JPS59200775A - Electrolyzing method and electrolytic cell used therefor - Google Patents

Abstract

PURPOSE:To permit easy discharging of gaseous H2 generated in a cathode and to improve the efficiency in electrolyzing operation by modifying a mercury method electrolytic cell for an NaCl soln. to a horizontal diaphragm type electrolytic cell and inclining the electrolytic cell at a specific angle. CONSTITUTION:The part above a cation exchange membrane 3 is used as an anode chamber 1 having an insoluble anode plate 12 formed of graphite and the part below the membrane 3 is used as a cathode chamber 2 having a cathode plate 15 formed of a bottom part and the entire part of the electrolytic cell is inclined at 1/10-60 deg. inclination relative to the horizontal plane, in the stage of modifying mercury method electrolytic cell for an NaCl soln. as it is to a diaphragm type electrolytic cell having the membrane 3 without discarding said cell as scrap. A catholyte is supplied through an inlet 19 in a low position to the inside of the chamber 2 and the mixed vapor-liquid phase soln. composed of the NaOH soln. and gaseous H2 formed by the electrolysis is discharged through a discharging port 20 in a high position, by which the stagnating and sticking of the gaseous H2 on the bottom surface of the membrane 3 and the consequent decrease in electrolytic refining efficiency are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention mainly relates to an alkali metal halogen arsenide aqueous solution,
In particular, the present invention relates to a method for electrolyzing an aqueous alkali chloride salt solution and an electrolytic cell. More specifically, a method and apparatus for stably and efficiently delivering high-quality 7.7-hydrocarbons using a horizontal electrolytic membrane using a cation-exchange membrane as an electrolytic separator. This is related to 1 da.

Water type 1/- type electrolysis (Sodium is divided into a part of the anode chamber and a lower cathode chamber by a diaphragm stretched over the water.Water type: type', L decomposition tank The most typical horizontal electrolyzer
j~ has been widely used as a lever f'Lt, which is a hydroxide with a relative sieving degree.

However, since the mercury used in the cathode is an environmental FR3 dye, it is destined to be discontinued in the near future. By the way, the mercury method 'flood/1'4.1 which has been widely used in the past
Scrapping all of the 11i and its ancillary equipment is not desirable from an economic or industrial policy perspective, but it is also an extremely serious problem for the industry. Under such circumstances, it is highly desirable to convert to other safer electrolysis methods without scrapping horizontal electrolyzers and auxiliary equipment.

From this point of view, the applicant has conducted intensive research and has developed a technique that can advantageously convert a horizontal electrolytic cell into a cation exchange membrane method electrolytic cell, and has previously obtained one patent (special patent). Gansho 57-
131377 sunny-).

Specifically, Japanese Patent Application No. 57-1.31377 relates to an electrolytic cell which is divided into two anode chambers and a lower cathode chamber by a cation exchange membrane stretched substantially horizontally. However, in such a horizontal electrolytic cell, it is extremely difficult to efficiently discharge the cathode scum generated in the cathode chamber to the outside of the electrolyzer without getting it caught up in the catholyte flow and accumulating it in the cathode chamber. This is an important point. If the cathode gas is not sufficiently discharged and the gas accumulates in the cathode chamber, it may vibrate the cation exchange membrane, prevent stable operation, damage the membrane, or even increase the sliding voltage. This results in extremely inconvenient results.

However, the cathode gas is moved by buoyancy in a direction perpendicular to the flow direction of the catholyte, and accumulates between the surface of the cathode plate and the cation exchange membrane. (lower surface), and once attached, cathode gas cannot be easily separated from the membrane or cathode plate.One way to separate this cathode gas from the membrane and cathode plate is to increase the circulation of the catholyte. ,
It is necessary to increase the capacity of the pump and the diameter of the piping, which poses a serious problem of increasing installation costs and energy costs.

