CN118186421A

CN118186421A - Diaphragm element, electrolytic cell, and gas production method

Info

Publication number: CN118186421A
Application number: CN202311718249.1A
Authority: CN
Inventors: 田中康行; 则安佑亮
Original assignee: Tokuyama Corp
Current assignee: Tokuyama Corp
Priority date: 2022-12-14
Filing date: 2023-12-13
Publication date: 2024-06-14
Also published as: WO2024128196A1

Abstract

The invention provides a diaphragm element, an electrolytic cell and a gas manufacturing method. The diaphragm element can improve the assembly workability of the electrolytic cell suitable for pressurized operation. The diaphragm element includes a diaphragm, a spacer for sandwiching a peripheral portion of the diaphragm, and a frame-shaped protection member, the protection member includes a frame-shaped base body, a frame-shaped cover member, and a plurality of screws, the base body includes a housing portion provided on an inner peripheral side of the base body and housing the spacer and the cover member, and a support portion extending so as to protrude from the housing portion toward the inner peripheral side of the base body, the support portion includes a screw hole to which the screws can be screwed, the cover member, the spacer, and the diaphragm include a1 st through hole, a2 nd through hole, and a 3 rd through hole through which the screws can pass, the cover member and the spacer sandwiching the diaphragm are housed in the housing portion, and the screws pass through the 1 st through hole to the 3 rd through hole and are screwed to the screw hole, whereby the spacer sandwiching the diaphragm is fastened by the cover member and the support portion, and the spacer, and the diaphragm are detachably fixed to the base body.

Description

Diaphragm element, electrolytic cell, and gas production method

Technical Field

The present invention relates to a diaphragm element, an electrolytic cell, and a gas production method, and more particularly, to a diaphragm element, an electrolytic cell, and a gas production method using the same, which can be suitably used in an electrolytic reaction (for example, electrolysis of alkaline water) under a pressurized condition.

Background

As a method for producing hydrogen and oxygen, alkaline water electrolysis is known. In alkaline electrolysis, an alkaline aqueous solution (alkaline water) in which an alkali metal hydroxide (e.g., naOH, KOH, etc.) is dissolved is used as an electrolyte to electrolyze water, thereby generating hydrogen gas from a cathode and oxygen gas from an anode. As an electrolytic cell for alkaline water electrolysis, the following electrolytic cells are known: the ion-permeable separator is provided with an anode chamber and a cathode chamber, wherein the anode chamber is provided with an anode, and the cathode chamber is provided with a cathode.

Prior art literature

Patent literature

Patent document 1: international publication No. 2013/191140

Patent document 2: japanese patent laid-open No. 2002-332586

Patent document 3: japanese patent No. 4453973

Patent document 4: international publication No. 2014/178317

Patent document 5: japanese patent No. 6093351

Patent document 6: japanese patent laid-open No. 2015-117417

Patent document 7: international publication No. 2019/188261

Disclosure of Invention

Problems to be solved by the invention

Fig. 1 is a partial cross-sectional view schematically illustrating a conventional alkaline water electrolyzer 900 according to one embodiment. The zero gap type electrolytic cell 900 includes: an electrolytic element (electrode chamber unit) 910, … including a flange portion 912 and an electrically conductive partition wall 911 that partitions the anode chamber a and the cathode chamber C; an ion-permeable separator 920 disposed between adjacent electrolytic elements 910, 910; gaskets 930, 930 disposed between the diaphragm 920 and the flange 912 of the electrolytic element 910, sandwiching the peripheral edge of the diaphragm 920; an anode 940 held by conductive ribs 913, … provided to stand up from the partition wall 911; a current collector 950 held by conductive ribs 914, … provided to stand up from the partition wall 911; and a flexible cathode 970 held by an electrically conductive elastic body 960, wherein the elastic body 960 is disposed in contact with the current collector 950. The peripheral edge of cathode 970 and the peripheral edge of conductive elastomer 960 are fixed to the peripheral edge of current collector 950. In electrolytic cell 900, flexible cathode 970 is pressed against separator 920 and anode 940 by conductive elastic body 960, and separator 920 is interposed between adjacent cathode 970 and anode 940.

The gas generated by electrolysis of alkaline water is generally circulated commercially in a state compressed to a predetermined pressure. When the pressure inside the electrode chamber is substantially normal pressure, the gas recovered from the electrode chamber is also substantially normal pressure, and therefore an external compression device for compressing the gas recovered from the electrolytic cell to a predetermined pressure outside the electrolytic cell is required. If the pressure in the polar chamber is higher than the normal pressure, it is considered that the capacity of such an external compression device is low or such an external compression device is not required, and the production cost of the gas can be reduced. Further, if the pressure in the polar chamber is increased, bubbles formed in the polar liquid by the gas generated in the polar chamber become small, and therefore the resistance between the electrodes decreases, and it is considered that even if the current density is the same, the electrolytic voltage can be reduced, and energy saving can be achieved.

However, in the conventional electrolytic cell 900 shown in fig. 1, further improvement in sealing performance is desired in order to increase the pressure inside the pole chamber. For example, in the electrolytic cell 900, electrolyte and/or gas may leak out of the electrolytic cell 900 via the porous membrane 920 itself and/or the contact of the membrane 920 with the gasket 930. Therefore, the peripheral edge portion of the diaphragm and the contact portion of the diaphragm and the gasket are preferably not communicated with the outside of the electrolytic cell. However, the structure in which the diaphragm is completely housed inside the electrolytic cell causes a problem in workability in the assembly process of the electrolytic cell.

In the conventional electrolytic cell 900, the electrolytic elements 910 and 910 having components (the gasket 930, the anode 940, the cathode current collector 950, the elastic body 960, and the cathode 970) other than the separator 920 are vertically erected (that is, in the posture of the paper surface of fig. 1), and the separator 920 is temporarily held in the vertical direction by another temporary holding means (for example, the hands of the operator), and the held separator 920 is sandwiched by the erected electrolytic elements 910 and 910, whereby the conventional electrolytic cell 900 is assembled. In the assembled electrolytic cell 900, the peripheral edge portion of the diaphragm 920 slightly protrudes from the outer peripheral portion of the electrolytic cell 900. In contrast, when an electrolytic cell having a structure in which a diaphragm is completely housed in the cell is assembled, it is not possible to use a structure in which the diaphragm temporarily held by another temporary holding means is sandwiched by electrolytic elements. The reason for this is that the temporary holding means of the membrane interfere with the electrolytic element. Thus, the method is implemented as follows: the electrolytic element 910 is placed in the horizontal direction, and the separator 920 and the adjacent electrolytic element 910 are placed in this order on the surface, and when a certain number (usually about 5 to 15 elements) are stacked, they are vertically erected, incorporated, and stacked. However, in this method, when the separator 920 is raised in the vertical direction, the holding force against the separator 920 in a soft state is insufficient, and a part of the separator tends to be deflected downward and fall.

Thus, it is desired to improve the workability of assembling an electrolytic cell suitable for a pressurizing operation.

The invention provides a diaphragm element capable of improving assembling workability of an electrolytic cell suitable for pressurized operation. Further, an electrolytic cell provided with the diaphragm element and a method for producing a gas using the electrolytic cell are provided.

Solution for solving the problem

The invention comprises the following technical schemes of [1] to [5 ].

