JPH10158877A - Method for joining gas diffusion electrode and gas chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture technique capable of making the structure over the entire part of a cathode part inclusive of a gas diffusion electrode compact, lowering an electrolytic voltage down to the extreme limit, suppressing the electrolytic voltage to an extremely low level in spite of an increased in the size of an alkali chloride metal electrolytic cell and securely joining the electrode and a gas chamber. SOLUTION: This method for joining the gas diffusion electrode and the gas chamber consists in joining the gas diffusion electrode 2 and the gas chamber 4 by heating and pressurizing the diffusion layer side surface of the gas diffusion electrode 2 and the surface of the gas permeable porous body 5 packed in the gas chamber at a temp. within a range of 200 to 400 deg.C via a joining member consisting of metal silver or silver alloy at the time of manufacturing the alkali chloride metal electrolytic cell consisting of the gas diffusion electrode, the gas chamber packed with the gas permeable porous body 5 and a cathode outside frame 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an alkali metal chloride electrolytic cell which can be electrolyzed at a low electrolysis voltage and can be strongly bonded, and more particularly to a method for joining a cathode side member of an alkali metal chloride electrolytic cell having a gas diffusion electrode. About the method.

[0002]

2. Description of the Related Art As an alkali metal chloride aqueous solution electrolyzer, a salt electrolyzer used for producing caustic soda using an aqueous sodium chloride solution (hereinafter referred to as "salt water") is well known. The metal aqueous solution electrolyzer will be described as a salt electrolyzer. As shown in FIG. 7, an outline of the structure of this type of salt cell is composed of an anode chamber 19 having an anode 18 and containing salt water and a cathode chamber 17 having a cathode and containing water or an aqueous solution of sodium hydroxide. A gas diffusion electrode 15 which is partitioned by an ion exchange membrane 15 having an ion exchange capacity, whose material is a porous material as a cathode, and to which an oxygen-containing gas is supplied.
(So-called oxygen cathode) is used, and when electricity is supplied between the two electrodes to perform electrolysis, the catholyte is charged by performing electrolysis as a cathode while an oxygen-containing gas is supplied to the gas diffusion electrode 15. An electrolytic product is obtained as a caustic soda aqueous solution obtained by enriching caustic soda in a cathode chamber (hereinafter referred to as a "catholyte chamber"). In this electrolytic cell, since an oxygen gas diffusion electrode is used as a cathode, no hydrogen gas is generated there, so that the reaction can proceed at an extremely low electrolysis voltage as compared with a normal hydrogen generation type electrolysis method. It has the advantage that.

Since it is desired that the cost of producing caustic soda be reduced as much as possible, even when producing caustic soda by the salt electrolysis method, it is necessary to lower the electrolysis voltage and reduce the power consumption for electrolysis. is required. Since salt gas electrolysis using a gas diffusion electrode does not generate hydrogen gas, there is an advantage that the electrolysis voltage can be reduced as compared with a normal hydrogen generation type electrolysis method. However, salt electrolysis performed using a gas diffusion electrode also has the following points to be improved. That is, in the ion exchange membrane method salt electrolysis without using a normal gas diffusion electrode, the distance between the anode and the ion exchange membrane is zero, the distance between the ion exchange membrane and the cathode is 2 mm or less, and the distance between the electrodes is extremely small. Can be suppressed. This is because both electrodes are composed of members through which gas and liquid can pass, and anolyte and catholyte can be supplied from the back of both electrodes, and gas generated on the electrode surface can be discharged to the back of the electrode. With such a structure, such a structure can be realized. In particular, the distance between the anode and the ion-exchange membrane can be reduced to zero by using such a structure.

