JP2014214350A - Ion exchange membrane electrolytic bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion exchange membrane electrolytic bath which achieves a zero-gap configuration of a conventional narrow-gap ion exchange membrane electrolytic bath by a simple and inexpensive method and is improved in electrolytic performance.SOLUTION: In an ion exchange electrolytic bath, an anode chamber 2 and a cathode chamber 3 are divided with an ion exchange membrane 1, and the cathode chamber 3 has a cathode composed of a rigid cathode 4, a metal-made elastic body 5 and a hydrogen generation cathode 6, superimposed together. A concave part 4a is formed in a region of the rigid cathode 4 in contact with the metal-made elastic body 5, and the metal-made elastic body 5 is arranged in the concave part 4a.

Description

  The present invention relates to an ion exchange membrane electrolytic cell (hereinafter, also simply referred to as “electrolytic cell”). Specifically, the conventional narrow gap ion exchange membrane electrolytic cell has a zero gap formed by a simple and inexpensive method. The present invention relates to an improved ion exchange membrane electrolytic cell.

  Hydrogen generation reaction occurs during electrolysis at the cathode installed in the cathode chamber of an ion exchange membrane electrolytic cell used for salt electrolysis, water electrolysis and the like. This cathode is usually formed in the shape of a perforated plate in order to smoothly desorb the generated hydrogen gas for the purpose of reducing the electrolysis voltage. In order to reduce the hydrogen overvoltage during electrolysis, an active catalyst is supported on the surface.

  When the electrolytic cell is used for a long period of time, the performance of the hydrogen generating catalyst is lowered, and the hydrogen overvoltage increases with time, so that the energy required for electrolysis increases. Therefore, in order to reduce electrolytic energy, it is necessary to renew or reactivate the cathode at regular intervals. In general, the cathode is renewed by removing the deteriorated cathode from the electrolytic cell and attaching the newly prepared cathode to the electrolytic cell.

  For example, an electrolytic cell described in Patent Document 1 is a so-called zero gap that presses a flexible hydrogen-generating cathode against an ion-exchange membrane by the elastic repulsion of a metal coil body, holds the cathode, and conducts electricity. It is an electrolytic cell. In such a zero gap electrolytic cell, the flexible hydrogen generating cathode does not need to be firmly fixed to the electrolytic cell, so that the flexible hydrogen generating cathode can be attached and detached very easily. Therefore, it is very easy to remove the deteriorated hydrogen generating cathode from the electrolytic cell and attach the newly produced hydrogen generating cathode to the electrolytic cell.

Japanese Patent Laid-Open No. 2004-300547

  Today, a so-called narrow gap electrolytic cell in which the distance between the ion exchange membrane and the cathode is set to 0 to 1 mm is known. As a cathode of a narrow gap electrolytic cell, (1) a type in which a rigid cathode is attached to the cathode chamber frame by welding, and (2) an electrolysis made of a single conductive substrate having corrosion resistance and made porous by punching or the like There is a type in which a cathode frame portion which has a cathode catalyst portion having a catalyst only on the surface and which does not carry a catalyst around the surface forms a cathode chamber by being clamped and fixed to a cathode chamber frame made of a gasket or a corrosion-resistant material.

  When the cathode of the electrolytic cell as in the former is renewed, the rigid cathode is removed from the frame, and a new rigid cathode is fixed to the frame again by welding. Moreover, in order to fix a cathode by welding, what has the corrosion resistance with respect to electrolyte solution, such as nickel, has been used as the base material. On the other hand, when the latter cathode is renewed, the cathode member is not fixed to the cathode chamber frame and can be easily removed, and the cathode member is replaced or the catalyst component is re-plated to improve the performance. It was. For such a removable cathode member, a copper or iron-based porous plate coated with nickel and a surface coated with an active catalyst has been used.

  However, since such a cathode member is very expensive, it is preferable to reuse it. However, when re-plating the electrode catalyst, it is necessary to renew the cathode because it is plated once removed. there were. Therefore, also in the narrow gap electrolytic cell, as in the zero gap electrolytic cell described in Patent Document 1, a metal coil body and a flexible hydrogen generating cathode are stacked on the existing cathode to achieve a zero gap. Thus, a method for easily improving the electrolytic performance can be considered.

