JP4246530B2 - Electrode for electrolysis and ion exchange membrane electrolytic cell using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode for electrolysis that can be used for electrolysis of an aqueous alkali metal chloride solution and the like, and an ion exchange membrane electrolytic cell using the same.
[0002]
[Prior art]
The electrolytic industry represented by chloralkali electrolysis plays an important role as a material industry. Although having such an important role, the energy consumption required for chloralkali electrolysis is large, and in countries with high energy costs such as Japan, there is a strong demand for achieving energy saving.
For example, chloralkali electrolysis has been converted from the mercury method to the ion exchange membrane method through the diaphragm method in order to achieve environmental conservation as well as solving environmental problems, and has achieved energy saving of about 40% in about 25 years. . However, even this energy saving is not enough, and the power cost of energy accounts for about half of the total manufacturing cost, but no further power savings are possible using the current method.
[0003]
In the electrolytic cell equipped with a hydrogen generating cathode used for salt electrolysis, the anode, ion exchange membrane and hydrogen generating cathode are arranged in close contact to reduce the electrolysis voltage, but the electrolysis area reaches several square meters. In a large electrolytic cell, when the anode and the cathode are made into electrode chambers with rigid members, it is difficult to keep both electrodes in close contact with the ion exchange membrane and to keep the electrode spacing at a predetermined value.
An electrolytic cell using an elastic material is known as a means for reducing the distance between electrodes or the distance between an electrode and an electrode current collector or maintaining it at a substantially constant value.
As this elastic material, non-rigid materials such as metal woven fabrics, nonwoven fabrics, and nets, and rigid materials such as leaf springs are known.
[0004]
The non-rigid material is partially deformed when it is excessively pressed from the counter electrode after being attached to the electrolytic cell, resulting in non-uniform distance between the electrodes, or the thin wire of the non-rigid material pierces the ion exchange membrane. There is. Further, a rigid material such as a leaf spring has a drawback that the ion exchange membrane is damaged, or plastic deformation occurs and the reuse becomes impossible.
Also, in an ion exchange membrane electrolytic cell such as a salt electrolytic cell, it is desirable that the anode and the cathode be in close contact with the ion exchange membrane so that the operation can be continued at a low voltage, and there are various methods for pressing the electrode in the direction of the ion exchange membrane. Proposed.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 63-53272 (FIGS. 1 to 8)
[0006]
[Problems to be solved by the invention]
As described above, the structural feature of the electrolytic cell that holds the ion exchange membrane between the positive and negative electrodes is to prevent the ion exchange membrane from being damaged by uniformly adhering the electrode to the ion exchange membrane and to both the positive and negative electrodes. In order to keep the distance between the electrodes at least, the structure is such that the movement of at least one of the electrodes in the inter-electrode distance direction is free, and the electrode can be pushed by an elastic member to adjust the holding pressure.
Elastic members include knitted or woven fabrics made of metal wires or laminates of these, or shapes that are three-dimensionally knitted or three-dimensionally knitted and then swelled, etc., and metal fibers There are non-woven fabrics, coil springs (springs), leaf springs, etc., all of which have some spring elasticity.
[0007]
On the other hand, in an industrial electrolytic cell such as a salt electrolytic cell, a leaf spring or a metal mesh may be used in order to smoothly supply power from the electrode current collector to the electrode.
However, as described above, since the leaf spring and the metal net are rigid bodies, the ion exchange membrane may be damaged, the deformation rate may be small, and sufficient electrical connection may not be obtained.
In order to eliminate such drawbacks, there is provided an electrolytic cell in which a metallic coil body is mounted between the cathode and the cathode end plate instead of the metal mesh body, and the cathode is uniformly pressed in the direction of the diaphragm and the respective members are brought into close contact with each other. (Patent Document 1).
[0008]
Since this metal coil body has a very small wire diameter and a high deformation rate, each member can be brought into close contact with each other, and a stable electrolytic cell operation can be performed.
However, in the electrolytic cell described in Patent Document 1, since the metal coil body is installed in the electrolytic cell in addition to the anode or the cathode, the number of parts increases, and sufficient adhesion is obtained when the cathode is a rigid body. There is a drawback that it may not be possible.
