JPS6041716B2 - Multipolar filter press type electrolytic cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bipolar filter press type ion exchange membrane method electrolytic cell.

More specifically, by making one or both surfaces of the ion exchange membrane hydrophilic and electrolyzing the anode and cathode in close contact with the ion exchange membrane, the electrolytic sliding voltage is reduced, power efficiency is improved, and the electrolytic cell An object of the present invention is to provide an electrolytic cell suitable for electrolysis of aqueous liquids such as alkali chloride, hydrochloric acid, and water, which can greatly reduce manufacturing costs. Conventionally, electrolytic cells have been used to produce chlorine gas, caustic alkali, and hydrogen by electrolyzing aqueous solutions of alkali chloride salts, and to produce oxygen and hydrogen by electrolyzing water. Hereinafter, alkali chloride electrolysis will be explained in detail. Methods for electrolyzing an aqueous alkali chloride salt solution include a mercury electrolytic cell that uses mercury as a cathode and a diaphragm electrolytic cell that does not use mercury.

In mercury electrolyzers, mercury is used in the cathode, which results in mercury being contained in the caustic soda product and in the wastewater that comes into contact with the mercury. Due to environmental pollution issues, non-mercury processes are being adopted worldwide. There is a tendency.

In addition, the mercury method has an average electrolytic power consumption of 3,200 KWH.
/t・Poor power efficiency due to caustic soda. Diaphragm method electrolytic cells include asbestos diaphragm method electrolytic cells and ion exchange membrane method electrolytic cells. Asbestos diaphragm electrolyzers do not use mercury, so there is no problem of environmental contamination due to mercury, but the problem of environmental contamination due to asbestos remains. In addition, the electrolysis power consumption is on average 2,500 KWH/t of caustic soda, which is good power efficiency, but the concentration of the generated caustic soda is 1
Since the concentration is as low as 0 to 12%, approximately 2.5 t/t of caustic soda steam is required to concentrate it to 50%.
In terms of overall energy efficiency, it is worse than the mercury method. on the other hand,
The ion-exchange membrane method electrolyzer does not use mercury or asbestos, so there is no problem of environmental pollution.The concentration of the caustic sorter produced is as high as 20-40%, and the average electrolysis power consumption is 2,500 KWH. /t・caustic soda, 50%
To concentrate up to approx. Although 0.4 t/t of caustic soda steam is required, the overall energy efficiency is the best.

The diaphragm method electrolytic cell includes a box-shaped monopolar electrolytic cell as described in JP-A-51-63371, and a box-shaped monopolar electrolytic cell as described in JP-A-52-68.
There are bipolar electrolytic cells as described in 075, and monopolar electrolytic cells are mainly used in small and medium-sized caustic soda manufacturing plants, while bipolar electrolytic cells are mainly used in large-scale factories. Adopted.

The reason for this is thought to be that bipolar electrolytic cells are more economical by having a larger current capacity than monopolar electrolytic cells. Also, in the case of ion-exchange membrane electrolytic cells, there are two types: a monopolar electrolytic cell as described in JP-A-53-28573, and a bi-polar electrolytic cell as described in JP-A-51-43377. Yes, each uses a filter breath type. Single-pole electrolyzers and bi-polar electrolyzers each have their own advantages and disadvantages, and single-pole filter-breath electrolyzers allow you to freely select the current capacity according to the production scale, and can be used with either the mercury method or the asbestos diaphragm method. ) When converting, the substation equipment can be used as is. Further, there are advantages such as stable operation with little fluctuation in production volume when stopping or starting up the electrolytic cell for maintenance of the electrolytic cell. On the other hand, bipolar filter breath type electrolytic cells have the advantage that the voltage drop due to the metal conductor between unit electrolytic cells is small and the power loss of the metal conductor can be reduced. It has the disadvantage that the production amount fluctuates greatly when starting up. Another disadvantage is that the manufacturing cost of the electrolytic cell is higher than that of a monopolar electrolytic cell. In order to develop an energy-saving and low-cost electrolytic cell in such a bipolar ion-exchange membrane electrolytic cell, the present inventors conducted various studies and experiments, and found that an ion-exchange membrane was interposed between the anode and the cathode. A multi-electrode filter breath type electrolytic cell with a conductive metal plate on the anode side that can withstand the anode chamber conditions and has a protrusion on the anode side and a conductive metal plate on the cathode side that can withstand the cathode chamber conditions and has a protrusion on the cathode side. By using a separator that electrically and mechanically connects the two electrolytic cells with each other via a conductive connecting member, the electrical resistance between unit electrolytic cells does not increase.
We have discovered an electrolytic cell that is inexpensive to produce.

