JP2000212785A - Water-electrolysis gas generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower an electric resistance and to minimize resistance loss by bringing an ion-exchange membrane into full contact with an electrode plate in a generator for generating a gas by electrolyzing water by the use of the membrane because of that the magnitude of the contact resistance depends on whether contact of the membrane with the electrode plate is sufficient or not to cause a heat loss. SOLUTION: An anode plate 1b and a cathode plate 1a are set on both sides of an ion-exchange membrane 2 in this water-electrolysis gas generator. In this case, the surface of the membrane 2 is coated with platinum or palladium by sputtering, the upper surface is electroless-plated with platinum and iridium, and a carbon grain 3 is firmly held between the membrane and cathode plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water electrolysis gas generator for electrolyzing water using an ion exchange membrane to generate oxygen gas, hydrogen gas or ozone gas, and hydrogen gas. The present invention relates to a water electrolysis gas generator using an ion exchange membrane having a structure and a close contact material made of carbon particles.

[0002]

2. Description of the Related Art A diaphragm electrolysis method using an ion exchange membrane is used as a water electrolysis gas generator. In particular, in order to provide a water electrolysis device with high electrolysis efficiency, an anode and a cathode are provided on both sides of a solid polymer electrolyte diaphragm. Electrolytic devices have been developed which improve the electrolytic efficiency by bringing a porous electrode such as carbon fiber into close contact.

However, even in the above-described conventional water electrolysis gas generator, it is difficult to make the electrode plate and the ion exchange membrane adhere to each other over the entire surface, and it is not possible to achieve a sufficiently satisfactory electrolysis efficiency, In use, there was a problem that the catalyst on the ion exchange membrane fell off. That is, although the electro-exchange plating such as platinum is applied as a catalyst to the ion exchange membrane used in the conventional water electrolysis gas generator, it does not have a satisfactory function in the adhesiveness, and in long-term use. In addition, there has been a problem that the catalyst on the ion exchange membrane drops off. Furthermore, a method of reducing contact resistance and reducing power consumption by adhering a porous electrode such as carbon fiber as an anode and a cathode on both sides of the diaphragm has been studied. The need for generators is increasing.

[0004] That is, when the cell voltage of water electrolysis using a conventional ion exchange membrane is V _t (V),

[0005] V _t (V) is given by the following equation.

[0006]

(Equation 1)

The power consumption at this time is V _t · I, and the amount of gas obtained by electrolysis depends only on the current (I). Therefore, the power consumption should be reduced by lowering the cell voltage (V _t ) as much as possible. Less and more energy efficient. Generally, when platinum is used for the cathode and anode, the overvoltage is about 2
V (100 A / dm ² ). The cell voltage (V _t ) is about 3 V, and the difference of about 1 V is a voltage drop due to the contact resistance and the conductor resistance, resulting in a loss of about 100 W.

Therefore, attempts have been made to reduce the contact resistance (Rc) while keeping the conductor resistance (R _L ) as close to zero as possible. As part of this attempt, the inventor provided box-shaped partitions 5 on both sides of the ion-exchange membrane 2 first, as shown in FIG.
By forming the uneven surface as the metal-coated surface 6 subjected to the metal coating, the surface area of the electrode can be increased and the electric resistance can be reduced. Therefore, the voltage between the electrodes is reduced, and the electrolytic efficiency of electrolysis is improved. Oxygen / hydrogen electrolysis gas generator that can perform the process (Japanese Patent Application No. 7-307627 and US Pat.
In the figure, reference numeral 7 denotes a bar, 8 denotes a cutout, 9 denotes a gas discharge port, 10 denotes an electrode, 11 denotes an oxygen gas chamber, and 12 denotes a hydrogen gas chamber. For details, refer to Japanese Patent Application No. 7-3.
Reference is made to Japanese Patent Application Laid-Open No. 07627, and description thereof will be omitted.

Further, as shown in FIG. 2, a fibrous or mat-like close contact material 3a is inserted between the ion exchange membrane 2 and the electrode plate 1, and the generated gas is easily extracted through the space between the fibers. Thus, the gas-generating device which can maintain a constant contact state at all times without the possibility that the electrical contact between the fibrous electric good conductor 3a and the ion exchange membrane 2 is cut off by gas generation, and also substantially expands the contact surface. Was developed.