An object of the present invention is to provide an electrode for electrolysis used as an electrode itself and an electrolytic cell using the same, instead of using a conventional metal coil body in a mode of pressing an electrode in the direction of an ion exchange membrane. .
[0009]
[Means for Solving the Problems]
Electrolytic electrode of the present invention is the electrode for electrolysis, characterized in that it comprises a resilient cushioning material bearing the formed electrode catalyst by winding a metal coil body corrosion resistance frames. The ion exchange membrane electrolyzer of the present invention, in the ion exchange membrane electrolytic cell is partitioned into a cathode chamber containing an anode chamber and a cathode for accommodating the anode by an ion exchange membrane, at least one of the anode and cathode, corrosion resistance An ion exchange membrane electrolytic cell characterized by being an elastic cushion material carrying an electrode catalyst formed by winding a metal coil body around a frame.
[0010]
Hereinafter, the present invention will be described in detail.
In the ion exchange membrane electrolytic cell which is the subject of the present invention , an elastic cushion material is used as at least one of the anode and the cathode.
As a result, the electrode itself has elasticity, so there is no need to install an elastic member other than the electrode in the electrolytic cell as in the prior art. Thus, there is an effect that, for example, the electrode and the ion exchange membrane are uniformly adhered. The elastic cushion material, for example, is recessed when pressed locally with a finger and restored when the finger is released, and has extremely high adhesion to the unevenness of other members.
The electrolytic reaction in the ion exchange membrane electrolytic cell of the present invention is preferably a reaction for producing alkali hydroxide (caustic soda) by chloralkali (sodium chloride) electrolysis, but any reaction that can use the elastic cushion material described above as an electrode. If it does not specifically limit.
[0011]
An elastic cushion material is used as the anode or cathode of the ion exchange membrane electrolytic cell of the present invention .
A coil body made of metal is made by rolling a wire produced by coating nickel, nickel alloy, stainless steel, or copper, which has good corrosion resistance, with nickel, which has good corrosion resistance, on a metal having low specific resistance by plating or the like. It is obtained by processing into a spiral coil. The cross-sectional shape of the wire is preferably a circle, an ellipse, a rectangle with round corners, or the like. In order to prevent damage to the ion exchange membrane, a cross-sectional shape with sharp corners such as a triangle or rectangle is not desirable. For example, when a nickel wire (NW2201) having a diameter of 0.17 mm is rolled, a square wire having a cross-sectional shape of about 0.05 mm / 0.5 mm is formed into a round rectangle, and a coil wire having a winding diameter of about 6 mm is obtained. A coil wire can be preferably used.
Metal coil body, to use as the elastic cushion material formed by winding a corrosion frame in the present invention.
[0012]
That is, since the metal coil body has a high deformation rate, it is difficult to handle and it is often difficult to install the metal coil body 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 in the electrolytic cell, the position is biased by the electrolyte or generated gas in the electrolytic cell, making it difficult to evenly adhere to each member There is.
The elastic cushion material is formed by winding one or a plurality of metal coil bodies so as to obtain a substantially uniform density between two opposing frame frames of a rectangular corrosion resistant frame, for example. Is obtained. In this elastic cushion material, two layers of metal coil bodies are usually laminated on the left and right sides of the corrosion-resistant frame. However, since the metal coil bodies themselves are easily deformed, the adjacent coils are engaged with each other in a comb-like shape, and apparently. The top is a single layer. The elastic cushion material thus obtained has an appearance like a metal scrub for tableware washing.
[0013]
Since the assembly of the elastic cushion material using the metal coil body is an operation outside the electrolytic cell, it can be easily performed, and the obtained elastic cushion material is the target electrode in the electrolytic cell when the electrolytic cell is assembled. The elastic cushion material itself is not deformed so as to hinder the assembly due to the strength of the corrosion-resistant frame, and can be easily installed at a predetermined location.
