JP2015086454A - Differential pressure-system high-pressure water electrolysis apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress drying of a solid polymer electrolyte membrane as much as possible with a simple configuration.SOLUTION: An anode power supply body 40, a constituent of a differential pressure-system high-pressure water electrolysis apparatus 10, includes an electrolysis part 44 provided with an opening 44h for passing water through an anode catalyst layer 40a and a frame part 46 which is provided in the outer periphery of the electrolysis part 44 and formed more densely than the electrolysis part 44. While the anode catalyst layer 40a is provided only within the range of the electrolysis part 44, a cathode catalyst layer 42a is provided over a range including the range opposite to the anode catalyst layer 40a and the range facing the frame part 46.

Description

  The present invention relates to a differential pressure type high pressure water electrolysis apparatus that electrolyzes water to generate oxygen and hydrogen having a pressure higher than that of the oxygen.

  For example, hydrogen gas is used as a fuel gas for generating power from a fuel cell. Generally, when producing hydrogen gas, a water electrolysis apparatus is employed. This water electrolysis apparatus uses a solid polymer electrolyte membrane in order to electrolyze water and generate hydrogen (and oxygen). A catalyst layer is provided on both sides of the solid polymer electrolyte membrane to form an electrolyte membrane / electrode structure, and a power feeder is provided on each side of the electrolyte membrane / electrode structure to form a unit. It is configured.

  Therefore, in a state where a plurality of units are stacked, a voltage is applied to both ends in the stacking direction, and water is supplied to the anode power feeder. For this reason, water is decomposed and hydrogen ions (protons) are generated on the anode side of the electrolyte membrane / electrode structure. The hydrogen ions permeate the solid polymer electrolyte membrane and move to the cathode side, and combine with electrons to produce hydrogen. On the other hand, on the anode side, oxygen produced together with hydrogen is discharged from the unit with excess water.

  The water electrolysis apparatus employs a differential pressure type high pressure water electrolysis apparatus that produces oxygen and hydrogen having a pressure higher than that of oxygen by electrolysis of water. For example, in the electrochemical device disclosed in Patent Document 1, a first catalyst and a first power feeder are provided on one surface of the electrolyte membrane, and a second electrode is provided on the other surface of the electrolyte membrane. The catalyst and the second power feeder are provided.

  And as for the electric power feeding body with a small contact area range which contacts an electrolyte membrane, the contact surface with the said electrolyte membrane protrudes in the said electrolyte membrane side rather than the contact surface with the said electrolyte membrane of a separator. Therefore, the first power supply body and the second power supply body can reliably apply a desired surface pressure to the first and second catalysts provided on both sides of the electrolyte membrane, with a simple configuration. It is said that the electrolytic performance can be improved.

International Publication No. 2011/118482 Pamphlet

  By the way, in the differential pressure type high pressure water electrolysis apparatus, hydrogen in the high pressure cathode chamber easily passes through the solid polymer electrolyte membrane and moves (cross leak) to the anode chamber side at normal pressure. For this reason, in the solid polymer electrolyte membrane, there is a problem that water is discharged along with the cross leak in the portion where the catalyst is not applied and electrolysis is not performed, and membrane drying is caused.

  An object of the present invention is to solve this type of problem, and to provide a differential pressure type high pressure water electrolysis apparatus capable of suppressing the drying of a solid polymer electrolyte membrane as much as possible with a simple configuration. And

  The differential pressure type high pressure water electrolysis apparatus according to the present invention includes an electrolyte membrane in which an anode catalyst layer is provided on one surface and a cathode catalyst layer is provided on the other surface. An anode power supply is laminated on the anode catalyst layer, and an anode separator is laminated on the anode power supply. A cathode power supply is stacked on the cathode catalyst layer, and a cathode separator is stacked on the cathode power supply. In this differential pressure type high pressure water electrolysis apparatus, oxygen is generated on the anode side and hydrogen having a pressure higher than that of oxygen is generated on the cathode side by electrolysis of water.

