JP2000239881A - Gas diffusion electrode with metallic frame or gas chamber and electrolytic cell of brine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas diffusion electrode with a metallic frame or a gas chamber capable of constituting an electrolytic cell of brine which may be easily replaced with a conventional hydrogen generating cathode and extremely hardly gives rise to the occurrence of liquid leakage and gas leakage and an electrolytic cell of brine using the same. SOLUTION: This gas diffusion electrode with the metallic frame is constituted by joining the gas diffusion electrodes 1 via silver plates to the apertures of the corrosion resistant metallic frames 15 having the apertures 16 at 2 >=points. The gas diffusion electrode with gas chambers is constituted by joining the gas diffusion electrode with the metallic frame and an electrode pan composed of a nickel plate to constitute a gas chamber and attaching an inlet and outlet for gas thereto. The electrolytic cell of brine is constituted by disposing the gas inlet and outlet from the outside of the electrolytic cell to the gas diffusion electrode with the gas chamber and directly joining the metallic joint part of the electrode to the power feeding rib of the electrolytic cell and/or the electrolytic cell frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas diffusion electrode with a metal frame or gas chamber and a salt cell using the same, and more particularly, to a metal frame or gas chamber which can be easily attached to an ion exchange membrane type salt cell. The present invention relates to a gas diffusion electrode provided with a salt solution and a salt cell using the electrode.

[0002]

2. Description of the Related Art The cathode of an existing ion exchange membrane type salt cell is a cathode made of nickel and generating hydrogen.
In order to change the hydrogen generation type cathode to the oxygen cathode, it is necessary to adopt a three-chamber structure in which a gas chamber is newly provided. That is, in the electrolytic cell, the order is an ion exchange membrane, an aqueous solution of caustic soda (liquid chamber), a gas diffusion electrode, and a gas chamber. It is desirable that these are layered and each have a thickness of about 1 mm, so that the supply of gas and liquid is restricted, and it is difficult to take measures against liquid leakage and gas leakage.

[0003]

In the conventional hydrogen-cathode-salt electrolyzer, only the entrance of the caustic soda had to be attached to the catholyte compartment having a thickness of about 4 cm. However, it is necessary that both the liquid chamber and the gas chamber of the salt electrolytic cell provided with the oxygen cathode are formed in a thin layer of several mm or less. In this case, it is necessary to provide an electrolyte inlet and an outlet between the ion exchange membrane and the gas diffusion electrode in the liquid chamber. The electrolyte chamber is sandwiched between the exchange membrane and the gas diffusion electrode together with the packing. In such a structure, it is impossible to make the electrolyte solution chamber thinner, and the resistance loss of the solution is increased, and there is a disadvantage that the electrolytic cell voltage does not decrease.

FIG. 9 is a sectional view of a conventional electrolytic cell using an oxygen cathode. A gas chamber 22 is provided on one surface side (back side) of the flat gas diffusion electrode 1, and a gas inlet 23 is provided in the gas chamber 22. On the surface side of the gas diffusion electrode 1, a cathode chamber 2 is sandwiched between the gas diffusion electrode 1 and the ion exchange membrane 23.
5, and a cathode chamber 25 is provided with an electrolyte inlet 27 whose periphery is sealed by a packing 26. For this reason, the cathode chamber 25 is provided with a metal frame of about 3 mm and a hole is formed, and this is used as an entrance for the electrolytic solution, and between the ion exchange membrane 24 and the metal frame and between the metal frame and the gas diffusion electrode 1. Each have a packing 26 interposed therebetween. With such a structure, it is impossible to make the cathode chamber 25 as thin as required by the oxygen cathode. If the width of the cathode chamber 25 is large, the electric resistance loss of the solution increases, and there is a disadvantage that the electrolytic cell voltage does not decrease.

In practice, the thickness of the liquid chamber is desirably 1 mm or less. In addition, in the above-described structure, the structure of the electrolytic cell is complicated, the required packing is increased, and leakage of gas and liquid is a problem due to the increased number of seals. It is desired to develop an electrolyzer with less gas and liquid leakage problems. SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas diffusion electrode capable of forming a salt electrolysis tank in which liquid leakage and gas leakage hardly occur, and a salt electrolysis cell using the same.