[0014]
The diameter of this metal coil body (the apparent diameter of the coil) is usually reduced to 10 to 70% by mounting in the electrolytic cell, and elasticity is generated. This elasticity causes the electrode itself to collect current with, for example, an ion exchange membrane. It becomes possible to hold between the bodies, and power supply from the current collector to the electrode becomes easy. If a metal coil body having a small wire diameter is used, the number of contact points between the electrode or current collector and the elastic cushion material inevitably increases, and uniform contact becomes possible. Since the shape of the elastic cushion material after being attached to the electrolytic cell is held by the corrosion-resistant frame, the elastic cushion material is hardly subjected to plastic deformation and can be reused in most cases even when the electrolytic cell is disassembled and reassembled.
[0015]
When an ion exchange membrane electrolytic cell is assembled using the elastic cushion material (or metal coil body) of the present invention as an electrode, an elastic cushion material or the like is positioned between the ion exchange membrane and the electrode current collector, and thereafter, as usual. As a result, an electrolytic cell in which an elastic cushion material or the like is held at the position of the electrode can be obtained.
[0016]
In order to perform salt electrolysis using the ion exchange membrane electrolytic cell having the above-described configuration, 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, so that the ion exchange membrane or the like is not mechanically damaged. Caustic soda or the like can be manufactured with high efficiency without excessive deformation and insufficient power supply.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the elastic cushion material that can be used in the electrolytic cell according to the present invention will be described with reference to FIGS. 1 is a perspective view of a corrosion resistant frame, FIG. 2 is a perspective view illustrating an elastic cushion material, FIG. 3 is a longitudinal sectional view taken along line AA in FIG. 2, and FIG. 4 is a longitudinal sectional view taken along line BB in FIG. .
[0018]
As shown in FIG. 1, the corrosion-resistant frame 3 is composed of a rectangular frame 1 made of a metal round bar such as nickel and a reinforcing bar 2 spanned between a pair of round bars in the longitudinal direction.
The metal coil body 4 shown in FIGS. 3 and 4 is obtained by rolling a thin metal wire into a coil shape, and becomes a material that can be freely deformed without rigidity, such as a metal scrubber for cleaning. Yes. As shown in FIG. 2, the metal coil body 4 is wound over almost the entire length between a pair of round bars in the longitudinal direction of a nickel corrosion resistant frame 3 having a diameter of about 2 mm, for example, to produce an elastic cushion material 5. Is done.
The elastic cushion material 5 manufactured in this manner is held in the shape of the corrosion-resistant frame 3 because the metal coil body 4 is wound around the corrosion-resistant frame 3, and the metal coil body 4 is removed from the corrosion-resistant frame 3. The metal coil body 4 is hardly detached and can be handled as an integral part of the corrosion-resistant frame 3.
[0019]
FIG. 5 is a schematic plan view showing an example in which an elastic cushion material is used as a cathode of a monopolar salt electrolytic cell.
In the figure, a pair of conductive rods 41 are provided in the electrolytic cell 40 so as to face in the vertical direction, and a catholyte circulation energizing member 42 is installed around the conductive rod 41, along the surface of the energizing member 42. A cathode current collector 43 is electrically connected.
Next, an elastic cushion material 5 that functions as a cathode is electrically connected to the cathode current collector 43.
[0020]
FIG. 6 is a schematic plan view showing an example in which an elastic cushion material is used as a cathode of a bipolar salt electrolytic cell.
In the figure, in the electrolytic cell 50, four integrated anode holding members 53 facing the vertical direction are formed on the anode side of the anode partition 51 and the cathode partition 52 bonded to each other. An anolyte circulation passage 55 is secured in each anode holding member 53.
[0021]
Further, a cathode holding member 56 corresponding to the anode holding member 53 is fixed to the cathode side of the bonding partition by joining a strip-shaped joining portion 57 to the cathode partition 52, and each cathode holding member 56 has a catholyte circulation. A passage 58 is secured.
A convex portion 59 is formed outside the center of the anode holding member 53, and power is supplied to the expanded metal anode 60 through the convex portion 59.
The flat surfaces of the four cathode holding members 56 are in electrical contact with the elastic cushion material 5 (or the metal coil body 4) functioning as a cathode, and power is supplied from the cathode holding member 56 to the elastic cushion material 5. Done.
[0022]
When the elastic cushion material 5 is used as a cathode, the metal coil body 4 is wound around the corrosion-resistant frame 3, so that the handling is easy and the shape is hardly lost.