In addition, a wire mesh or mesh anode and/or cathode with appropriate flexibility is used, and a membrane with one or both surfaces of the ion exchange membrane made hydrophilic is interposed between the anode and the cathode. The ion exchange membrane is brought into almost complete contact with the anode and the cathode, or the anode and the cathode are alternately bitten into each other so that the ion exchange membrane and the anode and the cathode are brought into almost complete contact. It has been found that the voltage of the electrolytic cell can be significantly reduced by this method. That is, in a bipolar filter breath type electrolytic cell divided into an anode chamber and a cathode chamber by an ion exchange membrane, (a) at least one surface of the ion exchange membrane does not have gas and liquid permeable catalytic activity; (b) the separator is composed of an anode-side conductive metal plate that can withstand the anolyte electrolyte and a cathode-side conductive metal plate that can withstand the cathode electrolyte; an anode; The side conductive metal plate has one or more protrusions on the anode side,
In addition, the cathode-side conductive metal plate must also have one or more protrusions on the cathode side: the positions of the protrusions on the anode-side conductive metal plate and the cathode-side conductive metal plate are different. Between the flat part of the conductive metal plate on the anode side and the protruding part of the conductive metal plate on the cathode side, and between the flat part of the conductive metal plate on the cathode side and the protrusion of the conductive metal plate on the anode side. The anode is placed on the top of the protrusion of the conductive metal plate on the anode side, and the anode is electrically and mechanically connected. In addition, the cathode is placed on the top of the protrusion of the cathode-side conductive metal plate, and the electrical
(c) The separator is connected to the anode chamber frame with the anolyte supply nozzle and the anolyte/gas discharge nozzle, and the catholyte supply nozzle and the catholyte/gas discharge. (d) an ion exchange membrane is arranged between the anode of the separator and the cathode of an adjacent separator; When an electrolytic cell is assembled, the anode, ion exchange membrane, and cathode are either in almost complete contact with each other, or the anode and cathode are nested into each other, so that the anode, ion exchange membrane, and cathode are in close contact with each other. By making almost complete contact, we have discovered an energy-saving electrolytic cell that is inexpensive to manufacture and can significantly reduce the electrolytic sliding voltage.

The anode chamber frame and/or cathode chamber frame of such an electrolytic cell are manufactured in a free shape separately from the separator, and the manufacturing cost is 112 to 213 yen less than that of a conventional bipolar filter breath type electrolytic cell. obtain.

Further, according to studies by the present inventors, the thickness of the anode chamber frame and/or cathode chamber frame used in the electrolytic cell of the present invention can be made extremely thin.

In conventional electrolytic cells, if the gas generated as a result of the electrode reaction is not quickly removed from the electrode chamber, the sliding voltage will increase. The thickness of the chamber frame is required to be at least a certain level relative to the height, and conversely, when the thickness of the chamber frame is made thinner than this limit thickness, the gas inside the extreme chamber cannot escape quickly (i.e.,
There was a problem that the amount of gas accumulated in the electrode chamber increased) and the sliding voltage increased. For the above-mentioned reasons, conventionally, the ratio between the height and the thickness of the chamber frame has been limited to a maximum of 30. On the other hand, in the electrolytic cell of the present invention, this ratio is at most 50
It can be taken up to 0. That is, even if a chamber frame with a height of 50 mm is used, the phenomenon of an increase in sliding voltage due to gas accumulation in the electrode chamber does not occur. As a result, the electrolytic cell of the present invention has a great industrial advantage in that it can be made into a large-capacity electrolytic cell without increasing the installation floor space. Although it has not yet been fully elucidated why the battery case of the present invention has the above-mentioned special effects, the biggest reason is that it is attributable to the porous layer provided on the ion exchange membrane. It is imagined.

