrogen gas. We also provide a method for producing high-purity hydrogen gas. [Solution] A hydrogen gas production apparatus having a cathode, an anode disposed opposite to one side of the cathode, and a solid electrolyte member disposed between the cathode and the anode, wherein a hydrogen gas recovery passage is disposed on the other side of the cathode.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen gas production apparatus and a method for producing hydrogen gas.

Background Art

[0002] Using hydrogen gas as clean energy has been considered. As a method for producing hydrogen gas, for example, a method of electrolyzing pure water using an electrode and a PEM (Polymer Electrolyte Membrane: solid polymer electrolyte membrane) is known. In the method of producing hydrogen gas by electrolyzing pure water using an electrode and a PEM, usually, water vapor is mixed into the produced hydrogen gas. This is because the PEM has a very high water vapor permeability, and when hydrogen ions move from the anode side to the cathode side during electrolysis, water vapor also moves together.

[0003] Patent Document 1 describes a hydrogen generator that generates hydrogen using electrodes and a PEM, and is capable of generating hydrogen from which water vapor has been removed. The hydrogen generator described in Patent Document 1 has an anode section equipped with a positive electrode, a cathode section equipped with a negative electrode, and a solid electrolyte membrane separating the anode section and the cathode section, and includes a water electrolysis cell that generates oxygen gas in the anode section and hydrogen gas in the cathode section by electrolyzing water, and includes a hydrogen separation tank that is in communication with the cathode section and separates the hydrogen gas and water from the cathode section under pressure so that the hydrogen gas generated in the cathode section can be extracted under pressure. Furthermore, Patent Document 1 describes that the hydrogen gas stored in hydrogen separation tanks 4 and 40 is transported and supplied to the hydrogen gas usage location via hydrogen gas supply piping sections 21 and 21', that hydrogen gas dehumidification means 23 and 23' are provided in the hydrogen gas supply piping sections 21 and 21' for dehumidifying the hydrogen gas, that the hydrogen gas dehumidification means 23 and 23' dehumidifies the hydrogen gas by circulating hydrogen gas inside a hollow fiber membrane and circulating dry air outside the hollow fiber membrane, and that in order to obtain hydrogen gas of higher purity (for example, 6N (99.9999) or higher), it is preferable to provide a purifier made of molecular sieves such as zeolite and activated alumina downstream of the hydrogen gas dehumidification means 23 and 23', or in place of the hydrogen gas dehumidification means. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2006-124772 [Overview of the project] [Problems that the invention aims to solve]

[0005] According to the hydrogen generator described in Patent Document 1 above, hydrogen can be generated with water vapor removed. However, since alcohol and ammonia dissolve in PEM and permeate through PEM, if alcohol or ammonia is mixed into pure water, the hydrogen generated by permeating through PEM may contain alcohol or ammonia as impurities.

[0006] The problem addressed by this disclosure is to provide an apparatus capable of producing high-purity hydrogen gas. Another problem addressed by this disclosure is to provide a method capable of producing high-purity hydrogen gas. [Means for solving the problem]

[0007] The contents of this disclosure are as follows: [1] A hydrogen gas production apparatus having a cathode, an anode disposed opposite to one side of the cathode, and a solid electrolyte member disposed between the cathode and the anode, wherein a hydrogen gas recovery passage is disposed on the other side of the cathode. [2] The hydrogen gas production apparatus according to [1], wherein the shape of the cathode is cylindrical with a longitudinal direction. [3] The hydrogen gas production apparatus according to [2], wherein the cylindrical cathode is closed at one end in the longitudinal direction and open at the other end in the longitudinal direction. [4] The hydrogen gas production apparatus according to [2] or [3], wherein a support member is arranged inside the cylindrical cathode. [5] The cathode is permeable to hydrogen ions. A hydrogen gas production apparatus according to any one of [1] to [4]. [6] The hydrogen gas production apparatus according to [5], wherein the cathode is permeable to hydrogen ions but not to hydrogen molecules. [7] The hydrogen gas production apparatus according to [5] or [6], wherein the cathode contains at least one selected from the group consisting of titanium, vanadium, manganese, nickel, copper, zirconium, niobium, palladium, silver, tantalum, platinum, and gold. [8] The anode comprises at least one selected from the group consisting of carbon, platinum, and gold. [1] to [7] The hydrogen gas production apparatus according to any one of these. [9] The hydrogen gas production apparatus according to any one of [1] to [8], wherein the solid electrolyte member contains perfluorocarbon.

[10] A method for producing hydrogen gas, comprising immersing a hydrogen gas production apparatus having a cathode, an anode disposed opposite to one side of the cathode, a solid electrolyte member disposed between the cathode and the anode, and a hydrogen gas recovery passage disposed on the other side of the cathode in a raw material liquid, energizing the cathode and the anode, and recovering hydrogen gas from the hydrogen gas recovery passage.

[11] The manufacturing method according to

[10] , wherein the shape of the cathode is cylindrical with a longitudinal direction.

[12] The manufacturing method according to

[11] , wherein the cylindrical cathode is closed at one end in the longitudinal direction and open at the other end in the longitudinal direction.

[13] The cathode is permeable to hydrogen ions. The manufacturing method according to any one of

[10] to

[12] .

[14] The method for manufacturing the cathode described in

[13] , wherein hydrogen ions are permeable but hydrogen molecules are not.

[15] The manufacturing method according to any one of

[10] to

[14] , wherein the temperature of the raw material liquid is controlled to 60°C to 95°C.