In this state, when a saline solution is supplied to the anode chamber and a dilute caustic soda solution is supplied to the cathode chamber, and electricity is applied between both electrodes, a concentrated caustic soda solution is obtained in the cathode chamber.
[0023]
Next, although the Example and comparative example regarding an ion exchange membrane electrolytic cell which use the hydrogen generating cathode which concerns on this invention are described, these do not limit this invention.
[0024]
[Example 1]
A unit ion exchange membrane electrolytic cell was assembled as follows.
The anode used is a dimensionally stable electrode with an effective area of 1540cm ² (width 11cm x height 140cm) formed by the electrode catalyst coating with platinum group metal oxide on titanium expanded metal manufactured by Permerek Electrode Co., Ltd. did. This anode was attached to the anode chamber partition of the electrolytic cell using anode ribs.
Using a cathode rib made of flat nickel, a nickel expanded metal cathode current collector was attached to the cathode chamber partition.
[0025]
The metal coil body has a wire diameter of 0.17 mm, a nickel wire (NW2201) with a tensile strength of 620 to 680 N / m ² is rolled into a coil wire with a width of about 0.5 mm, and the coil winding diameter is about 6 mm. Was used.
This metal coil body was wound around a nickel round bar frame (corrosion-resistant frame) having a diameter of 2 mm to adjust the shape to a rectangular parallelepiped shape, and an elastic cushion material having an approximate size of 10 mm thickness × 110 mm width × 350 mm length was obtained. The coil linear density of this elastic cushion material was about 7 g / dm ² .
[0026]
Next, this elastic cushion material was subjected to platinum plating as follows to obtain an elastic cathode.
In other words, by the brush plating method (current 0.5A, plating time 5 minutes per 1 dm ² ) using the elastic cushion material as a cathode and a plastic brush containing a titanium rod impregnated with hexachloroplatinic acid aqueous solution (20 g / liter) as an anode. Platinum plating was performed on the ion exchange membrane side surface of each metal coil body constituting the elastic cushion material.
Four platinum-carrying elastic cushion materials were arranged side by side on the cathode current collector.
A cation exchange membrane (Flemion-F8934 manufactured by Asahi Glass Co., Ltd.) was placed between the anode and the cathode to assemble an ion exchange membrane electrolytic cell.
Electrolysis was performed at a current density of 40 A / dm ² and a temperature of 85 ° C. while supplying a saline solution of 310 g / liter to the anode chamber and an aqueous sodium hydroxide solution to the cathode chamber to a concentration of 32% by weight. went. The electrolytic cell voltage was 2.89V.
[0027]
[ Reference Example 1 ]
An ion exchange membrane electrolytic cell was assembled as follows.
The anode is a dimensionally stable electrode having an effective area of 1540 cm ² (width 11 cm, height 140 cm) in which an electrode catalyst coating having a platinum group metal oxide is formed on titanium expanded metal manufactured by Permerek Electrode Co., Ltd. used. This anode was attached to the anode chamber partition of the electrolytic cell using anode ribs.
Using a cathode rib made of flat nickel, a nickel expanded metal cathode current collector was attached to the cathode chamber partition.
[0028]
A uniform cotton-like woven fabric made of nickel fiber with a thickness of 5 mm x width 11 cm x length 20 cm in a fiber spreader is mixed with a mixture of hexachloroplatinic acid aqueous solution (20 g / liter) and hydrochloric acid (10 g / liter) at room temperature for 1 hour. It was immersed to deposit platinum to form a cathode.
Seven of these cathodes (platinum-supporting fabrics) were arranged on a cathode current collector, and a cation exchange membrane (Flemion F8934 manufactured by Asahi Glass Co., Ltd.) was placed between the anode and the cathode to assemble an ion exchange membrane electrolytic cell.
Electrolysis was performed at a current density of 40 A / dm ² and a temperature of 85 ° C. while supplying a saline solution of 310 g / liter to the anode chamber and an aqueous sodium hydroxide solution to the cathode chamber to a concentration of 32% by weight. went. The electrolytic cell voltage was 2.87V.
[0029]
[Comparative Example 1]
The anode was prepared in the same manner as in Reference Example 1, and the cathode current collector was attached in the same manner as in Reference Example 1 .