The porous layer is preferably made of the materials described below, but since the porous layer made of such a material provides hydrophilicity to the ionic membrane, it is easy to remove gas adhering to the ionic membrane surface. It is presumed that the accumulation of gas in the electrode chamber can be kept to a minimum by tightening and even promoting it. Of course, such a phenomenon is also related to the characteristics of the ion exchange membrane used. When using an ion exchange membrane, the porous layer having gas and liquid permeability and corrosion resistance and/or chlorine resistance may be made of materials such as titanium, zirconium, niobium, tantalum, vanadium, manganese, molybdenum, tin, antimony,
Oxides, nitrides, and carbides of tungsten, bismuth, indium, cobalt, nickel, beryllium, aluminum, chromium, iron, gallium, germanium, selenium, yttrium, silver, lanthanum, cerium, hafnium, lead, thorium, rare earth elements, etc. These may be used singly or in mixtures, among which titanium, zirconium, niobium, tantalum, vanadium, manganese, molybdenum,
Oxides, nitrides, and carbides of tin, antimony, tungsten, bismuth, etc. alone or in combination are preferred. On the cathode side, oxides, nitrides, and carbides of titanium, zirconium, niobium, tantalum, indium, tin, manganese, cobalt, nickel, etc. alone or in mixtures are preferable.

A preferred method for forming a porous layer using the above-mentioned materials is, for example, applying a powder forming the porous layer to an ion exchange membrane by screen printing or the like, and then applying heat and pressure to the membrane. This method involves forming a porous layer on the surface of an ion exchange membrane.

That is, as an anode, a valve metal such as titanium or zirconium coated with a noble metal such as platinum or palladium, or a noble metal oxide can be used, and as a cathode, in addition to iron or stainless steel, Raney nickel or the like can be used. Those provided with a particle coating layer such as the like are preferably used.

Furthermore, the membrane used in the electrolytic cell of the present invention is preferably made of perfluorofluorinated carbon, and as the ion exchange group, a membrane having a carboxylic acid group, a sulfonic acid group, a phosphonic acid group, etc. can be preferably used. However, the preferred ones are JP-A-51-140899 and JP-A-52-4.
This is a carboxylic acid type perfluorinated carbon film disclosed in No. 8598 and the like.

Next, the conductive connecting members that connect the anode and cathode of the separator include
Titanium (or titanium alloy), copper, iron (or stainless steel)
A clad plate made of

A flexible wire mesh or mesh electrode can be used as the electrode, and the distance between the electrodes (the distance between the anode and the cathode that sandwich the ion exchange membrane) is substantially the same as the thickness of the ion exchange membrane. The electrolytic sliding voltage can be greatly reduced. In order to further deepen the understanding of the present invention, the present invention will be explained with reference to the accompanying drawings, but the present invention is not limited to the drawings. FIG. 1 is a plan view showing an example of a separator preferably used in the electrolytic cell of the present invention, and FIGS. 2 and 3 are examples of sectional views taken along the line AA in FIG. 1.

FIG. 4 is an installation diagram of the conductive connecting member. FIG. 5 is a partial sectional view of the electrolytic cell of the present invention. In FIG. 1, reference numeral 1 denotes a separator plate, which is composed of an anode-side conductive metal plate and a cathode-side conductive metal plate that can withstand the conditions of the anode chamber. 4 or 5 is an anode or a cathode electrically and mechanically connected to the top of the protrusion 8 or 9 of the anode-side conductive metal plate or the cathode-side conductive metal plate.

10 is a conductive connecting member.

In FIG. 2, the separator 1 includes an anode-side conductive metal plate 2 having at least one row of protrusions 8 protruding toward the anode 4 side, and a cathode having at least one row of protrusions 9 protruding toward the cathode 5 side. The side conductive metal plate 3 is configured to be electrically and mechanically connected to the side conductive metal plate 3 through a conductive connecting member 10 with a gap therebetween.

FIG. 3 shows the conductive connecting member 10 in a state where the anode-side conductive metal plate 2 and the cathode-side conductive metal plate 3 are in close contact with each other without any gaps.
1 shows a separator plate 1 configured to be electrically and mechanically connected via.

The material of the anode side conductive metal plate 2 is titanium, tantalum,
Metals such as niobium and alloy plates such as titanium radium alloys can be used.