[16] The shape of the solid electrolyte member is strip-shaped. Hydrogen gas production apparatus according to any one of [1] to [9].

[17] The hydrogen gas production apparatus according to any one of [1] to [9],

[16] , wherein the shape of the anode is linear or strip-shaped. [Effects of the Invention]

[0008] The hydrogen gas production apparatus of this disclosure includes a cathode positioned opposite the anode, and a hydrogen gas recovery passage is provided on the side of the cathode opposite the anode, through which hydrogen gas is recovered. High-purity hydrogen gas can be produced using this hydrogen gas production apparatus. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a cross-sectional view showing an embodiment of a hydrogen gas production apparatus. [Figure 2]Figure 2 is a schematic diagram showing another embodiment of the hydrogen gas production apparatus. [Figure 3] Figure 3 is a side view showing another embodiment of the hydrogen gas production apparatus. [Figure 4] Figure 4 is a side view showing another embodiment of the hydrogen gas production apparatus. [Figure 5] Figure 5 is a perspective view showing another embodiment of the hydrogen gas production apparatus. [Figure 6] Figure 6 is a graph showing the relationship between the temperature of the raw material liquid, the current applied to the electrodes, the hydrogen gas generation flow rate, or the hydrogen gas generation efficiency. [Modes for carrying out the invention]

[0010] The Disclosure will be described in more detail below based on embodiments, but the Disclosure is not limited by the embodiments described below, and it is certainly possible to implement modifications to the extent that are consistent with the spirit described above and below, and all such modifications are included within the technical scope of the Disclosure.

[0011] The embodiment of the hydrogen gas production apparatus is a hydrogen gas production apparatus having a cathode, an anode disposed opposite to one side of the cathode, and a solid electrolyte member disposed between the cathode and the anode, wherein a hydrogen gas recovery passage is disposed on the other side of the cathode.

[0012] Embodiments of the hydrogen gas production apparatus will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the hydrogen gas production apparatus 100. The hydrogen gas production apparatus 100 has a cathode 1. An anode 2 is arranged opposite to one side of the cathode 1. A solid electrolyte member 3 is arranged between the cathode 1 and the anode 2. A solid electrolyte is a solid that can permeate ions. A hydrogen gas recovery passage 4 is arranged on the other side of the cathode 1. By immersing the hydrogen gas production apparatus 100 in a raw material liquid and applying an electric current between the cathode 1 and the anode 2, hydrogen gas can be recovered and produced through the hydrogen gas recovery passage 4. That is, by immersing the hydrogen gas production apparatus 100 in a raw material liquid and applying an electric current between the cathode 1 and the anode 2, oxygen gas is generated from the anode 2 side and ionized hydrogen ions move inside the solid electrolyte member 3 and reach the surface of the cathode 1. It is considered that the hydrogen ions reaching the surface of the cathode 1 are adsorbed and occluded by the cathode 1 and diffuse inside the cathode 1. The diffused hydrogen ions move to the other side of the cathode 1 (that is, the side opposite to the side of the cathode 1 facing the anode 2), and hydrogen ions recombine again on the surface of the other side of the cathode 1 to become hydrogen gas. The generated hydrogen gas can be recovered through the hydrogen gas recovery passage 4 arranged on the other side of the cathode 1.

[0013] The anode 2 may be made of a known material. For example, it preferably contains at least one selected from the group consisting of carbon, platinum, and gold, and is more preferably composed of at least one selected from the group consisting of carbon, platinum, and gold.

[0014] The shape of the anode 2 is not particularly limited, and examples include planar, curved, cylindrical, linear, and strip-shaped.

[0015] The anode 2 may have elasticity. Thereby, even if the solid electrolyte member 3 swells, the anode 2 absorbs the swelling of the solid electrolyte member 3, so that the contact state between the cathode 1 and the solid electrolyte member 3 and the contact state between the solid electrolyte member 3 and the anode 2 can be optimally maintained. As a result, the recovery efficiency of hydrogen gas can be increased.

[0016] When the shape of anode 2 is cylindrical, the cross-sectional shape perpendicular to the longitudinal direction is not particularly limited and may be, for example, circular, triangular, quadrilateral, rectangular, polygonal, elliptical, egg-shaped, or a combination thereof, with circular or elliptical being preferred, and circular being more preferred. When the shape of anode 2 is cylindrical and the cross-sectional shape perpendicular to the longitudinal direction is triangular, quadrilateral, rectangular, or polygonal, at least one of the corners may be rounded.

[0017] When the shape of anode 2 is linear, the cross-sectional shape perpendicular to the longitudinal direction is not particularly limited and may be, for example, circular, triangular, quadrilateral, rectangular, polygonal, elliptical, egg-shaped, or a combination thereof. Circular, triangular, quadrilateral, rectangular, or elliptical shapes are preferred, and circular, quadrilateral, or rectangular shapes are more preferred. When the shape of anode 2 is linear and the cross-sectional shape perpendicular to the longitudinal direction is triangular, quadrilateral, rectangular, or polygonal, at least one of the corners may be rounded.

[0018] If the shape of anode 2 is strip-shaped, the cross-sectional shape perpendicular to the longitudinal direction may be, for example, a rectangle, and at least one corner of the rectangle may be rounded. If the shape of anode 2 is strip-shaped, the width of anode 2 may be, for example, 1.3 mm to 4 mm, 1.5 mm to 3.5 mm, or 1.8 mm to 3 mm. If the shape of anode 2 is strip-shaped, the thickness of anode 2 may be, for example, 0.5 mm to 2 mm, 0.8 mm to 1.8 mm, or 1 mm to 1.5 mm.

