JP3686270B2 - Electrolytic cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides an electrolytic cell, for example, an electrolytic cell used for electrolysis of an aqueous alkali metal salt solution, water electrolysis or a fuel cell, particularly an ion exchange membrane, and a shape in which an anode and a cathode are respectively in contact with both sides. Related to the electrolytic cell.
[0002]
[Prior art]
A solid electrolyte membrane such as an ion exchange membrane is used as a diaphragm to partition into an anode chamber and a cathode chamber, and an electrolytic cell having an anode and a cathode in each chamber is used, and alkali metal salts such as sodium chloride and potassium chloride are used. A method of recovering chlorine with sodium hydroxide or potassium hydroxide, a method of obtaining alkali hypochlorite, etc., a method of electrolyzing water to obtain hydrogen or oxygen, and a fuel cell A method for recovering energy is known.
[0003]
As such an electrolytic cell, there is an electrolytic cell having a structure in which a solid electrolyte membrane, for example, an ion exchange membrane is sandwiched between both positive and negative electrodes.
[0004]
In this type of electrolytic cell, the distance between the electrodes is substantially zero, so that an electric loss due to the electric resistance of the electrolytic solution is omitted, so that it can be said to have an excellent structure.
[0005]
However, since a solid electrolyte membrane such as an ion exchange membrane generally composed of organic matter is sandwiched between electrodes made of metal, due to vibration during operation of the electrolytic cell, errors during assembly work of the electrolytic cell, etc., due to the electrode, The solid electrolyte membrane may be damaged.
[0006]
Further, in a large electrolytic cell used industrially, it is considerably difficult to install both the positive and negative electrodes flat and in parallel.
[0007]
Therefore, a structure is proposed in which one electrode is a flexible and flexible perforated plate, the electrode is further pressed with a conductive and elastic mat, and the other electrode surface is softly pressed through a solid electrolyte membrane. Has been.
[0008]
For example, according to Japanese Examined Patent Publication No. 63-53272, an electrode layer-one membrane assembly obtained by bonding a substance made of electrocatalyst particles to the surface of an ion exchange membrane, and one electrode layer side of the assembly A relatively rigid coarse screen provided on the other electrode layer and a resiliently compressible mat provided on the other electrode layer side of the assembly and having a volume 1.5 times or more that of the compressed state, and ribs or protrusions on the inside. An alkali metal chloride aqueous solution that is formed by compressing between a cathode end plate having an anode end plate having ribs or protrusions on the inside, and the elastic compression mat is a series of spiral coil fabrics made of metal wires A relatively rigid coarse screen used as one electrode provided on one surface of the electrolytic cell and the ion exchange membrane and the ion exchange membrane, and the other of the ion exchange membrane A flexible or flexible thin screen provided on the surface and used as the other electrode, and an elastic compressible mat provided on the outer surface of the thin screen and having a volume of 1.5 times or more of that when compressed; Is formed between a cathode end plate having ribs or protrusions on the inside and an anode end plate having ribs or protrusions on the inside, and the elastic compression mat is a series of spiral coil fabrics made of metal wires. An electrolytic cell of an alkali metal chloride aqueous solution is proposed. Further, as an electrolytic cell with improved practicality, Japanese Patent Publication No. 5-34434 has an anode chamber and a cathode chamber separated by a cation exchange membrane. The anode chamber has an anode, and the cathode chamber has a cathode. consists structures each present, among the anode and cathode, at least one of the electrodes, a thickness of less than 0.3 mm, the area of one location hole a number of holes of 0.05 mm ² 1.0 mm ² An ion-exchange membrane method alkali metal having a porous electrode surface having a porosity of 20% or more and comprising a wire assembly having a diameter of 0.1 to 1 mm and backed by a current collector having a porosity of 30% or more An electrolytic cell for salt electrolysis has been proposed.
[0009]
[Problems to be solved by the invention]
As described above, the common structure in the electrolytic cell having the structure in which the solid electrolyte membrane is sandwiched between the positive and negative electrodes is that at least one of the electrodes is a flexible and flexible porous plate, and an elastic current collector is provided on the back side. The body, generally a mat-like material, is placed in a compressed state, and the repulsion resilience keeps the electrical conductivity between the electrode and the elastic mat by pressing the solid electrolyte membrane, and the solid electrolyte membrane and / or the elastic mat. The position is kept so as not to change.