The thickness of the metal plate is 0.1T! Rm~5W0fL can be used, but preferably 0.17r$L~
It is 2wn. Moreover, the height of the protrusion of the metal plate is 1TW
L~50T! Although it can be set to $L, it is preferably 5Tfrm to 30TI$L for manufacturing reasons and for smooth rise of the anolyte and gas. The spacing between the protrusions of the metal plate can be 30Tf$L to 300Tr0Tt, but is preferably 50TWL200TfrIn in consideration of the manufacturing cost of the electrolytic cell and the voltage drop of the electrodes. As the material of the cathode side conductive metal plate 3, a metal plate such as iron or stainless steel or an alloy plate can be used. The thickness of the metal plate is 1
T! UrL to 5TnIn can be used, preferably 1 to 3 TnIn. The height of the protrusion 8 of the metal plate can be 1Tm to 50Tr0rL, but is preferably 5Tm to 3H for manufacturing reasons and for smooth rise of the catholyte and gas. The spacing between the protrusions 9 of the metal plate can be 30 m to 30 m1n, but is preferably 5 h to 20 m in consideration of the manufacturing cost of the electrolytic cell and the voltage drop (voltage loss) of the electrodes. Projection 8 of the anode-side conductive metal plate 2 and projection 9 of the cathode-side conductive metal plate 3
The protrusion 9 of the conductive metal plate 3 on the cathode side is positioned approximately at the center of the two protrusions 9 on the conductive metal plate 2 on the anode side. The material used for the anode 4 is titanium or titanium alloy wire mesh, or expanded mesh valve metal coated with oxides of ruthenium oxide, palladium oxide, or platinum-iridium alloy.

Further, as the wire mesh or expanded mesh of the anode 4, one having a wire diameter of 0.2 Tr$l to 2 W$L1 and an opening of 2 to 2-2 is used. For the cathode 5, a wire mesh or expanded mesh made of iron or stainless steel is used.

It is also possible to use the wire mesh or expanded mesh coated with Raney nickel or the like. In addition, the wire mesh or expanded mesh of the cathode 5 has a wire diameter of 0.2Tfr1n to 2Tf0fL1 and an opening of 2 to 2.
Marshal's is used. The conductive connecting member 10 is made of titanium (or titanium alloy) 12, copper 1, as shown in FIG.
A clad plate made of 3-iron iron (or stainless steel) is used, and is placed between the protruding part 8 of the anode-side conductive metal plate 2 and the flat part 7 of the cathode-side conductive metal plate 3, and is attached to an electric resistance welder. electrically and mechanically connected.

Further, a conductive connecting member 10 is arranged between the flat part 6 of the anode side conductive metal plate 2 and the protrusion part 9 of the cathode side conductive metal plate 3, and electrically and mechanically connected by an electric resistance welder. be done. The height of the conductive connection member 10 depends on the height of the protruding parts of the anode-side conductive metal plate 2 and the cathode-side conductive metal plate 3.
．． 5? Although it can be set to 45Tf0n, preferably it is 3wn to 28 order. The width of the conductive connecting member 10 can be 5 to 20 wL, but in reality, it depends on the current density on the effective electrolytic surface of the electrolytic cell and the protrusion of the anode-side conductive metal plate 2 or the cathode-side conductive metal plate 3. Determined by the number of columns. FIG. 5 is an assembled diagram of the electrolytic cell of the present invention, in which an anode side conductive metal plate 2 is attached to an anode side end plate 22 and a conductive connecting member 1 is attached to the anode side end plate 22.
It is electrically and mechanically attached via 0.

Further, an anode 4 is electrically and mechanically attached to the top of the protrusion 8 of the conductive metal plate. The cathode-side conductive metal plate 3 is electrically and mechanically connected to the cathode-side end plate 23 via a conductive connecting member 10 . Further, a cathode 5 is electrically and mechanically attached to the top of the protrusion 9 of the conductive metal plate. The material of the anode and cathode side end plates is iron, and can also be an electrical conductor. Anode chamber frame 1
6 has an anode electrolyte supply nozzle (not shown) at the bottom, and an anode electrolyte/gas discharge nozzle (not shown) at the top.
have. The material of the anode chamber frame 16 is an iron frame lined with titanium, titanium radium alloy, or natural rubber, or a synthetic resin such as polypropylene, carbon fiber reinforced polypropylene, polyvinyl chloride, fluororesin, or epoxy resin. can also be used. Furthermore, the surface of the iron room frame can be lined or coated with such a resin. The cathode chamber frame 17 has a cathode electrolyte supply nozzle (not shown) at the bottom, and a catholyte/gas discharge nozzle (not shown) at the top.

