JPS6244589A - Electrode for electrolysis - Google Patents

Abstract

PURPOSE:To decrease the resistance loss of conductors and to lower an electrolytic voltage by providing a pair of rectangular apertures at many points to the surface of an electrode plate and successively providing eaves-like members corresponding to the apertures to the electrode plate. CONSTITUTION:A pair of the rectangular apertures 5 are provided at many points to the electrode plate 4 of an anode electrode 1 and the eaves-like members 6 formed by bending the members in the direction opposite from the surface to contact with a diaphragm 2 are successively provided to a pair of the apertures 5 of the electrode plate 4 so as to face the apertures 5. The flow of the electrode liquid and the venting of gas are smoothly executed by such construction. In addition, the base plate of the electrode plate 4 functions fully as the electrode conductor. The increase of the conductor resistance by the decrease of the electrode conductor parts corresponding to the aperture 5 parts is obviated. The size of the apertures 5 is preferably about 1.5-5X5-100mm and the thickness of the plate 4 is about 0.5-2mm.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrolytic electrode used in diaphragm electrolysis, and in particular an electrode that is disposed close to a diaphragm such as an ion exchange membrane and generates gas at the electrode. The present invention relates to an electrode for electrolysis suitable for electrolysis.

[Prior art] In the electrolysis industry, which produces chlorine and caustic soda by electrolyzing salt water, the ion exchange membrane method, which uses an ion exchange membrane as a diaphragm and places electrodes close to it to perform electrolysis, has recently become superior. Electrolysis systems have been developed to prevent pollution and save energy, and there is a demand for excellent electrodes suitable for this purpose.

In the electrolysis of salt water, chlorine gas is generated at the anode, hydrogen gas is generated at the cathode, and caustic soda is generated at the cathode chamber.

At this time, if the electrode is placed close to the ion exchange membrane, the electrolytic voltage can be lowered, but problems arise in the distribution of the electrolytic solution and the removal of generated gas.

For this reason, porous plate bodies such as expanded metal as shown in FIG. 3 and punched perforated plates (punched metal) as shown in FIG. 4 have conventionally been used as electrodes. For example, the one related to Exband Metal is JP-A-52-1)
No. 4571, Utility Model Publication No. 1983-83756, Japanese Patent Application Publication No. 1983
No. 185786.

Further, Japanese Patent Laid-Open No. 146884/1984 discloses the use of a perforated flat plate electrode as an anode.

For expanded metal, by making a cut in the base and expanding it by pulling it in a direction perpendicular to the cut line, and for punched perforated plates, by punching the base plate into a shape such as a circle or square, generated gas etc. can be removed. A necessary opening for extraction is formed to form an electrode plate.

On the other hand, the aperture of such an electrode requires that the aperture ratio on the effective electrode surface of the electrode plate is usually 30 to 60%.
Therefore, in these conventional electrodes, the electrode conductor volume decreases by the volume corresponding to the aperture ratio of 30 to 60% compared to the original electrode plate, and the conductor resistance of the electrode plate increases.
This inevitably causes problems such as an increase in electrolytic voltage and non-uniformity in current distribution. Further, JP-A-58-23582 describes an electrode in which an electrode plate is provided with a large number of curved ribbon-shaped punched openings, but the curved ribbon-shaped punched portions are alternately provided on both sides of the electrode plate. Therefore, even if the electrode is brought close to the diaphragm, there is always a certain distance between the main plane of the electrode plate and the diaphragm, and there is a problem in that the distance between the electrodes increases accordingly.

[Problem that the invention seeks to solve]

As mentioned above, in diaphragm electrolysis that involves gas generation at the electrode, conventional electrodes allow the electrode to be brought close enough to the diaphragm to ensure sufficient electrolyte flow and gas release, while at the same time reducing the conductor resistance due to the openings in the electrode plate. It is impossible to prevent the increase in electrolytic voltage, and there is a problem in that the increase in electrolytic voltage leads to an increase in electric power cost. The present invention provides an excellent electrode for electrolysis that solves the problems of these conventional techniques.

[Means to solve the problem]

The present invention provides a pair of many rectangular openings whose longitudinal direction is substantially horizontal on the electrode plate surface of an electrode for electrolysis, and each opening in each pair is bent in a direction opposite to the contact surface with the diaphragm. The above problem is solved by providing an electrode structure in which a corresponding eave-like member is connected to the electrode plate.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a unit electrolytic cell for ion-exchange decoupling electrolysis in which the electrode 1 of the present invention applied as an anode is placed close to a diaphragm 2 such as an ion-exchange membrane, and a cathode 3 is placed on the opposite side. Here is an example. In the anode electrode 1, a large number of pairs of rectangular openings 5 are provided in an electrode plate 4, and a diaphragm 2 is provided in the pair of openings.
A canopy-like member 6 corresponding to each pair of openings 5 formed by bending in a direction opposite to the contact surface with the electrode plate 4 is connected to the electrode plate 4 . Each opening 5 and the eave-like member 6 are easily formed by cutting the electrode plate 4 with two parallel knives and bending the cut. Such processing requires that the material has some degree of plasticity and ductility, but metals normally used for anode or cathode electrode plates, such as valve metals such as titanium and tantalum, iron, nickel, or Since alloys etc. have such properties,
The present invention can be applied to both. Although it is preferable that the rectangular opening 5 is horizontal in its longitudinal direction for the purpose of electrolyte flow and gas release, it may be slightly inclined.