[0019] Anode 2 may be non-porous or porous, and if it is porous, it may be porous as well. Anode 2 may also be solid.

[0020] The oxygen gas generated from the anode 2 side (i.e., the oxygen gas generated between the anode 2 and the solid electrolyte member 3) can be recovered and used as needed. Furthermore, the recovered oxygen gas may be purified as needed.

[0021] The solid electrolyte member 3 is a solid that can permeate ions, and in particular, it is a solid that can permeate hydrogen ions (protons), and can be made of any known material.

[0022] Examples of materials for the solid electrolyte member 3 include polymer electrolytes, specifically fluorine-based polymer electrolytes and aromatic hydrocarbon-based polymer electrolytes.

[0023] Examples of fluorinated polymer electrolytes include perfluorinated sulfonic acid polymers, perfluorinated phosphonic acid polymers, and perfluorinated carboxylic acid polymers. It is preferable that the fluorinated polymer electrolyte contains perfluorocarbon. Specifically, examples of fluorinated polymer electrolytes that can be used include Nafion® manufactured by DuPont, Aciplex® manufactured by Asahi Kasei Chemicals Corporation, Flemion® manufactured by Asahi Glass Co., Ltd., and Dowex® manufactured by The Dow Chemical Company.

[0024] Aromatic hydrocarbon polymer electrolytes are electrolytes that contain aromatic hydrocarbon polymers having ionic groups. Aromatic hydrocarbon polymers are polymers consisting of a hydrocarbon skeleton having aromatic rings in the main chain. Specifically, examples include polymers having structures selected from polysulfone, polyethersulfone, polyetherketone, polyetherphosphine foxide, polyetherimide, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene ether polymers, polyarylene polymers, polyarylene ketone, polyarylenephosphine foxide, polybenzoxazole, polybenzothiazole, polybenzimidazole, polyamide, polyimide, and polyimide sulfone in the main chain along with aromatic rings. Polysulfones, polyethersulfones, polyetherketones, etc., are general terms for structures having sulfone bonds, ether bonds, and ketone bonds in their molecular chains, and include polyetherketone ketones, polyetheretherketones, polyetheretherketone ketones, polyetherketone ketones, polyetherketone etherketone ketones, and polyetherketone sulfones. The hydrocarbon skeleton may have multiple of these structures. Among these, polyetherketones are preferred.

[0025] A mixture of multiple polymers may be used as the polymer electrolyte. For example, a mixture of aromatic hydrocarbon polymers having ionic groups and aromatic hydrocarbon polymers not having ionic groups may be used.

[0026] The shape of the solid electrolyte member 3 is not particularly limited and can be, for example, planar, curved, cylindrical, linear, string-like, mesh-like, or strip-like.

[0027] If the solid electrolyte member 3 has a planar or curved shape, the solid electrolyte member 3 may be in the form of a plate, a membrane, or a film.

[0028] When the solid electrolyte member 3 is linear in shape, the cross-sectional shape perpendicular to the longitudinal direction is not particularly limited and may be, for example, circular, triangular, quadrilateral, rectangular, polygonal, elliptical, egg-shaped, or a combination thereof. Circular, triangular, quadrilateral, rectangular, or elliptical shapes are preferred, and circular, quadrilateral, or rectangular shapes are more preferred. When the solid electrolyte member 3 is linear in shape and the cross-sectional shape perpendicular to the longitudinal direction is triangular, quadrilateral, rectangular, or polygonal, at least one of the corners may be rounded.

[0029] When the solid electrolyte member 3 is strip-shaped, the cross-sectional shape perpendicular to the longitudinal direction may be rectangular, and at least one corner of the rectangle may be rounded. When the solid electrolyte member 3 is strip-shaped, the width of the solid electrolyte member 3 may be, for example, 1.3 mm to 4 mm, 1.5 mm to 3.5 mm, or 1.8 mm to 3 mm. When the solid electrolyte member 3 is strip-shaped, the thickness of the solid electrolyte member 3 may be, for example, 0.5 mm to 5 mm, 0.8 mm to 4 mm, or 1 mm to 3 mm.

[0030] The surface of the solid electrolyte member 3 may have irregularities, which may be protrusions or grooves. The presence of irregularities on the cathode 1 side of the solid electrolyte member 3 facilitates the discharge of hydrogen gas generated on the surface of the cathode 1 facing the solid electrolyte member 3. This prevents hydrogen gas from accumulating on the surface of the cathode 1 facing the solid electrolyte member 3, which can lead to unstable electrolysis or cessation of electrolysis. As a result, the hydrogen gas recovery efficiency can be increased. The presence of irregularities on the anode 2 side of the solid electrolyte member 3 facilitates the discharge of oxygen gas generated on the surface of the anode 2 facing the solid electrolyte member 3. This prevents oxygen gas from accumulating on the surface of the anode 2 facing the solid electrolyte member 3, which can lead to unstable electrolysis or cessation of electrolysis. As a result, the hydrogen gas recovery efficiency can be increased. The solid electrolyte member 3 may have irregularities on both its cathode 1 and anode 2 sides.