In view of the above-mentioned circumstances, the present inventors conducted extensive research and found that by using electrolytic sulfur with an inclined cathode plate, and by flowing the cathode (night) from the bottom to the top in the cathode chamber, the flow rate of the catholyte was adjusted to the cathode. The inventors have discovered that the rate of flow of the cathode is accelerated by the rising speed of the gas, and that the one-electrode gas accumulated in the cathode chamber, especially the cathode gas adhering to the membrane, can be efficiently discharged, and the present invention has been completed. Ta.

That is, the first aspect of the present invention is that the membrane is partitioned into an upper anode chamber and a lower cathode chamber by a cation exchange membrane stretched at an inclination of 1/10 to 60 degrees with respect to the horizontal, and is impermeable to liquid and gas. 4. Electrolysis with a cathode plate arranged approximately parallel to the cation exchange membrane; The second aspect of the present invention is an electrolysis method characterized in that a catholyte is caused to flow from below to above over the cathode plate in the cathode chamber using SpJ. /10-5
) A cation exchange membrane stretched at an angle of 60 degrees is divided into an upper anode chamber and a lower cathode chamber, and the anode chamber has an anode plate arranged approximately parallel to the cation exchange membrane. It is surrounded by a lid body, an anode chamber side wall surrounding the anode plate, and the upper surface of the cation exchange membrane, and has an anolyte inlet and an anode gas outlet as well as an anode gas outlet. a cathode plate, wherein the cathode chamber is impermeable to liquid and gas and is arranged substantially parallel to the cation exchange membrane;
The cathode chamber is surrounded by a side wall of the cathode chamber surrounding the cathode plate and the lower surface of the cation exchange membrane, and the catholyte is introduced [1] below the inclination of the cathode plate, and the cathode gas and the cathode are The electrolytic cell is characterized in that an outlet for the mixed 4'O liquid with the liquid is provided above the slope of the catholyte.

In the present invention, in order to perform electrolysis efficiently, the inclination of the cation exchange membrane and cathode plate is preferably within the following range.

In other words, the lower limit is about 1/10 slope, and everything after this is 1/10.
Regardless of whether the flow direction of the I-shaped pole or the opposite flow is set to 1° or 1°, there is no significant difference in terms of the bubble entrainment effect.The upper limit is not particularly limited, but When gas separation is carried out in the anode chamber, it is known that when the gas space passes through the cation exchange membrane, chlorine gas permeates through the membrane, leading to a '+' quality defect. Therefore, in order to perform gas-liquid separation in the anode chamber without installing a new anode gas-liquid separator, and economically convert from mercury electrolysis to the cation exchange membrane method. - As mentioned above, it is preferable that the gas space in the anode chamber be tilted to the cation exchange membrane in the range of 1 inch.
The limit is 0 degrees.

Hereinafter, the present invention will be explained based on drawings showing embodiments of the present invention. In the following explanation, typical examples of alkali metal halides and the most common chloride 1-II
um and caustic soda as its electrolytic product are used for convenience, but these do not represent the intention to limit the present invention, and inorganic salt water qf solution exclusively for potassium chloride, water electrolysis, etc. Of course, it can be applied.

Fig. 1 is a partially cutaway front view showing an embodiment of the present invention's electrolyzer, showing an example in which the electrolyzer is tilted in the longitudinal direction. 1 is a side sectional view showing an embodiment, showing an example in which the electrolytic cell is inclined in the width direction.

1 and 2, the present invention'llJ, W(,I
It consists of a rectangular anode chamber (1) with a length that is large, preferably several times longer than the width of the Q diode, and a cathode chamber (2) located at the edge of the rectangular anode chamber (1). Cathode (2)
and are separated by a cation exchange membrane (3).

The anode chamber (1) includes a lid (4), an anode chamber side wall (5) extending to surround one anode plate, and a cation exchange membrane (3).
) and the upper surface of the anode conductive rod (6).
is suspended by an anode suspension device (7) erected on the lid (4), and the anode conductive rods (6) are electrically connected to each other by an anode bus bar (8). The lid body (4) has a hole [10] through which the anode conductor rod cover (9) is inserted.
) is hermetically sealed by the sheet (11). An anode plate α is attached to the lower end of the anode conductive rod (G), and the anode plate O is connected to the anode suspension device (7). By operating 7), it can be arranged so as to touch the cation exchange membrane (3) with the ability to raise and lower the membrane.