  The anode power feeder includes an electrolysis part provided with an opening for allowing water to flow through the anode catalyst layer, and a frame part provided on the outer periphery of the electrolysis part and configured more densely than the electrolysis part. The anode catalyst layer is provided only within the range of the electrolysis portion, while the cathode catalyst layer includes the range facing the anode catalyst layer and is provided over the range facing the frame portion. Yes.

  In addition, this differential pressure type high pressure water electrolysis apparatus preferably includes a seal member that is disposed so as to surround the outer periphery of the cathode power supply and seals the cathode chamber in which hydrogen is generated. In that case, it is preferable that the seal member is disposed in a range facing the frame portion, and the cathode catalyst layer is provided inside the seal member.

  According to the present invention, the cathode catalyst layer has a larger area than the anode catalyst layer and is provided over a range facing the frame portion. For this reason, when water (entrained water) moves as protons move from the anode side to the cathode side during electrolysis, the water is supplied over a wide range to the cathode side.

  Therefore, the solid polymer electrolyte membrane can ensure a desired membrane water retention rate, and can effectively prevent membrane damage caused by electrolysis in a water-deficient state. Thereby, with a simple structure, drying of a solid polymer electrolyte membrane can be suppressed as much as possible, and deterioration of the said solid polymer electrolyte membrane can be suppressed.

It is a perspective explanatory view of a differential pressure type high pressure water electrolysis apparatus concerning an embodiment of the present invention. It is a disassembled perspective explanatory drawing of the unit cell which comprises the said differential pressure type high pressure water electrolyzer. FIG. 3 is a cross-sectional view of the unit cell taken along line III-III in FIG. 2. It is a cross-sectional explanatory drawing of the electrolyte membrane and electrode structure which comprises the said unit cell. It is principal part explanatory drawing of the electrolyte membrane and electrode structure of a comparative example.

  As shown in FIG. 1, a differential pressure type high pressure water electrolysis apparatus 10 according to an embodiment of the present invention includes a stacked body in which a plurality of unit cells 12 are stacked in a vertical direction (arrow A direction) or a horizontal direction (arrow B direction). 14.

  At one end (upper end) in the stacking direction of the stacked body 14, a terminal plate 16a, an insulating plate 18a, and an end plate 20a are sequentially disposed upward. Similarly, a terminal plate 16b, an insulating plate 18b, and an end plate 20b are sequentially disposed on the other end (lower end) in the stacking direction of the stacked body 14 in a downward direction.

  The differential pressure type high pressure water electrolysis apparatus 10 integrally clamps and holds the disk-shaped end plates 20a and 20b via four tie rods 22 extending in the direction of arrow A, for example. The differential pressure type high pressure water electrolysis apparatus 10 may employ a configuration in which the differential pressure type high pressure water electrolysis apparatus 10 is integrally held by a box-shaped casing (not shown) including the end plates 20a and 20b as end plates. Moreover, although the differential pressure type high pressure water electrolysis apparatus 10 has a substantially cylindrical shape as a whole, it can be set in various shapes such as a cubic shape.

  Terminal portions 24a and 24b are provided on the side portions of the terminal plates 16a and 16b so as to protrude outward. The terminal portions 24a and 24b are electrically connected to the electrolytic power source 28 via the wirings 26a and 26b.

  As shown in FIGS. 2 and 3, the unit cell 12 includes a substantially disc-shaped electrolyte membrane / electrode structure 32, and an anode separator 34 and a cathode separator 36 that sandwich the electrolyte membrane / electrode structure 32. The anode separator 34 and the cathode separator 36 have a substantially disc shape and are made of, for example, a carbon member. The anode separator 34 and the cathode separator 36 are formed by pressing or cutting a steel plate, a stainless steel plate, a titanium plate, an aluminum plate, a plated steel plate, or a metal plate whose surface is subjected to anticorrosion treatment. A surface treatment for anticorrosion may be applied.