  However, since the narrow gap electrolytic cell as described above is close to the ion exchange membrane and the existing cathode, it is made of a metal having a specification that is used as an elastic body in an ordinary electrolytic cell between the ion exchange membrane and the existing cathode. The coil body cannot be inserted. Therefore, in order to achieve a zero gap for the narrow gap electrolytic cell, there arises a problem that it is necessary to change the design of the thickness of the metal coil body, change of the gasket thickness between the cathode and the ion exchange membrane, and the like.

  Accordingly, an object of the present invention is to provide an ion exchange membrane electrolytic cell with improved electrolysis performance, in which a conventional narrow gap ion exchange membrane electrolytic cell is made zero gap by a simple and inexpensive method.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by making the rigid cathode have a predetermined structure, and the present invention has been completed.

That is, the ion exchange membrane electrolytic cell of the present invention is partitioned into an anode chamber and a cathode chamber by an ion exchange membrane, and the cathode chamber is arranged by sequentially superposing a rigid cathode, a metal elastic body, and a flexible cathode. In an ion exchange membrane electrolytic cell having the structure
A contact area of the rigid cathode with the metal elastic body is formed as a recess, and the metal elastic body is accommodated in the recess.

  In this invention, it is preferable that the depth of the said recessed part is 1.5-2.0 mm. In the present invention, it is preferable that the angle of the inclined portion connecting the region where the metal elastic body is not disposed in the rigid cathode and the bottom surface of the concave portion is 10 to 45 °. Furthermore, in the ion exchange membrane electrolytic cell of this invention, it is preferable that the said metal elastic body is an elastic cushion material formed by winding a metal elastic body around a corrosion-resistant frame. Furthermore, the metal elastic body is preferably an elastic cushion material formed by winding a metal elastic body around a corrosion-resistant frame.

  According to the present invention, a conventional narrow gap ion exchange membrane electrolytic cell can be made zero gap by a simple and inexpensive method, and the electrolytic performance of the conventional ion exchange membrane electrolytic cell can be improved.

It is a schematic cross-sectional view explaining the anode chamber and cathode chamber of the ion exchange membrane electrolytic cell which concerns on one preferable embodiment of this invention. It is sectional drawing of the cathode of the ion exchange membrane electrolytic cell which concerns on one suitable embodiment of this invention. (A) is a perspective view which shows the example of the corrosion-resistant frame used for the elastic cushion material, (b) is a perspective view which shows the example of an elastic cushion material.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view illustrating an anode chamber and a cathode chamber of an ion exchange membrane electrolytic cell according to a preferred embodiment of the present invention. The illustrated ion-exchange membrane electrolytic cell is partitioned into an anode chamber 2 and a cathode chamber 3 by an ion-exchange membrane 1, and the cathode chamber 3 includes a rigid cathode 4 and a metal elastic body 5 (in the illustrated example, made of metal). A coil body) and a hydrogen generating cathode 6 as a flexible cathode are stacked. In the illustrated example, the anode 7 is fixed to the anode chamber frame 8 by welding, and the rigid cathode 4 is fixed to the cathode chamber frame 9 by tightening. The anode chamber 2 and the cathode chamber 3 are provided with conductive ribs 10 for reinforcement.

  In the ion exchange membrane electrolytic cell according to one preferred embodiment of the present invention, a concave portion is formed in a contact region of the rigid cathode 4 with the metal elastic body 5, and the metal elastic body 5 is formed in the concave portion. Contained. FIG. 2 shows a cross-sectional view of a cathode of an ion exchange membrane electrolytic cell according to a preferred embodiment of the present invention. As described above, since the gap between the ion exchange membrane and the cathode is small in the narrow gap electrolytic cell, it is not possible to apply the zero gap technology using a metal coil body. Therefore, as shown in the figure, a recess 4a is provided in the rigid cathode 4, a metal elastic body 5 is disposed in the recess 4a, and a flexible hydrogen generating cathode 6 is disposed thereon, whereby an anode 7 and an ion are disposed. The exchange membrane 1 and the hydrogen generating cathode 6 are in close contact.