In this apparatus, as the close-contact material 3a, a carbon fiber having a thickness of several microns is used, and a plurality of bundles are bundled into a thin flat band, which is woven in a plain weave and a finished cloth. Using. This is because gold sputtering is performed on the front surface and the back surface to improve the contact with the ion exchange membrane, and also to improve the contact with the electrode plate 2. Further, as in the prior art, the contact plate 3a is pressed against the ion exchange membrane 2 by the electrode plate 1 so that the contact plate 3a is pressed.
The electrode plate 1 and the ion-exchange membrane 2a were made to be in electrical contact with each other with "a" interposed therebetween.

As a result, when the electrolytic current is 100 A / dm ² , the cell voltage (V _t ) is 2.5 (V). When 2 (V) of the overvoltage component is subtracted from this voltage, 2.5 (V) is obtained. )
−2 (V) = 0.5 (V), and 0.5 (V) × 10
0 (A) = 50 (W) is the loss due to the contact resistance,
Compared to the conventional method in which about 100 W is consumed as power loss, it has become possible to save about 17% by the energy effect.

[0012]

However, the present inventor has
Furthermore, as a result of research on improving the energy effect and the corrosion resistance of the ion exchange membrane, the energy efficiency was further improved by further reducing the cell voltage, and the corrosion resistance was further improved by the ion exchange membrane of a new configuration. A new water electrolysis gas generator was successfully developed.

According to the present invention, the resistance loss is reduced as much as possible and the efficiency is further improved by using a novel ion exchange membrane and bringing the carbon particles into close contact with the entire surface between the ion exchange membrane and the cathode side electrode plate. It is an object of the present invention to provide a water electrolysis gas generator for generating oxygen gas, hydrogen gas, ozone gas, and hydrogen gas.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a water electrolysis gas generator in which an anode electrode plate and a cathode electrode plate are brought into contact with both sides of an ion exchange membrane.
The surface of the ion-exchange membrane is coated with platinum or palladium by sputtering, the upper surface is subjected to electroless plating of platinum and iridium, and carbon particles are held tightly between the ion-exchange membrane and the cathode-side electrode plate. It is a water electrolysis gas generator.

According to the present invention, the surface of the ion exchange membrane is thinly coated with platinum or palladium, which functions as a catalyst, by sputtering, so that the surface of the ion exchange membrane can be uniformly and favorably electrolessly plated with platinum or iridium. It can be applied in a state, and furthermore, the carbon particles are tightly held between the ion-exchange membrane and the cathode-side electrode plate, so that the adhesion between the ion-exchange membrane and the electrode plate is further improved, and the outgassing is also good. And a water electrolysis gas generator having low contact resistance can be provided. According to the present invention, by adopting the above configuration, the electrolysis voltage can be reduced by about 12% as compared with that using the conventional carbon fiber, and a large energy-saving water electrolysis gas generator can be provided. Can be provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is directed to a water electrolysis gas generator in which an anode electrode plate and a cathode electrode plate are brought into contact with both sides of an ion exchange membrane. Alternatively, palladium is coated by sputtering, the upper surface is subjected to electroless plating of platinum and iridium, and carbon particles are held in close contact between the ion-exchange membrane and the cathode-side electrode plate. By coating the membrane surface with platinum or palladium, which functions as a catalyst, by thin sputtering, the surface of the ion-exchange membrane can be subjected to uniform and favorable electroless plating of platinum, iridium, and the like. The structure is such that carbon particles are held tightly between the membrane and the cathode side electrode plate, so that the adhesion between the ion exchange membrane and the electrode plate is improved, and gas is released. And a water electrolysis gas generator having a low contact resistance can be provided, and the electrolysis voltage can be reduced by about 12% as compared with a conventional apparatus using carbon fibers. This has the function of providing an energy-saving water electrolysis gas generator.

According to a second aspect of the present invention, the thickness of the platinum or palladium to be sputtered is 5 to 10 °, and the electroless plating of platinum and iridium is 1 to 3 m.
mg / cm ² , and in addition to the action of the invention according to claim 1, effectively contacting the ion exchange membrane with platinum and iridium as catalysts and water. And also has the effect of improving the contact resistance and the function as a catalyst.