  As shown in FIG. 4, the electrolyte membrane / electrode structure 32 includes a solid polymer electrolyte membrane 38 formed of, for example, a fluorine-based membrane or a hydrocarbon (HC) -based membrane. On both surfaces of the solid polymer electrolyte membrane 38, an anode power feeding body 40 and a cathode power feeding body 42 for electrolysis having a circular shape are provided.

  An anode catalyst layer 40 a is formed on one surface of the solid polymer electrolyte membrane 38, and a cathode catalyst layer 42 a is formed on the other surface of the solid polymer electrolyte membrane 38. The anode catalyst layer 40a uses, for example, a Ru (ruthenium) -based catalyst, while the cathode catalyst layer 42a uses, for example, a platinum catalyst. The planar dimension (application area) S1 of the cathode catalyst layer 42a includes a range facing the anode catalyst layer 40a, and is set to a dimension larger than the planar dimension (application area) S2 of the anode catalyst layer 40a.

  The anode power supply body 40 includes, for example, an electrolysis unit 44 that is formed of a sintered body (porous conductor) of spherical atomized titanium powder and is provided with an opening 44h through which water for electrolysis flows to the anode catalyst layer 40a. The electrolytic section 44 is provided with a smooth surface portion that is etched after the grinding process, and the porosity is set within a range of 10% to 50%, more preferably 20% to 40%.

  The anode power supply body 40 includes a ring-shaped frame portion 46 that is provided on the outer periphery of the electrolysis unit 44 and is configured more densely than the electrolysis unit 44. The electrolysis part 44 is fitted to the inner peripheral surface of the frame part 46, and the frame part 46 is made of pure titanium, for example. The anode catalyst layer 40 a is provided only within the range of the electrolysis unit 44. Specifically, the planar dimension (area) S2 of the anode catalyst layer 40a is set to be smaller than the planar dimension (area) S3 of the electrolysis unit 44.

  The cathode power supply 42 is, for example, a porous conductor integrally formed on the plate member 56 by low pressure plasma spraying using pure titanium particles as a spraying material. The porosity of the porous conductor is set within a range of 10% to 50%, and an opening 42h through which hydrogen flows is provided.

  The planar dimension (area) S4 of the cathode power supply 42 has a larger outer dimension than the planar dimension (area) S3 of the electrolysis unit 44 constituting the anode power supply 40, and the planar dimension (area) of the frame 46. Has a smaller dimension than S5. The planar dimension (area) S1 of the cathode catalyst layer 42a is the same as or less than the dimension of the planar dimension (area) S4 of the cathode power supply body 42, and is substantially in a range facing the anode catalyst layer 40a. It is provided over a range that includes and faces the frame portion 46.

  As shown in FIG. 2, a first protrusion 48 a, a second protrusion 48 b, and a third protrusion 48 c that protrude outward in the separator surface direction are formed on the outer periphery of the unit cell 12. The first protrusion 48a is provided with a water supply communication hole 50a that communicates with each other in the direction of arrow A, which is the stacking direction, and supplies water (pure water).

  The second projecting portion 48b is provided with a discharge communication hole 50b that communicates with each other in the direction of the arrow A and discharges oxygen generated by the reaction and used water. The third protrusion 48c is provided with a hydrogen communication hole 50c that is in communication with each other in the direction of arrow A, which is the stacking direction, for flowing high-pressure hydrogen generated by the reaction.

  As shown in FIGS. 2 and 3, the anode separator 34 is provided with a supply passage 52a communicating with the water supply communication hole 50a and a discharge passage 52b communicating with the discharge communication hole 50b. An anode chamber 53 in which the anode power feeding body 40 is disposed is provided on a surface 34 a of the anode separator 34 facing the electrolyte membrane / electrode structure 32. The anode chamber 53 is provided with a first flow path 54 communicating with the supply passage 52a and the discharge passage 52b.

  The cathode separator 36 is provided with a discharge passage 52c that communicates with the hydrogen communication hole 50c. On the surface 36a of the cathode separator 36 facing the electrolyte membrane / electrode structure 32, a cathode chamber (high pressure chamber) 60 in which the cathode power feeder 42, the plate member 56, and the disc spring 58 are disposed is provided.