On the other hand, in the case of salt electrolysis using an ion exchange membrane method using a gas diffusion electrode, the distance between the anode and the ion exchange membrane can be the same as in the case of normal salt electrolysis using an ion exchange membrane method. In a gas diffusion electrode (oxygen cathode), gas must be supplied on the side opposite to the side facing the ion exchange membrane, so from the back side of the electrode to the front side through the inside of the electrode as in normal electrolytic technology. It is not possible to supply the catholyte, it is necessary to supply the liquid only to the side facing the ion exchange membrane, and it is not possible to shorten the distance between the ion exchange membrane and the cathode. Further, in order to supply the liquid to the side facing the ion exchange membrane, a supply port and a drain for supplying the catholyte between the ion exchange membrane and the gas diffusion electrode (referred to as a catholyte chamber). It is necessary to provide an outlet, and there is a problem in shortening the distance between the ion exchange membrane and the gas diffusion electrode (cathode).

[0005] In an electrolytic cell having a gas diffusion electrode, conventionally, energization of the gas diffusion electrode extends a foot portion of a current collector embedded in a gas diffusion layer of the gas diffusion electrode, and the extension portion serves as an oxygen cathode. The current collector in the gas chamber and the current collector in the gas diffusion layer are connected to the gas chamber of the oxygen cathode by connecting the current collector in the gas chamber of the oxygen cathode. A method has been adopted in which the current collector foot is pulled out to the outside from a seal portion of an outer frame of the oxygen cathode and connected to a cathode power supply terminal to flow an electric current. In such a current collector system, current flows through the current collector buried in the gas diffusion layer and the current collector disposed in the gas chamber, so that when the electrolytic cell becomes large and the area of the gas diffusion electrode becomes large, There has been a problem that the distance over which the current flows through the current collector is increased, and the voltage of the electrolytic cell, and eventually the electrolytic voltage, is increased. For this reason, when trying to reduce the voltage drop by increasing the line width of the current collector from the seal portion of the cathode outer frame to the center of the gas diffusion electrode, the current collector hinders the supply of gas in the gas chamber, and the electrolytic overvoltage increases. Again, the electrolytic voltage increases. For this reason,
In the method using a current collector to pass electricity from the gas diffusion electrode to the cathode terminal, the size of the gas diffusion electrode could not be increased, and the size was up to about 30 cm square.

The gas diffusion electrode usually has a two-layer structure of a reaction layer 11 and a gas diffusion layer 12, as shown in FIG. Both layers are formed from a mixture of graphitic carbon and Teflon particles. Among these two layers, the reaction layer 11 faces the catholyte compartment and comes into contact with the electrolyte, and is mainly composed of a mixture of hydrophilic carbon fine particles and water-repellent carbon fine particles. On top, a catalyst made of a noble metal system such as platinum is supported.
The gas diffusion layer 12 is mainly composed of a mixture of fluororesin fine particles and water-repellent carbon, and a small amount of hydrophilic carbon fine particles and a binder particle connecting these fine particles are mixed with each other. It is molded into a body. As shown in FIG. 6, the reaction layer 11 and the gas diffusion layer 12 are arranged so that the hydrophilic reaction layer 11 is on the catholyte side and the hydrophobic gas diffusion layer 12 is on the gas chamber side. -Laminated to form the gas diffusion electrode 2. Electrical continuity between the inside and outside of the gas diffusion electrode is maintained by the conductivity of the conductive mesh and carbon inserted in and between the reaction layer 11 and the gas diffusion layer 12. The thickness of the gas diffusion electrode 2 is as thin as about 0.2 to 1 mm.

As described above, since the gas diffusion electrode is a thin layered body, if the gap between the ion exchange membrane and the gas diffusion electrode (cathode) is narrowed and a large amount of catholyte flows through the narrow gap, In addition, the liquid in the catholyte compartment generates a considerable liquid pressure, which causes deformation of the gas diffusion electrode and increases the electric resistance, thereby increasing the electrolysis voltage. These problems have not been adequately addressed by these methods.