[0031] The solid electrolyte member 3 may be non-porous or porous. By making the solid electrolyte member 3 non-porous, it acts as a diaphragm between the anode and the cathode, preventing the mixing of hydrogen gas generated between cathode 1 and the solid electrolyte member 3 with oxygen gas generated between anode 2 and the solid electrolyte member 3. By making the solid electrolyte member 3 porous, the hydrogen gas generated between cathode 1 and the solid electrolyte member 3 can be removed, thereby ensuring a sufficient contact area between cathode 1 and the solid electrolyte member 3 and increasing the efficiency of hydrogen gas generation. Furthermore, the pressure load on cathode 1 caused by the hydrogen gas generated between cathode 1 and the solid electrolyte member 3 can be reduced. If the solid electrolyte member 3 is porous, it may, for example, be porous.

[0032] The material constituting cathode 1 is preferably permeable to hydrogen ions. By using a hydrogen ion permeable material as cathode 1, the purity of the hydrogen gas recovered from the other side of cathode 1 can be increased.

[0033] The material constituting cathode 1 may be permeable to hydrogen ions but impermeable to hydrogen molecules. By using a material as cathode 1 that is permeable to hydrogen ions but impermeable to hydrogen molecules, the purity of the hydrogen gas recovered from the other side of cathode 1 can be further increased. Impermeability to hydrogen molecules means that the hydrogen gas generated on the surface of one side of cathode 1 (i.e., the side of cathode 1 facing anode 2) does not pass through cathode 1 in the form of hydrogen molecules. For example, if hydrogen gas dissolves and diffuses into cathode 1 in the form of hydrogen molecules, or if holes are formed that penetrate through the thickness direction of cathode 1, then the hydrogen gas has passed through cathode 1 in the form of hydrogen molecules.

[0034] Cathode 1 may be non-porous, solid, or non-porous. The bulk density of cathode 1 may be, for example, 97% or more, or 98% or more. The void ratio of cathode 1 may be, for example, 3 volume% or less, or 2 volume% or less.

[0035] Cathode 1 may be composed of a material that allows hydrogen ions to permeate, and preferably a material that allows hydrogen ions to permeate but impermeable to hydrogen molecules. Examples of materials that allow hydrogen ions to permeate but impermeable to hydrogen molecules include metals such as titanium, vanadium, manganese, nickel, copper, zirconium, niobium, palladium, silver, tantalum, platinum, and gold. Cathode 1 may contain at least one metal selected from this group, or it may be an alloy of two or more metals. Cathode 1 may also be a metal a selected from this group plated with a metal b selected from this group, but different from metal a. Cathode 1 may also be an alloy a containing two or more metals selected from this group, plated with a metal selected from this group, or an alloy b containing two or more metals selected from this group, but different from alloy a, plated with an alloy b. The cathode 1 is preferably composed of at least one metal selected from the group consisting of titanium, vanadium, manganese, nickel, copper, zirconium, niobium, palladium, silver, tantalum, platinum, and gold, and more preferably composed of palladium or a palladium alloy.

[0036] The shape of the cathode 1 is not particularly limited; for example, it can be planar, curved, or cylindrical, with a cylindrical shape being preferred. The cylindrical shape of the cathode 1, along with the use of the inner radial side of the cylindrical cathode 1 as the hydrogen gas recovery passage 4, facilitates the recovery of the generated hydrogen gas.

[0037] When the cathode 1 is cylindrical, the cross-sectional shape perpendicular to the longitudinal direction is not particularly limited and may be circular, triangular, square, rectangular, polygonal, elliptical, or egg-shaped, with circular or elliptical being preferred, and circular being more preferred. When the cathode 1 is cylindrical and the cross-sectional shape perpendicular to the longitudinal direction is triangular, square, rectangular, or polygonal, at least one of the corners may be rounded.

[0038] As described above, the shape of the solid electrolyte member 3 is not particularly limited; for example, it can be planar, curved, cylindrical, linear, string-like, or mesh-like, and even if the cathode 1 is cylindrical, the shape of the solid electrolyte member 3 is not particularly limited. That is, in the case of a hydrogen generator that generates hydrogen using electrodes and a PEM as described in Patent Document 1, the solid electrolyte membrane placed between the cathode and anode isolates the cathode and anode, and the solid electrolyte membrane is required to have the function of allowing ions to pass through but not gases. By isolating the cathode and anode with the solid electrolyte membrane, even if current is passed through the cathode and anode, the gases generated on the cathode side and anode side will not mix. In addition, by isolating the cathode and anode with the solid electrolyte membrane, when the gas generated on the cathode side is pressurized and extracted, it is possible to prevent the gas from leaking to the anode side. In order to perform these functions, the solid electrolyte membrane needs to have sufficient strength to withstand the generated gas. For this reason, the solid electrolyte membrane is required to be non-porous, solid, and defect-free. In contrast, if the cathode 1 is cylindrical and hydrogen gas is recovered from the side opposite the solid electrolyte member 3 of the cathode 1, it is sufficient for the cathode 1 and the solid electrolyte member 3 to be in contact, and the shape of the solid electrolyte member 3 does not need to be planar (film-like). Therefore, the solid electrolyte member 3 can be perforated, or its shape can be string-like, mesh-like, or linear. Furthermore, it can be used even if the solid electrolyte member 3 has some defects. In addition, since the solid electrolyte member 3 does not need to withstand the pressure of the gas generated on the cathode side, the thickness of the solid electrolyte member 3 can be reduced.

