JP2017088952A - Ion exchange membrane electrolytic tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion exchange membrane electrolytic tank, with an anode having a two layer structure, capable of efficiently performing an electrolytic operation under pressure lower than that of the conventional anode having one layer structure.SOLUTION: In an ion exchange membrane electrolytic tank comprising: an anode 20 having a conductive substrate having an opening and a catalyst layer provided on the conductive substrate; a cathode 30; and an ion exchange membrane I arranged therebetween, the anode 20 has the first anode 21 arranged at the side of the anode chamber and one or more layer of the second anodes 22 laminated in a state of being conducted to the first anode 21, in the second anodes 22, the opening ratio of the conductive substrate is 40 to 55%, and the opening ratio of the conductive substrate in the first anode 21 is being below the opening ratio of the conductive substrate in the second anode(s) 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ion comprising an anode having a conductive substrate having an opening and a catalyst layer provided on the conductive substrate, a cathode, and an ion exchange membrane disposed between the anode and the cathode. The present invention relates to an exchange membrane electrolytic cell. The present invention is effective not only when newly producing an ion exchange membrane electrolytic cell, but also when reactivating the anode of an existing ion exchange membrane electrolytic cell.

  This type of ion exchange membrane electrolytic cell is mainly composed of an anode chamber frame with an anode and a cathode chamber frame with a cathode, which are partitioned by an ion exchange membrane. In the case where a direct current is passed in a state where saline is sent to the chamber and pure water is sent to the cathode chamber, chlorine gas is generated on the anode surface and hydrogen gas is generated on the cathode surface. Soda is produced in the cathode chamber.

  In an ion exchange membrane electrolytic cell, the anode mounted on the anode chamber frame uses a conductive substrate made of titanium or an alloy containing titanium as a main component, and a noble metal having a catalytic activity function is supported on the conductive substrate. Has been. However, with the continuation of the electrolysis operation, the noble metal gradually wears or disappears, and the inherent catalytic activity function is reduced. Decreasing the function of the catalytic activity makes it difficult to perform electrolysis and makes electrolysis impossible at the end of the period. Therefore, in commercial electrolyzers, the specification capacity of the DC power supply device is exceeded. Periodic renewal of the anode is essential. In addition, as with the anode, the cathode is also renewed every several years or several decades from the viewpoint of reducing electric energy consumption.

  As a technique for using an old electrode as it is instead of performing such an electrode renewal operation, Patent Document 1 below discloses that a new electrode is installed when the activity of an insoluble electrode coated with an electrode catalyst is reduced. In the method of reactivation by welding, the expanded metal (also referred to as “expanded metal”), which has been flattened by rolling, etc., has a minor axis smaller than the minor axis of the existing electrode mesh A method for use as an electrode has been proposed. According to this method, an anode having a two-layer structure in which expanded metal having a smaller minor axis of the mesh is laminated on the upper side is obtained.

JP-A-4-32594

  However, the expanded metal usually has an opening ratio of less than 40%, and it is considered that the expanded metal is further reduced in the expanded metal flattened by rolling or the like as in Patent Document 1. In addition, since the expanded metal tends to have a smaller opening ratio as the minor axis of the mesh is smaller, in Patent Document 1, it is considered that the new expanded metal has a smaller opening ratio than the existing expanded metal.

  However, according to the study by the present inventors, as in Patent Document 1, when the aperture ratio of a newly laminated anode is smaller than a certain range and the aperture ratio is smaller than that of an existing anode, the function as a laminated anode is achieved. It turned out to be insufficient.

  Accordingly, an object of the present invention is to provide an ion-exchange membrane electrolytic cell capable of performing an electrolysis operation efficiently at a lower voltage than a conventional single-layered anode as a two-layered anode.

  Another object of the present invention is to provide an ion exchange membrane electrolytic cell capable of performing an electrolysis operation efficiently at a lower voltage than a conventional reactivated two-layer anode as a reactivated anode. There is to do.

The above object can be achieved by the present invention as described below.
That is, the ion exchange membrane electrolytic cell of the present invention is disposed between an anode having a conductive substrate having an opening and a catalyst layer provided on the conductive substrate, a cathode, and the anode and the cathode. In the ion exchange membrane electrolytic cell comprising an ion exchange membrane, the anode includes a first anode disposed on the anode chamber side, and one or more second anodes stacked in a conductive state with the first anode. The second anode has an opening ratio of the conductive substrate of 40 to 55%, and the opening ratio of the conductive substrate of the first anode is less than the opening ratio of the conductive substrate of the second anode. It is characterized by being.

  According to the ion exchange membrane electrolytic cell of the present invention, since the conductive substrate of the second anode has an aperture ratio of 40% or more and is larger than the aperture ratio of the conductive substrate of the first anode, the function of the first anode is not much. Without loss, it is believed that the active effective area of the catalyst increases and the chlorine generation overvoltage is significantly reduced. In addition, since the gas detachability due to the generation of chlorine gas or the like has been improved, the liquid permeability in the electrolytic cell is improved, the voltage loss due to the gas resistance is improved, and the efficiency of the electrode reaction is considered to be improved. As a result, the electrolysis operation can be performed efficiently at a lower voltage than the conventional single-layered anode.