Of course, the anode plate a is an anode suspended AAi installed upright on the lid.
It is not limited to the case where it is suspended from i and q, but it may be suspended, F or supported by other methods. Furthermore, the anode chamber has at least one anolyte center inlet (1), which can be provided on the lid (4) or on the side wall (5) of the anode chamber. ) are provided on at least one side, and these can be provided on the side wall (5).
Anode gas (chlorine gas) outlet (lυ) is provided at appropriate locations.

As the lid body (4) and the anode chamber side wall (5) constituting the above-mentioned anode chamber (1), the lid body and the anode chamber l1lI wall constituting the mercury method electrolyte can be used; There are no particular restrictions and it can be suitably used as long as it is resistant.For example, chlorine-resistant metals such as titanium and titanium alloys, fluorine-based polymers, hard rubber, etc. can be used.

Furthermore, it is also possible to use iron lined with the above-mentioned metals, fluorine-based polymers, hard rubber, or the like.

For the anode plate 02 that performs the anodic reaction, a graphite anode can be used, but titanium or aluminum can also be used.

Preferred are insoluble anodes made of metals such as metal, coated with, for example, platinum group metals or oxidized platinum group metals or mixtures thereof. Of course, it is economical to use the same size and shape of the one-metal electrode plate used in the mercury electrolyte.

Next, the cathode chamber (2) includes the 1': surface of the cation exchange membrane (3), the cathode plate θO, and the cathode chamber side wall (171 and The side wall 071 of the cathode chamber can be made of something like a frame edge that increases rigidity, or it can be made of something like a parakink-shaped bullet made of rubber, plastic, etc. that has a bow shape. It is also possible to configure

1st year room: solid wall (17J's (11 ladle rice), in addition to the first 11 ingredients, soak 1 g of seedlings in alkaline water with 1-1'1'lI master) If there are two, there is no special control device, and iron, stainless steel, nickel, nickel alloy, etc. can be used. It is also possible to suitably use paulownia wood, which is made of paulownia wood.Furthermore, it is also possible to use materials such as com, plastic, etc. As such, heat input rubber, butyl comb, and 4-1/embropylene rubber (EP't: ) and other rubber-based materials (silicates, fluorine-based polymers such as tetrafluoroethylene polymers, tetrafluoroethylene-hexafluorobutylene copolymers, ethylene-tetrafluoroethylene copolymers, etc.) vinyl chloride,
Examples include reinforced plastics (FR1).

The cathode plate OQ used in the present invention can be made from conductive paulownia materials such as iron, nickel, and stainless steel. Also, it is extremely economical to use the bottom plate for mercury electrolysis +1. In addition, in that case, the surface of the bottom plate of the mercury method electrolyte is generally very uneven, and the cation exchanger made contact with 14 rows during transfer and was damaged. Alternatively, it is advantageous to take a thin plate of iron or stainless steel, etc., and cut it into a thin plate to greatly extend the life of the membrane. The surface of the cathode plate is coated with nickel, platinum h),
1” nozma spraying of these alloys, or mixtures thereof;
It is preferable to perform a hydrogen permeation (L pressure and low pressure treatment) by plating or the like.

The catholyte inlet (19) and mixed-phase liquid outlet &0) may be used as long as they can generate a flow of the mixed-phase liquid in the cathode chamber (2). Therefore, the flow of the mixture is
Jl, 1 may be formed in either the length direction or the width direction, but the latter is preferable because of the pressure difference between the introduction 10 and discharge 1 and G/T, (cathode gas contained in a unit catholyte). For this purpose, the rib 1-shaped shinjin ['' is preferable. Mercury method'1°E solution 4:l! ! In the case of reusing the +1-plate, the assembly bolt holes previously drilled in the bottom plate may be used as they are or may be appropriately processed and used as the inlet and outlet.

