JPS59193291A - Electrolysis and electrolytic cell - Google Patents

Abstract

PURPOSE:To enable the preparation of high-grade caustic alkali in a low-cost device while facilitating the exhaustion of anodic gas, in a horizontal electrolytic cell, by forming the stream of a liquid anolyte flowing through an anodic chamber below a horizontal cation-exchange membrane while damping the lower surface of said membrane. CONSTITUTION:In a horizontal electrolytic cell equipped with an upper cathodic chamber 1 and a lower anodic chamber 2 through a substantially horizontal cation-exchange membrane 3, salty water is supplied through an inlet 19 for introducing a liquid anolyte to the anodic chamber 2 to smoothly promote electrolytic reaction while damping the lower surface of the exchange membrane 3. Formed chlorine gas is immediately entangled in the liquid anolyte being circulated through the chamber 2 to form a mixed- phase stream, withdrawn through an opening 20 for discharging a mixed-phase stream and then introduced into a separator 21 to separate it into chlorine gas and a liquid anolyte. The liquid anolyte from which gas has been separated is cyclically introduced through the introducing opening 19 into the chamber 2 by a pump 22. Hereon, conc. salty water (a) of approximate saturation concentration is supplied to a part of the system for circulating salty water, and dilute salty water is partially withdrawn from the separator 21.

Description

[Detailed description of the invention] related.

More specifically, it relates to the use and hardening of a horizontal type 7E solution using a cation exchange membrane as an electrolytic diaphragm to efficiently obtain high-quality caustic alkali at a low electrolytic voltage.

A horizontal electrolytic cell is divided into an anode chamber and a cathode chamber by a horizontally stretched diaphragm, and generally contains the desired electrolyzed products,
For example, since caustic alkali is generated in the cathode chamber, it has been widely used industrially because of the advantage that it does not migrate through the diaphragm to the anode chamber.

The most typical example of a horizontal electrolyzer is a mercury-based electrolyzer, but because the mercury used in the cathode is an environmental pollutant, it is destined to be discontinued in the near future. If we want to convert such a mercury cathode electrolyzer to a mercury-free diaphragm electrolyzer at the lowest possible cost, we will inevitably have to convert it into a horizontal diaphragm electrolyzer. The development of a method for producing electrolyzed products of a quality equivalent to that of the mercury method with high current efficiency in a diaphragm electrolyzer is an important issue facing the industry.

A method of converting the above-mentioned mercury electrolytic cell to a horizontal diaphragm electrolytic cell is disclosed in Japanese Patent Publication No. 53-25557.
The electrolytic cell obtained by this method uses a filter diaphragm, and the filtration diaphragm has a high water permeability. Therefore, the anode chamber liquid hydraulically permeates the diaphragm, and the liquid generated in the cathode chamber, for example, is mixed with caustic alkali. There is a drawback that the anolyte gets mixed in and reduces the purity.

On the other hand, a cation exchange membrane called a dense diaphragm does not allow the electrolyte to permeate hydraulically, but only allows water molecules coordinated with electrically moving alkali metal ions to pass through. On the other hand, Toru】
The small amount of water that is left evaporates, causing poor conductivity between the cation exchange membrane and the cathode, and eventually stopping the electrolytic reaction.

In order to solve this problem, JP-A-49-126596 and JP-A-50-55600 disclose a method in which a water retainer is present between the cation exchange membrane and the cathode, and a method in which a caustic alkaline bath solution is applied to the cathode. Methods of electrolyzing while supplying in the form of a spray or a fountain have been proposed.

However, the method proposed in JP-A No. 49-126596 not only has problems with the number of steps involved in intervening a water retaining body and the durability of the water retaining body, but also has the problem of moisture retention between the cation exchange membrane and the cathode. If a holder is used, the distance between the electrodes increases, and the increase in resistance due to the water holder increases the electrolytic voltage, which cannot be said to be an advantageous method in terms of performance. In addition, the method proposed in Japanese Patent Application Laid-Open No. 50-55600 is
In the case of large-scale electrolyzers such as commercial electrolyzers, it is difficult to uniformly inject and supply water, which poses a problem in terms of practical use.