[1] A diaphragm element, characterized in that,

The diaphragm element is provided with:

An ion-permeable separator having a1 st surface and a 2 nd surface;

a spacer that clamps a peripheral edge portion of the diaphragm; and

A frame-shaped protection member that accommodates and holds the gasket that sandwiches the diaphragm,

The protective member includes an electrically insulating frame-shaped base body, a frame-shaped cover member, and a plurality of screws,

The frame-shaped substrate is provided with:

A housing portion provided on an inner peripheral side of the base body and housing the gasket and the cover member; and

A support portion that extends from the storage portion toward the inner peripheral side of the base body and supports the gasket stored in the storage portion in a direction intersecting the main surface of the diaphragm,

The cover member has a shape and a size capable of being accommodated in the accommodating portion of the base body,

The cover member and the gasket holding the diaphragm are accommodated in the accommodation portion of the base body, whereby the gasket holding the diaphragm is held between the support portion of the base body and the cover member,

The support portion of the frame-shaped base body has a plurality of screw holes which are provided so as to face the gasket openings and can be screwed with the screws,

The cover member has a plurality of 1 st through holes provided at positions corresponding to the plurality of screw holes of the frame-shaped base body and through which the screws pass,

The gasket is provided with a plurality of 2 nd through holes which are arranged at positions corresponding to the plurality of screw holes of the frame-shaped basal body and can be penetrated by the screw,

The diaphragm is provided with a plurality of 3 rd through holes which are arranged at positions corresponding to the plurality of screw holes of the frame-shaped base body and can be penetrated by the screws,

The plurality of screw holes of the frame-shaped base body, the plurality of 1 st through holes of the cover member, the plurality of 2nd through holes of the gasket, and the plurality of 3 rd through holes of the diaphragm are communicated with each other,

The plurality of screws penetrate through the 1 st through hole of the cover member, the 2 nd through hole of the spacer, and the 3 rd through hole of the diaphragm, respectively, and are screwed into the screw holes of the frame-shaped base body, whereby the spacer sandwiching the diaphragm is fastened by the cover member and the support portion of the frame-shaped base body, and the cover member, the spacer, and the diaphragm are detachably fixed to the frame-shaped base body.

[2] An electrolytic cell, which is characterized in that,

The electrolytic cell is provided with:

A plurality of electrolytic elements stacked, each of the plurality of electrolytic elements including an anode, a conductive partition wall, and a cathode, the anode and the cathode being electrically connected to the partition wall; and

The separator element of claim 1 disposed between each adjacent one of said electrolytic elements,

The plurality of electrolytic elements are stacked in such a manner that anodes of the respective electrolytic elements appear on the same side of the conductive partition wall,

An anode chamber accommodating the anode is partitioned between the diaphragm of the diaphragm member and an electrolytic member adjacent to the diaphragm member,

A cathode chamber is defined between the diaphragm of the diaphragm element and another electrolytic element adjacent to the diaphragm element, which houses the cathode.

[3] A method for producing a gas, characterized in that,

At least hydrogen is produced by electrolysis of alkaline water,

The gas production method comprising a step (a) of electrolyzing alkaline water using the electrolytic cell according to claim 2,

The step (a) includes:

Supplying alkaline water as an electrolyte to each anode chamber and each cathode chamber of the electrolytic cell;

introducing direct current into the electrolytic tank; and

Hydrogen is recovered from the cathode chamber.

[4] The method of producing a gas according to [3], wherein the step (a) further comprises recovering oxygen from the anode chamber.

[5] The method for producing a gas according to [3] or [4], wherein in the step (a), the pressure in the anode chamber and/or the cathode chamber is maintained to be 20kPa or higher than the atmospheric pressure.

ADVANTAGEOUS EFFECTS OF INVENTION

In the diaphragm element of the present invention, the cover member and the spacer sandwiching the diaphragm are housed in the housing portion of the frame-shaped base body, and thereby the spacer sandwiching the diaphragm is sandwiched between the support portion of the base body and the cover member. The screws penetrate through the 1 st through hole, the 2 nd through hole, and the 3 rd through hole provided in the cover member, the spacer, and the diaphragm, respectively, and are screwed into the screw holes of the frame-shaped base body, whereby the spacer sandwiching the diaphragm is fastened by the cover member and the support portion of the frame-shaped base body, and the cover member, the spacer, and the diaphragm are detachably fixed to the frame-shaped base body. According to the diaphragm element of the present invention, the diaphragm element of the present invention is sandwiched by the electrolytic elements, and thus the electrolytic cell can be assembled, and therefore, the workability of assembling the electrolytic cell suitable for the pressurizing operation can be improved.

In the electrolytic cell of the present invention, the diaphragm element of the present invention is disposed between each adjacent electrolytic element. Therefore, according to the electrolytic cell of the present invention, the workability of assembling the electrolytic cell suitable for the pressurizing operation can be improved. In particular, even in the conventional method of assembling an electrolytic cell having a structure in which the diaphragm is completely housed in the electrolytic cell, when a predetermined number of electrolytic elements (usually about 5 to 15 elements) are stacked in the horizontal direction, the diaphragm is not likely to fall off due to a lack of holding force in some of the electrolytic elements when the electrolytic elements are vertically erected.

The gas production method of the present invention uses the electrolytic cell of the present invention to perform electrolysis, and therefore, even when the diaphragm 10 that deteriorates with use needs to be replaced with a new diaphragm 10, the time during which the electrolytic cell cannot be operated can be reduced, or the cost required for the replacement operation can be reduced.

Drawings

Fig. 1 is a cross-sectional view schematically illustrating a conventional alkaline water electrolyzer 900 according to one embodiment.

Fig. 2 (a) and 2 (B) are diagrams schematically illustrating a separator element 100 according to an embodiment of the present invention. Fig. 2 (a) is a top view of the diaphragm element 100. Fig. 2 (B) is a bottom view of the diaphragm element 100.

Fig. 3 (a) is a plan view of the base 31. Fig. 3 (B) is a plan view of the cover member 32.

Fig. 4 (a) is a top view of the diaphragm 10. Fig. 4 (B) is a top view of the gasket 20.

Fig. 5 (a) is a B-B cross-sectional view of fig. 2 (a). Fig. 5 (B) is an exploded view of fig. 5 (a).

Fig. 6 is a cross-sectional view schematically illustrating an electrolytic cell 1000 according to an embodiment of the present invention.

Fig. 7 is a B-B view of fig. 6.

Fig. 8 (a) is a view in which only the cathode-side pressing frame 62 is extracted from fig. 6. Fig. 8 (B) is a B-B cross-sectional view of fig. 8 (a).

Fig. 9 (a) is a drawing in which only the cathode-side insulating member 52 is extracted from fig. 6. Fig. 9 (B) is a B-B view of fig. 9 (a). Fig. 9 (C) is a C-C view of fig. 9 (a).

Fig. 10 (a) is a drawing in which only the cathode end member 220e is extracted from fig. 6. Fig. 10 (B) is a B-B view of fig. 10 (a). Fig. 10 (C) is a C-C view of fig. 10 (a).

Fig. 11 (a) is a view in which only the electrolytic element 200 is extracted from fig. 6. Fig. 11 (B) is a B-B view of fig. 11 (a). Fig. 11 (C) is a C-C view of fig. 11 (a).

Fig. 12 (a) is a drawing in which only the anode end member 210e is extracted from fig. 6. Fig. 12 (B) is a B-B view of fig. 12 (a). Fig. 12 (C) is a C-C view of fig. 12 (a).

Fig. 13 (a) is a view in which only the anode-side insulating member 51 is extracted from fig. 6. Fig. 13 (B) is a B-B cross-sectional view of fig. 13 (a).

Fig. 14 (a) is a view in which only the anode-side pressing frame 61 is extracted from fig. 6. Fig. 14 (B) is a B-B cross-sectional view of fig. 14 (a).