  Further, the ion exchange membrane electrolytic cell of the present invention is also effective when the catalyst layer of the first anode is deteriorated from the time of the new installation, in which case the second anode becomes the newly installed anode. As described above, according to the present invention, the electrode reaction can be efficiently performed while separating and diffusing the generated gas in the electrolytic solution in the newly installed second anode even with respect to the existing degraded anode. As a result, it is possible to provide an ion exchange membrane electrolytic cell capable of performing an electrolysis operation efficiently at a lower voltage than a conventional reactivated anode having a two-layer structure as a reactivated anode. In addition, the cost of removing the first anode at the time of renewal, the cost of manufacturing and installing a new anode, and the cost of correcting the distortion of the base necessary for installation, etc. do not occur. From this point, it is also economical.

  In the above, the conductive substrate of the second anode is any one of an expanded metal, a punching metal, or a plain weave mesh (also referred to as “plain weave wire mesh”) having a thickness of 0.1 mm to 1.2 mm. The conductive substrate of the anode is preferably any one of expanded metal, punched metal, or plain woven mesh having a thickness of 0.5 mm to 2.0 mm. With the combination of the first anode and the second anode having such a thickness and shape, the above-described effects can be achieved more effectively.

  The catalyst layer of the second anode includes at least one platinum group metal selected from the group consisting of platinum, iridium, rhodium, palladium, and ruthenium or an oxide thereof, and the catalyst layer has a thickness of 0. It is preferable that it is 1-50 micrometers. By setting the material and thickness of the catalyst layer of the second anode in this manner, the electrode reaction can be performed more efficiently, particularly when chlorine gas is generated at the anode using saline.

  In particular, the conductive substrate of the second anode is preferably a plain woven mesh having a thickness of 0.1 mm to 1.2 mm. The use of plain woven mesh provides a desired aperture ratio with an appropriate thickness, and the generated chlorine gas is instantaneously desorbed on the anode surface compared to expanded metal, so that chlorine gas can be generated efficiently. .

  Furthermore, the catalyst layer of the second anode preferably has a surface roughness of 0.5 to 70 μm. Due to the pressure from the cathode side, the second anode is usually in contact with the ion exchange membrane, but the surface roughness of the second anode is such that the electrolyte permeability and separation of generated gas. By ensuring the diffusibility, the electrode reaction can be performed more efficiently.

  The ion exchange membrane electrolytic cell of the present invention can be applied to any system of a monopolar type or a bipolar type electrolytic cell.

The longitudinal cross-sectional view which shows schematic structure of an example of the electrode unit used for the ion exchange membrane electrolytic cell of this invention 1 is a cross-sectional view taken along line AA in FIG. The longitudinal cross-sectional view which shows the principal part of the other example of the electrode unit used for the ion exchange membrane electrolytic cell of this invention The perspective view which shows the structure of the elastic body used for the ion exchange membrane electrolytic cell of this invention

(Structure of ion exchange membrane electrolytic cell)
The ion exchange membrane electrolytic cell of the present invention includes, for example, an anode 20, a cathode 30, and an ion exchange membrane I disposed therebetween, as shown in FIGS. Thus, the anode chamber 20A having the anode 20 and the cathode chamber 30A having the cathode 30 can be configured. In the illustrated example, a predetermined number of electrode units U are arranged in tandem with the same polarity in a tank (not shown), and an ion exchange membrane I is arranged between adjacent units U-U, thereby performing bipolar electrolysis. A tank is formed. In the case of a monopolar electrolytic cell, either the anode 20 or the cathode 30 is formed on both sides of one electrode unit U, and the electrode units U are alternately arranged via the ion exchange membrane I. In this way, a monopolar electrolytic cell is formed. That is, the ion exchange membrane electrolytic cell of the present invention can be applied to any system of a monopolar type or a bipolar type electrolytic cell. The structure of such an electrolytic cell is described on pages 195 to 218 of “Soda Technical Handbook 2009” (issued on June 30, 2009 by Nippon Soda Industrialization).

  As shown in FIGS. 1 to 2, each electrode unit U has, for example, a rigid structure anode 20 supported on one side of a partition wall 11 perpendicular to the column direction and a cathode 30 on the other side. An electrode support frame 10 for supporting is provided.

  In order to support the anode 20, a plurality of vertical vertical ribs 12 arranged at predetermined intervals in the lateral direction are attached to one surface of the vertical partition wall 11, and the anode 20 is attached to the tip thereof. Yes. Between the anode 20 and the partition wall 11 behind it is an anode chamber 20A, and each vertical rib 12 is provided with a plurality of through holes 12a so that the electrolyte can freely flow in the lateral direction in the anode chamber 20A. ing.

  Similarly, on the other surface of the vertical partition wall 11 of the electrode support frame 10, a plurality of vertical vertical ribs 13 arranged at predetermined intervals in the lateral direction are attached, and a cathode structure (cathode) is attached to the tip thereof. 30) is attached. A space between the cathode structure (cathode 30) and the partition wall 11 behind it is a cathode chamber 30A. In the cathode chamber 30A, each vertical rib 13 has a plurality of penetrating holes so that the electrolyte can freely flow in the lateral direction. A hole 13a is provided.

  In the ion exchange membrane electrolytic cell of the present invention, for example, as shown in FIGS. 1 to 2, the anode 20 includes a first anode 21 disposed on the anode chamber 20 </ b> A side and a single layer laminated on the first anode 21. The second anode 22 is included. In the illustrated example, the case where the second anode 22 is a single layer is shown, but the second anode 22 may be composed of two layers or three or more layers. When the second anode 22 is composed of two or more layers, each second anode 22 may be the same or different. Moreover, when each 2nd anode 22 is different, about the anode laminated | stacked on the 1st anode 21, the aperture ratio of an electroconductive base | substrate is 40 to 55%, and the aperture ratio of the electroconductive base | substrate of the 1st anode 21 is. Larger is preferred.