  That is, in the ion exchange membrane electrolytic cell of the present invention, the concave portion 4a is provided in the rigid cathode 4 in order to dispose the metal elastic body 5, so that the hydrogen generating cathode is formed over the entire area where the metal elastic body 5 is disposed. 6, the ion exchange membrane 1 and the anode 7 can be brought into close contact with each other (see FIG. 1). Thereby, the electrolytic performance of the conventional narrow gap electrolytic cell can be improved. In the example shown in FIG. 2, the rigid cathode 4, the metal elastic body 5, and the hydrogen generation cathode 6 are fixed by a corrosion-resistant pin 11.

  In the ion exchange membrane electrolytic cell according to one preferred embodiment of the present invention, the depth h of the concave portion 4a may be appropriately determined according to the gap of the narrow gap electrolytic cell. For example, in the case of a narrow gap electrolytic cell having a gap of 0.5 to 1.0 mm, the depth h of the recess 4a may be 1.5 to 2.0 mm. In the illustrated example, the metal elastic body 5 is disposed in the recess 4a, and the flexible hydrogen generation cathode 6 is disposed thereon, but according to a preferred embodiment of the present invention. The form of the ion exchange membrane electrolytic cell is not limited to this. For example, instead of the metal elastic body 5, an elastic cushion material configured by winding a metal elastic body around a corrosion-resistant frame, which will be described later, may be used. Further, the method of fixing the metal elastic body 5 (or the elastic cushion material) and the flexible hydrogen generating cathode 6 to the rigid cathode 4 is not limited to the fixing using the pins 11 as shown in the figure, You may fix by welding etc.

  In the ion exchange membrane electrolytic cell of the present invention, the angle of the inclined portion 4c (hereinafter referred to as the narrowing angle θ) connecting the region 4b of the rigid cathode 4 where the metal elastic body 5 is not disposed and the bottom surface of the recess 4a is as follows. It is preferable that it is 10-45 degrees. This is because if the narrowing angle θ is larger than 45 °, cracks may occur in the existing coating of the rigid cathode. By setting the narrowing angle θ in the above range, the existing coating of the rigid cathode is not cracked, and the reaction force of the elastic body can be obtained appropriately. More preferably, it is 10-35 degrees, More preferably, it is 10-15 degrees.

  In the ion exchange membrane electrolytic cell of the present invention illustrated in FIG. 1, a metal coil body is exemplified as the metal elastic body 5. However, in the ion exchange membrane electrolytic cell of the present invention, the metal elastic body 5 is used. There is no particular limitation as long as it is made of a conductive material and has an elastic property, and can supply power by pressing the flexible hydrogen generating cathode 6 against the ion exchange membrane 1. For example, in addition to the metal coil body, a corrugated metal thin wire may be used, or a metal nonwoven fabric may be used. Other metal elastic bodies include elastic mats that are woven metal wires, knitted fabrics made of metal wires, woven fabrics and laminates thereof, or three-dimensionally knitted or three-dimensionally knitted. After that, a shape obtained by subjecting this to swell processing or the like may be used.

  When a metal coil body is used as the metal elastic body 5, for example, nickel, nickel alloy, stainless steel, or copper having good resistance to corrosion such as nickel having good corrosion resistance is plated. It is obtained by processing the wire manufactured by coating with a spiral coil by roll processing. The cross-sectional shape of the obtained wire is preferably a circle, an ellipse, a rectangle with rounded corners, or the like from the viewpoint of preventing damage to the ion exchange membrane. Specifically, when a nickel wire (NW2201) having a diameter of 0.17 mm is rolled, a coil wire having a cross-sectional shape of about 0.05 mm × 0.5 mm with rounded corners and a winding diameter of about 6 mm is obtained. be able to.

  In FIG. 1, the metal elastic body 5 (metal coil body in the illustrated example) is mounted as it is between the rigid cathode 4 and the hydrogen generating cathode 6 in the electrolytic cell, but in the ion exchange membrane electrolytic cell of the present invention. As described above, instead of the metal elastic body 5, an elastic cushion material formed by winding a metal elastic body around a corrosion-resistant frame may be used. FIG. 3A is a perspective view showing an example of a corrosion-resistant frame used for the elastic cushion material, and FIG. 3B is a perspective view showing an example of the elastic cushion material.