From this point of view, the present applicant has conducted intensive research, developed a technology that solves the above-mentioned problems, and has filed a patent application (Japanese Patent Application No. 131377/1984, etc.).

However, as we continued our research, we found that by providing the cathode chamber at the top and the anode chamber at the bottom, we could obtain advantages that could not be obtained with an electrolytic cell consisting of an upper anode chamber and a lower cathode chamber. I found it. That is, the first G anode chamber is highly corrosive due to chlorine and salt water containing chlorine, and therefore requires an expensive corrosion-resistant material. Therefore, it is desirable that such an anode chamber has a small volume and requires less material.

Second, the cathode gas (e.g., hydrogen gas) in the concentrated catholyte (e.g., caustic soda) is MB71-< dispersed and difficult to separate into gas and liquid, whereas the anode gas (e.g., chlorine gas) in the anolyte (e.g., salt water) Since gas and liquid are easily separated, the liquid circulation process can be simplified.

The present invention has been made based on knowledge that goes beyond the conventional common sense in the industry as described above, and the present invention enables relatively easy conversion from a mercury electrolytic cell to a horizontal cation exchange membrane electrolytic cell. This makes it possible to produce high quality caustic alkali with high current efficiency. Also, this invention! It goes without saying that these four electrolysis tanks can be constructed using new materials.

That is, an object of the present invention is to obtain high quality caustic alkali using a horizontal diaphragm electrolytic cell with an inexpensive device. Another object is to provide an improved type of horizontal diaphragm electrolyzer using a novel anode construction and with increased performance. Still another object is to provide a high-performance horizontal diaphragm electrolytic cell, particularly a horizontal cation exchange membrane electrolytic cell, which is an alternative to the horizontal electrolytic cell 1.

Other purposes will become clear in the following description.

In order to achieve the second object, the present invention provides a water tank comprising a cathode chamber in the upper part and an anode chamber in the lower part of a cation exchange membrane stretched substantially horizontally. Using a crucible-type electrolytic chamber, a flow of anolyte is formed that flows through the anode chamber while moistening the lower surface of the cation exchange membrane, and the anode gas generated in the anode chamber is immediately drawn into the flow and discharged to the outside of the anode chamber. This article summarizes an electrolytic method characterized by the following.

In addition, in order to carry out the method of the present invention described above (this is divided into a part of the cathode chamber and a lower anode chamber by a cation exchange membrane stretched substantially horizontally, the cathode chamber is substantially a horizontal cathode plate, a lid body, a wall of the cathode chamber surrounding the cathode plate, and the cation exchange membrane.
a side wall of the anode chamber surrounding the anode chamber; and a side wall of the anode chamber surrounding the anode chamber; 2 of the anolyte and surrounded by the lower surface of the anolyte. A good population and a mixed flow of anode gas and anode i night 1-] are included.
The present invention provides a novel electrolytic cell characterized by comprising:

The following description will be made with reference to the drawings in which the embodiments of the present invention are shown. In the following description, we will use l-IJ chloride, which is the most commonly used in the current industry, as a representative example of alkali metal halides. In addition, the electrolytic product is caustic soda, or this number expresses the intention to limit the present invention to them, and other inorganic salt solutions and water are used. Needless to say, it can also be applied to the vagina.

Figures 1 and 2 are a cutaway front view (figure) and a 1 m side cross section (figure) of an electrolytic cell which is one embodiment of the present invention.