The cathode chamber frame 17 is made of iron, stainless steel, or synthetic resin, such as polypropylene, carbon fiber-reinforced polypropylene, polyvinyl chloride, polyvinyl chloride, fluororesin, or the like. The thickness of the anode chamber frame 16 and the cathode chamber frame 17 is determined by the height of the protrusions 8 and 9 of the anode side conductive metal plate 2 and the cathode side conductive metal plate 3, and the height of the anode and cathode when the electrolytic cell is assembled. Determined by the amount of bite. The gasket 24 is made of EPDM or natural rubber. The electrolytic cell of the present invention includes an anode side end plate 22 / gasket 24 / anode chamber frame 16 / gasket 24 / ion exchange membrane 15 / gasket 24 / cathode chamber frame 17 / gasket 24 / separator 1 /
Gasket 24 / Anode chamber frame 16 / Gasket 24 / Ion exchange membrane 15 / Gasket 24 / Cathode chamber frame 17 / Gasket 24 / Separator 1 / ...... / Anode chamber frame 1
6/Gasket 24/Ion exchange membrane 15/Gasket 2
4/Cathode chamber frame 17/Gasket 24/Cathode side end plate 23 are assembled and tightened using a tie rod or hydraulic device. The amount of penetration of the anode 4 and/or cathode 5 into each other after the electrolytic cell is assembled is 0 to 5 mg, preferably 0.
．． 5T0r1 to 3Tr0TL.

The manufacturing cost of the electrolytic cell designed and assembled in this manner is lower than that of conventional electrolytic cells, and the electrolytic sliding voltage can be significantly reduced. Example: 73mg of tin oxide powder with a particle size of 44μ or less in 50cc of water.
Polytetrafluoroethylene (P
TFE) suspension (DuPont, trade name Teflon 30J)
was added so that the volume of PTFE was 7.3 m9, and after adding one drop of a nonionic surfactant (Rohm and Haas, trade name: Triton X-100), the mixture was cooled on ice and stirred using an ultrasonic stirrer. Thereafter, the mixture was suction-filtered onto a porous PTFE membrane to obtain a porous tin oxide thin layer.

The thin layer has a thickness of 30P1, a porosity of 73%, and an air permeability coefficient of 3
．． It has 8×10-3 mol/Cli-Mln-CmHy and 5m9/C of tin oxide! l was included.

On the other hand, using the same method as above, nickel oxide of 44p or less was obtained at 7m9/C! l, thickness 35μ, porosity 73%,
Air permeability coefficient 3.5×10-3 mol/Crl-Min-
A thin layer of C7lH was obtained.

Next, each thin layer was coated with tetrafluoroethylene having an ion exchange capacity of 1.45n1eq/y resin and a thickness of 250p and CF2=CFO(CF2)3C0.
A porous PTFE membrane was laminated on both sides of an ion exchange membrane made of a copolymer of 0CH3, with the porous PTFE membrane facing outward from the ion exchange membrane, and the porous PTFE membrane was pressurized at a temperature of 160°C and a pressure of 60k9/d. The thin layer was attached to the ion exchange membrane, and then the porous PTFE membrane was removed to obtain an ion exchange membrane with porous layers of tin oxide and nickel oxide adhered to each surface.

The ion exchange membrane was immersed in a 900C 125% by weight aqueous solution of caustic soda for a period of time to hydrolyze the ion exchange membrane.
A separator as shown in the figure was manufactured and an electrolytic cell of the present invention was assembled.