  As shown in FIG. 3, the plate member 56 has a disk shape, and a second flow path 64 communicating with the discharge passage 52c is formed on the surface on the cathode power supply 42 side. The second flow path 64 is provided in a range corresponding to the contact area range of the cathode power supply body 42. The plate member 56 is provided with a pressing member, for example, a plurality of disc springs 58, on the surface opposite to the solid polymer electrolyte membrane 38 side. The disc spring 58 applies a load to the cathode power supply body 42 via a plate member 56 that is a disc spring holder.

  As shown in FIGS. 2 and 3, the surface 34 a of the anode separator 34 facing the electrolyte membrane / electrode structure 32 circulates outward from the first flow path 54 and the anode power supply body 40, and the first seal member 66 a. A first seal groove 68a is provided for disposing the first seal groove 68a.

  On the surface 34a, the second seal member 66b, the third seal member 66c, and the fourth seal member 66d are arranged around the outside of the water supply communication hole 50a, the discharge communication hole 50b, and the hydrogen communication hole 50c. A second seal groove 68b, a third seal groove 68c, and a fourth seal groove 68d are formed. The first seal member 66a to the fourth seal member 66d are, for example, O-rings.

  A first seal for disposing the first seal member 70a on the surface 36a of the cathode separator 36 facing the electrolyte membrane / electrode structure 32, orbiting the outside of the second flow path 64 and the cathode power feeder 42. A groove 72a is formed. The first seal member 70a is disposed in a range facing the frame portion 46 constituting the anode power feeder 40, and the cathode catalyst layer 42a is provided inside the first seal member 70a. Inside the first seal member 70a, there is a portion where drying due to cross leak is likely to occur. By covering this portion with the cathode catalyst layer 42a, it is possible to suppress a decrease in membrane water retention rate.

  On the surface 36a, the second seal member 70b, the third seal member 70c, and the fourth seal member 70d are arranged around the outside of the water supply communication hole 50a, the discharge communication hole 50b, and the hydrogen communication hole 50c. A second seal groove 72b, a third seal groove 72c, and a fourth seal groove 72d are formed. The first seal member 70a to the fourth seal member 70d are, for example, O-rings.

  As shown in FIG. 1, pipes 76a, 76b and 76c communicating with the water supply communication hole 50a, the discharge communication hole 50b and the hydrogen communication hole 50c are connected to the end plate 20a. Although not shown, the pipe 76c is provided with a back pressure valve (or electromagnetic valve), and the pressure of hydrogen generated in the hydrogen communication hole 50c can be maintained at a high pressure. A pressing force is applied between the end plates 20 a and 20 b by a pressing force applying device (not shown), and the end plates 20 a and 20 b are tightened via the tie rods 22 in this state.

  The operation of the differential pressure type high pressure water electrolysis apparatus 10 configured as described above will be described below.

  As shown in FIG. 1, water is supplied from a pipe 76a to the water supply communication hole 50a of the differential pressure type high-pressure water electrolysis apparatus 10, and is electrically connected to the terminal portions 24a and 24b of the terminal plates 16a and 16b. A voltage is applied via the electrolytic power supply 28. Therefore, as shown in FIGS. 2 and 3, in each unit cell 12, water is supplied from the water supply communication hole 50 a to the first flow path 54 of the anode separator 34, and this water constitutes the anode power supply body 40. It moves along the opening 44 h of the electrolysis unit 44.

  Therefore, water is decomposed by electricity in the anode catalyst layer 40a, and hydrogen ions, electrons, and oxygen are generated. Hydrogen ions generated by this anodic reaction permeate the solid polymer electrolyte membrane 38 and move to the cathode catalyst layer 42a side, and combine with electrons to obtain hydrogen.