  As shown in FIGS. 3A and 3B, the corrosion-resistant frame 100 according to the present invention is a metal round bar from a reinforcing rod 102 spanned between a pair of round bars in the longitudinal direction of a rectangular frame 101. It is made up. As this metal round bar, for example, a nickel round metal bar having a diameter of about 1.2 mm can be suitably used. The elastic cushion material 103 according to the present invention winds a metal elastic body 104 (a metal coil body in the illustrated example) over almost the entire length between a pair of round bars in the longitudinal direction of the corrosion-resistant frame 100. Can be obtained (FIG. 3B). The elastic cushion material 103 obtained in this manner is held in the shape of the corrosion-resistant frame 100 because the metal elastic body 104 is wound around the corrosion-resistant frame 103, and the metal elastic body 104 is removed from the corrosion-resistant frame 100. The metal elastic body 104 can be handled as being integrated with the corrosion-resistant frame 100 with little separation. By winding the metal elastic body 104 around the corrosion resistant frame 100, the following advantages can be obtained.

  That is, since the metal elastic body 104 has a high deformation rate, it is difficult to handle and it is often difficult to install the metal elastic body 104 at a predetermined location of the electrolytic cell as intended by the operator. Furthermore, since it is easily deformed (the strength is insufficient), even if it is once installed at a predetermined location of the electrolytic cell, it is displaced by the electrolytic solution or generated gas in the electrolytic cell, and it becomes difficult to uniformly adhere each member There is. On the other hand, the elastic cushion material 103 is composed of, for example, a frame rod having four rectangular corrosion-resistant frames as shown in FIG. It can be obtained by winding the metal elastic body 104 between the two facing each other so as to obtain a substantially uniform density (see FIG. 3B). In the electrolytic cell of the present invention, a metal coil body has been described as an example of a metal bullet body used for the elastic cushion material. However, in addition to the metal coil body, the metal such as a metal nonwoven fabric is used. An elastic body may be used.

  In the present invention, electricity is usually flowed by a contact energization method. The assembly of the elastic cushion material using a metal elastic body is an operation outside the electrolytic cell, so it can be easily performed, and the obtained elastic cushion material is the target in the electrolytic cell when the electrolytic cell is assembled. The electrode and the mounted current collector may be mounted so as to be electrically connected. Even at the time of wearing, the elastic cushion material itself is not deformed so as to hinder assembly due to the strength of the corrosion-resistant frame, so that it can be easily installed at a predetermined location.

  When a metal coil body is used as the metal elastic body, in the elastic cushion material 103 obtained by winding the metal coil body or the metal coil body, the diameter of the metal coil body (the apparent diameter of the coil) ) Is elastically contracted to 10 to 70% by being mounted in the electrolytic cell, and this elasticity makes it possible to elastically connect the rigid cathode 4 and the hydrogen generating cathode 6 to facilitate power feeding to the electrode. . If a metal coil body having a small wire diameter is used, the number of contact points between the rigid cathode 4 or the hydrogen generating cathode 6 and the elastic cushion material inevitably increases, and uniform contact is possible. In addition, the elastic cushion material 103 after being attached to the electrolytic cell is hardly subjected to plastic deformation because the shape is held by the corrosion-resistant frame 100, and is almost always re-assembled during the disassembly and reassembly of the electrolytic cell. Can be used.

  In the ion exchange membrane electrolytic cell of the present invention, when assembling a metal elastic body or an ion exchange membrane electrolytic cell including an elastic cushion material, an elastic cushion material or the like is positioned on the rigid cathode 4 and the hydrogen generating cathode 6, Thereafter, when assembled as usual, an ion exchange membrane electrolytic cell in which an elastic cushion material or the like is held at a predetermined position can be obtained.

  The ion exchange membrane electrolytic cell of the present invention relates to the improvement of the conventional narrow gap electrolytic cell, and it is only important to satisfy the above-mentioned configuration, and other structures are conventionally used structures. Can be used as appropriate, and is not particularly limited.