According to a third aspect of the present invention, in the electroless plating, the plating temperature is changed from room temperature to 5 minutes in 30 minutes from the start of the electroless plating.
The temperature was raised to 0 ° C., the temperature was maintained for 3 hours, then the temperature was raised to 60 ° C. in 30 minutes, and the temperature was maintained for 1 hour. In addition to the functions of the invention described in the above, the electroless plating is carried out under the above-mentioned temperature conditions, so that in the conventional electroless plating method without performing temperature control, the specific resistance is 10 ^-2 to 1.
At 0 ^-3 Ω · cm, there was a problem that a part of platinum, iridium, rhodium, etc. adhered to the inner surface of the plating bath container. Since the specific resistance can be reduced to 10 ⁻⁴ to 10 ⁻⁵ Ω · cm, the ion exchange membrane can be plated without waste.

According to a fourth aspect of the present invention, the electroless plating of rhodium is performed instead of the electroless plating of iridium, and the plating temperature is raised from room temperature to 25 ° C. in 30 minutes from the start of the electroless plating. This temperature is maintained for 3 hours, then 3
The temperature was raised to 40 ° C. in 0 minutes, and this temperature was maintained for 1 hour.
It is characterized by having been subjected to rhodium plating at ³ mmg / cm ² , and has the same effect as the first aspect of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an electrolysis cell of a water electrolysis gas generator of the present invention.
Is an electrode plate, 2 is an ion exchange membrane, 3 is a contact material filled with carbon particles, and 4 is a Pt plated portion. In the present embodiment, the cathode-side electrode plate 1a is formed in a box shape, and the inside thereof is filled with carbon particles 3, and is in close contact with the cathode-side ion exchange membrane 2 and the electrode plate 1a. Carbon particles having a thickness of 1 to 3 mm and a particle diameter of 0.5 to 1.0 mm are used.

The smaller the carbon particles, the better the physical contact between the ion exchange membrane and the electrode plate, but the worse the outgassing from the ion exchange membrane. On the other hand, when the diameter is larger than 1.0 mm, the outgassing is improved, but the contact area is reduced and the contact resistance is increased.
The range of from to 1.0 mm is most preferable. The thickness of the carbon particles is not particularly limited, but the thickness is appropriately determined in consideration of the shape of the irregularities of the ion-exchange membrane and the electrode plate. In the present embodiment, the thickness is set to 1 to 3 mm. . In addition, each carbon particle is independent and can change the mold flexibly with the change of the mold, so it has excellent adhesion with the ion exchange membrane and maintains a sufficient gap for gas and liquid to pass through As a result, the contact resistance could be kept low, the power consumption was small, and the corrosion resistance could be improved. According to the present embodiment, the use of carbon particles allows the cell voltage to be 2.5 V lower than that using a conventional carbon fiber.
To 2.2V. This is equivalent to an improvement in efficiency of about 12%, and it has become possible to realize a great energy saving industrially.

The surface of the ion exchange membrane 2 was coated with platinum or palladium by sputtering, and the upper surface thereof was subjected to electroless plating of platinum and iridium. The thickness of the platinum or palladium to be sputtered on the surface of the ion exchange membrane 2 is 5 to 10 °, the electroless plating is platinum and iridium at 1 to 3 mmg / cm ² , and the plating temperature is 30 minutes from the start of the electroless plating. The temperature was raised from room temperature to 50 ° C., and this temperature was maintained for 3 hours, then raised to 60 ° C. in 30 minutes, and the temperature was maintained for 1 hour.

In the present embodiment, the surface of the ion exchange membrane is thinly coated with platinum or palladium by sputtering to function as a catalyst for starting electroless plating of platinum, iridium, etc. Electroless plating of platinum and iridium can be performed. In addition, the electrolysis on the ion-exchange membrane needs to have a structure in which the ion-exchange membrane, the catalysts platinum and iridium, and the three bodies of water are effectively in contact with each other, and must be porous. However, if it is 3 mmg / cm ² or more, this contact is hindered, and if it is 1 mmg / cm ² or less, the contact resistance with the electrode plate 1 a and the function as a catalyst are hindered.

Therefore, 1-3 mmg / cm^TwoRange of
Most preferred. Also, in the present embodiment,
By performing electroless plating under different temperature conditions,
In the electroless plating method that does not control the
Is 10 ^-2-10^-3Ω · cm, platinum, iridium, lodge
The problem that some of the metals adhere to the inner surface of the plating bath
However, electroless plating was performed under the above temperature conditions.
By doing so, the specific resistance becomes 10^-Four-10^-FiveΩ · cm and ratio
Ion exchange without waste because resistance can be reduced
The film can be plated.