  For this reason, hydrogen flows along the second flow path 64 formed in the opening 42 h of the cathode power supply 42 and the plate member 56. This hydrogen is maintained at a pressure higher than that of the water supply communication hole 50a, and can flow out of the differential pressure type high pressure water electrolysis apparatus 10 through the hydrogen communication hole 50c. On the other hand, oxygen generated by the reaction and used water flow through the first flow path 54, and these are discharged to the outside of the differential pressure type high-pressure water electrolysis apparatus 10 along the discharge communication hole 50b. .

  In this case, in the present embodiment, as shown in FIGS. 3 and 4, the cathode catalyst layer 42 a includes a range facing the anode catalyst layer 40 a and is provided over a range facing the frame portion 46. ing. For this reason, when protons move from the anode side to the cathode side during electrolysis, when water (entrained water) moves, the water is supplied over a wide range to the cathode side.

  For example, an electrolyte membrane / electrode structure 1 as a comparative example shown in FIG. 5 has an anode catalyst layer 3a and a cathode catalyst layer 4a formed on both surfaces of a solid polymer electrolyte membrane 2. The cathode catalyst layer 4a has a smaller area than the anode catalyst layer 3a, and the anode power feeding body 3 is disposed on the anode catalyst layer 3a.

  In this electrolyte membrane / electrode structure 1, hydrogen cross leaks from the high-pressure cathode side to the normal-pressure anode side, and the accompanying water easily moves to the anode feeder 3 side. Therefore, in the solid polymer electrolyte membrane 2, the membrane water retention rate decreases in the region T in the vicinity of the end portion of the catalyst layer, which may cause membrane deterioration.

  On the other hand, in this embodiment, since the proton-accompanying water spreads well to the end of the catalyst layer of the solid polymer electrolyte membrane 38, the solid polymer electrolyte membrane 38 can ensure a desired membrane water retention rate. it can. Thereby, it becomes possible to prevent membrane damage due to electrolysis in a water-deficient state, and with a simple configuration, drying of the solid polymer electrolyte membrane 38 is suppressed as much as possible, and membrane degradation is suppressed. The effect of being able to be obtained.

DESCRIPTION OF SYMBOLS 10 ... Differential pressure type high voltage | pressure water electrolysis apparatus 12 ... Unit cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18b ... Insulating plate 20a, 20b ... End plate 28 ... Electrolytic power supply 32 ... Electrolyte membrane and electrode structure 34 ... Anode separator 36 ... Cathode separator 38 ... Solid polymer electrolyte membrane 40 ... Anode feeder 40a ... Anode catalyst layer 42 ... Cathode feeder 42a ... Cathode catalyst layer 44 ... Electrolyzer 46 ... Frame 53 ... Anode chamber 54, 64 ... Channel 56 ... Plate member 60 ... Cathode chamber 70a ... Seal member

Claims (2)

An electrolyte membrane provided with an anode catalyst layer on one side and a cathode catalyst layer on the other side;
An anode power feeder laminated on the anode catalyst layer and a cathode power feeder laminated on the cathode catalyst layer;
An anode separator laminated on the anode feeder and a cathode separator laminated on the cathode feeder;
A differential pressure type high pressure water electrolysis apparatus in which oxygen is generated on the anode side by hydrogen electrolysis and hydrogen having a pressure higher than that of oxygen is generated on the cathode side,
The anode feeder is an electrolysis unit provided with an opening through which the water flows through the anode catalyst layer;
A frame portion provided on an outer periphery of the electrolysis portion and configured more densely than the electrolysis portion;
With
While the anode catalyst layer is provided only within the electrolysis part,
The differential pressure type high-pressure water electrolysis apparatus, wherein the cathode catalyst layer includes a range facing the anode catalyst layer, and is provided over a range facing the frame portion. The differential pressure type high-pressure water electrolysis apparatus according to claim 1, further comprising a seal member disposed so as to surround an outer periphery of the cathode power supply body and sealing a cathode chamber in which the hydrogen is generated,
The seal member is disposed in a range facing the frame portion,
The differential pressure type high-pressure water electrolysis apparatus, wherein the cathode catalyst layer is provided inside the seal member.

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