The separator is a titanium plate with a thickness of 1T0fL, an anode-side conductive metal plate with three vertical rows of triangular protrusions with a height of 8mm and a base of 20TW1, and a triangular plate with a height of 87W and a base of 2-. The cathode-side conductive metal plate, which has two rows of protrusions in the vertical direction, has a width of 5TWt1 and a height of 105T, as shown in Fig. 3.
$L1 Weld the electric resistance welder so that the protruding part of the conductive metal plate on the cathode side is located in the center between the protruding parts of the conductive metal plate on the anode side. It was installed electrically and mechanically by On the top of the conductive metal plate on the anode side of the separator, there are apertures with a longitudinal dimension (LW) of 6T$t and a widthwise dimension (SW) of 3T0f.
t1 thickness 0.577j7! An anode coated with ruthenium oxide was attached electrically and mechanically to the surface of a titanium expanded mesh using an electric resistance welder.

In addition, on the top of the protruding part of the cathode side conductive metal plate, the longitudinal dimension (LW) of the opening is 6 and the width direction (SW) is 3 WI.
L1 thickness 0.5? The cathode of the stainless steel expanded mesh was attached electrically and mechanically using an electric resistance welder. The anode chamber frame and cathode chamber frame are made of polypropylene with a thickness of 5WL, and the gasket is 1.2mm thick.
・? The one made of EPDM was used. Using such electrolytic cell components, as shown in FIG. / gasket / ion exchange membrane / gasket / cathode chamber frame / gasket / cathode side end plate were assembled in this order and tightened with tie rods to complete the electrolytic cell of the present invention. After the electrolytic cell was assembled, the amount of penetration of the anode and/or cathode was about 1 cup. Add 15 liters of saturated salt water to each anode chamber of such an electrolytic cell.
water is supplied to each cathode chamber at a rate of 1.6 e/Hr, while the current density is 20 A/Dm2 and the caustic soda concentration is 3.
The results of operation for 26 days at 5% and operating temperature of 90'C were as follows. Unit electrolysis sliding voltage: 2.98■ Current efficiency: 94.2% Electrolysis power consumption: 2120KWH/t-100%NaOH
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing one example of a separator preferably used in the present invention.

Claims (1)

[Scope of Claims] 1. In a bipolar filter press type electrolytic cell divided into an anode chamber and a cathode chamber by an ion exchange membrane, (a) at least one surface of the ion exchange membrane is provided with gas and liquid permeability. A porous layer having no catalytic activity is provided; (b) the separator is composed of an anode-side conductive metal plate that can withstand anode chamber conditions and a cathode-side conductive metal plate that can withstand cathode chamber conditions; The conductive metal plate on the anode side has one or more protrusions on the anode side, and the conductive metal plate on the cathode side also has one or more protrusions on the cathode side. ; The protruding part of the anode-side conductive metal plate and the protrusion part of the cathode-side conductive metal plate are arranged in different positions; the flat part of the anode-side conductive metal plate and the cathode-side conductive metal plate electrically and mechanically connected by placing a conductive connecting member between the projecting part of the conductive metal plate on the cathode side and the flat part of the conductive metal plate on the cathode side and the protruding part of the conductive metal plate on the anode side. ; The anode is arranged on the top of the protrusion of the anode-side conductive metal plate and is electrically and mechanically connected, and the cathode is arranged on the top of the protrusion of the cathode-side conductive metal plate and is electrically and mechanically connected. (c)
The separator is between an anode chamber frame equipped with an anolyte supply nozzle and an anolyte and gas discharge nozzle, and a cathode chamber frame equipped with a catholyte supply nozzle and a catholyte and gas discharge nozzle. (d) The ion exchange membrane is arranged between the anode of the separator and the cathode of the adjacent separator; when the electrolytic cell thus arranged is assembled, The anode, the ion exchange membrane, and the cathode are in almost complete contact, or the anode and the cathode are nested into each other so that the anode, the ion exchange membrane, and the cathode are in almost complete contact. Features a filter press type electrolytic cell. 2. The electrolytic cell according to item 1, wherein the anode-side conductive metal plate is made of titanium or titanium-radium alloy. 3. The electrolytic cell according to items 1 and 2, wherein the cathode-side conductive metal plate is made of iron or stainless steel. 4
1. The conductive connecting member is a clad plate composed of titanium-copper-iron, titanium-copper-iron, titanium-copper-stainless steel, or titanium-copper-stainless steel. The electrolytic cell according to items 3 to 3. 5. The electrolytic cell according to claim 1, wherein the anode chamber frame and/or the cathode chamber frame has a vertical height to thickness ratio of 20 to 500.