Description of the reference numerals

10. A (ion-permeable) separator; 20. a gasket; 30. a (frame-like) protective member; 31. a (frame-like) substrate; 31a, a housing part; 31b, a supporting portion; 31h, screw holes; 31ea, the 1 st electrolyte supply flow hole (anode liquid supply flow hole); 31eb, the 2 nd electrolyte supply flow hole (catholyte supply flow hole); 31ec, 2 nd electrolyte-gas recovery flow holes (catholyte-gas recovery flow holes); 31ed, 1 st electrolyte-gas recovery flow hole (anolyte-gas recovery flow hole); 31ga, 1 st channel groove (branch channel); 31gc, 2 nd channel (branch channel); 31s, a sealing member; 31fa, 1 st face; 31fb, 2 nd side; 32h, the 1 st through hole; 32ha, narrow portion (of the 1 st through hole); 32hb wide portion (of the 1 st through hole); 20h, the 2 nd through hole; 10h, 3 rd through holes; 32. a (frame-like) cover member; 33. a screw; 33a, a stem; 33b, a head; 41. a (conductive) partition wall; 45. 46, conductive ribs; 43. an anode; 44. a cathode; 51. an anode side insulating member; 52. a cathode-side insulating member; 61. an anode side pressing frame; 62. a cathode side pressing frame; 71. a2 nd electrolyte supply channel (catholyte supply channel); 72. a1 st electrolyte supply channel (anode liquid supply channel); 73. a1 st electrolyte-gas recovery flow path (anolyte-gas recovery flow path); 74. a2 nd electrolyte-gas recovery flow path (catholyte-gas recovery flow path); 81. a catholyte supply pipe; 82. an anolyte supply pipe; 83. an anolyte-gas recovery tube; 84. a catholyte-gas recovery tube; 100. a diaphragm element; 200. an electrolytic element; 210e, anode end member; 220e, cathode end member; 1000. an electrolytic cell; a1, A2, A3, anode chamber; c1, C2, C3, cathode chamber.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the drawings do not necessarily reflect exact dimensions. In the drawings, some reference numerals are omitted. In the present specification, unless otherwise specified, the expression "a to B" means "a or more and B or less" with respect to the numerical values a and B. In such a notation, when only the unit is labeled for the value B, the unit is also applicable to the value a. The terms "or" and "or" mean logical OR unless otherwise specified. In addition, the expression "E ₁ and E ₂,"E₁ and/or E ₂" means "E ₁ or E ₂, or a combination thereof", and the expression "E ₁、…、E_N-1 and/or E _N" means "E ₁、…、E_N-1 or E _N, or a combination thereof", with respect to the element E ₁、…、E_N (N is an integer of 3 or more). In fig. N (N is an integer of 4 or more), elements already shown in fig. 3 to M (M is an integer of 3 or more and less than N) are denoted by the same reference numerals as those in fig. 3 to M, and the description thereof may be omitted.

< 1. Diaphragm element >

Fig. 2 (a) and 2 (B) are diagrams schematically illustrating a separator element 100 (hereinafter, may be simply referred to as "separator element 100") according to an embodiment of the present invention. Fig. 2 (a) is a top view of the diaphragm element 100, and fig. 2 (B) is a bottom view of the diaphragm element 100. The separator element 100 includes an ion-permeable separator 10, gaskets 20 and 20 (hereinafter, sometimes simply referred to as "gaskets 20") that sandwich the peripheral edge portion of the separator 10, and a frame-shaped protection member 30 that holds the gaskets 20. The protection member 30 includes an electrically insulating frame-shaped base 31, a frame-shaped cover member 32, and a plurality of screws 33, … (hereinafter, sometimes simply referred to as "screws 33"). Fig. 2 (a) shows the 1 st surface 10a of the diaphragm 10, and fig. 2 (B) shows the 2 nd surface 10B of the diaphragm 10. Fig. 2 (a) shows the 1 st surface 31fa of the base 31, and fig. 2 (B) shows the 2 nd surface 31fb of the base 31. Fig. 3 (a) is a plan view of the base 31, fig. 3 (B) is a plan view of the cover member 32, fig. 4 (a) is a plan view of the diaphragm 10, and fig. 4 (B) is a plan view of the gasket 20. Fig. 5 (a) is a B-B cross-sectional view of fig. 2 (a), and fig. 5 (B) is an exploded view of fig. 5 (a). The base 31 includes: a housing portion 31a provided on the inner peripheral side of the base 31, and housing the gasket 20 (sandwiching the diaphragm 10) and the cover member 32; and a support portion 31B that extends so as to protrude from the storage portion 31a toward the inner peripheral side of the base 31, and supports the gasket 20 (fig. 5 (B)) stored in the storage portion 31a in a direction intersecting the main surface of the separator 10 (a direction on the left and right sides of the paper surface of fig. 5 (a) and 5 (B). Hereinafter, sometimes simply referred to as "stacking direction").

The screw 33 includes a shank 33a and a head 33B provided at one end of the shank 33a (fig. 5B). The support portion 31b of the base 31 includes a plurality of screw holes 31h, … (hereinafter, sometimes simply referred to as "screw hole 31 h") provided so as to open toward the spacer 20 and capable of being screwed with (the shaft portion 33a of) the screw 33 (fig. 3 a). The cover member 32 includes a plurality of 1 st through holes 32h, … (hereinafter, sometimes simply referred to as "1 st through holes 32 h") provided at positions corresponding to the plurality of screw holes 31h of the base body 31 and through which (the shaft portions 33a of) the screws 33 can pass (fig. 3 (B)).

Here, the opening direction of the screw hole 31h in the support portion 31b of the base 31 may be directed to the anode side or the cathode side, and is not particularly limited. In view of the ease of assembly workability of the electrolytic cell, it is more preferable that the pressing frame openings are opened toward the pressing frame having the pipe members (anolyte supply pipe, catholyte supply pipe, anolyte-gas recovery pipe, and catholyte-gas recovery pipe) connected to the outer surfaces thereof, among the anode-side pressing frame and the cathode-side pressing frame located at both ends of the electrolytic cell. Specifically, in the electrolytic cell 1000 according to an embodiment of the present invention shown in fig. 6 described later, these pipe members are connected to the outer surface of the cathode-side pressing frame 62, and the screw holes 31h of the support portion 31b of the base 31 are opened to the cathode-side pressing frame 62. In other words, in the anode-side pressing frame 61, these pipe members are not joined to the outer surface thereof, and the entire surface is flat. In this case, in the assembly of the electrolytic cell 1000, the anode-side pressing frame 61 having such a flat outer surface can be stably placed in the stacking of the electrolytic elements in the horizontal direction in the vicinity adjacent to the anode end unit 300e, and then the electrolytic elements can be stacked thereon. If the electrolytic element is stacked in this direction, the screw hole 31h of the support portion 31b opens upward in the base 31, and the tightening operation of the screw 33 to the screw hole 31h is easy.

The 1 st through hole 32h includes: a narrow portion 32ha through which the shank portion 33a of the screw 33 can pass, but through which the head portion 33b cannot pass; and a wide portion 32hb having a size capable of receiving a head portion 33B of the screw 33 when a shank portion 33a of the screw 33 penetrates the narrow portion 32ha and is screw-engaged with the screw hole 31h of the base 31 (fig. 5 (B)). The spacer 20 includes a plurality of 2 nd through holes 20h, … (hereinafter, sometimes simply referred to as "2 nd through holes 20 h") provided at positions corresponding to the plurality of screw holes 31h of the base 31 and through which the shaft portions 33a of the screws 33 can pass (fig. 4 (B)). The diaphragm 10 includes a plurality of 3 rd through holes 10h, … (hereinafter, sometimes simply referred to as "3 rd through hole 10 h") provided at positions corresponding to the plurality of screw holes 31h of the base 31 and through which the shaft portions 33a of the screws 33 can pass (fig. 4 (a)). When the cover member 32 and the spacer 20 sandwiching the diaphragm 10 are accommodated in the accommodation portion 31a of the base 31, the screw hole 31h of the base 31, the 1 st through hole 32h of the cover member 32, the 2 nd through hole 20h of the spacer 20, and the 3 rd through hole 10h of the diaphragm 10 communicate with each other (fig. 5 (a) and 5 (B)).

The cover member 32 has a size that can be accommodated in a step between the face of the base 31 that accommodates the gasket 20 (sandwiching the diaphragm 10) in the accommodation portion 31a and the face of the gasket (fig. 2 (a), 3 (a) and 3 (B), and 5 (a) and 5 (B)). That is, the outer peripheral portion of the cover member 32 has the same size as the inner Zhou Buda of the housing portion 31a of the base 31, the inner peripheral portion of the cover member 32 has the same size as the inner Zhou Buda of the supporting portion 31b of the base 31, and the thickness of the cover member 32 in the stacking direction is set to be substantially the same as the depth of the housing portion 31a of the base 31, as the sum of the thickness of the gaskets 20, 20 sandwiching the diaphragm 10 in the stacking direction and the thickness of the cover member 32 in the stacking direction. As shown in fig. 5 (a) and 5 (B), the gasket 20 (with the diaphragm 10 interposed therebetween) is held by being accommodated in the accommodation portion 31a of the base body 31 with the cover member 32 and the gasket 20 (with the diaphragm 10 interposed therebetween) being sandwiched between the support portion 31B of the base body 31 and the cover member 32. Then, (the rod portion 33a of) each of the plurality of screws 33 penetrates the 1 st through hole 32h of the cover member 32, the 2 nd through hole 20h of the spacer 20, and the 3 rd through hole 10h of the diaphragm 10, and is screwed to the screw hole 31h of the base 31, whereby the spacer 20 sandwiching the diaphragm 10 is fastened by the cover member 32 and the support portion 31b of the base 31, and the cover member 32, the spacer 20, and the diaphragm 10 are detachably fixed to the base 31.