  The laminated second anode 22 may be laminated in a conductive state with respect to the first anode 21, but is fixed by TIG welding or spot welding rather than simply placing the two anodes in contact with each other. Is more preferable from the viewpoint of the stability of the conduction state and the mechanical strength.

  In the present invention, the adjustment of the interelectrode distance in which the anode 20 and the cathode 30 are partitioned by the ion exchange membrane I is performed, for example, as follows. When the first anode 21 is attached to an anode chamber frame (not shown), the anode chamber frame is only a predetermined height (for example, about 1.5 mm) in a direction perpendicular to the surface of the anode chamber frame in contact with the ion exchange membrane I. A step is provided to be higher. On the other hand, when the cathode 30 is mounted on a cathode chamber frame (not shown), the position is set so as to be smooth on the surface of the chamber frame in contact with the ion exchange membrane.

  Between the ion exchange membrane I and the anode chamber frame and the cathode chamber frame, an electrode unit U is installed with a sealing material such as a gasket interposed therebetween. At that time, the gasket between the ion exchange membrane I and the first anode 21 has a predetermined thickness (for example, 2 mm), and similarly the gasket between the ion exchange membrane I and the cathode 30 has a predetermined thickness (for example, 2 mm). Thus, the distance between the electrodes in which the first anode 21 and the cathode 30 are partitioned by the ion exchange membrane I can be adjusted. In addition, since the second anode 22 is laminated on the first anode 21, the distance between the electrodes is reduced by the thickness of the second anode 22.

  In addition, as shown in FIGS. 1-2, since the 2nd anode 22 normally contacts the ion exchange membrane I by the pressurization from the cathode 30 side, the thickness of the ion exchange membrane I is subtracted from the distance between electrodes. This distance is the distance between the cathode 30 and the ion exchange membrane I. In the present embodiment, an example in which a space (gap) is provided between the cathode 30 and the ion exchange membrane I is shown. However, in the present invention, an ion exchange membrane electrolytic cell having a zero gap structure in which the gap does not substantially exist. It may be present (see FIG. 3). In that case, it is preferable to use a structure in which the cathode 30 is pressed against the ion exchange membrane I using an elastic body 32 as will be described later.

  In the present invention, it is possible to newly provide the second anode 22 with respect to the catalyst layer of the first anode 21 that has deteriorated from the time of the new installation. In that case, the catalyst layer of the first anode 21 has deteriorated from the time of the new installation, and the second anode 22 becomes the newly installed anode.

  In other words, according to the present invention, in the ion exchange membrane electrolytic cell, the anode anode chamber can be removed without removing the first anode 21 before the active function of the catalyst of the first anode 21 is reduced and it is difficult to continue the electrolysis. The active function of the catalyst in the frame is reactivated, the life of the anode suitable for the electrolysis process accompanied by chlorine generation is extended, and the electric energy consumption can be reduced.

(Ion exchange membrane)
As the ion exchange membrane, any one used in a salt electrolytic cell or the like can be used. For example, perfluorosulfonic acid resin, perfluorocarboxylic acid resin having durability against chlorine can be used. These ion exchange membranes are described in detail in “Soda Technical Handbook 2009” (issued on June 30, 2009 by Japan Soda Industrialization).

  In addition, as thickness of an ion exchange membrane, 50-300 micrometers is preferable from a viewpoint of ion permeability and durability.

(First anode)
The first anode has a conductive substrate having an opening and a catalyst layer provided on the conductive substrate.

  The conductive substrate used for the first anode is titanium, titanium alloy, 1 type, 2 types, 3 types, 4 types of various industrial pure titaniums defined by the Japanese Industrial Standards (JIS Standard), nickel ruthenium, As an example, a titanium alloy added with tantalum, palladium, tungsten, or the like to improve corrosion resistance, or a titanium alloy added with aluminum, vanadium, molybdenum, tin, iron, chromium, niobium, or the like can be given.

  As the conductive substrate, a titanium expanded metal or a titanium punching metal is desirable from the viewpoint of corrosion resistance, and a titanium expanded metal is particularly desirable from the viewpoint of economy and a rigid structure. The open area ratio in these conductive substrates is preferably 25 to 50% in consideration of the compatibility between mechanical strength and electrolyte permeability, but in the present invention, A conductive substrate having an aperture ratio smaller than that of the second anode conductive substrate is used.

  After the conductive substrate is washed with an alkali or organic solvent, mechanical treatment or chemical treatment, which is a generally known surface treatment method, may be performed. As a mechanical surface treatment method such as the conductive substrate, there is a blast treatment method for forming dense irregularities of several microns to several tens of microns on the surface of the conductive substrate. As the blast treatment method, alumina, steel shot, There is a method of using a steel grid or the like as an abrasive and projecting the surface of a conductive substrate with compressed air.

  As a method for chemical surface treatment of the conductive substrate, there is a method of performing chemical etching treatment in a bath of oxalic acid, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid or the like. In these methods, the chemical dissolution of the surface of the conductive substrate can be achieved by immersing it in a fluid bath or a static bath in the range of 20 to 90 ° C. for 5 minutes to 6 hours. It becomes possible to form dense irregularities of several microns to several tens of microns.