[0039] When the cathode 1 is cylindrical, the solid electrolyte member 3 is preferably curved, linear, or strip-shaped, and more preferably strip-shaped. When the cathode 1 is cylindrical and the solid electrolyte member 3 is linear or strip-shaped, the solid electrolyte member 3 may be coiled around the surface of the cathode 1. By making the solid electrolyte member 3 covering the surface of the cathode 1 linear or strip-shaped and providing gaps between the solid electrolyte members 3 covering the surface of the cathode 1, hydrogen gas generated on the surface of the cathode 1 on the solid electrolyte member 3 side can be discharged through the gaps between the solid electrolyte members 3. Therefore, it is possible to prevent hydrogen gas from accumulating on the surface of the cathode 1 on the solid electrolyte member 3 side, which can cause electrolysis to become unstable or stop. As a result, the hydrogen gas recovery efficiency can be increased. When the solid electrolyte member 3 is strip-shaped, the spacing between the solid electrolyte members 3 may be, for example, 0.1 mm to 1 mm or 0.3 mm to 0.5 mm.

[0040] When the cathode 1 is cylindrical and the solid electrolyte member 3 is linear or strip-shaped, the direction in which the solid electrolyte member 3 is wound around the cathode 1 is not particularly limited and may be a right-handed helix (Z-winding) or a left-handed helix (S-winding).

[0041] When the cathode 1 is cylindrical, the anode 2 is preferably curved, linear, or strip-shaped, more preferably linear or strip-shaped, and even more preferably strip-shaped. When the cathode 1 is cylindrical and the anode 2 is linear or strip-shaped, it may be coiled around the surface of the solid electrolyte member 3 placed on the surface of the cathode 1. When the anode 2 covering the surface of the solid electrolyte member 3 is linear or strip-shaped, and gaps are provided between the anodes 2, oxygen gas generated on the surface of the anode 2 on the solid electrolyte member 3 side can be discharged through the gaps between the anodes 2. Therefore, it is possible to prevent oxygen gas from accumulating on the surface of the anode 2 on the solid electrolyte member 3 side, which can cause electrolysis to become unstable or stop. As a result, the hydrogen gas recovery efficiency can be increased. When the anode 2 is linear or strip-shaped and covers the surface of the solid electrolyte member 3, the distance between the anodes 2 may be, for example, 0.1 mm to 1 mm or 0.3 mm to 0.5 mm.

[0042] When the cathode 1 is cylindrical and the anode 2 is linear or strip-shaped, the direction in which the anode 2 is wound around the cathode 1 is not particularly limited; it can be a right-handed helix (Z-winding) or a left-handed helix (S-winding).

[0043] When the cathode 1 is cylindrical, the solid electrolyte member 3 is linear or strip-shaped, and the anode 2 is linear or strip-shaped, the direction in which the solid electrolyte member 3 and anode 2 are wrapped around the cathode 1 may be the same or different, but it is preferable that they be different. Because the direction in which the solid electrolyte member 3 and anode 2 are wrapped around the cathode 1 is different, the gaps between the solid electrolyte members 3 and the gaps between the anodes 2 do not overlap as much, making it easier to discharge hydrogen gas and oxygen gas.

[0044] Next, another embodiment of the hydrogen gas production apparatus will be described, in which the cathode has a cylindrical shape with a longitudinal direction. To avoid redundant explanations, the same reference numerals are used for parts that overlap with other drawings (the same applies hereafter).

[0045] Figure 2 is a schematic diagram showing another embodiment of the hydrogen gas production apparatus 100. The hydrogen gas production apparatus 100 has a cathode 11 and an anode 21. The cathode 11 is cylindrical with a longitudinal direction and a circular cross-sectional shape perpendicular to the longitudinal direction. The anode 21 is cylindrical with a longitudinal direction and a circular cross-sectional shape perpendicular to the longitudinal direction. The cylindrical anode 21 is positioned opposite one side of the cylindrical cathode 11. In Figure 2, for the sake of explanation, a part of the cylindrical anode 21 is cut open to show the inside of the hydrogen gas production apparatus 100. A hydrogen gas recovery passage 4 is positioned on the other side of the cylindrical cathode 11. In Figure 2, the hydrogen gas recovery passage 4 is positioned radially inside the cylindrical cathode 11 with a longitudinal direction. A cylindrical solid electrolyte member 3 is positioned between the cylindrical cathode 11 and the cylindrical anode 21.

[0046] In Figure 2, a solid electrolyte member 3 is positioned radially outside the cylindrical cathode 11, and a cylindrical anode 21 is positioned radially outside the solid electrolyte member 3. The arrangement order of the cylindrical cathode 11, cylindrical solid electrolyte member 3, and cylindrical anode 21 is not limited to this; the cylindrical solid electrolyte member 3 may be positioned radially outside the cylindrical anode 21, the cylindrical cathode 11 may be positioned radially outside the solid electrolyte member 3, and the hydrogen gas recovery passage 4 may be positioned radially outside the cylindrical cathode 11.

[0047] In Figure 2, the axis of the cylindrical cathode 11 and the axis of the cylindrical anode 21 are aligned. However, the arrangement of the cylindrical cathode 11 and the cylindrical anode 21 is not limited to this, and the axes of the cylindrical cathode 11 and the cylindrical anode 21 may be misaligned.