  For example, the hydrogen generating cathode 6 is not particularly limited as long as it is pressed by the metal elastic body 5 or the elastic cushion material and comes into contact with the ion exchange membrane 1, and is usually used for electrolysis. Any Ru-La-Pt system can be used, but the catalyst film is thin and highly active, the film surface is smooth, and the ion exchange film is not mechanically damaged. Pyrolytic active cathodes selected from the group consisting of Ru—Ce, Pt—Ce, and Pt—Ni are preferred.

  In order to perform salt electrolysis using the ion exchange membrane electrolytic cell of the present invention, current is passed between both electrodes while supplying an electrolyte such as a saline solution to the anode chamber and a dilute caustic soda solution to the cathode chamber. In an electrolytic cell in which an elastic cushion material or the like functions as an electrode, this state is maintained for a long time due to the high strength and toughness of the elastic cushion material or the like. Caustic soda or the like can be manufactured with high efficiency without excessive deformation and insufficient power supply.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Example 1>
As the ion exchange membrane electrolytic cell, AZEC-F2 (Asahi Glass Co., Ltd.) was used. A dimensional stability electrode made in China was adopted as the anode, and a nickel micromesh base active cathode was adopted as the hydrogen generation cathode. As the rigid cathode, copper punching metal with nickel plating and cathode coating was adopted. The reaction surface sizes of the anode and the cathode were 1140 mm in width and 1500 mm in height, respectively. As the ion exchange membrane, Flemion F-8030 manufactured by Asahi Glass Co., Ltd. was used.

The front surface of the reaction surface of the rigid cathode was a recess. The depth h of the recess was 2.0 mm, the narrowing angle θ was 12 °, and an elastic cushion material was disposed here. The elastic cushion material was produced in the following procedures. A coil wire having a width of about 0.5 mm was produced by rolling a nickel wire (NW2201) having a wire diameter of 0.14 mm and a tensile strength of 750 to 900 N / m ² . Using the obtained coil wire, a metal coil body having a coil winding diameter of about 5 mm was produced. This metal coil body is wound around a nickel round bar frame (corrosion-resistant frame) with a diameter of 1.2 mm to adjust the shape to a rectangular parallelepiped shape, and an elastic cushioning material having an approximate size of 5 mm thick × 1100 mm wide × 470 mm long is used. Produced. The coil linear density of this elastic cushion material was about 1.2 g / dm ² . The obtained elastic cushion material was inserted between the rigid cathode and the hydrogen generating cathode so that the elastic cushion material was elastic, and electrolysis was continuously performed at a current density of 5.93 kA / m ² .

<Result>
According to the ion exchange membrane electrolytic cell of the present invention, a voltage reduction of 170 to 210 mV can be achieved as compared with the case where electrolysis is performed at 5.93 kA / m ² using the conventional AZEC-F2.

DESCRIPTION OF SYMBOLS 1 Ion exchange membrane 2 Anode chamber 3 Cathode chamber 4 Rigid cathode 5 Metal elastic body 6 Hydrogen generating electrode 7 Anode 8 Anode chamber frame 9 Cathode chamber frame 10 Conductive rib 11 Pin 100 Corrosion resistant frame 101 Rectangular frame 102 Reinforcement rod 103 Elastic cushion Material 104 Metal elastic body

Claims (5)

In an ion exchange membrane electrolytic cell having a structure in which an anode chamber and a cathode chamber are partitioned by an ion exchange membrane, and the cathode chamber has a structure in which a rigid cathode, a metal elastic body, and a flexible cathode are sequentially stacked.
An ion exchange membrane electrolytic cell characterized in that a contact region of the rigid cathode with the metal elastic body is formed as a recess, and the metal elastic body is accommodated in the recess.   The ion-exchange membrane electrolytic cell according to claim 1, wherein the depth of the recess is 1.5 to 2.0 mm.   The ion exchange membrane electrolytic cell according to claim 1 or 2, wherein an angle of an inclined portion connecting a region where the metal elastic body is not disposed in the rigid cathode and a bottom surface of the concave portion is 10 to 45 °.   The ion exchange membrane electrolytic cell according to any one of claims 1 to 3, wherein the metal elastic body is an elastic cushion material formed by winding a metal elastic body around a corrosion-resistant frame.   The ion exchange membrane electrolytic cell according to any one of claims 1 to 4, wherein the metal elastic body is a metal coil body.

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