[0010]
In the case of a large electrolytic cell, when assembling an electrolytic cell main body that is a heavy weight, it is possible to overlap a solid electrolyte membrane such as an ion exchange membrane, a flexible electrode, and an elastic mat and sandwich them between electrode chambers. It is not easy and often causes misalignment and requires reassembling. In addition, during the operation of the electrolytic cell, the solid electrolyte membrane is strongly sandwiched and fixed at the periphery of the electrolytic cell, etc., but the flexible electrode and the elastic mat are simply crimped and fixed by the pressure of the elastic mat. For this reason, the position may be shifted due to vibrations based on internal pressure fluctuations or the like during operation of the electrolytic cell.
[0011]
In addition, a method in which an elastic mat or a flexible electrode is fixed to an electrolytic cell frame, in particular, a back partition wall or a current collecting porous body fixed to the back partition wall by welding or the like can be considered. There is a difficulty that requires a lot of labor to attach and detach the fixed part during repair.
[0012]
Accordingly, the present inventors have conducted various studies based on the novel idea of securing the flexible electrode及beauty bullet mat detachably, and completed the present invention.
[0013]
[Means for Solving the Problems]
Therefore, the present invention provides a solid electrolyte membrane electrolytic cell in which one of the electrodes is a fixed rigid electrode (A) and the other is a detachable flexible soft electrode (B). (A) The electrode and the elastic mat are pressed against the solid electrolyte membrane together with the solid electrolyte membrane by an elastic mat existing between the electrode plate, and the (B) electrode contacts the solid electrolyte membrane. From (B), the electrolytic cell is characterized in that it is fixed with a pin that penetrates through the electrode and the elastic mat and engages with a hole of the porous collector plate.
[0014]
Further, according to the present invention, the pin used in the electrolytic cell has an enlarged head portion, and forms a shoulder portion for preventing removal through the neck portion . An electrolytic cell characterized by being a pin is proposed.
[0015]
That is, one aspect of the present invention, a flexible electrode及beauty bullets mat with a plurality of pins, in the electrolytic cell was detachably fixed to the porous current collector plate of elastic mat back surface.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below. For convenience of explanation, the electrolytic cell of the present invention will be described by taking electrolysis of an aqueous solution of an alkali metal halide salt such as sodium chloride as an example.
[0017]
FIG. 1 is a conceptual diagram for explaining an electrolytic cell of the present invention. 1 is an anode chamber frame, and 2 is an anode chamber back partition. 3 is an anode conductive rib, and 4 is an anode. In the electrolysis of an alkali metal halide aqueous solution, for example, sodium chloride electrolysis, chlorine is generated at the anode, so that it is usually composed of a chlorine-resistant material such as titanium or the anode chamber is lined. The anode rib and anode are also made of titanium. The anode is a perforated plate with relatively high rigidity, such as expanded metal, a metal mesh composed of a thick metal wire having punched metal rigidity, or a metal rod connected in a grid, and the size of one hole is 2 to 2. 100 mm ^2, preferably there are many holes of 2 to 30 mm ^2. The porosity is a perforated plate having a porosity of 20% or more. The anode is coated with an anode active material such as a mixture of a white metal oxide or a platinum group metal oxide and a Group 4 to Group 8 metal oxide in the synchronization table. 5 is a cation exchange membrane. Usually, it has a perfluoroalkyl ether such as Nafion (trade name) as a skeleton and an ion exchange group such as a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, or a mixed group thereof. 6 is a flexible and soft cathode, which is usually a perforated plate of mild steel or nickel, that is, a punched metal or a mesh (wire net). In some cases, as a cathode active material, for example, sulfur-containing nickel plating, nickel and Alloy plating with a Group 6 or Group 8 metal (except nickel) in the periodic table is performed. Reference numeral 7 denotes an elastic mat, which is an aggregate of mild steel or nickel wires, particularly a structure in which coiled materials are entangled with each other, a woven fabric (or knitted fabric) crimped, and further subjected to helibone processing to give elasticity. It is a mat. Usually, with the electrolytic cell assembled, the elastic mat is compressed to a volume of 30 to 70%, thereby pressing the ion exchange membrane and the flexible cathode toward the anode side. Pressing at this time is generally 200 g / cm ² or less, preferably 30 to 50 g / cm ² approximately. 8 is a cathode current collector plate, which is generally a rigid porous plate, such as an expanded metal, a punched metal, a fabric of a rigid metal wire, or a saddle-like material in which metal bars are arranged in parallel at appropriate intervals. Reference numeral 9 denotes a cathode rib, which is electrically connected to the rear partition wall 11 of the cathode chamber frame 10 and mechanically fixes the cathode current collector plate.