In order to reinforce the gas diffusion electrode, conventionally, as shown in FIG. 8, for example, an oxygen passage 23 is provided in the gas chamber 4 and the gas diffusion electrode 2 is supported. There is an example in which a net-like support is provided on the back surface. However, in the prior art, the purpose of inserting the support is mainly to reinforce the gas diffusion electrode in order to compensate for the drawback that the strength of the gas diffusion electrode is low. Since the gas flow is partially obstructed, the gas flow becomes uneven and the gas supply is insufficient.
This will increase the electrolysis voltage. Therefore, it cannot be said that the above reinforcing measures can sufficiently cope with the problem of preventing the gas diffusion electrode from being deformed. Also, the previously attempted materials for supporting and reinforcing the gas diffusion electrode were not joined to the gas diffusion electrode, so the support was incomplete, and the assembly of the cathode of the gas diffusion electrode was troublesome. Was. Further, even if an attempt is made to join the reinforcing material to the gas diffusion electrode, a bonding agent that can be joined at an appropriate temperature without impairing the function of the gas diffusion electrode has not been obtained.

In salt electrolysis performed using a gas diffusion electrode, it is desired to lower the electrolysis voltage, and particularly to apply the gas diffusion electrode to a larger salt electrolysis apparatus. Improvements in ion exchange membrane method electrolysis using gas diffusion electrodes that have been carried out for this purpose have hitherto focused only on the manufacturing method and performance improvement of gas diffusion electrodes. Almost no consideration has been given to the structural improvement of the membrane electrolytic cell. As can be seen from the above description, the problem of preventing deformation of the gas diffusion electrode, the problem of increasing the electric resistance between the gas diffusion electrode and the cathode terminal, and the problem of supplying a uniform and sufficient gas from the gas chamber to the gas diffusion electrode are improved. Thus, it is considered that the electrolysis voltage can be further reduced from the current state, and the gas diffusion electrode can be applied to a larger salt electrolysis apparatus.

The inventor of the present invention has been mainly concerned with improving the structure of a salt electrolyzer for an ion-exchange membrane method by reducing the electrolysis voltage and increasing the size of the electrolyzer in salt electrolysis using a gas diffusion electrode. After careful examination of
By filling the gas chamber of the gas diffusion electrode with a conductive rigid gas permeable porous body, preferably a metal rigid gas permeable porous body in a manner as shown in FIG. 5, the deformation of the gas diffusion electrode can be prevented. Improving the uniformity of gas supply from the gas supply chamber to the gas diffusion electrode, ion exchange (by removing the supply port and discharge port connected to the cathode chamber provided in the conventional cathode frame by improving the catholyte supply means) The gap between the membrane and the gas diffusion electrode can be reduced, and the distance from the gas diffusion electrode to the cathode terminal can be reduced, so that the electrolysis voltage in salt electrolysis can be greatly reduced. It has been found that a gas diffusion electrode can be applied to a practical soda electrolyzer.

[0011]

SUMMARY OF THE INVENTION The present invention provides an ion exchange membrane electrolytic cell using a gas diffusion electrode, in which the entire structure of the cathode section including the gas diffusion electrode is made compact, and the electrolysis voltage is reduced to the limit. Further, the efficiency of the preparation work of the salt electrolyzer is improved, and the increase in the electrolysis voltage is suppressed even if the apparatus is enlarged, so that the ion exchange membrane method electrolyzer (salt electrolyzer) can maintain the operability and operability of the apparatus. ). Especially for the above purpose,
It is an object to improve the preparation workability and operability of the apparatus by firmly joining a rigid gas-permeable porous body filled in the gas chamber and a gas diffusion electrode while maintaining a gas diffusion function. is there.

[0012]