1 and 2, the device of the present invention has a rectangular cathode chamber (1) whose length is larger than its width, preferably several times the length, and an anode chamber (2) located directly below the rectangular cathode chamber (1). ), and the cathode chamber (1) and anode chamber (2) are partitioned by a cation exchange membrane (3) stretched substantially horizontally between the side walls. Motoyama Middle [Substantially horizontal J shall also include the case where it is slightly inclined as necessary (the case where a slope of about 2/10 is given).

Examples of cation exchange membranes suitable for the present invention include membranes made of perfluorocarbon polymers having cation exchange groups.

A membrane made of a perfluorocarbon polymer having a sulfonic acid group as an exchange group was manufactured by E.I.D.
'onl; de Nem0u, ITS &; C0m
1B), n, y) under the trade name [-Nafion], and its chemical structure is as shown in the following formula.

-(-CF'-CF'2→r--(-〇F2cF2-)
-r-f-LO-CF2- CF-), O-CF2-
The preferred equivalent weight of a cation exchange membrane of CF'2-8O3H0 is 1.000
乃'+'j, 2.000, 小丑shi<is 1. , l
The equivalent weight here is the weight (g) of the dry membrane per equivalent of exchange group. Further, cation exchange membranes in which part or all of the sulfonic acid groups of the above-mentioned exchange membranes are replaced with levonic acid groups and other commonly used cation exchange membranes can also be applied to the present invention. These cation exchange membranes have extremely low water permeability and only allow sodium ions with 3 to 4 water molecules to pass through the hydraulic flow.

The cathode chamber (1) has a lid body (4), a cathode chamber side wall (5) extending so as to surround the cathode formed from the cathode plate 02 (14), etc., and an anode. The cathode conductive rod (6) is suspended by a cathode suspension device (7) erected on the lid (4), and each cathode is The conductive rods (6) are connected to each other by cathode busbars (8). The lid body (4) has a hole (10) through which the cathode conductive rod (6) is inserted, and the nucleus (10) has a hole (10) through which the cathode conductive rod (6) is inserted.
It is more airtightly sealed. Cathode conductor (6)
A cathode plate (7) is attached to the lower end of the frame, and the cathode plate (7) is connected to the cathode suspension device (7), so that the cathode suspension device (7) cannot be operated. It can be raised and lowered vertically and can be placed in contact with the cation exchange membrane (3). Of course, the cathode is not limited to being suspended from a cathode suspension device erected on the lid, and may be suspended or supported by other methods. In addition, the cathode chamber has at least one catholyte inlet
These can be provided on the lid (4) or the cathode chamber side wall (5). The catholyte can or may not be circulated as appropriate. If the catholyte does not circulate, water can be added from the catholyte inlet to control the concentration. On the other hand, a catholyte outlet (14) is provided on at least one side, and these can be provided on the side wall (5). Further, the container body (4) is provided with a cathode gas (hydrogen gas) outlet 0 at an appropriate location on the side wall (5).

Also, after the cathode gas is discharged from the electrolytic cell together with the catholyte,
It is also possible to carry out gas-liquid separation.

As the lid body (4) and cathode chamber side wall (5) constituting the cathode chamber (1) described above (J, the lid body and anode chamber side wall constituting the mercury electrolytic cell can be reused, or caustic soda etc. There is no particular restriction on the material that can withstand caustic alkali, and iron, stainless steel, nickel, nickel alloy, etc. can be used.Also, a material in which an iron base material is lined with an alkali-resistant IJ tel material can also be suitably used. It is also possible to use materials such as rubber and plastic.

Such materials include, for example, natural rubber, butyl rubber,
Rubber-based materials such as ethylene propylene rubber (EPR)] Fluorine-based polymer materials such as Siwa 1, tetrafluoroethylene polymer, tetrafluoroethylene-hexafluoropropylene copolymer, and ethylene-tetrafluoroethylene copolymer, PVC, reinforced plastic.

An example is plastic (FRP) 7z.