As the separator 10, an ion permeable separator that can be used in an electrolytic cell (for example, an electrolytic cell for alkaline water electrolysis) using the separator element 100 can be used without particular limitation. The separator 10 is preferably low in gas permeability, low in electrical conductivity, and high in strength. Examples of the separator 10 include porous membranes made of asbestos or modified asbestos, porous membranes made of polysulfone-based polymers, cloth made of polyphenylene sulfide fibers, fluorine-based porous membranes, and porous membranes made of a mixed material containing both inorganic and organic materials. In addition to these porous separators, a fluorine ion exchange membrane or other ion exchange membrane can be used as the separator 10.

As the gasket 20, a gasket usable in an electrolytic cell (for example, an electrolytic cell for alkaline water electrolysis) using the diaphragm element 100 can be used without particular limitation. Fig. 5 (a) and 5 (B) show cross sections of the gasket 20. The gasket 20 has a flat shape, and holds the peripheral edge portion of the diaphragm 10, while the gasket 20 is held by being sandwiched between the support portion 31b of the base 31 and the cover member 32 in the housing portion 31a of the base 31. The gasket 20 is preferably formed of an elastomer having alkali resistance. Examples of the material of the gasket 20 include elastomers such as Natural Rubber (NR), styrene-butadiene rubber (SBR), chloroprene Rubber (CR), butadiene Rubber (BR), nitrile rubber (NBR), ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), isobutylene-isoprene rubber (IIR), and chlorosulfonated polyethylene rubber (CSM). In the case of using a gasket material having no alkali resistance, a layer or the like having an alkali resistance may be formed by coating the surface of the gasket material.

The substrate 31 is preferably electrically insulating to voltage application from the outside. In one embodiment, the base 31 is formed of an electrically insulating material. As the electrically insulating material forming the base 31, a resin material having alkali resistance and strength against a pressing force applied in the lamination direction can be preferably used, and preferable examples of such a resin material include a hard vinyl chloride resin, a polypropylene resin, a polyethylene resin, a polyetherimide resin, a polyphenylene sulfide resin, a polybenzimidazole resin, a polytetrafluoroethylene resin, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, a tetrafluoroethylene-ethylene copolymer resin, and the like. In another embodiment, the base 31 includes a core material made of a metal material and a cover layer made of an electrically insulating material covering the surface of the core material. Examples of the metal material forming the core material of the substrate 31 include a single metal such as iron and a rigid metal material such as stainless steel such as SUS 304. Further, as a preferable example of the electrical insulating material forming the cover layer of the substrate 31, an elastomer having electrical insulation and alkali resistance can be cited in addition to the above-mentioned electrical insulating resin material. Preferable examples of such an elastomer include elastomers such as Natural Rubber (NR), styrene-butadiene rubber (SBR), chloroprene Rubber (CR), butadiene Rubber (BR), nitrile rubber (NBR), ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), isobutylene-isoprene rubber (IIR), and chlorosulfonated polyethylene rubber (CSM). In the case of using an elastomer having no alkali resistance, a layer or the like having an alkali-resistant material may be formed on the surface of the elastomer.

The cover member 32 may be made of metal or an electrically insulating material. As an example of the metal material forming the cover member 32, the same metal material as described above with respect to the base 31 can be given. In one embodiment, the cover member 32 is formed of an electrically insulating material. As a preferable example of the electrical insulating material forming the cover member 32, the same resin material as that described above with respect to the base 31 can be given. In another embodiment, the cover member 32 includes a core material made of a metal material and a cover layer made of an electrically insulating material covering the surface of the core material. As an example of the metal material forming the core material of the cover member 32, a metal material having the same rigidity as the above description of the core material of the base 31 can be given. Further, as a preferable example of the electrical insulating material forming the cover layer of the cover member 32, the same resin material and elastomer as those described above with respect to the cover layer of the base 31 can be given.

Referring again to fig. 2 (a), 2 (B) and 3 (a). The 1 st electrolyte supply flow hole 31ea and the 2 nd electrolyte supply flow hole 31eb are provided as through holes in the lower portion of the base 31, respectively. The base 31 has a 2 nd electrolyte-gas recovery flow hole 31ec and a1 st electrolyte-gas recovery flow hole 31ed as through holes in the upper portion thereof, respectively. These through-holes, namely, the 1 st electrolyte supply through-hole 31ea and the 2 nd electrolyte supply through-hole 31eb and the 2 nd electrolyte-gas recovery through-hole 31ec and the 1 st electrolyte-gas recovery through-hole 31ed are provided on the outer peripheral sides of the housing portion 31a and the supporting portion 31 b. Referring to fig. 2 (B), the 2 nd surface 31fb of the base 31 is provided with the 1 st channel groove 31ga and the 2 nd channel groove 31gc which are in fluid communication with the electrode chamber facing the 2 nd surface 10B of the diaphragm 10. The 1 st flow channel 31ga is in fluid communication with the 1 st electrolyte supply flow hole 31 ea. The 2 nd flow channel 31gc is in fluid communication with the 1 st electrolyte-gas recovery flow hole 31ed. When the electrolytic cell is assembled, the diaphragm member 100 and the electrolytic element are laminated, whereby the 1 st electrolyte supply flow hole 31ea forms part of the 1 st electrolyte supply flow path, the 2 nd electrolyte supply flow hole 31eb forms part of the 2 nd electrolyte supply flow path, the 2 nd electrolyte-gas recovery flow hole 31ec forms part of the 2 nd electrolyte-gas recovery flow path, and the 1 st electrolyte-gas recovery flow hole 31ed forms part of the 1 st electrolyte-gas recovery flow path. At this time, the 1 st flow channel 31ga and the 2 nd flow channel 31gc are covered with adjacent electrolytic elements or end elements. The 1 st flow channel groove 31ga thus covered functions as a flow channel for guiding the 1 st electrolyte from the 1 st electrolyte supply flow channel to the electrode chamber facing the 2 nd surface 10b of the separator 10. The covered 2 nd flow channel groove 31gc functions as a flow channel for guiding the 1 st electrolyte and gas from the electrode chamber facing the 2 nd surface 10b of the separator 10 to the 1 st electrolyte-gas collection flow channel.

A seal 31s is provided at the peripheral edge of each of the 1 st electrolyte circulation hole 31ea and the 1 st electrolyte-gas recovery circulation hole 31ed so as to face at least the 1 st surface 31fa of the base 31. Further, a seal 31s is provided on the outer peripheral portion so as to face the 1 st surface 31 fa. The seal 31s functions to further improve the sealing properties of the electrolyte and gas during the pressurized operation of the electrolytic cell.

As a material of the seal 31s, an elastomer having resistance to an electrolyte (for example, alkaline water) of an electrolytic cell using the diaphragm element 100 can be used. As a preferable example of the alkali-resistant elastomer, the same elastomer as described above with respect to the gasket 20 can be given.

In the above description of the present invention, the diaphragm element 100 having the form of the seal 31s is described with reference to, but the diaphragm element of the present invention is not limited to this form. For example, the separator element may be configured without the seal 31 s.

In the above description of the present invention, the description has been made with reference to the separator element 100 having the 1 st flow channel groove 31ga and the 2 nd flow channel groove 31gc as the branched flow channels, but the separator element of the present invention is not limited to this form. For example, the separator may be configured without a branch flow path. For example, a diaphragm element having a form of a branched flow path passing through the inside of the base 31 may be provided instead of the 1 st and 2 nd flow path grooves 31ga and 31 gc.