  The active material having an active function of generating chlorine contained in the catalyst layer coated on the surface of the conductive substrate includes platinum group metals such as iridium, ruthenium, platinum, and palladium, and titanium, tantalum, niobium, tungsten, and zirconium. A mixed oxide with at least one metal oxide selected from the group consisting of valve metals such as tin and the like is preferred. Typical examples include iridium-ruthenium-titanium mixed oxide and iridium-ruthenium-platinum-titanium mixed oxide. Platinum metal and ruthenium-titanium oxide can also be used.

  As described above, mechanical treatment and chemical treatment of conductive substrates are performed by single or combined treatment, and metals or mixed oxides (also referred to as catalyst layers) having an active function of generating chlorine are added. The first anode can be used.

  The thickness of the first anode including the catalyst layer is preferably 0.5 to 2.0 mm from the viewpoint of achieving both mechanical strength and economy, and the thickness of the conductive substrate of the first anode is 0.5 mm to 2.0 mm. It is preferable that That is, if the thickness of the conductive substrate is too thin, the mechanical strength is lowered, and the surface is roughened to cause deformation and distortion. As a result, a gap is generated between the ion exchange membrane and the anode, and the electrolysis voltage increases. Further, it is not preferable because deformation may occur due to electrolytic pressure during operation. On the other hand, when the thickness of the conductive substrate is too thick, the cost of the raw material increases, which is not preferable from the viewpoint of economy.

  In order to provide a catalyst function of chlorine generation, the maximum uneven height difference on the surface of the first anode is preferably 5 to 70 μm from the viewpoint of achieving both electrolyte permeability and ion exchange membrane protection. 10-40 micrometers is more preferable. In order to apply the catalyst layer to the surface of the conductive substrate, a roughening treatment method is performed by a mechanical treatment method or a chemical treatment method, and the unevenness of the surface due to this is reflected in the unevenness of the catalyst layer. It is as described in the patent document (Japanese Patent Laid-Open No. 2013-104090) that it falls within the range of 5 to 70 μm even if not intended.

(Second anode)
The second anode has a conductive substrate having an opening and a catalyst layer provided on the conductive substrate. The aperture ratio of the conductive substrate of the second anode is 40 to 55%, and an aperture ratio of 42 to 50% is more preferable from the viewpoint of achieving both mechanical strength and electrolyte permeability. The aperture ratio of the conductive substrate of the second anode is larger than the aperture ratio of the conductive substrate of the first anode.

  As described in the above-mentioned first anode, the conductive substrate used for the second anode is one, two, three, or four types defined by Japanese Industrial Standards (JIS standard) as titanium or a titanium alloy. Examples of various industrial pure titanium, titanium alloys with improved corrosion resistance by adding nickel ruthenium, tantalum, palladium, tungsten, etc., and titanium alloys with added aluminum, vanadium, molybdenum, tin, iron, chromium, niobium, etc. Can be mentioned.

  The conductive substrate is preferably a titanium expanded metal, a titanium punched metal or a titanium plain woven mesh from the viewpoint of corrosion resistance, and is economical and has a flexible structure and a rigid structure, and the generated chlorine gas is an anode. A plain weave mesh is particularly desirable because chlorine gas can be generated efficiently because it is instantaneously desorbed on the surface.

  As the surface treatment method of the conductive substrate, there is a mechanical treatment or a chemical treatment method as in the case of the first anode, and the treatment method is as described above. The second anode provided with a metal or mixed oxide having a catalytic function for generating chlorine can be used by performing mechanical treatment or chemical treatment on the conductive substrate, or a single treatment or a combination of both treatments.

  As the active material having an active function of generating chlorine, which is contained in the catalyst layer coated on the surface of the conductive substrate, as with the first anode described above, platinum group metals such as iridium, ruthenium, platinum, and palladium are used. A mixed oxide of one or more metal oxides selected from the group consisting of valve metals such as titanium, tantalum, niobium, tungsten, and zirconium and tin is preferable. Typical examples include iridium-ruthenium-titanium mixed oxide and iridium-ruthenium-platinum-titanium mixed oxide. Platinum metal and ruthenium-titanium oxide can also be used.

  The thickness of the second anode of the titanium expanded metal including the catalyst layer, the titanium punching metal or the titanium plain woven mesh is 1.5 mm or less, and the effect of reducing the voltage can be obtained. From the viewpoint, 0.1 to 1.2 mm is desirable, and preferably 0.2 to 0.8 mm. When a titanium plain woven mesh is used, the wire diameter is 0.1 to 0.6 mm, and the distance between the wire diameters is 20 to 60 meshes per inch. Preferably, the wire diameter is 0.2 to 0.4 mm, and 30 to 50 mesh is good. When the thickness and the wire diameter of the conductive substrate are too thin, the mechanical strength is lowered, and the surface is roughened to cause deformation and distortion. As a result, a gap is generated between the ion exchange membrane and the second anode, and the electrolysis voltage increases. Further, it is not preferable because deformation may occur due to electrolytic pressure during operation. On the other hand, when the thickness of the conductive substrate is too thick, the cost of the raw material increases, which is not preferable from the viewpoint of economy.

  In order to provide an active function of chlorine generation, the maximum unevenness height difference on the surface of the second anode, as with the first anode described above, ensures both electrolyte permeability and ion exchange membrane protection. From the viewpoint, 2 to 70 μm is preferable, and 2 to 40 μm is more preferable. In order to apply the catalyst layer to the surface of the conductive substrate, a roughening treatment method is performed by a mechanical treatment method or a chemical treatment method, and the unevenness of the surface due to this is reflected in the unevenness of the catalyst layer. It is as described in the patent document (Japanese Patent Laid-Open No. 2013-104090) that it falls within the range of 2 to 70 μm without intention. As a result, the surface roughness of the catalyst layer of the second anode is preferably 0.5 to 70 μm, more preferably 5 to 50 μm.