As the cathode plate 02 used in the present invention, porous cathode plates such as expanded metal, punched metal, and metal net are suitable. The cathode plate 02 can be manufactured from a conductive material such as iron, nickel, or stainless steel, and the surface of the cathode plate is coated with nickel, silver spraying, nickel alloy plating, etc. to reduce hydrogen overvoltage. This is a preferred aspect.

Next, the anode chamber (2) is connected to the lower surface of the cation exchange membrane (3), the anode plate OQ, and the anode chamber side wall θ which is erected along the edge of the anode plate so as to surround the anode plate. defined.

The anode plate (16) is electrically connected to the anode bottom plate (24), +1. It consists of a thin plate of metal such as titanium or tantalum, the surface of which is coated with a platinum group metal, a platinum group metal oxide, or a mixture thereof. Furthermore, an anode in which a titanium or tantalum lining on the anode bottom plate is welded to an expanded metal made of titanium or tankle coated with the above noble metal, spaghetti, or a net is also suitable. In the case of the former non-porous anode plate, it may be substantially flat, or may have irregularities parallel to the liquid flow, wavy irregularities, or other non-flat surfaces.

The anode chamber side wall 071 can be made of something like a rigid frame edge, or can be made of a backing-like material made of elastic rubber, plastic, or the like. Furthermore, as shown in FIG. 3, it is also possible to leave a peripheral portion of the anode bottom plate and scrape away the portion facing the cathode with the cation exchange membrane interposed therebetween, thereby configuring a part of the anode bottom plate as a side wall. When modifying a mercury electrolytic cell, it is preferable to leave the peripheral edge of the anode bottom plate facing the lower flange of the side wall of the cathode chamber as described above and use it as a base material for the side wall, and to construct the anode plate on the surface of this. This is one of the aspects. Furthermore, Oite may also provide a suitable sidewall for the depiction shown in FIG.

That is, a thin layer of backing (23
), the cathode plate α is fixed above the flan surface at the bottom of the side wall constituting the cathode chamber, and the cation exchange membrane (
Using the flexibility of 3), the cation exchange membrane is stretched along the inner surface of the side wall of the cathode chamber to form an anode chamber.

The anode chamber side wall θ which constitutes the anode chamber (2) is not particularly limited and can be suitably used as long as it is made of a material that is resistant to chlorine. For example, chlorine-resistant metals such as titanium and titanium alloys, fluorine thread polymers, hard rubber, etc. can be used. Furthermore, it is also possible to use iron lined with a metal mentioned above, a fluorine-based polymer, or a hard core J-1.

Next, there is the anolyte inlet and the outlet for the anode gas and anolyte mixture. It is only necessary to cause a flow of a liquid mixture of the anode sludge and the anode chamber (2) surrounded by the chamber side wall Q71 and the anode plate 06). Therefore, it can be provided at an appropriate location on the anode plate 06) or the anode chamber side wall 07). The cross-sectional structure of the anolyte introduction 1-11 is sufficient as long as it can make the flow of the anolyte equal to q, and there is no particular restriction, but it is preferable that the anolyte flows uniformly. For this purpose, slit-shaped introduction "1" is preferable, and the direction of the mixed liquid flow may be either the longitudinal direction of the electrolytic cell or the direction perpendicular to this, but the latter is preferable. This method is preferable because it can reduce the differential pressure (△P) of the liquid flow between one outlet and reduce G/Tj (ratio of anode gas contained in a unit anolyte). be.

Figure 5 shows an embodiment in which the anolyte inlet and the extraction [-1 are provided on the side wall of the anode chamber. )
, and on the other side opposite to the introduction L1 (1 [existence]
The anolyte is uniformly dispersed in the anode chamber through the inlet (19), and the mixed phase liquid is collected and discharged.