In the above description relating to the present invention, the following description is made with reference to the separator element 100: the gasket 20 sandwiching the diaphragm 10 is fastened by the cover member 32 and the support portion 31b of the frame-shaped base 31 by a total of 8 screws 33, and the cover member 32, the gasket 20, and the diaphragm 10 are detachably fixed to the base 31, but the diaphragm element of the present invention is not limited to this form. The number of screws 33 provided in the diaphragm element 100 and the number of through holes through which the screws 33 pass and screw holes through which the screws 33 are screwed can be appropriately changed as necessary by those skilled in the art.

In the above description relating to the present invention, the following description is made with reference to the separator element 100: the separator 10 having a quadrangular shape includes a spacer 20 having a shape corresponding to the quadrangular shape of the separator 10 and a frame-shaped protection member 30, but the separator element of the present invention is not limited to this form. For example, the separator element may be configured as follows: the diaphragm has a circular shape, and includes a spacer having a shape corresponding to the circular shape of the diaphragm and a protection member.

< 2. Electrolytic cell >)

Fig. 6 is a cross-sectional view schematically illustrating an electrolytic cell 1000 according to an embodiment of the present invention. The electrolytic cell 1000 is an electrolytic cell for alkaline water electrolysis. Fig. 7 is a B-B view of fig. 6. In fig. 6 and 7, the vertical direction corresponds to the vertical direction. As shown in fig. 6, the electrolytic cell 1000 includes: a plurality of stacked electrolytic elements 200, … (hereinafter, sometimes simply referred to as "electrolytic element 200"), each electrolytic element 200 of the plurality of electrolytic elements 200 includes an anode 43, a conductive partition wall 41, and a cathode 44 in this order, and each of the anode 43 and the cathode 44 is electrically connected to the partition wall 41; and a separator element 100 (see fig. 2 to 5) disposed between the adjacent electrolytic elements 200, 200. The number of layers of the electrolytic element 200 between the anode end element 210e and the cathode end element 220e is not particularly limited, and is usually 10 to 400, more preferably 50 to 350.

The plurality of electrolytic elements 200 are stacked in such a manner that the anode 43 of each electrolytic element 200 appears on the same side of the conductive partition wall 41. Anode chambers a (A2, A3) accommodating the anode 43 are partitioned between the diaphragm 10 of the diaphragm element 100 and one electrolytic element 200 adjacent to the diaphragm element 100, and cathode chambers C (C1, C2) accommodating the cathode 44 are partitioned between the diaphragm 10 of the diaphragm element 100 and the other electrolytic element 200 adjacent to the diaphragm element 100.

Each of the electrolytic elements 200 further includes a flange portion 42, and the flange portion 42 is provided on the outer peripheral portion of the partition wall 41 and extends to both sides of the partition wall 41.

The electrolytic cell 1000 further comprises: an anode end element 210e including a conductive partition wall 41, A1 st flange portion 212e provided on an outer peripheral portion of the partition wall 41 and extending to one side of the partition wall 41, and an anode 43 electrically connected to the partition wall 41, the anode end element 210e defining an anode chamber A1; and a cathode end member 220e including a conductive partition wall 41, a 2 nd flange portion 222e provided on an outer peripheral portion of the partition wall 41 and extending to one side of the partition wall 41, and a cathode 44 electrically connected to the partition wall 41, the cathode end member 220e being configured to partition a cathode chamber C3. An anode chamber a (A1) that accommodates the anode 43 is partitioned between the anode end member 210e and the separator 10 of the separator member 100 adjacent to the anode end member 210 e. In addition, a cathode chamber C (C3) accommodating the cathode 44 is partitioned between the cathode end member 220e and the separator 10 of the separator member 100 adjacent to the cathode end member 220 e.

In each anode chamber a (A1 to A3), the anode 43 is connected to and held by a plurality of conductive ribs 45, … (hereinafter, sometimes simply referred to as "conductive ribs 45") protruding from the partition wall 41. In each of the cathode chambers C (C1 to C3), the cathode 44 is connected to and held by conductive ribs 46, … (hereinafter, sometimes simply referred to as "conductive ribs 46") protruding from the partition wall 41.

The anode end member 210e is contained in an anode end unit 300 e. The anode end unit 300e includes an anode-side pressing frame 61, an anode-side insulating member 51, and an anode end element 210e, which are disposed in this order from the anode-side end side of the electrolytic cell (right side of the drawing sheet of fig. 6). The cathode end member 220e is included in the cathode end unit 400 e. The cathode end unit 400e includes a cathode-side pressing frame 62, a cathode-side insulating member 52, and a cathode end element 220e, which are disposed in this order from the cathode-side end side of the electrolytic cell (left side of the drawing sheet of fig. 6).

Fig. 8 (a) is a view in which only the cathode-side pressing frame 62 is extracted from fig. 6, and fig. 8 (B) is a B-B cross-sectional view in fig. 8 (a). As shown in fig. 8 (B), the cathode-side pressing frame 62 includes a1 st electrolyte supply flow hole 62B and a2 nd electrolyte supply flow hole 62a provided as through holes in the lower portion thereof, respectively, and a1 st electrolyte-gas recovery flow hole 62c and a2 nd electrolyte-gas recovery flow hole 62d provided as through holes in the upper portion thereof, respectively. The cathode-side pressing frame 62 is a metal member.

Fig. 9 (a) is a view in which only the cathode-side insulating member 52 is extracted from fig. 6, and fig. 9 (B) is a B-B view in fig. 9 (a). As shown in fig. 9 (B), the cathode-side insulating member 52 includes a1 st electrolyte supply flow hole 52B and a2 nd electrolyte supply flow hole 52a provided as through holes in the lower portion thereof, respectively, and a1 st electrolyte-gas recovery flow hole 52c and a2 nd electrolyte-gas recovery flow hole 52d provided as through holes in the upper portion thereof, respectively. The seal 31s is provided on the outer peripheral portions of the 1 st electrolyte supply flow hole 52b, the 2 nd electrolyte supply flow hole 52a, the 1 st electrolyte-gas recovery flow hole 52c, and the 2 nd electrolyte-gas recovery flow hole 52d, respectively. Fig. 9 (C) is a C-C view of fig. 9 (a), and the cathode-side insulating member 52 includes a1 st electrolyte supply flow hole 52b, a2 nd electrolyte supply flow hole 52a, a1 st electrolyte-gas recovery flow hole 52C, and a2 nd electrolyte-gas recovery flow hole 52d. In fig. 6, the 1 st electrolyte supply flow hole 52b, the 2 nd electrolyte supply flow hole 52a, the 1 st electrolyte-gas recovery flow hole 52c, and the 2 nd electrolyte-gas recovery flow hole 52d of the cathode-side insulating member 52 are respectively in communication with the 1 st electrolyte supply flow hole 62b, the 2 nd electrolyte supply flow hole 62a, the 1 st electrolyte-gas recovery flow hole 62c, and the 2 nd electrolyte-gas recovery flow hole 62d of the cathode-side pressing frame 62.

Fig. 10 (a) is a view in which only the cathode end member 220e is extracted from fig. 6, fig. 10 (B) is a B-B view in fig. 10 (a), and fig. 10 (C) is a C-C view in fig. 10 (a). However, in fig. 10 (C), the conductive ribs 46 and the cathode 44 are omitted. As shown in fig. 10 (B) and 10 (C), a catholyte supply flow 25ea and an anolyte supply flow 25eb are provided below the 2 nd flange 222e of the cathode end member 220 e. Further, an anolyte-gas recovery flow-through portion 25ec and a catholyte-gas recovery flow-through portion 25ed are provided above the 2 nd flange portion 222e of the cathode end member 220 e.

Fig. 11 (a) is a view in which only the electrolytic element 200 is extracted from fig. 6, fig. 11 (B) is a B-B view in fig. 11 (a), and fig. 11 (C) is a C-C view in fig. 11 (a). However, in fig. 11 (B), the conductive ribs 45 and the anode 43 are omitted. In fig. 11 (C), the conductive ribs 46 and the cathode 44 are omitted. As shown in fig. 11 (B) and 11 (C), an anode liquid supply flow-through portion 42eb and a cathode liquid supply flow-through portion 42ea are provided below the flange portion 42 of the electrolytic element 200. A catholyte-gas recovery flow 42ed and an anolyte-gas recovery flow 42ec are provided above the flange 42 of the electrolytic element 200.