  The thickness of the catalyst layer of the second anode is preferably 0.1 to 50 μm and more preferably 1 to 30 μm from the viewpoint of durability and cost of the catalyst layer. Furthermore, 1-20 micrometers is the most preferable.

(cathode)
The cathode mounted on the cathode chamber frame has a conductive substrate having an opening and a catalyst layer provided on the conductive substrate. Examples of the conductive substrate of the cathode include nickel, stainless steel, copper, etc., but from the viewpoint of corrosion resistance, nickel expanded metal, nickel punched metal, nickel fine mesh, or nickel plain woven mesh is desirable, economical and From the standpoint of reducing damage to the ion exchange membrane, a nickel fine mesh and a nickel plain weave mesh are particularly desirable.

  The aperture ratio of the conductive substrate of the cathode is preferably 25 to 75% from the viewpoint of economic strength such as mechanical strength and liquid permeability and a rigid structure, and the thickness of the cathode including the catalyst layer is mechanical strength. From the standpoint of achieving both economy and economy, 0.01 to 0.5 mm is desirable, and the thickness of the catalyst layer is preferably 1 to 30 μm. Further, when using a nickel plain woven mesh, the wire diameter is 0.1 to 0.4 mm, and the distance between the wire diameters is 20 to 60 meshes per inch, so-called 20 to 60 mesh, Preferably, the wire diameter is 0.2 to 0.3, and 20 to 50 mesh is good.

  As the active material contained in the catalyst layer of the cathode, it is preferable to use metals such as platinum, palladium, ruthenium, iridium, copper, silver, cobalt and lead, or oxides thereof.

  On the other hand, when configuring an ion exchange membrane electrolytic cell having a zero gap structure, the cathode 30 is preferably a cathode structure as shown in FIG. The cathode structure includes a first cathode 31, an elastic body 32, and a second cathode 33.

(First cathode)
Examples of the conductive substrate of the first cathode mounted on the cathode chamber frame include nickel, stainless steel, copper, etc., but from the viewpoint of corrosion resistance, nickel expanded metal, nickel punched metal, or nickel fine mesh is desirable. From the viewpoint of economic efficiency and a rigid structure that reduces damage to the ion exchange membrane, nickel expanded metal and nickel punched metal, which are rigid structures, are particularly desirable. The aperture ratio in these conductive substrates is preferably 25 to 75% from the viewpoint of economic strength such as mechanical strength and liquid permeability and a rigid structure, and the thickness of the cathode including the catalyst layer is mechanical strength. And 0.7 to 2.0 mm are desirable from the viewpoint of achieving both economy and economy.

(Elastic body)
For attachment of the first cathode and elastic body, the junction or contact state changes from the initial setting position, deformation of the elastic body at the time of attachment, and back pressure action due to gas pressure fluctuations during operation of the electrolytic cell In order to prevent the repulsive force of the elastic body from being reduced, a flat substrate (hereinafter referred to as a fixed body) having a conductivity of 0.05 to 0.5 mm is mounted and fixed between the gaps of the first cathode. preferable. In this case, a flat substrate is interposed between the first cathode and the elastic body.

  As shown in FIG. 3, the elastic body 32 in the cathode structure (cathode 30) is preferably a conductive cushion mat or a spring-shaped elastic body 32 in which conductive fine metal wires are mixed to form a mat shape. This is because it is highly flexible and economical. As the material of the elastic body 32, the same nickel as the material of the cathode is preferable. The wire diameter of the conductive cushion mat is usually 0.05 to 0.3 mm, preferably 0.07 to 0.2 mm, and more preferably 0.1 to 0.15 mm.

The bulk density of the conductive cushion mat is preferably 0.2 to ² kg / m ² , and the thickness is preferably 5 to 10 mm in a state where it is not subjected to a load, and 4 to 8 mm in a state of being in close contact with the ion exchange membrane after the electrode unit is connected. . This is because the pressing pressure of the ion exchange membrane from the cathode to the anode cannot be secured unless it has a certain mechanical strength.

  As the spring-shaped elastic body 32, the spring height before compression is preferably 1.5 mm to 6 mm, and after that, even when the spring height is uniformly compressed to 1.0 to 2.5 mm, compression is performed. What is restored more than the set distance is preferable. The elastic repulsion force of the elastic body 32 is preferably 7 to 15 kPa.

  As the spring-shaped elastic body 32, for example, as shown in FIG. 4, a smooth fixing portion 41 extending in the longitudinal direction and an elastic portion 42 extending from the fixing portion 41 in the lateral direction and formed in an uneven shape are provided. Is mentioned. The fixing portion 41 of the elastic body 32 can be attached to the back plate 31 by a fixing member using the hole 41a. In addition, the elastic portion 42 formed in a concavo-convex shape has a wave shape or a shape in which one or more sides are bent at least once. In the illustrated example, the base support portion 42a is supported by the back plate 31, and the cathode support portion. 42 b has a structure for supporting the active cathode 33. In FIG. 4, the elastic part 42 is provided at a symmetrical position on both sides of the fixed part 41, but the elastic part 42 may be provided at an asymmetrical position (for example, an alternating position) on both sides.