[0048] If the cathode 11 is cylindrical with a longitudinal direction, both one end 11a and the other end 11b in the longitudinal direction of the cylindrical cathode 11 may be open, or one end 11a in the longitudinal direction may be open and the other end 11b may be closed, and it is preferable that one end 11a in the longitudinal direction is open and the other end 11b is closed. By having one end 11a in the longitudinal direction open and the other end 11b closed, hydrogen gas generated on the other side of the cylindrical cathode 11 can be collected in one direction. In addition, by having the other end 11b in the longitudinal direction closed, it is possible to suppress the effects of the cylindrical cathode 11 expanding due to the absorption of hydrogen ions into the cylindrical cathode 11, or contracting due to the permeation of hydrogen ions absorbed into the cylindrical cathode 11.

[0049] If the cathode 11 is cylindrical with a longitudinal direction, and a solid electrolyte member 3 is arranged on the radially outer side of the cathode 11, and a cylindrical anode 21 is arranged on the radially outer side of the solid electrolyte member 3, then a support member may be arranged on the radially inner side of the cylindrical cathode 11. By providing the support member, the support member acts as a reinforcement for the cylindrical cathode 11, preventing deformation of the cylindrical cathode 11 even when negative pressure is applied to the radially inner side of the cylindrical cathode 11.

[0050] The shape of the support member is not particularly limited; for example, it may be a wire or a plate, and the plate may be in the shape of a strip. If the shape of the support member is a wire, the cross-sectional shape perpendicular to the longitudinal direction is not particularly limited; for example, it may be circular, triangular, square, rectangular, polygonal, elliptical, or egg-shaped, with circular, square, rectangular, or elliptical being preferred, and circular or rectangular being more preferred. A straight wire may be arranged on the inner surface of the cylindrical cathode 11, or a curved wire may be arranged. Furthermore, if the wire arranged on the inner surface of the cylindrical cathode 11 is curved, the wire may be annular or coiled, and a coiled shape is preferred.

[0051] Examples of materials that make up the support members include steel (especially stainless steel), titanium, vanadium, manganese, nickel, copper, zirconium, niobium, palladium, silver, tantalum, platinum, and gold.

[0052] Next, another embodiment of the hydrogen gas production apparatus, in which the cathode has a cylindrical shape with a longitudinal direction, will be described.

[0053] Figure 3 is a side view showing another embodiment of the hydrogen gas production apparatus 100. The hydrogen gas production apparatus 100 has a cathode 11 and an anode 22. The cathode 11 is cylindrical with a longitudinal direction, and its cross-sectional shape perpendicular to the longitudinal direction is circular. The anode 22 is linear (coil-shaped). The linear anode 22 is coil-shaped and opposite one side of the cylindrical cathode 11. A hydrogen gas recovery passage 4 is located on the other side of the cylindrical cathode 11. In Figure 3, the hydrogen gas recovery passage 4 is located radially inside the cylindrical cathode 11 with a longitudinal direction. A cylindrical solid electrolyte member 3 is located between the cylindrical cathode 11 and the linear (coil-shaped) anode 22.

[0054] Next, another embodiment of the hydrogen gas production apparatus, in which the cathode has a cylindrical shape with a longitudinal direction, will be described.

[0055] Figure 4 is a side view showing another embodiment of the hydrogen gas production apparatus 100. The hydrogen gas production apparatus 100 has a cathode 11 and an anode 23. The cathode 11 is cylindrical with a longitudinal direction, and its cross-sectional shape perpendicular to the longitudinal direction is circular. The anode 23 is strip-shaped, and its cross-sectional shape perpendicular to the longitudinal direction is rectangular. The strip-shaped anode 23 is positioned opposite one side of the cylindrical cathode 11. A hydrogen gas recovery passage 4 is positioned on the other side of the cylindrical cathode 11, and in Figure 4, the hydrogen gas recovery passage 4 is positioned radially inside the cylindrical cathode 11 with a longitudinal direction. A solid electrolyte member 31 is positioned between the cylindrical cathode 11 and the strip-shaped anode 23. The solid electrolyte member 31 is strip-shaped, and its cross-sectional shape perpendicular to the longitudinal direction is rectangular. The strip-shaped solid electrolyte member 31 is wound around the cylindrical cathode 11 in a right-handed helix (Z-winding), and the strip-shaped anode 23 is wound around the cylindrical cathode 11 in a left-handed helix (S-winding).

[0056] Next, another embodiment of the hydrogen gas production apparatus, in which the cathode has a cylindrical shape with a longitudinal direction, will be described.

[0057] Figure 5 is a perspective view showing another embodiment of the hydrogen gas production apparatus 100. The hydrogen gas production apparatus 100 shown in Figure 5 has a cathode 12 and a holding member 5, and a solid electrolyte member and an anode are arranged radially outside the cathode 12, but the solid electrolyte member and anode are not shown. The cathode 12 is cylindrical with a longitudinal direction, and the cross-sectional shape perpendicular to the longitudinal direction is circular. A hydrogen gas recovery passage is arranged radially inside the cylindrical cathode 12 with a longitudinal direction. The cathode 12 has one end 12a and the other end 12b in the longitudinal direction. The cathode 12 is curved in a U shape so that one end 12a and the other end 12b are in contact with the same surface. One end 12a and the other end 12b of the cathode 12 are fixed to one surface 5a of the holding member 5. The retaining member 5 has a hole formed in the thickness direction of the retaining member 5, extending from one surface 5a to the other surface 5b at the position where one end 12a of the cathode 12 is fixed to one surface 5a of the retaining member 5. Furthermore, the retaining member 5 has a hole formed in the thickness direction of the retaining member 5, extending from one surface 5a to the other surface 5b at the position where the other end 12b of the cathode 12 is fixed to one surface 5a of the retaining member 5. When current is passed through the cathode 12 and anode, hydrogen ions that reach the surface of the cathode 12 are adsorbed and stored in the cathode 12 and diffuse within the cathode 12. The diffused hydrogen ions move radially inward to form hydrogen gas, which then passes through a hydrogen gas recovery passage located radially inward of the cathode 12, through the hole formed in the retaining member 5, and can be recovered from the other surface 5b of the retaining member 5.