The object of the present invention is to provide a method for joining a gas diffusion electrode and a gas chamber according to the present invention, and more particularly, to a method for forming a gas diffusion electrode and a rigid gas-permeable porous body filled in the gas chamber. Are achieved by the bonding method of the present invention shown in FIG. When manufacturing an alkali metal chloride electrolytic cell comprising a gas diffusion electrode, a gas chamber filled with a gas-permeable conductive porous body, and a cathode outer frame, the gas diffusion electrode is filled in the diffusion layer side surface and the gas chamber. The surface of the conductive porous body is heated from 200 ° C. to 4 ° C. through a joining member made of metallic silver or a silver alloy.
A method for joining a gas diffusion electrode and a gas chamber, wherein the joining is performed by heating and pressing within a temperature range of 00 ° C. The gas permeable conductive porous body filled in the gas chamber may be a rigid conductor, but is preferably a metal gas permeable porous body having excellent conductivity.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described more specifically.
However, the present invention is not limited by the following specific description. The gas diffusion electrode preferably used in the present invention is the reaction layer 1 shown in FIG.
A typical gas diffusion electrode has a two-layer structure in which a gas diffusion layer 1 and a gas diffusion layer 12 are stacked. Preparation for joining the gas diffusion electrode of the present invention to a gas-permeable conductive porous body (hereinafter also referred to as “gas-permeable porous body” for simplicity) includes preparing the gas of the two-layer gas diffusion electrode. As shown in FIG. 4, a silver net 13 or a wire as a joining member is joined in advance to the surface of the diffusion layer (the back surface of the gas diffusion electrode). Gas diffusion layer 12
The method of joining the silver net 13 (or wire) to the gas diffusion layer 12 is preferably a method of firmly joining the gas diffusion layer 12 using a mesh material used for a support frame when press-molding the gas diffusion layer 12.

The mesh 13 as a joining member used here
Is preferably a silver net or a silver-coated nickel net (eg, a nickel net plated with silver), and the following net shape is suitable. The line width of the mesh is 0.3 mm or less, the mesh width is 3 mm or less, and the aperture ratio is preferably 80 to 90%. Line width increases,
Or, if the aperture ratio is small, gas permeation is hindered,
If the aperture ratio is 95% or more, conductivity becomes a problem. As shown in FIG. 9, the cross-sectional shape of the line of the net 13 is preferably long in the thickness direction from the viewpoint of conductivity. If the aperture ratios are the same, the shape of the net is preferably a rhombus rather than a square. Further, a part of the net may be buried inside the gas supply layer of the gas diffusion electrode.

As a preparation for the gas chamber side, a gas chamber made of foamed nickel (sponge nickel) or a metal net manufactured by corrugating a metal net in a space of the gas chamber (a gas chamber frame including the cathode outer frame 3 in FIG. 5). The permeable porous body 5 is filled, and preferably, the gas permeable porous body 5 is fixed to the gas chamber frame 3 by welding. Next, the surface of the gas-permeable porous body 5 filled in the gas chamber is plated with silver (while maintaining gas permeability). This silver-plated portion also serves as a joining member. The joining material may be a silver alloy.

The silver mesh 1 on the front surface of the gas-permeable porous body 5 plated with the surface silver and the back surface of the gas diffusion electrode (12 in FIG. 4).
3 is heated and pressed, as shown in FIG. The joining temperature is from 200 ° C. to 400 ° C., but a temperature around 250 ° C., which is a temperature at which the gas diffusion electrode does not deteriorate by oxidation in air, is desirable. The pressure is preferably 10 kg / cm ² or more. By this step, the silver wire on the back surface of the gas diffusion electrode and the silver-plated portion on the surface of the gas-permeable porous body 5 form a joint, and the back surface of the gas diffusion electrode and the surface of the gas-permeable porous body 5 It will be joined by the joint. In addition,
In this manufacturing process, the back surface of the gas diffusion electrode and the surface of the gas permeable porous body 5 were joined without first welding the gas permeable porous body 5 to the gas chamber frame. It can also be welded to the gas chamber frame. As a result, in FIG.
It is possible to conduct electricity from the (electrolysis tank frame) to the reaction layer 11 of the gas diffusion electrode at the shortest distance and at a portion with low electric resistance, and it is possible to realize a reduction in electrolysis voltage. Further, since the gas diffusion electrode 2, the gas-permeable porous body 5 and the cathode outer frame 3 can be integrated, even if the electrolysis apparatus is enlarged, the preparation workability and operability of the apparatus become simple.