  As the spring-shaped elastic body 32, for example, the base material thickness is 0.02 to 0.3 mm, the width of the fixing portion 41 smooth in the longitudinal direction is 5 to 30 mm, and the period of the concavo-convex shape of the elastic portion 42 is. Is 10 mm or more, and the width of the gap formed by the concavo-convex shape is 2 to 20 mm. The elastic body 32 preferably has a shape in which the substrate thickness is 0.20 mm, the width of the fixing portion 41 is 10 mm, the period of the uneven shape of the elastic portion 42 is 10 mm, and the width of the gap portion is 8 mm. is there.

(Second cathode)
Examples of the conductive substrate of the second cathode disposed on the elastic body include nickel, stainless steel, copper, etc., as in the case of the first cathode. From the viewpoint of corrosion resistance, etc., nickel expanded metal, nickel punched Metal, nickel fine mesh or nickel plain weave mesh is desirable, and nickel fine mesh and nickel plain weave mesh which are flexible structures are particularly desirable from the viewpoint of economy and reducing damage to the ion exchange membrane. The thickness of the cathode including the catalyst layer is preferably from 25 to 75% from the viewpoint of economic strength such as mechanical strength and liquid permeability and a rigid structure, and the thickness of the cathode including the catalyst layer is 0.01 to 0.5 mm is desirable, and the thickness of the catalyst layer is preferably 1.0 to 20 μm. Further, when using a nickel plain woven mesh, the wire diameter is 0.1 to 0.4 mm, and the distance between the wire diameters is 20 to 60 meshes per inch, so-called 20 to 60 mesh, Preferably, the wire diameter is 0.2 to 0.3 mm, and 30 to 50 mesh is good.

  As described above, the second anode is disposed on the first anode, the second cathode is disposed in a state where the elastic body is disposed between the ion exchange membrane and the separated first cathode, and the second cathode Is adhered to the ion exchange membrane uniformly and at a uniform pressure, so that the renewal work of the first anode is reduced as compared with the conventional ion exchange membrane electrolytic cell composed of the first anode and the first cathode, and the anode It is possible to extend the life and reduce the electric energy consumption.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to an Example at all. About the effect at the time of laminating and attaching the 2nd anode on the 1st anode, compared with the case of only the 1st anode as follows, an electrolysis performance test was carried out.

  In addition, about the aperture ratio of the electroconductive base | substrate, the percentage was calculated | required by dividing the area of an opening by the whole area about what projected the electroconductive base | substrate on the plane.

(Comparative Example 1)
For the electrolytic performance test, an ion exchange membrane electrolytic cell having an electrolysis area of 100 × 100 mm was used. The conductive substrate of the first anode is a titanium expanded metal conductive substrate with an opening ratio of 31%, the SW length of the opening is 3.5 mm, the LW length is 6.0 mm, and the thickness is 1.0 mm. It is. The surface of the conductive substrate was treated with # 180 alumina blast, and then etched in a 10% 90 ° C. oxalic acid bath for 3.5 hours. The average surface roughness of the conductive substrate after etching was 30 μm. An acidic solution containing a platinum group metal (Ir, Ru, the same shall apply hereinafter) is applied to the surface of the conductive substrate thus roughened, followed by drying at 100 ° C. for 10 minutes, and then at 20 ° C. for 20 minutes. A calcination treatment for a minute was performed. This coating-drying process was repeated to produce an anode in which the thickness of the catalyst layer having an active function of generating chlorine was about 15 μm on the surface of the conductive substrate. The maximum height of the unevenness on the surface of the catalyst layer of the anode was 30 μm, which is the same as the average roughness after etching. The chlorine generation overvoltage at this time was confirmed in advance to be 40 mV at 200 g / L sodium chloride, 85 degrees, and the electrolysis current density of 4 kA / m ² .

The conductive substrate of the first cathode has a SW length of 5.0 mm, an LW length of 10.0 mm, and a thickness of 1.0 mm at the opening of the expanded metal made of nickel having an aperture ratio of 38%. Etching was performed in a 10% 50 ° C. hydrochloric acid bath for 4 hours. The average surface roughness of the conductive substrate after etching was 10 μm. An acidic solution containing a platinum group metal was applied to the surface of the conductive substrate thus roughened, dried at 100 ° C. for 10 minutes, and then fired at 400 ° C. for 10 minutes. . This coating and drying process was repeated to produce a first cathode in which the thickness of the catalyst layer having an active function of generating hydrogen was about 10 μm on the surface of the conductive substrate. The maximum height of the irregularities on the surface of the catalyst layer of the first cathode was 10 μm, which is the same as the average roughness after etching. The hydrogen generation overvoltage at this time was confirmed in advance to be 80 mV at 32% sodium hydroxide, 85 ° C., and the electrolysis current density of 4 kA / m ² .

  Adjustment of the distance between the electrodes in which the first anode and the first cathode were partitioned by the ion exchange membrane was performed as follows. When the first anode was attached to the anode chamber frame, a step was provided so as to be 1.5 mm higher in a method perpendicular to the surface of the anode chamber frame in contact with the ion exchange membrane. On the other hand, when the first cathode was mounted on the cathode chamber frame, the position was made smooth on the surface of the chamber frame in contact with the ion exchange membrane. As the ion exchange membrane, F8020SP ion exchange membrane manufactured by Asahi Glass Co., Ltd. was used, and the gasket between the ion exchange membrane and the first anode was 2 mm, and the gasket between the ion exchange membrane and the first cathode was similarly 2 mm. In other words, the distance between the first anode and the first cathode is theoretically a distance of 2.5 mm, but the distance is estimated to be in the range of 2 mm to 2.5 mm because it is partitioned by the ion exchange membrane. Is done. Tables 1 and 2 describe the details of the electrolytic performance test.