[0018]
In the above description, the anode is a rigid electrode and the cathode is a flexible electrode. However, a structure in which the cathode and the anode are reversed is also possible.
[0019]
As described above, in the electrolytic cell of the present invention, as shown in FIG. 2, the flexible cathode 6 exists on the front surface of the cathode chamber frame 10, and the elastic mat exists on the back of the cathode (not shown in FIG. 2). Absent). The flexible cathode and the elastic mat penetrate from the front surface (the side in contact with the solid electrolyte membrane, that is, the ion exchange membrane) and are fixed by the fixing pins 12. FIG. 3 is a side view conceptually showing that the fixing pin 12 passes through the flexible cathode 6 and the elastic mat 7 and is engaged with the hole of the cathode current collector plate to fix the flexible cathode and the elastic mat. . The fixing pin has an action of enlarging the head portion and holding the flexible cathode, and has a shoulder portion for preventing pull-out that can be engaged with the hole of the porous cathode current collector plate through the neck portion. The shape is not particularly limited as long as it has a substantially conical tip portion, but the shape as shown in FIG. 4 is generally preferable. 4A is a perspective view of a general fixing pin, and FIG. 4B is a side view thereof. Further, (c) is a side view showing an example of another aspect of the fixing pin.
[0020]
The fixing pin will be further described with reference to FIG. 4 (a). A is an enlarged head, and plays a role of pressing down a metal mesh or the like constituting the flexible cathode by the enlarged portion. B is a neck portion, as shown in FIG. 3, which is a portion penetrating the flexible cathode and the elastic mat. C is a tip portion, and has a conical shape in which the tip is thinned so that the flexible pin and the elastic mat can be penetrated when penetrating the fixing pin. Although it is shown as a conical shape in FIG. 4A, a pyramid can be used similarly. The distal end portion has a shoulder portion for preventing removal near the joint portion with the neck portion. This shoulder is locked to the edge of the hole of the porous cathode current collector plate. Therefore, it is preferable that the diameter of the shoulder portion of the fixing pin (in the case of a circle) is just enough to fit in the hole of the cathode current collector plate. In particular, when the fixing pin is made of a synthetic resin such as Teflon, it is slightly larger than the hole diameter, so that it deforms somewhat due to the flexibility of the resin and easily penetrates the hole of the cathode current collector plate, and then the shape As a result of the recovery, the shoulder portion engages with the edge of the hole on the back surface of the current collector plate and becomes a stopper. However, it is possible to pull out with greater power such as human power.
[0021]
FIG. 4 (c) shows a structure in which the tip is cut, and when it is inserted, the tip is sunk, the diameter of the shoulder is reduced and the shoulder is restored after passing through the hole of the cathode current collector plate. Play a role. Therefore, in the case of this shape, it is preferably employed for a metal fixing pin or the like.
[0022]
Further, the material of the fixing pin must naturally be able to withstand the electrode chamber liquid used. In general, a synthetic resin having high chemical resistance such as Teflon is preferable, but a durable metal may be used depending on the liquid in the electrode chamber.
[0023]
Fixing pin from its purpose, it is apparent compliant electrode及beauty bullets mat, since it is intended for fixing the current collector plate of the back surface, but are a plurality of used depending on the purpose, What is necessary is just to determine suitably the position and number which fix with this pin. In general, it is often preferable to use it in the periphery of the electrode.
[0024]
The present invention will be specifically described below with reference to comparative examples.