[0006]

Means for Solving the Problems The present inventor has conducted various studies to achieve the above-mentioned object. As a result, the gas diffusion electrode and the silver plate were superimposed, and 200 to 400 ° C., 20 kg / kg.
It has been found that the hot pressing under the condition of not less than ² cm ² firmly joins the silver plate and the gas diffusion electrode, and there is no liquid leakage. Furthermore, if the silver plates are between 200 ° C. to 400 ° C.
It was found that if hot pressing is performed at 10 ° C. and 10 kg / cm ² or more, strong joining can be achieved. Therefore, by using these technologies, we have developed that the gas diffusion electrode can be held on the corrosion-resistant metal member. Then, there is a gas inlet and an outlet, and there is a gas chamber with a thickness of about 1 mm. We have developed a technology that can configure a gas diffusion electrode with a thickness of about 3 mm. Oxygen cathode type salt electrolyzer with no gas leakage and gas piping can be made flexible because gas inlet and outlet are independent of the electrolytic cell frame, and can be easily replaced with the conventional hydrogen generating cathode. Can be configured.

That is, the above-mentioned object has been achieved by the following means. (1) A gas diffusion electrode with a metal frame, wherein a gas diffusion electrode is joined to an opening of a corrosion-resistant metal frame having two or more openings by a hot press via a silver plate. (2) A gas chamber comprising a gas chamber formed by joining the gas diffusion electrode with a metal frame described in the above (1) and an electrode pan made of a nickel plate, and having an inlet and an outlet for gas. With gas diffusion electrode. (3) The gas diffusion electrode with a gas chamber according to (2), wherein a gas inlet / outlet from the outside of the electrolytic cell is arranged, and the metal joint of the electrode is directly joined to the power supply rib of the electrolytic cell and / or the electrolytic cell frame. Characteristic salt electrolyzer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below.
The present invention is not limited to this. Gas diffusion electrodes are usually
It has a form in which a power supply, a reaction layer, and a gas supply layer are stacked. A silver mesh, silver-plated nickel foam, or the like can be suitably used as the power supply of the gas diffusion electrode. The reaction layer is composed of carbon black, silver and PTFE, and the gas supply layer is
What mainly consists of carbon black and PTFE is used, and various gas diffusion electrodes composed of these can be used in the present invention.

FIG. 1 is a plan view of a gas diffusion electrode 18 with a metal frame according to the present invention. This gas diffusion electrode with metal frame 18
Is a gas diffusion electrode 1 formed by stacking a reaction layer and a gas supply layer.
Is joined to the silver plate frame 14, and the edge of the silver plate frame 14 is joined to the metal frame 15.
In order to manufacture the gas diffusion electrode 18 with a metal frame, a silver plate is used in which a plurality of windows (openings 16) each having a size larger than the size of the gas diffusion electrode 1 and smaller than the gas diffusion electrode by about 10 mm in length and width are opened in the middle. A metal frame 15 is formed by forming a plurality of small windows in the middle of the entire size of the silver plate frame 14.
Are stacked so that each window fits at the center.
On the other hand, by stacking a plurality of gas diffusion electrodes 1 so that the gas diffusion electrodes come to the respective openings and hot-pressing the mating portion, the three members can be simultaneously joined.

The hot press is performed at a temperature of 200 ° C. to 400 ° C. and a pressure of 10 to 100 kg / cm ^{2 on the} overlapping portion.
The gas diffusion electrode can be firmly fixed to the metal frame. In this way,
The gas diffusion electrode 18 with a metal frame of the present invention can be manufactured. The timing of joining the gas diffusion electrode 1 and the metal frame 15 does not matter. The silver plate frame 14 may be joined to the metal frame 15 after the silver plate frame 14 is joined to the outer periphery of the finished gas diffusion electrode once in the form of an ordinary conventional gas diffusion electrode. It becomes complicated. Also,
In the process of manufacturing the gas diffusion electrode, a silver frame material is interposed between the sheet-like laminates constituting the gas diffusion electrode, and substantially one sheet is integrally formed with the sheet-like material constituting the gas diffusion electrode. It may be obtained by hot pressing twice.

When the gas diffusion electrode with a metal frame is actually used, it is bonded to, for example, a silver-plated nickel electrode pan. 2 to 4 are views showing a gas diffusion electrode with a gas chamber in which a gas diffusion electrode with a metal frame and an electrode pan are joined. 2 is a plan view, FIG. 3 is a sectional view from the front, and FIG. 4 is a sectional view from the side. As shown in FIG. 2, the gas diffusion electrode 18 with a metal frame is overlapped on the cathode pan 19, and the overlapped portion between the periphery of the gas diffusion electrode 18 with a metal frame and the inner frame portion is joined by hot pressing and welding. The metal frame 15 is joined to the outer periphery of the gas diffusion electrode around the cathode pan 19 and at the frame portion to form a joint portion 17, and a gas chamber is formed by attaching the cathode pan 19, and the gas diffusion electrode with the gas chamber is formed. 21 are manufactured. In the gas diffusion electrode 21 with a gas chamber, the metal frame 15 joined to the gas diffusion electrode 1 has a substantially band-like area surrounding the gas diffusion electrode 18 with a metal frame arranged in a plane.
The gas diffusion electrode 1 is arranged corresponding to a dish-shaped concave portion (gas chamber) of the cathode pan 19 as shown in FIGS. 3 and 4.