However, from the flange on the side wall of the anode chamber or to the flange,
At this time, the catholyte is introduced from the edges of the electrode plate in a direction approximately perpendicular to the water 311 of the cathode plate, and discharged. [-1, υ1 out f2]
By providing this, it is possible to easily reduce the size of the interpolation layer.

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

A polymer made of a perfluorocarbon polymer having a sulfonate group as an exchange group is manufactured by I. Dupont Tee Nemores Annex Co., Ltd., as shown in 1111.
(+';, Wang, Du, Pon, t de Nemo
It is commercially available under the trade name "Nafion" from UrS&Comm, y), and its chemistry 47? , the structure is as shown in the following formula.

F3 A suitable equivalent coulometric capacity of such a cation exchange membrane is 1.000 to 2.0.00, preferably 1.000 to 2.0.00. l 00no-'J'
1°500, and here the weight is the size (g) of the dry film of the exchange equivalent weight.Also, some or all of the sulfonic acid groups of Cation exchange membranes substituted with carboxylic acid groups and other commonly used c.

Cation exchange membranes that have the same structure can also be applied to the present invention. The water permeability through these cation exchangers is extremely small, and only thorium ions with 3 to 4 water molecules can be passed through without hydraulic flow. In the present invention, in addition to the above description, Ilu'l so-called S P E
(So top id, J, 'o]-ymer E]-ec
t, rod, e) % J Royle.

When the present invention is applied to a cationic chlorination membrane electrolyzer A.71j which is a modified mercury method electrolyzer, a cathode plate having the above-mentioned inclination is placed on a bottom plate installed in a substantially water type. Objective 1 can also be achieved by attaching the bottom plate itself, and use it as an electrode plate, or fix a thin plate, etc. to the tilted bottom plate and use it as a cathode surface. etc., it is possible to achieve the purpose of the present invention with a small modification cost.

Figure 3 shows the tun 1 of the present invention shown in Figure 2.
FIG. 1 is a schematic diagram illustrating an example of the continuation of the '1HJIIi ring. To explain based on FIGS. 2 and 3, nearly saturated water is supplied to the anode chamber (1) from the anolyte inlet, and the chlorine scum generated by electrolysis is transferred to the anode. The fresh salt water was taken out from the gas outlet 1"l, and the anolyte was 1/1 [-1
Ka・raυ1 is issued.

If necessary, part of the brine can be circulated to make the brine reaction and l-' I- uniform in the electrolytic chamber.Although not shown, Anode I ('l-min 11) connected to the anolyte inlet 1 and extending over almost the entire anode chamber
It is also possible to homogenize the anolyte in the anode chamber by providing a distribution tube and dispersing and supplying the anolyte into the anode chamber through perforations provided in the distribution tube at appropriate intervals 111b.

The catholyte is supplied from 0 catholyte inlets, and the catholyte chamber (2)
The rate of rise of the hydrogen gas generated in this process is increased by the rising speed of the hydrogen gas, which becomes a mixed flow with hydrogen gas and is taken out from 1 (2 tons) to the mixed phase liquid discharge, and the hydrogen gas and catholyte are separated by a minute! '! f[i'
? It is divided into E by i÷(21). The gas-separated catholyte, which does not contain gas in the firebox, is pumped to the cathode g! by a pump (22). It is circulated and introduced into the cathode chamber (2) through the 2 inlet port 09) 7111h.

The separator (21) and the pump (22) may be provided in one piece for each electrolytic cell, or may be provided for each electrolytic cell.

Current is supplied from the anode busbar (8) and the cathode chamber (2)
pass through the bottom plate 06) of the cathode bus bar (18).

In the anode chamber (1), a reaction according to the formula: Cβ□1/2Cβ2 occurs, and the thorium ions in the anode chamber (1) pass through the cation exchange membrane (3) and reach the cathode chamber (2).