As shown in fig. 11 (a) and 11 (C), the electrolytic element 200 includes a cathode supply branch flow path 42gb provided in fluid communication with the cathode supply flow portion 42ea and the cathode chambers C (C1, C2), and the cathode is supplied from the 2 nd electrolyte supply flow path 71 to the cathode chambers C (C1, C2) via the cathode supply branch flow path 42gb, and the cathode supply flow portion 42ea constitutes a part of the 2 nd electrolyte supply flow path 71. The electrolytic element 200 further includes a catholyte-gas recovery branch flow path 42gd provided in fluid communication with the catholyte-gas recovery flow path 42ed and the cathode chamber C (C1, C2), and the catholyte-gas recovery flow path 42ed is provided to allow the gas in the catholyte and the cathode chamber to be recovered from the cathode chamber C (C1, C2) to the 2 nd electrolyte-gas recovery flow path 74 via the catholyte-gas recovery branch flow path 42gd, and the catholyte-gas recovery flow path 42ed constitutes a part of the 2 nd electrolyte-gas recovery flow path 74.

In each of the anode chambers a (A1 to A3), the anode solution is supplied from the 1 st electrolyte supply channel 72 to the anode chambers a (A1 to A3) via the 1 st channel groove 31ga (fig. 2 (B)) of the diaphragm member 100, and the 1 st electrolyte supply flow hole 31ea constitutes a part of the 1 st electrolyte supply channel 72. In each of the anode chambers a (A1 to A3), the 1 st electrolyte-gas recovery flow path 73 is recovered from the anode chamber a (A1 to A3) through the 2 nd flow path groove 31gc (fig. 2 (B)) of the diaphragm member 100, and the 1 st electrolyte-gas recovery flow hole 31ed constitutes a part of the 1 st electrolyte-gas recovery flow path 73.

Fig. 12 (a) is a view in which only the anode end member 210e is extracted from fig. 6, fig. 12 (B) is a B-B view in fig. 12 (a), and fig. 12 (C) is a C-C view in fig. 12 (a). However, in fig. 12 (B), the conductive ribs 45 and the anode 43 are omitted.

Fig. 13 (a) is a view in which only the anode-side insulating member 51 is extracted from fig. 6, and fig. 13 (B) is a B-B cross-sectional view of fig. 13 (a). As shown in fig. 13 (B), the anode-side insulating member 51 does not have a through hole communicating with any one of the 2 nd electrolyte supply channel 71, the 1 st electrolyte supply channel 72, the 1 st electrolyte-gas recovery channel 73, and the 2 nd electrolyte-gas recovery channel 74.

Fig. 14 (a) is a view in which only the anode-side pressing frame 61 is extracted from fig. 6, and fig. 14 (B) is a B-B cross-sectional view of fig. 14 (a). As shown in fig. 14 (B), the anode-side pressing frame 61 does not have a through hole communicating with any one of the 2 nd electrolyte supply channel 71, the 1 st electrolyte supply channel 72, the 1 st electrolyte-gas recovery channel 73, and the 2 nd electrolyte-gas recovery channel 74.

In the electrolytic cell 1000, the anolyte supply flow-through portion 42eb of each electrolytic element 200, the 1 st electrolyte supply flow-through hole 31ea of each diaphragm element 100, and the anolyte supply flow-through portion 25eb of the cathode end element 220e are in fluid communication with each other to form an integrated anolyte supply flow-through portion 72.

The anolyte-gas recovery flow-through portion 42ec of each electrolytic element 200, the 1 st electrolyte-gas recovery flow-through hole 31ed of each separator element 100, and the anolyte-gas recovery flow-through portion 25ec of the cathode end element 220e are in fluid communication with each other, forming an integrated anolyte-gas recovery flow-through portion 73.

The catholyte-supplying flow portion 42ea of each electrolytic element 200, the 2 nd electrolyte-supplying flow hole 31eb of each separator element 100, and the catholyte-supplying flow portion 25ea of the cathode end element 220e are in fluid communication with each other to form an integrated catholyte-supplying flow portion 71.

The catholyte-gas recovery flow 42ed of each electrolytic element 200, the 2 nd electrolyte-gas recovery flow 31ec of each separator element 100, and the catholyte-gas recovery flow 25ed of the cathode end element 220e are in fluid communication with each other to form an integrated catholyte-gas recovery flow 74.

The catholyte supply pipe 81 for supplying the catholyte to the catholyte supply flow portion 71 is connected to the catholyte supply flow portion 71 via the 2 nd electrolyte supply flow holes 62a, 52a, and the 2 nd electrolyte supply flow holes 62a, 52a are provided in the cathode side pressing frame 62 and the cathode side insulating member 52 so as to communicate with the catholyte supply flow portion 71 (see fig. 6 to 9).

The anolyte supply pipe 82 for supplying the anolyte to the anolyte supply flow-through portion 72 is connected to the anolyte supply flow-through portion 72 via the 1 st electrolyte supply flow-through holes 62b, 52b, and the 1 st electrolyte supply flow-through holes 62b, 52b are provided in the cathode side pressing frame 62 and the cathode side insulating member 52 so as to communicate with the anolyte supply flow-through portion 72 (see fig. 6 to 9).

The anolyte-gas recovery pipe 83 that recovers the anolyte and the gas from the anolyte-gas recovery flow-through portion 73 is connected to the anolyte-gas recovery flow-through portion 73 via the 1 st electrolyte-gas recovery flow-through holes 62c, 52c, and the 1 st electrolyte-gas recovery flow-through holes 62c, 52c are provided in the cathode-side pressing frame 62 and the cathode-side insulating member 52 so as to communicate with the anolyte-gas recovery flow-through portion 73 (see fig. 6 to 9).

The catholyte-gas recovery pipe 84 that recovers the catholyte and the gas from the catholyte-gas recovery flow portion 74 is connected to the catholyte-gas recovery flow portion 74 via the 2 nd electrolyte-gas recovery flow holes 62d, 52d, and the 2 nd electrolyte-gas recovery flow holes 62d, 52d are provided in the cathode side pressing frame 62 and the cathode side insulating member 52 so as to communicate with the catholyte-gas recovery flow portion 74 (see fig. 6 to 9).

As a material of the conductive partition wall 41, a rigid conductive material having resistance to the environment in operation of the electrolytic cell 1000 (for example, having alkali resistance) can be used without particular limitation, and for example, a metal material such as the following is preferably used: monomer metals such as nickel and iron; common steels (i.e., low carbon steel and medium carbon steel), high carbon steel and the like, stainless steels (e.g., SUS304, SUS310S, SUS, SUS316L and the like), and the like. In order to improve corrosion resistance and conductivity, these metal materials may be used by plating nickel. As a material of the flange portions 42, 212e, and 222e, for example, a material having rigidity against alkali can be used without particular limitation, and for example, a metal material such as the following can be preferably used: monomer metals such as nickel and iron; common steels (i.e., low carbon steel and medium carbon steel), high carbon steel and the like, stainless steels (e.g., SUS304, SUS310S, SUS, SUS316L and the like), and the like. In order to improve corrosion resistance, the metal material may be plated with nickel. The partition wall 41 and the flange 212e of the anode end member 210e may be joined by welding, adhesion, or the like, or may be integrally formed of the same material. Similarly, the partition wall 41 and the flange 222e of the cathode end member 220e may be joined by welding, adhesion, or the like, or may be integrally formed of the same material. The partition wall 41 and the flange 42 of each electrolytic element 200 may be joined by welding, adhesion, or the like, or may be integrally formed of the same material. However, in terms of easily improving the resistance to the pressure inside the polar chamber, the partition wall 41 and the flange 212e of the anode end element 210e are preferably integrally formed of the same conductive material (for example, the metal material described above), the partition wall 41 and the flange 222e of the cathode end element 220e are preferably integrally formed of the same conductive material (for example, the metal material described above), and the partition wall 41 and the flange 42 of each electrolytic element 200 are preferably integrally formed of the same conductive material (for example, the metal material described above).