The gas diffusion electrode and the porous body filled in the gas chamber can be easily and firmly combined with each other without damaging the function of the gas diffusion electrode and without significantly changing the gas permeability of the gas diffusion electrode and the porous body. It is very technically difficult to join them. Gas diffusion electrodes, as already mentioned above,
In particular, the fluorine resin fine particles and the binder particles connecting the fine particles, which are constituent materials used in the gas diffusion layer, are not materials having high heat resistance, and are decomposed when exposed to a high temperature of 400 ° C. or more, and the space between the fine particles is reduced. The gas permeability is lost because it is blocked. Therefore, the bonding temperature suitable for bonding the gas diffusion electrode and the porous body is 200 ° C. to 400 ° C., and particularly when the gas diffusion electrode is bonded in air, the platinum catalyst is oxidized. Therefore, it is preferable that the bonding be performed at a temperature of up to about 250 ° C., and a temperature of up to 300 ° C. is allowable depending on conditions.

The material used as the joining medium is a material which does not affect the electrolytic reaction at the time of joining or during electrolysis, and which is not susceptible to corrosion of the joining agent itself, and which has an electric conductivity. It must be a material that does not increase electrical resistance. As such materials, silver and silver alloys were selected as a result of intensive studies. Silver is not oxidized by air at all temperatures and is not oxidized at the cathode in aqueous sodium hydroxide solution. Furthermore, in order to form a joint with the silver or silver alloy, a thin wire is used for the gas diffusion layer of the gas diffusion electrode, these are arranged in a grid or parallel lines, and fixed, and a porous The bonding side surface of the body is plated so as not to lose porosity to form a bonding surface. The following materials can be given as silver alloys suitable for the joining material. That is, it is a silver-copper alloy, a silver-tin alloy, a silver-tin-lead alloy, a silver-lead alloy, or the like.

The preferred form of the gas chamber in the cathode of the electrolytic cell of the present invention will be described. That is, the gas chamber of the cathode of the electrolytic cell of the present invention is filled with a porous body through which gas can flow three-dimensionally, so that the gas is uniformly supplied to the gas diffusion layer side of the gas diffusion electrode. This prevents deformation of the gas diffusion electrode. In the present invention, the term "filling the gas chamber with a porous body" does not mean "filling the gas chamber with a porous body" in this case, but means that the gas chamber is provided until it comes into contact with the surface of the gas diffusion electrode. Since the object of the present invention is to uniformly supply the gas to the surface of the gas diffusion electrode, the gas must not be densely packed so as to hinder the flow of the gas, and it means “insert” or “provide”. It should be understood that there may be.

Filling the gas chamber of the salt cell of the present invention with 3
The porous body through which gas can flow in a three-dimensional manner is not limited to a metal but may be an electrically conductive one that can uniformly flow gas into the gas diffusion electrode. Preferably, there is. That is, if the porous body to be filled is made of metal, the porous body made of metal is in contact with the gas diffusion electrode on the entire surface.By connecting a cathode terminal to the porous material, the porous body becomes The current collector is wide, and the current distribution can be made more uniform than that of a conventionally used current collector. Furthermore, if the metal porous body and the gas diffusion electrode are joined to be integrally formed, a conventional current collector is not required. At this time, the current applied to the gas diffusion electrode is also uniformly applied to the entire surface of the gas diffusion electrode as compared with the current flowing when the current is applied from a terminal provided at the peripheral end of the gas diffusion electrode. can do.

FIG. 2 shows a cathode section configured to fill a gas porous chamber capable of uniformly supplying gas three-dimensionally into the gas chamber of the cathode section of the electrolytic cell. In FIG. 2, (a) shows a front view of the cathode portion viewed from the gas diffusion electrode side,
(B) shows the longitudinal side view. 2 is a gas diffusion electrode, 4
Is a gas chamber, 5 is a porous body, and 6 is a cathode terminal.

The rigid porous body may take various forms, and among these, a form such as a wire mesh or an expanded mesh or a porous metal such as foamed nickel is preferable. Porous metals such as wire mesh and foamed nickel can pass gas three-dimensionally,
In addition, since it is made of metal, it also has a function as a current collector. When such a metal porous body is used, a conventional current collector is unnecessary. As shown in FIG. 2, when the cathode portion 1 of the electrolytic cell in which the metal porous body 5 was filled in the oxygen gas chamber 4 was formed, the cell voltage was lowered, and even when air was used, the voltage did not increase and was low. It has been found that electrolysis can be stably continued at a voltage.