On the other hand, in the cathode chamber (2), the formula, H-e -H2O-1/
A reaction of 2H2+OH occurs, generating hydrogen gas, and receiving the sodium ions that have migrated from the anode chamber (1) through the cation exchange membrane (3) to generate caustic soda.

The catholyte that is supplied into the cathode chamber and flows through it is carried outside the cathode chamber together with the hydrogen gas and the generated caustic soda, and after the hydrogen scum is removed by the separator (21),
Return a small amount of HUB to the catholyte inlet 09).If it is a stock solution, it is also advisable to increase the depth of 1'1'1 to 7 degrees as appropriate. It is also possible to adjust the concentration by diluting with water during the process.

FIG. 4 shows an example in which a cation exchange membrane is attached to each of the mercury 7'/, -electrolysis 111, and the body is tilted at an angle of about 45 degrees in the width direction.

Of course, when tilting the anode in this way, it is also necessary to seal the part where the anode conductive rod (the in-phase cover L) passes through the lid, and modify the anode scrap υ1 outlet. By tilting the anode in this way, a large liquid pool is created in the anode chamber, and the anolyte is mixed efficiently due to the stirring effect of the chlorine gas, which makes the anolyte uniform throughout the tank. There is.

Hereinafter, the present invention will be further described based on Examples and Comparative Examples.
ffJI+, but the present invention is not limited thereto.
There is no need to say that there is no L.

Example 1 As a cation exchange membrane, [Nafion 901 (manufactured by DuPont) was used as a firebox of an electrolytic cell having a =j method of 8 m, flat in the width direction as a firebox covered with Ni bath. The catholyte was stretched approximately flat on a cathode plate installed at an inclination of 2/10 to the horizontal.The circulation of the catholyte in the cathode chamber was in the width direction.
The water was allowed to flow upwardly two times along the inclined cathode surface.

The anode is R on the titanium expanded metal surface.
A coach ink of uO2, T:LO2 was used, and the anode plate was placed so that the surface of the anode plate was in contact with the membrane. The distance between poles is 3
It was mm. The anode chamber is supplied with a saline solution with a NaCd concentration of 5N, and the fresh salt water is circulated so that the discharge 1] is 3N, while the cathode chamber is supplied with a catholyte flow rate of 607 no.1'/Hr.
Electrolysis was carried out while circulating the catholyte so that the raw concentration of caustic acid was 32%.

Current density 40 A/dn? When the operation was carried out under the electrolysis conditions at an electrolysis temperature of 85°C (7), the electrolysis voltage was 3.30°C.
V, current efficiency 96%, amount of NaCβ in caustic is 70 I
) I) m/50% NaOHT ara fc.

Examples 2 to 3 Electrolysis was carried out in the same manner as in Example 1, except that the inclinations of the cathode plates were set to 0.1/1o, respectively, with respect to the direction of flow of the catholyte.

Electrolytic z pressure, haso'h, soha a, aa v, 3.3
There were 6 at 3V.

Comparative Example 1 Electrolysis was carried out in the same manner as in Example 1, except that the cathode plate was tilted downward at an angle of 1710 degrees with respect to the direction of flow of the catholyte. The electrolysis voltage was 3.34V.

Example 4 Electrolysis was carried out in the same manner as in Example 1 except that the inclination of the cathode plate was changed to 10/10.

The electrolytic voltage was 3.31 V, and the NaCp amount was 65 pprn / 50% NaOH - current efficiency was 96
Ivy in %.

Comparative Example 2 Electrolysis was carried out in the same manner as in Example 1 except that the inclination of the cathode plate was changed to 25/10.

The electrolytic voltage was 3.30 V, but NaC4 in caustic
was 280 ppm. This is due to the diffusion of chlorine gas through the membrane.