Figures 6 and 7 are based on the introduction of Section 11i1 [
] is provided on the anode plate. In Fig. 6, an inlet IQ,9) consisting of a plurality of holes is provided at one end of the anode plate 06), and a υr outlet is provided at the other end of the anode plate opposite to the inlet (Q9). Figure 7 shows introduction D (
10 is placed in the inside of the anode plate q0, and one discharge ``1@'' is placed at both ends of the anode plate (this is an example of installing the same.Furthermore, the introduction shown in FIG. 7) and the discharge 10 are reversed. Used for (-1 anode plate Q6)
It is also possible to introduce the anolyte from both ends of the anode plate and drain it from within the anode plate. Although there is no particular restriction on the positional relationship between the anolyte inlet and the outlet, it is preferable that they be provided at opposite positions on the anode plate or the side wall of the anode chamber.

FIG. 8 is a schematic diagram showing the anolyte circulation system of the horizontal cation exchange membrane electrolytic cell shown in FIGS. 1 and 2. FIG.

In the figure, the cathode chamber (1) has a lid and a plurality of cathode plates q.
Cathode chamber side wall (5) erected so as to surround the
and -L surface ii'+i of the cation exchange membrane (3) which is clamped and stretched between the flange of the cathode chamber side wall (5) and the anode chamber side wall α force. The catholyte α is suspended by a cathode suspension device (7) installed upright on the lid (4), and each cathode is connected to each other by a cathode bus bar (8). -1: The cathode chamber (1) is provided with a catholyte inlet (1), catholyte outlet 04 and a catholyte gas outlet 00. In addition, in the cathode chamber (1), in order to make the catholyte concentration uniform, catholyte introduction [Iα [phase], catholyte discharge "" (
] 4) The majority theory is that it is also possible to supply 11 parts or 1 part.

On the other hand, the anode chamber (2) has a substantially horizontal anode plate θ6),
an anode chamber side wall (17) installed on the periphery of the anode plate;
and the lower surface of the cation exchange IIA (3). The anode plate 00 is connected to an anode bus bar (18). The anode chamber (2) is provided with an anolyte introduction port and an anolyte and anode gas mixed grain solution outlet (a).

The salt water is supplied to the anode chamber (2) through the anolyte introduction DQ9), and the chlorine gas that has undergone electrolysis is immediately introduced into the anolyte chamber (2), which flows through the anode chamber. The multiphase liquid is taken out from 1 (4) in a stream, and the multiphase liquid is taken out from 1 (4) for 1 minute.
The gas is introduced into a vessel (21) where the chlorine gas and anolyte are separated.

The anolyte containing the gas +1f is introduced by the pump (22) (+9
) is circulated into the anode chamber (2). The concentrated salt water is supplied to a part of the salt water 11 ring system at a substantially saturated concentration, and a portion of the salt water is discharged from the separator (21) as fresh salt water.

The separator (21) and the pump (22) have multiple electrolysis
It may be provided one per li or may be provided for each electrolytic cell.

On the other hand, the catholyte is introduced from catholyte introduction D (1) and taken out from discharge D (14), and the catholyte concentration is
Adjusted by quantity. The generated hydrogen gas is discharged through the 1-electrode gas exhaust route.

Current is supplied from the anode busbar (to) and the anode chamber (2)
passes through the anode plate 00 and is taken out from the cathode busbar (8).

In the anode chamber (2), a reaction of the formula CI-1-→1/2Ch occurs, and the thorium ions in the anode chamber (2) pass through the cation exchange membrane (3) and reach the cathode chamber (1).

On the other hand, in the cathode chamber (1), a reaction according to the formula H20-1/2 H2+○H occurs to generate hydrogen gas, which is then passed through the cation exchange membrane (3) from the anode chamber (2). It receives the moving sodium ions and generates a caustic soak.