[0058] As shown in Figure 5, one end 12a and the other end 12b of the cathode 12 may be fixed to one surface 5a of the retaining member 5, or, for example, one end and the other end of the cathode 12 may be embedded in a hole that penetrates from one surface 5a to the other surface 5b of the retaining member 5, with one end 12a and the other end 12b of the cathode 12 reaching the other surface 5b of the retaining member 5, or a part of the end of the cathode 12 may protrude from the other surface 5b of the retaining member 5. The shape of the retaining member 5 is not limited to the disc shape shown in Figure 5, and may be cylindrical, for example. One end 12a and the other end 12b of the cathode 12 may be fixed to the side surface of a cylindrical retaining member 5. Examples of materials that make up the retaining member 5 include steel (especially stainless steel).

[0059] Next, an embodiment of the hydrogen gas production method will be described.

[0060] Hydrogen gas can be produced using the hydrogen gas production apparatus described above. For example, hydrogen gas can be produced by immersing the hydrogen gas production apparatus, shown in Figure 1, which has a cathode 1, an anode 2 positioned opposite to one side of the cathode 1, a solid electrolyte member 3 positioned between the cathode 1 and the anode 2, and a hydrogen gas recovery passage 4 positioned on the other side of the cathode 1, in a raw material liquid, energizing the cathode 1 and the anode 2, and recovering hydrogen gas from the hydrogen gas recovery passage 4.

[0061] For example, water can be used as the raw material liquid, and pure water is preferred.

[0062] The temperature of the raw material solution is not particularly limited, but it is preferable to control it to, for example, 60°C to 100°C. By setting the temperature of the raw material solution to 60°C or higher, the rate at which hydrogen ions permeate the cathode can be increased. The temperature of the raw material solution is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher. The higher the temperature of the raw material solution, the faster the rate at which hydrogen ions permeate the cathode, but if the temperature of the raw material solution is too high, the solid electrolyte member 3 may be damaged. Therefore, the temperature of the raw material solution is preferably, for example, 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower. That is, the temperature of the raw material solution may be 60°C to 100°C, 60°C to 95°C, 65°C to 90°C, or 70°C to 90°C.

[0063] Since the hydrogen gas recovered from the hydrogen gas recovery passage 4 does not contain moisture, it can be used for its intended purpose without dehumidification. However, if necessary, it may be purified by dehumidification or other methods before being used for its intended purpose. [Examples]

[0064] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited by the examples below, and it is certainly possible to implement it with modifications to the extent that they are in line with the spirit described above and below, and all such modifications are included within the technical scope of the present disclosure.

[0065] Hydrogen gas was produced using the hydrogen gas production apparatus shown in Figure 3.

[0066] (No.1) The hydrogen gas production apparatus shown in Figure 3 was immersed in a raw material liquid, and current was passed through the cylindrical cathode 11 and the linear (coil-shaped) anode 22. Pure water was used as the raw material liquid. A container equipped with a heater was used to hold the raw material liquid. A silicon cord heater was used as the heater. The cylindrical cathode 11 was a hollow tube made of an alloy containing palladium, silver, and gold, with the remainder being unavoidable impurities. This alloy, containing palladium, silver, and gold, with the remainder being unavoidable impurities, is permeable to hydrogen ions but impermeable to hydrogen molecules. The coil-shaped anode 22 was a solid wire made of platinum. A cylindrical solid electrolyte member 3 was placed between the cylindrical cathode 11 and the coil-shaped anode 22, and Nafion®, manufactured by DuPont, was used as the solid electrolyte member 3. The pressure on the radially outer side of the cylindrical cathode 11 (i.e., on the coil-shaped anode 22 side) was set to 0.2 MPa. The temperature of the raw material liquid was set to 120°C, and the current supplied to the cylindrical cathode 11 and the coiled anode 22 was set to 0.785A, with a voltage of 5V. The theoretical hydrogen gas generation flow rate when the current supplied to the cylindrical cathode 11 and the coiled anode 22 was 0.785A and the voltage was 5V was 5.5 SCCM. The results of the energization are shown in Table 1 and Figure 6 below. Figure 6 is a graph showing the relationship between the temperature of the raw material liquid, the current supplied to the electrodes, the hydrogen gas generation flow rate, or the hydrogen gas generation efficiency (= hydrogen gas generation flow rate / theoretical generation flow rate × 100). In Figure 6, the black dotted lines represent the relationship between the temperature of the raw material liquid and the current supplied to the electrodes (left axis), the black solid lines represent the relationship between the temperature of the raw material liquid and the hydrogen gas generation flow rate (left axis), and the black squares with fine dotted lines represent the relationship between the temperature of the raw material liquid and the hydrogen gas generation efficiency (right axis).