As wire meshes, wire meshes of various weaves, expanded meshes, and the like are suitable. Regarding the flatness, it is possible to use a material that has been woven and stretched, a material that has been subjected to a certain degree of smoothing treatment by rolling, and a material that has been formed by pressing a corrugated plate (corrugated material). Excessive smoothing is not preferred because it hinders the passage of gas in the plane direction. The pitch of the short diameter (dense direction) of the wire mesh is preferably about 0.5 to 5 mm. One sheet can be used alone, or a plurality of sheets can be used. A thickness of 0.2 mm to 2 mm can be used. When wire meshes having different pitches in the vertical and horizontal directions are stacked, it is preferable to change the directions so as not to hinder the passage of gas. To ensure electrical continuity, the superimposed wire meshes are welded together by spot welding, etc.
Further, it is preferable to weld to the gas container body. In order to ensure contact with the gas diffusion electrode, silver plating of the wire mesh gives good results. Also, silver bonding can be used for laminating wire meshes.

The thickness of the gas chamber is also important. Although the appropriate thickness varies depending on the size of the electrolytic cell, it is preferably about 0.5 mm to 3 mm for a normal-sized electrolytic cell. 0.5
mm, the pressure loss associated with the passage of gas increases,
If the thickness is larger than 0 mm, supply of oxygen to the electrode is deteriorated, and an overvoltage is increased. The gas chamber has a thickness of about 1 mm and is completely filled with a wire mesh. By using the electrolytic cell having such a configuration, the cell voltage can be reduced to 2 V or less.
Further, even if air is used as the oxygen source, the rise in voltage is reduced to 0.1.
It can be suppressed to 1 V or less.

The effect of filling these porous bodies is understood as follows. The oxygen in the gas chamber is diluted with steam and nitrogen,
It is considered that a boundary film having an extremely low oxygen concentration is formed on the gas layer surface of the gas diffusion electrode. It is considered that the presence of the filler causes the flow of the oxygen-containing gas to be turbulent, the film to be thinned, the supply of oxygen to be promoted, and the overvoltage to be reduced. Therefore, the porosity of a wire mesh is larger than that of a simple groove-shaped passage,
It is considered that filling with a material having a large turbulence effect is more suitable.

[0026]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to only this embodiment. Example 1 A nickel end plate made of nickel having a thickness of 0.3 mm, a line width of 0.3 mm, and an opening width of 1.5 mm was formed into a corrugated material having a height of 1 mm and a pitch of 1 mm on a nickel-side cathode end plate, followed by silver plating. 10 microns, depth 1m
m was welded with a spot welder to produce a gas chamber shown in FIG. A gas diffusion electrode with a silver mesh having a mesh line width of 0.1 mm and a mesh width of 1 mm is placed on the end plate with a porous body and heated and pressed at 270 ° C. and a pressure of 10 kg / cm ² , and the oxygen of FIG. A cathode was obtained. Using this end plate with electrodes, an ion exchange membrane type electrolytic cell is assembled,
The distance between the ion exchange membrane and the oxygen cathode is 2 mm, 32% Na
As a result of supplying the OH cathode solution supply solution, 80 ° C. and pure oxygen, and operating the electrolytic cell, the cell voltage was 30 A / dm ² and the cell voltage was 2.10 V
Met.

Comparative Example 1 A nickel-made expanded metal having a thickness of 0.3 mm, a line width of 0.3 mm, and an opening width of 1.5 mm was formed on a nickel cathode-side end plate into a corrugated material having a height of 1 mm and a pitch of 1 mm. , Silver plating 10 microns, depth 1m
m was welded with a spot welder to produce a gas chamber shown in FIG. When a conventional gas diffusion electrode is sandwiched on the end plate with a porous body and a current collector made of silver is applied from around the electrolytic cell, a gap between the ion exchange membrane and the oxygen cathode is reduced by two.
As a result of operating the electrolytic cell under the same conditions as in Example 1 in which mm, 32% NaOH, 80 ° C., and pure oxygen were supplied, 30 A / d was obtained.
The cell voltage was 2.30 V at m ² .