The most distinctive feature of the method of the present invention is that it consists of a cathode chamber (1) in the upper part and an anode chamber (2) in the lower part through the cation exchange membrane (3). An anolyte is supplied into an anode chamber configured by arranging a lower surface and a substantially horizontal anode plate 00 surface close to each other, and the anolyte and anode on-exchange membrane (3) that fills the anode chamber and flows through it. The lower surface is sufficiently moistened with a current flow to allow the electrolytic reaction to proceed smoothly, and the chlorine gas generated between the cation exchange membrane (3) and the anode plate α6) is immediately drawn into this flow and transferred to the anode chamber ( 2
) is to be discharged to the outside.

The anolyte that is supplied into the anode chamber and flows through it is carried outside the anode chamber together with chlorine gas, and after the chlorine gas is separated by the separator (21), at least one portion is returned to the anolyte inlet 09). If the circulating fluid is used to reflux the anolyte, it is advantageous because the concentration distribution of the anolyte can be made small and the concentration of the anolyte can be arbitrarily adjusted.

As described above, according to the present invention, high-quality caustic alkali can be produced at low equipment cost by arranging a cathode chamber in the upper part and an anode chamber in the lower part through a cation exchange membrane in a horizontal diaphragm electrolyzer. Moreover, it can be manufactured efficiently. Furthermore, the electrolytic cell of the present invention can be easily manufactured by converting a mercury electrolytic cell, and can be used to scrub not only electrolytic cells but also almost all existing equipment such as busbars, rectifiers, fresh salt water treatment equipment, salt water system equipment, etc. Since it can be easily converted to other uses without being pumped, conversion of mercury-based electrolytic cells can be carried out with great economical advantage.

[Brief explanation of drawings]

Figures 1 and 2 are a partially cutaway front view and a cross-sectional view of the electrolytic cell according to the present invention, respectively, and Figures 3 and 4 are side views showing other embodiments of the anode chamber, respectively. 5, 6 and 7 (respectively, a perspective view showing the failure of the anolyte inlet and outlet, and FIG. nu showing the tank anolyte circulation system
Each figure. l... Cathode chamber 2... Anode chamber 3... Cation exchange membrane 4... Lid 5... Cathode chamber side wall
6... Cathode electrocardiogram rod 7... Cathode suspension device 8-- Cathode gas/<-lO... Hole 11... Sheet 12... Cathode plate 13... Cathode fluid inlet 14... Cathode Liquid discharge port 15...Cathode gas discharge 8
．． ! 1 port 16...Anode plate 17...Anode chamber side wall 18...Anode busbar 19...Anolyte inlet 20...Anode mixed phase liquid outlet 21...Separator 22...
... Pump 23 ... Parakink 24 ...
Anode bottom plate patent applicant Kanebuchi Chemical Industry Co., Ltd. 20 Figure 6 Figure 7 493- Figure 8

Claims (1)

[Claims] 1. Using a horizontal electrolytic cell consisting of a cathode chamber in the upper part and an anode chamber in the lower part of the cation exchange membrane stretched horizontally, An electrolysis method characterized by forming a flow of anolyte flowing through the anode chamber while moistening the lower surface, and immediately involving the anode gas generated in the anode chamber in the flow and discharging it to the outside of the anode chamber. 2. At least a portion of the anolyte discharged from the anode chamber is
After separating the anode gas, it is circulated inside the anode chamber.
i [solution method] according to claim 1. 3. The upper cathode chamber and the upper part of the anode chamber are divided by the horizontally stretched cation exchange membrane, r3.
The cathode chamber has a substantially horizontal cathode plate, a lid, a side wall of the cathode chamber surrounding the cathode plate,
The anode house is surrounded by the upper surface of the cation exchange membrane and includes a catholyte inlet and outlet as well as a cathode gas outlet [-1; an anode chamber side wall provided around the anode plate;
The electrolysis device 1 is surrounded by the lower surface of the cation exchange membrane and has an anolyte inlet and a mixed solution outlet of an anode gas and an anolyte (1f7i). .'+!!i04 The electrolytic cell according to claim 3, characterized in that the electrolytic method is converted from the mercury method electrolytic method.