The ion exchange membrane electrolytic cell installed as described above supplies 280 g / L of saline as an electrolytic solution to the anode chamber and 31% sodium hydroxide (kei soda) to the cathode chamber. The electrolysis test was performed under conditions of a density of 4 kA / m ² . Table 3 lists the electrolytic performance test conditions.

  From the start of the comparative test, the initial value of the cell voltage (electrolytic voltage) increased to 3.350 V, and the value after 180 days increased to 3.490 V.

(Comparative Example 2)
As the first anode, an anode used for 20 years in an actual commercial tank at a continuous operation time of 4 kA / m ² was used. The conductive substrate of the anode is a titanium expanded metal having an aperture ratio of 31%, the SW length of the opening is 3.5 mm, the LW length is 6.0 mm, and the thickness is 1.0 mm. The chlorine generation overvoltage at this time was confirmed in advance to be 70 mV at 200 g / L NaCl at 85 ° C. and an electrolytic current density of 4 kA / m ² . The rest is the same as Comparative Example 1.

  From the start of the comparative test, the initial value of the cell voltage (electrolytic voltage) increased to 3.370 V, and the value after 180 days increased to 3.510 V.

(Comparative Example 3)
The conductive substrate for the second anode provided on the first anode similar to Comparative Example 1 is a titanium expanded metal conductive substrate with an aperture ratio of 31%, and the SW length of the opening is 5.0 mm, LW A sample having a length of 10.0 mm and a thickness of 1.5 mm was prepared. The surface of the conductive substrate was treated with # 180 alumina blast, and then etched in a 10% 90 ° C. oxalic acid bath for 3.5 hours. The average surface roughness of the conductive substrate after etching was 30 μm. An anode chamber frame in which a second anode in which the thickness of a catalyst layer containing a platinum group metal and having an active function of generating chlorine is about 15 μm is prepared on the surface of a conductive substrate, and is laminated and attached on the first anode by Ti welding. Prepared. It was confirmed in advance that the chlorine generation overvoltage of only the second anode at this time was 40 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² . The rest is the same as Comparative Example 1.

  The initial value of the cell voltage (electrolysis voltage) from the start of the test was 3.330 V, and the value after 180 days was increased to 3.470 V.

(Comparative Example 4)
Unlike Comparative Example 1, the first anode has a wire diameter of 0.35 mm and a thickness of 0.7 mm, and the interval between the wire diameters and the wire diameter has 20 openings per inch, so-called 20 Using a conductive substrate made of a plain woven wire mesh as a mesh and having an aperture ratio of 50%, the catalyst layer containing a platinum group metal and having an active function of generating chlorine was prepared to have a thickness of about 10 μm. The chlorine generation overvoltage of only the first anode at this time was confirmed in advance to be 30 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² .

The second anode is an expanded metal conductive base made of titanium having an opening ratio of 31%. The SW length of the opening is 3.5 mm, the LW length is 6.0 mm, and the thickness is 1.0 mm. Using a certain conductive substrate, a catalyst layer containing a platinum group metal and having an active function of generating chlorine was prepared so as to have a thickness of about 15 μm. It was confirmed in advance that the chlorine generation overvoltage of only the second anode at this time was 40 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² . On the first anode, an anode chamber frame was prepared in which the second anode was laminated and attached by spot welding. The rest is the same as Comparative Example 1.

  From the start of the comparative test, the initial value of the cell voltage (electrolysis voltage) increased to 3.340V, and the value after 180 days increased to 3.480V.

(Comparative Example 5)
Unlike Comparative Example 1, the first anode has a wire diameter of 0.25 mm and a thickness of 0.7 mm, and the interval between the wire diameters and the wire diameter has 30 openings per inch, so-called 30. Using a conductive substrate made of a plain woven wire mesh as a mesh and having an aperture ratio of 50%, the catalyst layer containing a platinum group metal and having an active function of generating chlorine was prepared to have a thickness of about 10 μm. The chlorine generation overvoltage of only the first anode at this time was confirmed in advance to be 30 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² .

Further, the second anode has a wire diameter of 0.6 mm and a thickness of 1.2 mm, and the distance between the wire diameter and the wire diameter is 10 so that the opening ratio is 10 mesh per inch. Using a conductive substrate made of 59% plain weave wire mesh, a catalyst layer containing a platinum group metal and having an active function of generating chlorine was prepared to have a thickness of about 10 μm. The chlorine generation overvoltage of only the second anode at this time was confirmed in advance to be 30 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² . On the first anode, an anode chamber frame was prepared in which the second anode was laminated and attached by spot welding. The rest is the same as Comparative Example 1.

  From the start of the comparative test, the initial value of the cell voltage (electrolysis voltage) increased to 3.340V, and the value after 180 days increased to 3.480V.

Example 1
On the same first anode as Comparative Example 1, the wire diameter is 0.35 mm, the thickness is 0.7 mm, and the distance between the wire diameters is 20 so that there are 20 openings per inch. Using a conductive base made of a plain weave wire mesh (opening ratio 50%), a second anode having a thickness of about 10 μm of a catalyst layer containing a platinum group metal and having an active function of generating chlorine is produced and laminated by spot welding. The anode chamber frame attached was prepared. The chlorine generation overvoltage of only the second anode at this time was confirmed in advance to be 30 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² . The rest is the same as Comparative Example 1.

  From the start of the comparative test, the initial value of the cell voltage (electrolytic voltage) increased to 3.260 V, and the value after 180 days increased to 3.400 V.