As mentioned above, according to the present invention, a mercury method electrolyzer can be easily converted to a cation exchange membrane electrolyzer, and can be used not only for electrolyzers but also for almost all existing equipment such as busbars, rectifiers, fresh salt water treatment equipment, salt water system equipment, etc. Equipment can be repurposed without being scrapped.

Furthermore, according to the present invention, the flow rate of the catholyte is accelerated by the rising speed of the cathode gas, and the cathode gas adhering to the membrane or cathode plate is separated and engulfed in the catholyte flow, effectively transporting it out of the electrolytic cell. Can be discharged. In this way, the vibration of the membrane due to cathode gas accumulation is greatly reduced, allowing stable operation over a long period of time at low voltage. Furthermore, compared to the method of increasing the flow rate of the catholyte, this method is significantly advantageous in terms of equipment cost and energy consumption, and its practical value is extremely large.

Further, by making the flow of the catholyte in the catholyte chamber upward, a head pressure of the catholyte is generated, so that variations in the flow rate of the catholyte can be made uniform, and a secondary effect can be expected.

Furthermore, as shown in Figures 2 and 3, when an electrolytic cell converted from a 4-mercury electrolyzer is installed tilted, the anolyte is uniformly mixed in the wide anode chamber by bubbles, and the anolyte is mixed evenly in the large anode chamber. There is an effect of uniformity even without circulation.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the electrolytic cell of the present invention, and FIG. 2 is a side view showing another embodiment. The cross-sectional view in FIG. 3 is a schematic diagram showing an example of the catholyte circulation system of the electrolytic cell shown in FIG. 2. FIG. 4 is a schematic diagram showing another embodiment of the cathode R (inlet/outlet port. 1... Anode chamber 2... Cathode chamber 3...
Cation exchange membrane 4...Lid body...Anode chamber side wall
6...Anode conductive rod 7...Anode suspension device
8... Anode bus bar 9... Anode conductive rod cover
10...hole 11...sheet 12...
Anode plate 13...Anolyte inlet 14...Anolyte inlet 15...Anode gas outlet 16...Cathode plate 17...Cathode chamber side wall 18...Cathode busbar 19...Cathode solution Inlet 20...Cathode mixed phase liquid outlet 21...Separator 22...Pump patent applicant Kanebuchi Chemical Industry Co., Ltd. Figure 3 Figure 4

Claims (1)

[Claims] 1. Water' - [by means of a cation exchange membrane stretched at an inclination of 1/1o to 60 degrees with respect to 1], two anode chambers and -
Using an electrolytic cell which is divided into a cathode chamber in section F and has a cathode plate that is impermeable to liquid and gas and that is aligned and substantially parallel to the cation exchange membrane, the cathode plate in the cathode chamber is An electrolysis method characterized by flowing catholyte upward. 2 It is divided into an upper anode chamber and a lower cathode chamber by a cation exchange membrane stretched at an inclination of 1/1o to 60 degrees with respect to the horizontal; It has an anode plate arranged approximately parallel to the ion exchange membrane, and is surrounded by an intangible body, an anode chamber side wall surrounding the anode plate, and an upper surface of the cation exchanger 1*I model. Formation hole 1, and anolyte ZD 1 and discharge 1 and anode gas ino 1: Outlet and Ji-(Ii''J, fjiJ Mein F3
The chamber is surrounded by a cathode plate that is impermeable to liquid and gas and is approximately parallel to the cation exchange membrane, a side wall of the cathode chamber surrounding the cathode plate, and a lower surface of the cation exchange membrane. The catholyte is introduced below the inclination of the cathode plate, and the catholyte gas and catholyte are mixed together. electrolytic cell. 3. The electrolytic cell according to claim 2, wherein a catholyte inlet is provided at one end or side wall in the length direction of the cathode plate, and a mixed phase liquid outlet is provided at the other end or side wall. 4. The catholyte is mixed at one end or side wall in the width direction of the cathode plate, and the catholyte is mixed at the other end or side wall. Electrolysis 4:□71J according to claim 2, wherein the tank is a modified mercury method electrolyzer.