As shown in FIGS. 3 and 4, a gas diffusion electrode 18 with a metal frame is superimposed on an electrode pan (cathode pan 19) made of silver-plated nickel material. By hot pressing at 10 to 100 kg / cm ² , the joint portion 17 is formed. If hot pressing is performed under such temperature and pressure conditions, the metal frame 15 can usually be firmly fixed. The joining between the gas diffusion electrode with a metal frame and the electrode pan (cathode pan 19) may be performed by laser welding or continuous resistance welding.

Next, this gas diffusion electrode with a gas chamber was joined to a cathode power supply rib of a bipolar electrolyzer. FIG. 5 is a cross-sectional view of an example of the joining. By joining the metal part around the electrode and the electrolytic cell frame by laser welding, a structure without liquid leakage can be easily achieved. The power supply rib 6 supports the bipolar plate 5 in parallel with the gas diffusion electrode 1 with a metal frame, and has an anode DSA8 in parallel with the bipolar plate 5.

FIG. 6 is a sectional view of another example in which a gas diffusion electrode with a gas chamber is joined to a power supply rib of a bipolar electrolytic cell. In this example, the electrode pan (cathode pan 19) is formed by sheet metal processing, and a concave portion is formed. The method of making the gas diffusion electrode 21 with a gas chamber differs depending on the shape of the electrode pan. Electrode pan 1
Manufacturing is easy if any irregularities are formed on either the metal frame 9 or the metal frame 15. FIG. 5 shows an example in which the metal frame 15 is processed to be uneven, and FIG. 6 shows an example in which the electrode pan 19 is processed to be sheet metal. As shown in FIG. 4, the electrode pan 19 preferably has a gas inlet / outlet pipe and a gas reservoir for making the gas flow uniform. Suitable gas piping is a flexible plastic, rubber or bellows metal tube. If a coupler is used, piping can be easily performed. A junction between the metal frame 15 and the electrode pan 19 is used as a portion to be joined to the power supply rib 6 of the monopolar or bipolar electrolytic cell. Resistance welding and laser welding can be used as the method of directly joining to the power supply rib. FIG. 7 is a diagram showing a method of bonding with the cathode pan 19 when the waveform bipolar plate 5 is used. Weld directly to the corrugated bipolar plate.

FIG. 8 is a sectional view showing an example of the salt electrolysis cell of the present invention constituted by using the gas diffusion electrode with a gas chamber. This salt cell is a bipolar electrolytic cell. FIG.
In the above, both ends of the gas diffusion electrode with a gas chamber in which the cathode pan is bonded to the back surface are supported by a corrosion-resistant frame. . On the surface side of the gas diffusion electrode 1, an ion exchange membrane 2 is disposed in parallel with a slight gap therebetween, and a cathode chamber 3 is formed in the gap. I understand. The electrolyte enters the electrolyte inlet 8, flows from the inlet 10 of the liquid chamber to the cathode chamber 3, enters the liquid chamber from the outlet 11, and forms an electrolyte path exiting from the electrolyte outlet 9.

The cathode pan on the back side of the gas diffusion electrode 1 is joined to a conductive rib 6, which is joined to and held by the bipolar plate 5. An oxygen gas inlet 12 is provided at an upper portion of the gas diffusion electrode 1, and an oxygen gas outlet 13 is provided at a lower portion thereof, and oxygen gas is supplied to a gas chamber of the gas diffusion electrode 1. An anode DSA 8 is provided on the opposite side of the bipolar plate 5 via a conductive rib 6. This bipolar plate 5
A gas diffusion electrode 1 and an anode DSA4 are provided on both sides of the cell, and a large number of these units are arranged to form a bipolar electrolytic cell.