The size and arrangement of the openings 5 can be appropriately determined depending on the material and dimensions of the electrode plate and the required aperture ratio, and are not particularly limited. In the case of ion exchange FIJA salt electrolysis, as shown in Figure 2, the thickness of the titanium electrode plate is usually 0.5.
~2 mm, length a is 1.5 to 51, width is 5 to 100
mm, the bending angle of the eaves-like member 6 is 30 degrees or more, and it is preferable that a large number of the openings 5 are arranged so that the aperture ratio on the effective electrode surface is about 30 to 60%.

In addition, in order to make it easier for generated air bubbles to escape to the back surface in the opposite direction to the membrane contact surface, it is generally preferable to make the length a of the opening 5 larger than the thickness of the electrode plate.

The shape of the eaves-like member 6 corresponding to the opening 5 can be determined as appropriate from the thickness t, length a, width b, bending angle, and elongation characteristics of the material, but the shape shown in FIGS. 1, 2, and 3 ( stomach)
As shown in , (b) and (c), usually the eaves-shaped member 6
It is preferable that the bending angle between the electrode plate 4 and the electrode plate 4 is about 30 to 45 degrees or more. In addition, the cross-sectional shape of the canopy member 6 connected to the electrode plate 4 is U-shaped or semicircular with a bending angle of about 90 degrees as shown in FIG. It may have any shape, such as a shape bent more deeply than 90 degrees, or a shape shallowly bent less than 90 degrees as shown in FIG. 4(C). In addition, the opening 5 is shown in Figures 1 and 2.
The case is shown in which both ends of the eave-like member 6 corresponding to the electrode 4 are cut by an amount a in the direction perpendicular to the electrode 4, but due to the ductility of the electrode plate metal used, it is necessary to cut only in the horizontal direction and bend it without cutting in the vertical direction. It is also possible to form the opening 5 and the canopy member 6 by processing.

Further, as shown in FIGS. 1 and 2, it is practical to arrange a large number of pairs of openings 5 alternately with adjacent ones shifted by a distance d in order to obtain a good gas venting effect. At that time, d
= can be appropriately determined within the range of ob to b. It goes without saying that the electrode can be constructed by providing an electrode active coating as an anode or a cathode on at least the membrane contacting surface of the electrode plate 4 as appropriate in the same way as in conventional electrodes. The electrode active coating can be applied either before or after the open extrusion bending process of the electrode plate 4 is carried out. Furthermore, by providing a large number of vertical grooves on at least the membrane contacting surface of the electrode plate 4, as described in Japanese Patent Publication No. 55-38432, it is possible to further improve the flow of the electrolytic solution and the release of gas.

As shown in FIG. 1, when the electrode of the present invention is incorporated into an electrolytic cell for electrolysis, a plurality of power supply terminals 7 are provided at the lateral ends of the electrode plate 4, and the current is directed in the longitudinal direction of the canopy member 6. It is preferable to feed power from the lateral direction in parallel with the electrode conductor resistance tA in order to prevent a voltage increase due to the electrode conductor resistance tA.

[Effect]

In the electrode of the present invention, by providing a large number of rectangular openings 5 as described above, the openings of the electrode plate 4 (
The requirements for the aperture ratio (usually 30 to 60%) are sufficiently met, and the electrolyte can flow and gas can escape smoothly.
In addition, a canopy member 6 corresponding to each opening 5 is attached to the electrolytic plate 4.
Since the electrode plate is bent while being connected to the electrode plate, the entire electrode base plate remains as it is and functions as an electrode conductor. Therefore, in the case of conventional punched perforated plates (Fig. 5) and expanded metal (Fig. 4), the conductor resistance increases due to the reduction of the electrode conductor part corresponding to the part removed or opened from the original plate. It disappears. Furthermore, by providing a plurality of power supply terminals 7 at the lateral ends of the electrolytic plate 4 and supplying power from the lateral direction, the current flows parallel to the canopy member 6, so that the effect of donor cutting due to the opening 5 is substantially eliminated. It is not received well. At the same time, the current distribution on the electrode plate surface is made uniform.

Since the eave-like member 6 is bent only in the direction opposite to the contact surface of the electrode plate 4 with the diaphragm, the main operating surface of the electrode can be brought into sufficient contact with the diaphragm 2.

〔Example 〕

Example electrodes according to the present invention and conventional comparative electrodes were prepared as described below, and tested by using them as anodes for ion exchange membrane electrolysis. In both electrodes, a coating containing the same noble metal oxide was applied to a titanium metal base by a pyrolysis method on the contact surface of the diaphragm.