A mat-like body (nickel elastic conductive body) obtained by crimping two knitted wire meshes of eight nickel wires having a wire diameter of 0.08 mm was placed on the cathode current collector.
[0030]
Subsequently, a nickel wire net having a wire diameter of 0.15 mm, a hole area ratio of 68%, and an area of each hole of 0.49 mm ² was coated with the active substance by the following operation. In other words, after steam degreasing the nickel wire mesh and then etching in 15% nitric acid for 1 minute, hexachloroplatinic acid hexahydrate aqueous solution (20 g / liter), cesium nitrate hexahydrate aqueous solution (30 g / liter) and nitric acid (50 g / liter) Liter) of paint, applied and dried at 50 ° C. for 5 minutes, then heated in a 500 ° C. heater for 10 minutes and cooled to room temperature. This cycle (paint coating-drying-decomposition) was repeated until the platinum concentration reached 5 g / m ² .
The nickel wire mesh was placed as a cathode in contact with the nickel mat thus obtained, and a cation exchange membrane (Flemion F8934 made by Asahi Glass Co., Ltd.) was placed between the anode and the cathode to provide an ion exchange membrane electrolytic cell. Assembled.
[0031]
Electrolysis was performed at a current density of 40 A / dm ² and a temperature of 85 ° C. while supplying a saline solution of 310 g / liter to the anode chamber and an aqueous sodium hydroxide solution to the cathode chamber to a concentration of 32% by weight. went. The electrolytic cell voltage was 2.90V.
[0032]
Comparing Example 1 and Comparative Example 1, towards the Example 1 using the nickel elastic cushion material as a cathode, the nickel matte and nickel wire net to lower cell voltage than Comparative Example 1 was used as a cathode, effect It was found that electrolysis can be performed.
[0033]
【The invention's effect】
The present invention is an electrode for electrolysis comprising an elastic cushion material carrying an electrode catalyst formed by winding a metal coil body around a corrosion-resistant frame.
This electrode for electrolysis maintains its form for a long period of time due to its high strength and toughness, so that the ion exchange membrane or the like is not mechanically damaged or excessively deformed, resulting in insufficient power supply. No caustic soda can be produced with high efficiency.
Furthermore, in an electrolytic cell containing an elastic electrode, the elastic electrode can be freely deformed and has sufficient conductivity, so that the electrode and the electrode current collector can be reliably electrically connected, and reliable power supply becomes possible. .
[Brief description of the drawings]
FIG. 1 is a perspective view of a corrosion-resistant frame in an elastic cushion material that can be used in the present invention.
FIG. 2 is a perspective view illustrating an elastic cushion material that can be used in the present invention.
3 is a vertical sectional view taken along line AA in FIG. 2;
4 is a longitudinal sectional view taken along line BB in FIG. 2. FIG.
FIG. 5 is a schematic plan view showing an example of a monopolar salt electrolytic cell using an elastic cushion material as a cathode.
FIG. 6 is a schematic plan view showing an example of a bipolar salt electrolytic cell using an elastic cushion material as a cathode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rectangular frame 2 Reinforcement rod 3 Corrosion-resistant frame 4 Metal coil body 5 Elastic cushion material
40 single electrode electrolytic cell
41 Conductive rod
42 Catholyte circulating energization member
43 Cathode current collector
50 Bipolar electrolytic cell
51 Anode barrier
52 Cathode barrier
53 Anode holding member
54 Band joint
55 Anolyte circulation passage
56 Cathode holding member
57 Strip joint
58 Catholyte circulation passage
59 Convex
60 anode

Claims (3)

Electrolytic electrodes, characterized in that it comprises a resilient cushioning material bearing the formed electrode catalyst by winding a metal coil body corrosion resistance frames. In the ion exchange membrane electrolytic cell is partitioned into a cathode chamber containing an anode chamber and a cathode for accommodating the anode by an ion exchange membrane, at least one of the anode and cathode, by winding a metal coil body corrosion resistance frame structure An ion exchange membrane electrolytic cell characterized by being an elastic cushion material carrying an electrode catalyst. The ion exchange membrane electrolytic cell according to claim 2 , wherein the elastic cushion material is in contact with the electrode current collector and is supplied with power from the electrode current collector.

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