As the anode 43, an anode that can be used in the anode reaction of the electrolytic cell 1000 (for example, in the case where the electrolytic cell 1000 is an electrolytic cell for alkaline water electrolysis, an oxygen generation reaction) can be used without particular limitation. The anode 43 is generally provided with a conductive substrate and a catalyst layer covering the surface of the substrate. The catalyst layer is preferably porous. As the conductive substrate of the anode 43 suitable for the oxygen generation reaction, for example, nickel alloy, nickel iron, vanadium, molybdenum, copper, silver, manganese, platinum group element, graphite or chromium, or a combination thereof can be used. In the anode 43, a conductive base material made of nickel can be preferably used. The catalyst layer preferably contains nickel element. The catalyst layer preferably contains nickel oxide, metallic nickel or nickel hydroxide, or a combination thereof, and may contain an alloy of nickel and 1 or more other metals. The catalyst layer is particularly preferably composed of metallic nickel. The catalyst layer may further contain chromium, molybdenum, cobalt, tantalum, zirconium, aluminum, zinc, a platinum group element, a rare earth element, or a combination thereof. Rhodium, palladium, iridium, ruthenium, or a combination thereof may be further supported on the surface of the catalyst layer as an additional catalyst. The conductive substrate of the anode 43 may be either a rigid substrate or a flexible substrate. Examples of the rigid conductive substrate constituting the anode 43 include a porous metal mesh and a punched metal. Further, as the flexible conductive base material constituting the anode 43, for example, a metal mesh woven (or knitted) from metal wires, or the like can be cited.

As the cathode 44, a cathode that can be used in the cathode reaction of the electrolytic cell 1000 (for example, in the case where the electrolytic cell 1000 is an electrolytic cell for alkaline water electrolysis, hydrogen generation reaction) can be used without particular limitation. The cathode 44 generally includes a conductive substrate and a catalyst layer covering the surface of the substrate. As the conductive base material of the cathode 44 suitable for the hydrogen generation reaction, for example, nickel alloy, stainless steel, mild steel, nickel alloy, or a material obtained by plating nickel on the surface of stainless steel or mild steel can be preferably used. As the catalyst layer of the cathode 44, a noble metal oxide, nickel, cobalt, molybdenum, or manganese, or an oxide thereof, or a catalyst layer composed of a noble metal oxide can be preferably used. The conductive substrate constituting the cathode 44 may be, for example, a rigid substrate or a flexible substrate. Examples of the rigid conductive substrate constituting the cathode 44 include a porous metal mesh and a punched metal. Further, as the flexible conductive base material constituting the cathode 44, for example, a metal mesh woven (or knitted) from metal wires, or the like can be cited.

As the conductive ribs 45 and 46, known conductive ribs can be used. In the electrolytic cell 1000, the conductive rib 45 is provided so as to protrude from the partition wall 41 of the electrolytic element 200 and the anode end element 210e, and the conductive rib 46 is provided so as to protrude from the partition wall 41 of the electrolytic element 200 and the cathode end element 220 e. The connection method, shape, number, and configuration of the conductive ribs 45 are not particularly limited as long as the conductive ribs 45 fix and hold the anode 43 with respect to the electrolytic element 200 and the anode-end element 210 e. In addition, as long as the conductive ribs 46 fix and hold the cathode 44 with respect to the electrolytic element 200 and the cathode end member 220e, the connection method, shape, number, and arrangement of the conductive ribs 46 are not particularly limited. As the material of the conductive ribs 45 and 46, a rigid conductive material having resistance (for example, alkali resistance) to the environment in operation of the electrolytic cell 1000 can be used without particular limitation, and for example, a metal material such as the following is preferably used: monomer metals such as nickel and iron; common steels (i.e., low carbon steel and medium carbon steel), high carbon steel and the like, stainless steels (e.g., SUS304, SUS310S, SUS, SUS316L and the like), and the like. These metal materials may be plated with nickel for the purpose of improving corrosion resistance and conductivity.

As the anode-side insulating member 51 and the cathode-side insulating member 52 (refer to fig. 6, 9, and 13, hereinafter, sometimes simply referred to as "insulating member 51 and insulating member 52"), insulating members that can be used for electrical insulation between the anode end element and the anode-side pressing frame and electrical insulation between the cathode end element and the cathode-side pressing frame in an electrolytic cell (for example, for alkaline water electrolysis) can be used without particular limitation. Examples of the material of the insulating member 51 and the insulating member 52 include a hard vinyl chloride resin, a polypropylene resin, a polyethylene resin, a nylon resin, a polyacetal resin, an amorphous polyester resin, a polyether ether ketone resin, a polyether imide resin, a polyphenylene sulfide resin, a polybenzimidazole resin, a polytetrafluoroethylene resin, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, a tetrafluoroethylene-ethylene copolymer resin, and the like.

The anode side pressing frame 61 and the cathode side pressing frame 62 (see fig. 6 to 8 and 14, hereinafter, sometimes simply referred to as "pressing frame 61 and pressing frame 62") are fastened by tie bars, not shown, whereby the insulating members 51 and 52, the respective electrolytic elements 200, the respective separator elements 100, the anode end element 210e and the cathode end element 220e, which are disposed between the anode side pressing frame 61 and the cathode side pressing frame 62, are integrated. The pressing frame 61 and the pressing frame 62 are formed of a metal material having rigidity that withstands the load of the above-described fastening. Examples of the metal material constituting the pressing frame 61 and the pressing frame 62 include carbon steel such as SS400, stainless steel such as SUS304 and SUS316, and the like.

In the electrolytic cell 1000, the peripheral edge portion of the diaphragm 10 and the contact portion of the diaphragm 10 with the gasket 20 do not communicate with the outside of the electrolytic cell, and therefore, have a structure suitable for the pressurizing operation. On the other hand, in the electrolytic cell 1000, the flexible diaphragm 10 is housed and held in the diaphragm element 100, and therefore, it is not necessary to use a separate temporary holding means to temporarily hold the diaphragm 10 at the time of assembly work of the electrolytic cell 1000. Even if the assembly of the electrolytic cell is performed by vertically standing and stacking a predetermined number of electrolytic elements (usually about 5 to 15 elements) in the horizontal direction, the problem that the separator is deflected downward and falls down in a part of the electrolytic elements due to insufficient holding force does not occur when the vertical standing is performed. Therefore, the electrolytic cell 1000 is suitable for pressurized operation, and can improve the workability of assembly.

In addition, in the electrolytic cell 1000, workability of the disassembly and reassembly work for replacing the diaphragm 10 deteriorated by use is also improved. In the diaphragm element 100, the screw 33 is screwed into the screw hole of the frame-shaped base body 31, whereby the spacer 20 sandwiching the diaphragm 10 is fastened by the support portion 31b of the frame-shaped base body 31 and the cover member 32, the spacer 20, and the diaphragm 10 are detachably fixed to the frame-shaped base body 31. Therefore, when the diaphragm 10 is replaced, the frame-shaped base 31 and the cover member 32 can be reused, and if the gasket 20 is in a good state, the gasket 20 can be reused. Moreover, when the new diaphragm 10 is used to assemble the diaphragm element 100, no operation such as heating is required that negatively affects the performance or lifetime of the diaphragm 10.

An anode terminal is connected to the anode end member 210e, and a cathode terminal is connected to the cathode end member 220 e. The anode side pressing frame 61, the cathode side pressing frame 62, the catholyte supply pipe 81, the anolyte supply pipe 82, the anolyte-gas recovery pipe 83, and the catholyte-gas recovery pipe 84 are preferably electrically grounded (fig. 6 and 7).