Example 1 An electrode plate with an effective electrode surface width of 30 cm and a height of 25 cm has a thickness of L.l mm, and each opening has a length of A.2 mm and a width of B.45 cm.
mm, the bending angle of the eave-like member is 90 degrees, and d=
0 and an electrode with an aperture ratio of approximately 40%. (Eave-shaped) Example 2 The electrode of Example 1 was further added to the electrode with a width of 0.5 mm and a depth of 0.3 m.
Grooves with a pitch of 1 mm are vertically placed on the entire surface of the membrane contact surface. (Grooved eaves shape) Comparative example 1 Plate with a thickness of 1 mm.

Comparative example 2 LW 8 X SW 3.6 X St 1.2 X
Expanded metal with t 1 mm and aperture ratio of approximately 35%.

Comparative example 3 t = l mm, diameter 2 mm circular hole, pitch 3 mm,
Punched metal with an aperture ratio of approximately 40%.

Each of these electrodes was used as an anode and tested under the following electrolytic conditions. In both cases, power was supplied from the side.

anode? fl: 200 g/L NaCl water? 8
Water and land 8 liquid catholyte 5% NaOH aqueous solution Cathode: Ni minikisband metal IIa: Ion exchange membrane (manufactured by DuPont, trade name Nafion 902) Interpolar path 1i Itf: 2 mm Electrolysis temperature: 90°C Current density: 308 to dm ” The above test results are summarized in Table-1.

Table-1 *1) *1) Conductor resistance loss V was calculated using the formula shown below.

Vw = 1ol) l”/3t (10: Electrolytic current density (A/dmz) ρ: Conductor specific resistance (0 cm) l2 Current conduction distance (cm) t: Conductor plate thickness (cm) *2) Non-porous electrode Therefore, electrolysis is impossible (Effect of the invention) As is clear from the results shown in Table 1, the electrode according to the present invention has the same low voltage corresponding to conductor resistance loss as the non-porous plate, and the electrode according to the present invention has a lower voltage equivalent to the conductor resistance loss than the conventional plate with the same thickness and aperture ratio. As a result, by applying the electrode of the present invention, the electrolytic voltage is approximately 80 mν.
The degree has decreased.

As described above, the electrode of the present invention has the advantage of not only being able to efficiently distribute the electrolyte and removing the generated gas as an electrode that is installed close to the diaphragm to generate gas, but also to reduce the electrolysis voltage at the same time. It has excellent performance and is extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is a partial perspective view showing an example of an ion exchange membrane electrolytic cell in which an electrode of the present invention is arranged, and FIG. 2 is a partially enlarged sectional view and a plan view showing an example of the electrode of the present invention. Figure 3 (a), (
B) and (C) are partially enlarged sectional views showing examples of electrodes of the present invention. FIG. 4 is a sketch showing an example of a conventional expanded metal electrode, and FIG. 5 is a sketch showing an example of a conventional punched metal electrode. 1. Anode 2. Diaphragm 3, cathode 4. Electrode plate 5, opening 6.6゛ eave-like member 7 Power supply terminal a indicates the vertical length of the opening, b indicates the horizontal length, d indicates the shift distance of the opening arrangement, and [ indicates the electrode plate thickness. Engraving of the drawings (no changes to the content) 2 drawings 3 drawings ■ Eyes Mouths (I) (B) Cノ＼9'' (51L Engineering N Sunozushito'Metal Thunder) 〹No Manchi F Metal 异 异 似 弹似amendment Written December 1, 1985 Michibe Uga, Commissioner of the Japanese Patent Office1, Indication of the case, Patent Application No. 183976, filed in 19852, Name of the invention Electrode for electrolysis 3, Person making the amendment Relationship to the case Patent application Address: 1) 59 Ishiyo, Fujisawa City, Kanagawa Prefecture Name: Bellmeresoc Electrode Co., Ltd. Representative: Seiji Nakagawa 4, Agent: 5 Date of amendment order: January 6, 1985 (Despatch date: January 1, 1985) 26th) 6. Drawing 7 to be amended, content of amendment Drawing 2 of the drawing will be corrected as shown in the attached sheet.

Claims (6)

[Claims] (1) The electrode plate surface has a pair of many rectangular openings whose longitudinal direction is approximately horizontal, and each pair of openings corresponds to each opening formed by bending in the opposite direction to the contact surface with the diaphragm. An electrolysis electrode characterized in that a canopy-like member is connected to an electrode plate. (2) The aperture ratio on the effective electrode surface of the electrode plate is 30 to 60
% of the electrolytic electrode according to claim (1). (3) The size of the rectangular opening is 1.5 to 5 mm vertically,
The electrode for electrolysis according to claim 1, which has a width of 5 to 100 mm and a thickness of the electrode plate of 0.5 to 2 mm. (4) The electrode for electrolysis according to claim (1), wherein a vertical groove is provided in at least the contact surface of the electrode plate with the diaphragm. (5) The electrode for electrolysis according to claim (1), wherein an electrode active coating is provided on at least the contact surface of the electrode plate with the diaphragm. (6) The electrode for electrolysis according to claim (1), wherein a plurality of power supply terminals are provided at the lateral ends of the electrode plate.