[0067] (No.2) In Example 1, the conditions were the same as in Example 1 above, except that the temperature of the raw material liquid was set to 100°C and the current supplied to the cylindrical cathode 11 and the coiled anode 22 was set to 0.61A. The theoretical hydrogen gas flow rate when the current supplied to the cylindrical cathode 11 and the coiled anode 22 was 0.61A and the voltage was 5V was 4.2 SCCM. The results of the energization are shown in Table 1 and Figure 6 below.

[0068] (No.3) In Example 1, the conditions were the same as in Example 1 above, except that the temperature of the raw material liquid was set to 80°C and the current supplied to the cylindrical cathode 11 and the coiled anode 22 was set to 0.62A. The theoretical hydrogen gas flow rate when the current supplied to the cylindrical cathode 11 and the coiled anode 22 was 0.62A and the voltage was 5V was 4.3 SCCM. The results of the energization are shown in Table 1 and Figure 6 below.

[0069] (No.4) In Example 1, the conditions were the same as in Example 1, except that the temperature of the raw material liquid was set to 60°C and the current supplied to the cylindrical cathode 11 and the coiled anode 22 was set to 0.6A. The theoretical hydrogen gas flow rate when the current supplied to the cylindrical cathode 11 and the coiled anode 22 was 0.6A and the voltage was 5V was 4.2 SCCM. The results of the energization are shown in Table 1 and Figure 6 below.

[0070] [Table 1]

[0071] Next, the purity of the hydrogen gas obtained in samples No. 1-4 was measured using a dew point meter. The amount of impurities in the hydrogen gas was also measured using a gas chromatograph. Synthetic zeolite (MS-5A) or silica gel (Unibeads S) was used as the column packing material. The results showed that the impurities in the hydrogen gas obtained in samples No. 1-4 were less than 1 ppm, and the impurities included water vapor, oxygen, and carbon dioxide.

[0072] From Table 1, Figure 6, and the measurement results of hydrogen gas purity, the following conclusions can be drawn: High-purity hydrogen gas can be produced by using a hydrogen gas production apparatus that satisfies the requirements specified in this disclosure. It can be seen that increasing the temperature of the raw material liquid increases the current, increases the hydrogen gas generation flow rate, and improves the hydrogen gas generation efficiency. Although hydrogen gas could be produced even when the temperature of the raw material liquid was controlled to 120°C, the durability of the hydrogen gas production apparatus was slightly deteriorated because the heat resistance of Nafion® used as the solid electrolyte material 3 was only about 100°C.

[0073] Thus, by using the apparatus and method of this disclosure, it becomes possible to produce high-purity hydrogen gas, and the production efficiency can be increased compared to conventional technologies. As a result, greenhouse gas emissions can be reduced, and some of the Sustainable Development Goals (SDGs) can be achieved. [Explanation of Symbols]

[0074] 1 cathode 2 Anode 3. Solid electrolyte component 4. Hydrogen gas recovery passage 11. Cylindrical cathode 12 U-shaped cathode 21. Cylindrical anode 22 Linear (coil-shaped) anode 23. Band-shaped anode 31 Strip-shaped solid electrolyte member 100 Hydrogen gas production equipment

Claims

1. Cathode and, An anode is positioned opposite to one side of the cathode, A hydrogen gas production apparatus having a solid electrolyte member disposed between the cathode and the anode, A hydrogen gas production apparatus in which a hydrogen gas recovery passage is located on the other side of the cathode.

2. The hydrogen gas production apparatus according to claim 1, wherein the shape of the cathode is cylindrical with a longitudinal direction.

3. The hydrogen gas production apparatus according to claim 2, wherein the cylindrical cathode is closed at one end in the longitudinal direction and open at the other end in the longitudinal direction.

4. The hydrogen gas production apparatus according to claim 2, wherein a support member is arranged inside the cylindrical cathode.

5. The hydrogen gas production apparatus according to claim 1, wherein the cathode is permeable to hydrogen ions.

6. The hydrogen gas production apparatus according to claim 5, wherein the cathode is permeable to hydrogen ions but impermeable to hydrogen molecules.

7. The hydrogen gas production apparatus according to claim 5, wherein the cathode contains at least one selected from the group consisting of titanium, vanadium, manganese, nickel, copper, zirconium, niobium, palladium, silver, tantalum, platinum, and gold.

8. The hydrogen gas production apparatus according to claim 1, wherein the anode contains at least one selected from the group consisting of carbon, platinum, and gold.

9. The hydrogen gas production apparatus according to claim 1, wherein the solid electrolyte member contains perfluorocarbon.

10. Cathode and, An anode is positioned opposite to one side of the cathode, A solid electrolyte member is disposed between the cathode and the anode. A hydrogen gas production apparatus having a hydrogen gas recovery passage located on the other side of the cathode is immersed in a raw material liquid. The cathode and the anode are energized, A method for producing hydrogen gas, which involves recovering hydrogen gas from the aforementioned hydrogen gas recovery passage.

11. The manufacturing method according to claim 10, wherein the shape of the cathode is cylindrical with a longitudinal direction.

12. The manufacturing method according to claim 11, wherein the cylindrical cathode is closed at one end in the longitudinal direction and open at the other end in the longitudinal direction.

13. The manufacturing method according to claim 10, wherein the cathode is permeable to hydrogen ions.

14. The manufacturing method according to claim 13, wherein the cathode is permeable to hydrogen ions but not to hydrogen molecules.

15. The manufacturing method according to claim 10, wherein the temperature of the raw material liquid is controlled to 60°C to 95°C.

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