[0025]
[Comparative Examples and Examples]
Comparative Example 1
Electrolysis of the sodium chloride aqueous solution was performed using an electrolytic cell having an electrode chamber having the structure shown in FIG. The hollow part of the chamber frame serving as the energization part was 116 cm long and 238 cm wide, and the thickness of the electrode chamber was 4.4 cm. The anode used was a 1 mm thick titanium punched metal coated with an active material. As for the flexible cathode, Ni ₃ Sn ₂ alloy-plated nickel having a wire diameter of 0.15 mm, a hole area ratio of 68%, and a hole area of 0.49 mm ² was used. As the elastic mat, a nickel wire having a diameter of 0.08 mm and four knitted metal meshes were crimped and used, and a height of about 9 mm was used. As the current collector plate, expanded metal 1t × 4.5 _SW × 10 _LW × 1.2 _ST was used. The flexible cathode and the elastic mat were fixed to the current collector plate by spot welding, and the 4 even and upper sides were fixed at 11 places in the middle, 1 each at the center of both sides, and the lower sides were fixed at 3 places at equal intervals. As the ion exchange membrane, Nafion N-962 (manufactured by DuPont) was used.
[0026]
After operation for about 4 years in the electrolytic cell having the above structure, the electrolytic cell was disassembled for replacement of the elastic mat. As a result, the ion exchange membrane was scraped at a portion where spot welding was partially removed. Further, when removing the flexible cathode, the welded portion was damaged and could not be reused.
[0027]
Comparative Example 2
The structure of the electrolytic cell was the same as in Comparative Example 1, but the flexible cathode and elastic mat were fixed to the current collector plate using Ni wire having a wire diameter of 0.2 mm. As compared with Comparative Example 1, it took time to process and fix the tip of the Ni wire, and the electrolytic cell had to be stopped for a long time. The operation was started in the electrolytic cell having the above structure, but a hole was opened in the ion exchange membrane at the tip of the Ni wire, and the electrolytic cell was stopped.
[0028]
Example 1
The structure of the electrolytic cell is the same as that of Comparative Example 1, but the flexible cathode and the elastic mat are fixed to the current collector plate with a Teflon pin having the shape of FIG. The diameter of 1 mm, the diameter of the neck 2 mm, the diameter of the shoulder for removal prevention is 2.4 mm, and the total length is 8 mm. The fixing time of the flexible cathode and the elastic mat to the current collector plate was the same as in Comparative Example 1, and the operability was easy because no instrument was used. After operating for 4 years in the electrolytic cell with the above structure, the electrolytic cell was disassembled, but there was no pin removal at the time of disassembly, and when removing the flexible cathode, it was easy to remove the pin without damaging the flexible cathode. I was able to remove it.
[0029]
【The invention's effect】
According to the present invention, not only the assembly and disassembly work is particularly easy in a large electrolytic cell, but also the electrode during operation of the electrolytic cell, the displacement of the elastic mat, and the solid electrolyte membrane caused thereby, such as an ion exchange membrane Can be prevented from being damaged or deteriorated.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an example of an electrolytic cell of the present invention. FIG. 2 is a conceptual diagram of an electrode chamber showing an embodiment using the fixing pin of the present invention. FIG. 3 is an explanatory diagram using the fixing pin of the present invention. FIG. 4 is a diagram showing an example of the fixing pin of the present invention.
1 is an anode chamber frame 2 is a back partition wall 4 is an anode 5 is a cation exchange membrane 6 is a flexible cathode 7 is an elastic mat 8 is a cathode current collector plate
10 is the back wall
11 is the cathode chamber frame

Claims (2)

One of the electrodes is a solid electrolyte membrane electrolytic cell comprising a fixed rigid electrode (A) and the other is a detachable flexible soft electrode (B). (B) The electrode is between the porous current collector plate. The (A) electrode is pressed against the (A) electrode together with the solid electrolyte membrane by the existing elastic mat, and the (B) electrode and the elastic mat are (B) from the contact surface side of the electrode with the solid electrolyte membrane. ) An electrolytic cell characterized in that it is fixed with a pin that penetrates the electrode and the elastic mat and engages with the hole of the porous collector plate. 2. The fixing pin according to claim 1, wherein the pin is a fixing pin having a substantially conical tip portion that forms a shoulder portion for preventing removal through a neck portion with an enlarged head portion. Electrolyzer.

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