In place of the iridium electroless plating used in the above embodiment, rhodium is electrolessly plated, and the plating temperature is raised from room temperature to 25 ° C. 30 minutes after the start of the electroless plating. By maintaining this temperature for 3 hours, then increasing the temperature to 40 ° C. in 30 minutes, maintaining this temperature for 1 hour, and applying rhodium plating of 1 to 3 mmg / cm ² , the same effect as in the above-described embodiment is obtained. A water electrolysis gas generator having the same can be provided.

[0026]

According to the present invention, there is provided a water electrolysis gas generator, wherein platinum or palladium is thinly coated on the surface of an ion exchange membrane by sputtering, and electroless plating of platinum and iridium is performed on the upper surface thereof. It is characterized in that carbon particles are held in close contact between the side electrode plates, and platinum or iridium, which functions as a catalyst, is thinly coated on the ion exchange membrane surface by sputtering, so that platinum and iridium are coated on the ion exchange membrane surface. Etc. can be applied in a uniform and good condition,
By improving the corrosion resistance of the ion-exchange membrane and maintaining the carbon particles in close contact between the ion-exchange membrane and the cathode-side electrode plate, the adhesion between the ion-exchange membrane and the electrode plate is excellent, and gas is evacuated. It is possible to provide a water electrolysis gas generator having a good contact resistance and a low contact resistance. According to the present invention, by adopting the above configuration, the electrolysis voltage can be reduced by about 12% as compared with that using the conventional carbon fiber, and a large energy-saving water electrolysis gas generator can be provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an electrolysis cell of a water electrolysis gas generator of the present invention.

FIG. 2 is a schematic view showing an electrolysis cell of a water electrolysis gas generator developed as a prior application of the present invention.

FIG. 3 is a schematic view showing a single unit of the oxygen / hydrogen electrolysis gas generator of the prior application, (a) is an exploded perspective view, (b)
Is an assembly drawing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode plate 2 Ion exchange membrane 3 Carbon particle 3a Close contact material 4 Pt plating 5 Box-shaped partition wall 6 Metal coating surface 7 Bar 8 Notch 9 Gas discharge port 9a Oxygen gas discharge port 9b Hydrogen gas discharge port 10 Electrode 11 Oxygen gas Room 12 Hydrogen gas chamber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoji Watanabe 5-4-1-14 Shinjuku, Shinjuku-ku, Tokyo Inside Suga Test Machine Co., Ltd. (72) Inventor Koichi Taniguchi 5-4-1-14 Shinjuku, Shinjuku-ku, Tokyo F-term in Suga Test Machine Co., Ltd. (reference) 4K021 AA01 BA02 CA09 DB05 DB18 DB20 DB31 DB43 DB46 DB53 DC01 DC03 4K022 AA02 AA11 AA43 BA18 DA01 DB26 DB29 4K044 AA16 BA08 BB04 CA13 CA15

Claims (4)

[Claims] In a water electrolysis gas generating apparatus in which an anode-side electrode plate and a cathode-side electrode plate are brought into contact with both sides of an ion exchange membrane, platinum or palladium is coated on the surface of the ion exchange membrane by sputtering, and platinum and A water electrolysis gas generator characterized in that iridium is electrolessly plated and carbon particles are held tightly between an ion exchange membrane and a cathode side electrode plate. 2. The method according to claim 1, wherein the thickness of the platinum or palladium to be sputtered is 5 to 10 °, and the electroless plating of platinum and iridium is 1 to 3 mmg / cm ² . Water electrolysis gas generator. 3. In the electroless plating, the plating temperature is raised from room temperature to 50 ° C. in 30 minutes from the start of the electroless plating, this temperature is maintained for 3 hours, and then the temperature is raised to 60 ° C. in 30 minutes. 3. The water electrolysis gas generator according to claim 1, wherein the temperature is maintained for one hour. 4. An electroless plating of rhodium is performed in place of the electroless plating of iridium, and a plating temperature is raised from room temperature to 25 ° C. in 30 minutes from the start of the electroless plating, and this temperature is maintained for 3 hours. 2. The water electrolysis gas generator according to claim 1, wherein the temperature is raised to 60 [deg.] C. in 30 minutes, the temperature is maintained for one hour, and rhodium plating of 1 to 3 mmg / cm < ² > is performed.