[0028]

For example, a gas chamber capable of supplying gas from the rear surface is provided in a cathode outer frame capable of supplying catholyte from the rear surface, and the gas chamber is made of, for example, a corrugated metal mesh or nickel foam. A gas-permeable conductive porous body is filled, silver plating is performed on the surface of the porous body, and a gas diffusion electrode lined with silver or silver alloy net or wire is placed on the silver-plated porous body. By heating and pressing, the diffusion layer side surface of the gas diffusion electrode of the alkali metal chloride aqueous solution electrolysis tank having a gas diffusion electrode on the cathode and the surface of the porous metal body filled in the gas chamber with metallic silver or Through the joint made of silver alloy, while maintaining good electrical conductivity and gas permeability, and firmly adhered, the electrical resistance between the cathode outer frame having the cathode terminal and the gas diffusion electrode is extremely low. , Gas permeability is uniform, the distance between the ion exchange membrane and the gas diffusion electrode can also shortened to the limit, now electrolysis performance of alkali metal chloride aqueous solution electrolysis device having a gas diffusion electrode can be sufficiently exhibited. Furthermore, even if the size of the alkali metal chloride aqueous solution electrolysis apparatus is increased, the increase in electrolysis voltage can be minimized, and the preparation workability and operability of the apparatus become simple. It has been found that the device can be applied.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing an example in which a cathode portion having a gas diffusion electrode of the present invention is assembled with an ion exchange membrane.

FIG. 2 shows an example in which a cathode section having a gas diffusion electrode of the present invention is assembled with an ion exchange membrane;
(A) is a front view seen from the gas diffusion electrode side, (b)
Is a longitudinal sectional side view.

FIG. 3 is an explanatory sectional view showing an example of a cathode section having a gas diffusion electrode of the present invention.

FIG. 4 is a cross-sectional explanatory view showing an example of the gas diffusion electrode of the present invention in which a silver mesh is lined on the back surface.

FIG. 5 is an explanatory sectional view showing an example of a gas chamber filled with a porous body of the present invention.

FIG. 6 is an explanatory sectional view showing an example of the gas diffusion electrode of the present invention.

FIG. 7 is an explanatory cross-sectional view showing a typical example of a conventional ion exchange membrane electrolytic cell having a gas diffusion electrode.

FIG. 8 is an explanatory view showing an example of a conventional gas diffusion electrode support provided in a gas chamber.

FIG. 9 is a longitudinal sectional view of the gas diffusion electrode showing an arrangement state of the silver mesh in the gas diffusion electrode of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cathode part 2 Gas diffusion electrode 3 Cathode outer frame 4 Gas chamber 5 Porous body 6 Cathode conductor 7 Catholyte supply path 8 Catholyte discharge path 9 Oxygen supply path 10 Oxygen discharge path 11 Reaction layer 12 Gas diffusion layer 13 Silver net 15 Ion Exchange membrane 17 Catholyte compartment 18 Anode 19 Anode compartment 20 Electrolyzer 21 Salt water supply path 22 Salt water discharge path

Continued on the front page (72) Inventor Choichi Furuya 2-14 Nakamuracho, Kofu City, Yamanashi Prefecture

Claims (1)

[Claims] When producing an alkali metal chloride electrolytic cell comprising a gas diffusion electrode, a gas chamber filled with a conductive porous material, and a cathode outer frame, the gas diffusion electrode is filled in the gas diffusion chamber side surface and the gas chamber. The surface of the conductive porous body at 200 ° C. via a joining member made of metallic silver or a silver alloy.
A method of joining a gas diffusion electrode and a gas chamber, wherein the joining is performed by heating and pressurizing within a temperature range of from 400 to 400 ° C.