(Example 2)
With respect to the first anode of Example 1, the wire diameter is 0.20 mm, the thickness is 0.40 mm, and the distance between the wire diameters is 40 so-called 40 meshes per inch. Using a conductive substrate made of a plain weave wire mesh (opening ratio 47%), a second anode having a thickness of about 10 μm of a catalyst layer containing a platinum group metal and having an active function of generating chlorine is produced and laminated by spot welding. The anode chamber frame attached was prepared. The chlorine generation overvoltage of only the second anode at this time was confirmed in advance to be 30 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² . The rest is the same as in the first embodiment.

  From the start of the comparative test, the initial value of the cell voltage (electrolytic voltage) increased to 3.260 V, and the value after 180 days increased to 3.400 V.

(Example 3)
With respect to the first anode of Example 1, the wire diameter is 0.15 mm, the thickness is 0.30 mm, and the interval between the wire diameters is 60 so-called 60 meshes per inch. Using a conductive base made of a plain weave wire mesh (aperture ratio 42%), a second anode having a platinum layer metal-containing catalyst layer having an active function of generating chlorine and having a thickness of about 10 μm is prepared and laminated by spot welding. The anode chamber frame attached was prepared. The chlorine generation overvoltage of only the second anode at this time was confirmed in advance to be 30 mV at 200 g / L NaCl, 85 degrees, and the electrolysis current density of 4 kA / m ² . The rest is the same as in the first embodiment.

  From the start of the comparative test, the initial value of the cell voltage (electrolytic voltage) increased to 3.260 V, and the value after 180 days increased to 3.400 V.

Example 4
In Example 1, in order to laminate a new cathode on the first cathode, the wire diameter is 0.15 mm, and the distance between the wire diameters is 40 openings per inch, so-called 40. A conductive base of nickel plain woven wire mesh (opening ratio 55%) as a mesh was used. Etching was performed in a 10% 50 ° C. hydrochloric acid bath for 4 hours. The substrate surface average roughness after the etching was 15 μm. An acidic solution containing a platinum group metal was applied to the surface of the conductive substrate thus roughened, dried at 100 ° C. for 10 minutes, and then fired at 400 ° C. for 10 minutes. This coating-drying process was repeated to produce a second cathode in which the thickness of the catalyst layer having a catalytic function for hydrogen generation was about 10 μm on the surface of the conductive substrate. The maximum height of the irregularities on the surface of the catalyst layer of the second cathode was 10 μm, which is the same as the average roughness after etching. Platinum group metal firing was performed. It was confirmed beforehand that the hydrogen generation overvoltage of only the second cathode at this time was 70 mV at 32% sodium hydroxide, 85 degrees, and the electrolysis current density at 4 kA / m ² . A conductive elastic body (shape: see FIG. 4, thickness 0.1 mm, elastic repulsive force 10 kPa) is interposed between the first cathode and the first cathode, and has a catalytic function for hydrogen generation. An ion exchange membrane electrolytic cell was prepared in such a manner that the ion exchange membrane was uniformly adhered to the ion exchange membrane in the arranged state.

  From the start of the comparative test, the initial value of the cell voltage (electrolytic voltage) increased to 3.080 V, and the value after 180 days increased to 3.180 V.

The above results are summarized in Tables 1 to 3 together with the electrolysis conditions.

U electrode unit I ion exchange membrane 10 electrode support frame 11 partition 12, 13 vertical rib 12a, 13a through hole 20 anode 20A anode chamber 21 first anode 22 second anode 30 cathode 30A cathode chamber 31 first cathode 32 elastic body 33 first Two cathodes

Claims (7)

An ion exchange membrane electrolytic cell comprising an anode having a conductive substrate having an opening and a catalyst layer provided on the conductive substrate, a cathode, and an ion exchange membrane disposed between the anode and the cathode In
The anode has a first anode disposed on the anode chamber side, and one or more second anodes laminated in a conductive state with the first anode,
The second anode has an opening ratio of the conductive substrate of 40 to 55%,
An ion exchange membrane electrolytic cell, wherein an opening ratio of the conductive substrate of the first anode is less than an opening ratio of the conductive substrate of the second anode.   2. The ion exchange membrane electrolytic cell according to claim 1, wherein the catalyst layer of the first anode is deteriorated from the time of newly installed, and the second anode is a newly installed anode. The conductive substrate of the second anode is either an expanded metal having a thickness of 0.1 mm to 1.2 mm, a punching metal, or a plain woven mesh,
3. The ion exchange membrane electrolytic cell according to claim 1, wherein the conductive substrate of the first anode is any one of an expanded metal, a punching metal, or a plain woven mesh having a thickness of 0.5 mm to 2.0 mm.   The catalyst layer of the second anode includes at least one platinum group metal selected from the group consisting of platinum, iridium, rhodium, palladium, and ruthenium or an oxide thereof, and the catalyst layer has a thickness of 0.1 to 0.1. The ion exchange membrane electrolytic cell according to any one of claims 1 to 3, which is 50 µm.   The ion exchange membrane electrolytic cell according to any one of claims 1 to 4, wherein the conductive substrate of the second anode is a plain woven mesh having a thickness of 0.1 mm to 1.2 mm.   The ion exchange membrane electrolytic cell according to any one of claims 1 to 5, wherein the catalyst layer of the second anode has a surface roughness of 0.5 to 70 µm.   The ion exchange membrane electrolytic cell according to any one of claims 1 to 6, which is a monopolar or bipolar electrolytic cell.

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