JPS60221595A - Method for operating alkali chloride electrolytic cell provided with air electrode as cathode - Google Patents

Abstract

PURPOSE:To prevent the deterioration of an air electrode in an alkali chloride electrolytic cell by reducing the concn. of an aqueous alkali hydroxide soln. as a catholyte or replacing the soln. with water when the operation of the electrolytic cell is suspended. CONSTITUTION:When the operation of the alkali chloride electrolytic cell provided with the air electrode as a cathode 1 is suspended, the catholyte 8 is replaced with water by drawing out the catholyte 8 from an outlet 9 for descharging a produced aqueous sodium hydroxide soln. and by feeding water from an inlet 7 for feeding water. Part of the catholyte 8 may be replaced with water. By this method the deterioration of the air electrode 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating alkaline chloride electrolysis and carbon dioxide using an air electrode as one differential electrode, and its purpose is to prevent deterioration of the air electrode.

Alkaline chloride electrolysis 1st soda is usually operated continuously J'L
However, operation may be stopped due to power outages or other reasons. The current government cannot accept that the performance of the air electrode as the 113th electrode will deteriorate during this suspension of operation.

On the other hand, although carbon is not used as a catalyst in the air electrode, the deterioration in the performance of the air electrode is due to the adsorption of oxygen at the oxygen adsorption sites of carbon, according to research by the inventors of this carbon technology. The higher the temperature of the sodium hydroxide water bath solution as the cathode electrolyte is, the more the TM degree of sodium hydroxide is removed. It progresses in moderation. ML on the air pole
Carphones are more susceptible to J corrosion when the 1' stream is not full than when it is flowing.

The present invention has been made based on such knowledge. That is, in the present invention, the alkaline hydroxide aqueous solution used as the shade birch electrolyte is diluted with water or completely replaced with water when the operation of the alkali clarification tank is stopped, so that it can be used in the air electrode. This prevents corrosion of carbon in the air and prevents deterioration of air electrode performance.

An embodiment of the present invention will be described in detail below.

Embodiment: FIG. 1 shows a cross section 11iI structure of a salt electrolyte using a γ-cell empty electrode as a cathode to explain an embodiment of the present invention.

1111-) 4 Shu version 1 gourd 1 fishing meter name A 2 I
Catalyst 111 (81 and porous polytetrafluoroethylene m
It is composed of lt'J(4). (5) is the narrow air supply port, (6) is the excess air outlet, (7) is the water supply port, (8
) is an aqueous solution made of sodium hydroxide.
9) is a synthetic sodium hydroxide aqueous solution outlet (IOJ is an ion exchanger).

(11) is the anode, (December 2015) is the saline water supply port, (L8) is the chlorine outlet, (14) is the 1-nitrode electrolyte, and (15) is the frame body.

During normal operation of this eclipse 4 north aneurysm, while supplying air from the air supply port (5), a surface m electric current of VC30 to 40 A/dm2 is applied between the 111'
E Ka1llll 'j"J, Sun Ruto, Cathode (!2
Sodium hydroxide is generated, and the sodium hydroxide water bath solution as the catholyte (8) is kept at 80 to 40.
Chlorine is generated at the anode (11).

Concentrated sodium hydroxide is in the produced water! The sodium chloride solution is taken out of the tank from the aqueous outlet (9), and the chlorine is taken out from the chlorine outlet (L3). Cathode electrolyte (8) temperature 1
f: is set in the range of 80 to 95°C.

When the operation of this salt electrolyzer is stopped, the cathode electrolyte (8) is completely extracted from the M4 outlet (9) of 1 volume of produced sodium hydroxide water, and water is supplied from the water supply port (7).
The catholyte (8) is replaced with water. The temperature drops to room temperature when the machine stops operating.

Example of ratio of effectiveness: The method of the present invention in which the catholyte is replaced with water at the time of suspension of operation as in the above-mentioned embodiment is used as a method, and the suspension of operation of the catholyte with sodium hydroxide as in the conventional method is replaced with one cycle. During the current operation of the air electrode, we investigated how the potential (electrolayer against mercury oxide) changes with the cycle and obtained the results shown in Figure 2. I got one.

From Fig. 2, in the case of method A of this investigation, no deterioration in the performance of the air electrode was observed as the intermittent operation cycle progressed, whereas in the case of the conventional method B, the intermittent operation cycle As time progresses, the air electrode gradually deteriorates, and suddenly deteriorates at the 30th cycle.

These results show that the operating method investigated in this study is extremely effective in preventing deterioration of air electrode performance.

[Brief explanation of drawings]

@ Figure 1 shows a cross-sectional structure of a table for salt electrolysis with a cathode as the third perspective to explain an embodiment of this research. Figure 2 shows an air electrode according to an embodiment of this research. The operation method (A) of the salt solution tank with the IIJ electrode and the conventional operation method (with a toothless operation cycle with γ) are shown below. ... cathode, 2 ... porous 1 raw nickel j spring. 3 ... - @ soot layer, 4 ... - ... porous poly 47)
Ethylene chloride model, 5...Air supply port, 6
... Surplus air 'A discharge port, 7 ... Water supply port, 8 ... Song 1 Urokoen electrolysis t (g, 9 ... Produced sodium hydroxide water M Kinhiro outlet . 1O... Ion exchange membrane, 11...1 Ian. 12... & salt water supply port, 1B... Chlorine outlet. 14... 1 Kaan, solved. Liquid, 15...Kokuhaku frame body.

Claims (1)

[Claims] A stage 1b alkaline tank with air ffi as the cathode characterized by diluting or replacing the alkaline hydroxide water bath solution with water as a electrode electrolytic reformer when the operation of an alkaline chloride electrolytic cell with a nitrogen % electrode as one electrode is stopped. Solution h1 How to drive Hinoki.