When electrolysis is performed while maintaining at least one of the anode chamber and the cathode chamber at a high pressure higher than the atmospheric pressure, the pressure in the cathode chamber is preferably a high pressure higher than the atmospheric pressure by 20kPa or more, more preferably a high pressure higher than 400kPa or more, and still more preferably a high pressure higher than 800kPa or more. The upper limit of the pressure in the cathode chamber depends on the strength of the member constituting the electrolytic cell, and can be set to be less than atmospheric pressure +3000kPa, for example. By setting the pressure inside the cathode chamber to the lower limit value or more, the compression ratio in the pressure increasing step after hydrogen is recovered from the cathode chamber can be reduced, or the pressure increasing step can be omitted, so that the equipment cost can be reduced, and space saving and energy saving can be realized for the whole equipment. In addition, the pressure inside the cathode chamber is equal to or higher than the lower limit value, whereby the effect of reducing the electrolytic voltage can be obtained. This is considered to be because the size of the bubbles generated in the cathode chamber becomes small, and thus the bubble resistance between the anode and the cathode is lowered.

In the case of performing electrolysis while maintaining at least one of the anode chamber and the cathode chamber at a high pressure higher than the atmospheric pressure, the pressure in the anode chamber is preferably a high pressure higher than the atmospheric pressure by 20kPa or more, more preferably a high pressure higher than 400kPa or more, and still more preferably a high pressure higher than 800kPa or more. The upper limit of the pressure inside the anode chamber depends on the strength of the member constituting the electrolytic cell, and can be set to be less than atmospheric pressure +3000kPa, for example. By setting the pressure inside the anode chamber to the lower limit value or more, the compression ratio in the pressure increasing step after oxygen is recovered from the anode chamber can be reduced, or the pressure increasing step can be omitted, so that the equipment cost can be further reduced, and space saving and energy saving can be further realized in the whole equipment. In addition, the pressure inside the anode chamber is equal to or higher than the lower limit value, whereby the effect of reducing the electrolytic voltage can be obtained. This is considered to be because the size of the bubbles generated in the anode chamber becomes smaller, and thus the bubble resistance between anode and cathode is further reduced.

The difference between the pressure inside the cathode chamber and the pressure inside the anode chamber is, for example, preferably less than 5.0kPa, more preferably less than 1.0kPa. When the difference between the pressure in the cathode chamber and the pressure in the anode chamber is smaller than the upper limit value, the movement of the gas from the anode chamber to the cathode chamber or from the cathode chamber to the anode chamber due to the pressure difference between the anode chamber and the cathode chamber is easily suppressed, and the damage of the diaphragm due to the pressure difference between the anode chamber and the cathode chamber is easily suppressed.

In the above description of the present invention, the example of the electrolytic cell 1000 in which the respective polar liquid supply/recovery pipes 81 to 84 are connected to the respective polar liquid supply/recovery channels 71 to 74 via the 1 st through-holes 62a/52a to 4 th through-holes 62d/52d provided in the cathode side pressing frame 62 and the cathode side insulating member 52 has been described, but the present invention is not limited to this embodiment. For example, one or more of the respective polar liquid supply pipes and recovery pipes may be connected to the corresponding polar liquid supply flow path and recovery flow path via through holes provided in the anode side pressing frame and the anode side insulating member.

< 3. Gas manufacturing method >

The electrolytic cell of the present invention can be preferably used for, for example, production of a gas by electrolysis of alkaline water. The method for producing a gas according to one embodiment is a method for producing at least hydrogen by electrolyzing alkaline water, and includes (a) a step of electrolyzing alkaline water using the electrolytic cell of the present invention. As the electrolytic cell in the step (a), for example, the electrolytic cell 1000 described above can be used. As the alkaline water, a known alkaline aqueous solution (for example, KOH aqueous solution, naOH aqueous solution, etc.) used in producing hydrogen by alkaline electrolysis can be used without particular limitation.

The step (a) can be performed as follows: an electrolyte (alkaline water) is supplied to each anode chamber and each cathode chamber of the electrolytic cell of the present invention, and a voltage is applied so that a predetermined electrolytic current flows between the anode and the cathode (direct current is supplied to the electrolytic cell). The gas generated by electrolysis is recovered from each of the electrode chambers together with the electrolyte solution, and gas-liquid separation is performed, whereby hydrogen gas can be recovered from the cathode chamber and oxygen gas can be recovered from the anode chamber. The electrolyte separated from the gas by gas-liquid separation can be supplied with water again to each pole chamber as needed.

In the step (a), the pressure in the cathode chamber is preferably maintained at a high pressure of 20kPa or more higher than the atmospheric pressure. The pressure in the cathode chamber is preferably a high pressure of 400kPa or more, more preferably 800kPa or more, relative to the atmospheric pressure. The upper limit of the pressure inside the cathode chamber depends on the strength of the member constituting the electrolytic cell, and can be set to be less than atmospheric pressure +1000kPa, for example. By setting the pressure inside the cathode chamber to the lower limit value or more, the compression ratio in the pressure increasing step after hydrogen is recovered from the cathode chamber can be reduced, or the pressure increasing step can be omitted, so that the equipment cost can be reduced, and space saving and energy saving can be realized for the whole equipment. In addition, since the pressure inside the cathode chamber is equal to or higher than the lower limit, the size of bubbles generated in the cathode chamber is reduced, and the resistance between the anode and the cathode is reduced, so that the electrolytic voltage can be reduced.

In the step (a), the pressure in the anode chamber is preferably maintained at a high pressure of 20kPa or more higher than the atmospheric pressure. The pressure in the anode chamber is preferably a high pressure of 400kPa or more, more preferably 800kPa or more, relative to the atmospheric pressure. The upper limit of the pressure inside the anode chamber depends on the strength of the member constituting the electrolytic cell, and can be set to be less than atmospheric pressure +1000kPa, for example. By setting the pressure inside the anode chamber to the lower limit value or more, the compression ratio in the pressure increasing step after oxygen is recovered from the anode chamber can be reduced, or the pressure increasing step can be omitted, so that the equipment cost can be further reduced, and space saving and energy saving can be further realized in the whole equipment. In addition, since the pressure inside the anode chamber is equal to or higher than the lower limit, the size of the bubbles generated in the anode chamber is reduced, and the resistance between the anode and the cathode is further reduced, so that the electrolytic voltage can be further reduced.

In the step (a), the difference between the pressure in the cathode chamber and the pressure in the anode chamber is preferably less than 5.0kPa, more preferably less than 1.0kPa, for example. When the difference between the pressure in the cathode chamber and the pressure in the anode chamber is smaller than the upper limit value, the movement of the gas from the anode chamber to the cathode chamber or from the cathode chamber to the anode chamber due to the pressure difference between the anode chamber and the cathode chamber is easily suppressed, and the damage of the diaphragm due to the pressure difference between the anode chamber and the cathode chamber is easily suppressed.

The electrolytic cell of the present invention improves the workability of assembly, and therefore, even when the diaphragm 10 that deteriorates with use needs to be replaced with a new diaphragm 10, the time during which the electrolytic cell is not operated can be reduced, or the cost required for the replacement operation can be reduced.

In addition, the electrolytic cell of the present invention improves the resistance to the pressure inside the polar chamber and suppresses the performance degradation of the diaphragm caused by the heat and mechanical pressure to which the diaphragm is subjected. Accordingly, by using the electrolytic cell of the present invention to electrolyze alkaline water, electrolysis can be performed more safely and more efficiently even under conditions where the pressure inside the polar chamber is increased.

Claims

1. A diaphragm element, characterized in that,

The diaphragm element is provided with:

An ion-permeable separator having a1 st surface and a 2 nd surface;

a spacer that clamps a peripheral edge portion of the diaphragm; and

The frame-shaped substrate is provided with:

2. An electrolytic cell, which is characterized in that,

The electrolytic cell is provided with:

3. A method for producing a gas, characterized in that,

At least hydrogen is produced by electrolysis of alkaline water,

The step (a) includes:

introducing direct current into the electrolytic tank; and

Hydrogen is recovered from the cathode chamber.

4. A gas production method according to claim 3, wherein,

The process (a) further comprises recovering oxygen from the anode chamber.

5. A method for producing a gas according to claim 3 or 4, wherein,

In the step (a), the pressure in the anode chamber and/or the cathode chamber is maintained at a level higher than the atmospheric pressure by 20kPa or more.