[0017]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 (Reaction layer raw material) Hydrophobic carbon black (Denka Black, average particle size: 390 °, manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 200 parts (weight, the same applies hereinafter) of a 4% aqueous solution of Triton (surfactant). 2) Add 2 parts and stir to disperse the hydrophobic carbon black. An ultrasonic disperser (500 W, manufactured by Branson) while cooling this carbon black dispersion with water.
For a further 5 minutes. As a result, the average dispersed particle diameter of carbon black was 1.6 microns. To this dispersion, 10 parts of silver colloid (produced by Tanaka Kikinzoku Co., Ltd., average particle size: 0.1 micron) is added, followed by stirring and mixing. Furthermore, PTFE dispersion D-1 (average particle size 0.3
Micron, manufactured by Daikin Industries, Ltd.) and stirred to mix the PTFE dispersion. 300 parts of isopropyl alcohol was added to the obtained dispersion to form a self-assembly, followed by filtration to obtain a reaction layer raw material.

(Gas supply layer raw material) Hydrophobic carbon black (No. 6, average particle size 490 Å) was added to 200 parts of water containing 4% triton (surfactant).
6 parts (manufactured by Denki Kagaku Kogyo Co., Ltd.) were added, and the mixture was stirred for 10 minutes to disperse the hydrophobic carbon black. Furthermore, PT
4 parts of FE Dispersion D-1 (average particle size: 0.3 micron, manufactured by Daikin Industries, Ltd.) are added, and the mixture is stirred to form PTFE.
Mix. 200 parts of isopropyl alcohol was added to the obtained dispersion and self-organized to obtain a gas supply layer raw material.

(Reaction layer-gas supply layer bonding sheet) Solvent naphtha was added to the reaction layer raw material and the gas supply layer raw material thus obtained, and a laminated sheet comprising a reaction layer and a gas supply layer was produced by a roll method. Next, the mixture was dried at 80 ° C. for 3 hours, and the mixed surfactant was removed with an ethanol extraction device. Subsequently, drying was performed at 80 ° C. for 5 hours to obtain a gas diffusion electrode sheet (a reaction layer-gas supply layer laminated sheet).
The gas diffusion electrode sheet was cut into a rectangle of 121 cm × 21 cm. (Gas supply layer sheet) Separately, a gas supply layer sheet was also prepared from the gas supply layer raw material and cut into the same size.

(Gas diffusion electrode with silver plate frame) 130 cm ×
70cm, 0.2mm thick silver plate, 120cm × 20c
m were opened to form a silver plate frame. A silver screen having a wire diameter of 0.1 mm, 50 mesh, and a size of 122 cm × 22 cm is superimposed on each window of the obtained silver plate frame, the surface pressure of the overlapping portion is 40 kg / cm ² , and the pressing temperature is Bonding was performed by hot pressing at 260 ° C. Further, a gas diffusion electrode sheet is placed under the silver mesh, and a gas supply layer sheet is placed on the silver mesh, under a pressure of 50 kg / cm ² ,
By pressing at 350 ° C. for 60 seconds, a gas diffusion electrode with a silver plate frame was obtained.

(Gas Diffusion Electrode with Metal Frame) A metal frame was attached to the gas diffusion electrode with a silver plate frame. The metal frame has a thickness of 0.
Three rectangular windows having a size of 120 cm × 20 cm were opened in a rectangular nickel plate of 5 mm, 130 cm × 70 cm. This frame was silver-plated to a thickness of 5 microns. The silver-plated nickel frame and the gas diffusion electrode with the silver plate frame were overlapped, and a surface pressure of 60 kg / cm ² and a temperature of 28 were applied to the overlapped portion.
Hot pressing was performed at 0 ° C. to obtain a gas diffusion electrode with a metal frame.

(Gas Diffusion Electrode with Gas Chamber) Next, a nickel plate having a size of 130 cm × 70 cm and a thickness of 1 mm is subjected to sheet metal processing, and the upper and lower portions are 2 cm wide, 1 cm deep and 6 cm long.
A gas reservoir portion of 0 cm was formed, and holes serving as a gas inlet and a gas outlet having a hole diameter of 1.2 cm were formed. The electrode pan prepared beforehand was plated with silver of 5 microns. A 1 mm-thick corrugated nickel net was spot-mounted in the gas chamber of the electrode pan. Next, the electrode pan and the gas diffusion electrode with a metal frame are overlapped, and the periphery and only the portion where the power supply rib is welded are joined by hot pressing at a surface pressure of 60 kg / cm ² and a temperature of 250 ° C. for 60 seconds, A gas diffusion electrode with a gas chamber was obtained.

(Electrolysis tank) A gas inlet / outlet pipe is connected to the side of a monopolar salt electrolysis tank, a pipe for a gas diffusion electrode with a gas chamber is connected, and a metal part of the gas diffusion electrode with a gas chamber is spot-welded to a feeding rib. did. The portion where the electrolytic cell frame and the metal frame overlap was joined by laser welding so that there was no liquid leakage. An electrolytic cell was assembled, and a salt electrolysis operation was performed under the conditions of 90 ° C., 32% NaOH, and 30 A / dm ^{2 as} an oxygen cathode. This electrolytic cell can stably perform electrolysis without liquid leakage,
A cell voltage of V was obtained.

In this embodiment, a gas inlet and a gas outlet are provided.
A gas diffusion electrode with a gas chamber having a gas chamber could be formed with a thickness of about 3 mm. Independent of the electrolytic cell frame, there are gas inlets and outlets, so the gas piping can be made flexible and can be easily replaced with the conventional hydrogen generating cathode, and there is no liquid leakage or gas leakage. Can be configured. If these techniques are used, even if the gas diffusion electrode is attached to the electrolytic cell and the electrolysis is performed for a long period of time, the power supply resistance is low and a very stable oxygen cathode without liquid leakage can be obtained.

[0026]

Since the present invention has the above-mentioned structure, it can be easily replaced with a conventional hydrogen generating cathode electrode, and a metal frame capable of forming a salt electrolytic cell in which liquid leakage and gas leakage hardly occur. Alternatively, a gas diffusion electrode with a gas chamber and an electrolytic cell using the same can be provided.

[Brief description of the drawings]

FIG. 1 shows a plan view of a gas diffusion electrode with a metal frame of the present invention.

FIG. 2 is a plan view of a gas diffusion electrode with a gas chamber of the present invention.

FIG. 3 is a sectional view from the front of the gas diffusion electrode with a gas chamber of the present invention.

FIG. 4 is a cross-sectional view of a gas diffusion electrode with a gas chamber according to the present invention as viewed from a side surface.

FIG. 5 is a cross-sectional view of a joined body in which a gas diffusion electrode with a gas chamber is joined to a cathode power supply rib of a bipolar salt electrolytic cell.

FIG. 6 is a sectional view of a joined body in which a gas diffusion electrode with a gas chamber is joined to a cathode power supply rib of a bipolar electrolytic cell.

FIG. 7 is a sectional view of a joined body in which a gas diffusion electrode with a metal frame is joined to a bipolar electrolytic cell using a corrugated bipolar plate 7;

FIG. 8 shows a sectional view of an example of an electrolytic cell using the gas diffusion electrode with a gas chamber of the present invention.

FIG. 9 shows a sectional view of an electrolytic cell using a conventional oxygen cathode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas diffusion electrode 2 Ion exchange membrane 3 Cathode room 4 Anode DSA 5 Bipolar plate 6 Power supply rib 7 Frame 8 Electrolyte inlet 9 Electrolyte outlet 10 Inflow 11 Outflow 12 Oxygen gas inlet 13 Oxygen gas outlet 14 Silver plate frame 15 Metal frame 16 Opening 17 Joining part 18 Gas diffusion electrode with frame 19 Cathode pan 20 Gas diffusion electrode with gas chamber 21 Gas chamber 22 Gas inlet 23 Ion exchange membrane 24 Cathode chamber 25 Packing 26 Electrolyte inlet

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 000000941 Kanebuchi Chemical Industry Co., Ltd. 3-4-2 Nakanoshima, Kita-ku, Osaka-shi, Osaka (72) Inventor Choichi Furuya 2-14F, Nakamuracho, Kofu-shi, Yamanashi Prefecture Terms (reference) 4K011 AA12 AA23 AA68 DA03 4K021 BA03 DB16 DB18 DB47 EA03 EA05

Claims (3)

[Claims] 1. A gas diffusion electrode with a metal frame, wherein a gas diffusion electrode is joined to an opening of a corrosion-resistant metal frame having two or more openings by a hot press via a silver plate. 2. A gas, wherein a gas chamber is formed by joining the gas diffusion electrode with a metal frame according to claim 1 and an electrode pan made of a nickel plate, and a gas inlet and an outlet are provided. Gas diffusion electrode with chamber. 3. The gas diffusion electrode with a gas chamber according to claim 2, wherein a gas inlet / outlet from the outside of the electrolytic cell is arranged on the gas diffusion electrode with the gas chamber, and a metal joint of the electrode is directly joined to a power supply rib of the electrolytic cell and / or an electrolytic cell frame. A salt electrolysis tank characterized by the above-mentioned.