Electrolysis cell for synthesizing perchloric acid compound and method for electrolytically synthesizing perchloric acid compound

a perchloric acid compound and electrolysis cell technology, applied in the direction of electrodes, electrolysis processes, electrolysis components, etc., can solve the problems of deterioration, unstable electrode performance, consumption acceleration, etc., and achieve high purity, easy separation of chlorine gas, the effect of high yield and purity

Inactive Publication Date: 2007-07-26
DE NORA PERMELEC LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0025] Unlike the conventional methods wherein perchloric acid compound electrolytic synthesis is performed after obtaining sodium chlorate by using hydrochloric acid used as a feedstock, this invention enables to obtain the desired compound by one process step (chloric acid compound is produced as an intermediate product in one case, and chloric acid compound is not produced as the intermediate compound in the other case) by using the chloride as the feedstock. Further, when hydrochloric acid is used as the chloride, a part of the hydrochloric acid used as the feedstock becomes a chlorine gas and is dissolved, and it is possible to synthesize the high purity perchloric acid compound by degassing the chlorine gas since it is easy to separate the chlorine gas from the desired product as a post-treatment.
[0026] When the chloric acid compound is used as the feedstock, it is possible to obtain the desired compound at higher yield and purity as compared to the case of using the conventional anode. This method is applicable to improvement of product quality by electrolyzing an electrolysis liquid containing residual chloric acid of 0.1 M or less, which has been synthesized by the conventional electrolysis cell in the electrolysis cell having the diamond electrode, and such combined method is industrially effective.
[0027] When the electrolysis cell is partitioned by using an ion exchange membrane to obtain an anode chamber and a cathode chamber, it is possible to prevent ions or the like from migrating from one chamber to the other chamber, thereby enabling to obtain the desired compound at higher purity.
[0028] Also, when a gas electrode suitable for reduction of an oxygen gas is used as the cathode, it is possible to lower a cell voltage, thereby enabling to obtain the desired compound at a lower cost.
[0029] Though it is essential to separate chemicals such as sulfuric acid in the conventional chemical synthesis methods, this invention has the advantage of synthesizing high purity perchloric acid conveniently and contributes to industrial safety and environment.

Problems solved by technology

It is considered that such deterioration is caused since: an oxide film is formed on a surface of the platinum material under the above-mentioned electrolysis condition; performance of the electrode becomes unstable due to on / off of a current; and consumption is accelerated due to an additive such as a fluorine ion.
Though lead oxide is excellent in decomposition characteristic and useful as a substitute, it has drawbacks such as management difficulty since it generates sludge to deteriorate product purity and makes performance of an electrode unstable.
However, any study for the purpose of improving a current efficiency and purity of the perchloric acid compound for the purpose of industrial electrolytic synthesis is not found in the above patent publications.

Method used

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  • Electrolysis cell for synthesizing perchloric acid compound and method for electrolytically synthesizing perchloric acid compound
  • Electrolysis cell for synthesizing perchloric acid compound and method for electrolytically synthesizing perchloric acid compound

Examples

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example 1

[0074] An anode obtained by forming a thickness of 5 μm of an electroconductive diamond doped with boron of 5,000 ppm on electroconductive silicon having a thickness of 1 mm serving as a substrate was used. As a cathode, a platinum-plated titanium plate having a thickness of 1 mm was used. An electrode area of each of the anode and the cathode was 20 cm2.

[0075] These electrodes were disposed in the membraneless cell (capacity: 1000 ml) shown in FIG. 1 in such a fashion that they are opposed to each other with a gap of 1 cm being defined therebetween. The cell was charged with 500 ml of a 0.02 M sodium chlorate solution, and electrolysis was performed for one hour with a current of 1 A (current density: 0.05 A / cm2) with stirring with a water temperature being kept to 35° C.

[0076] Analysis was performed by using an ion chromatography device, and a current efficiency of the perchloric acid ion generation was calculated from the concentration. Sodium hypochlorite was measured by KI ti...

example 2

[0080] An anode obtained by forming an electroconductive diamond doped with boron of 5,000 ppm on a substrate which was a niobium mesh having an original plate thickness of 2 mm was used. As a cathode, a platinum-plated titanium mesh having an original plate thickness of 1 mm was used. An electrode area of each of the anode and the cathode was 20 cm2, and a two-chamber cell wherein an ion exchange membrane (117 Nafion) was sandwiched between the anode and the cathode of the membraneless cell of FIG. 1 is assembled (gap between electrodes: 1 mm), followed by injecting 200 ml of a 0.5 M hydrochloric acid solution to the anode chamber and the cathode chamber. By performing electrolysis for one hour under conditions of 40° C. and 20 A (current density: 1 A / cm2), perchloric acid ions were obtained at a current efficiency of 12%. A chloric acid concentration during the electrolysis was lowered to 0.05 M. A cell voltage was 5.5 V A residual chlorine gas was removed by degassing.

example 3

[0082] The anode of Example 2 was used, and a sheet having the size of 2 cm×2 cm×0.5 mm of thickness obtained by: mixing a graphite powder (product of Tokai Carbon Co., Ltd.; TGP-2), which was used as a catalyst, with a PTFE resin; applying the mixture on a core material which was a carbon cloth (product of Zoltek Corporation; PWB-3), and baking at 330° C. was used as the cathode. A platinum-plated titanium mesh was used as a cathode power feeding support, and a two-chamber cell wherein the ion exchange membrane of FIG. 2 (Nafion 117) was disposed between the chambers was assembled. As a result of electrolysis for one hour at 60° C. and 20 A in the same manner as in Example 2 with oxygen being supplied to the cathode chamber, perchloric acid ions were obtained at a current efficiency of 10%. A hydrochloric acid concentration during the electrolysis was lowered to 0.05 M. A cell voltage was 4.7 V.

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Abstract

The present invention provides an electrolysis cell for synthesizing a perchloric acid compound, the electrolysis cell having: a feedstock solution containing a chloride or a chloric acid compound; a cathode; and an anode having an electroconductive diamond as an anode substance, the anode electrolytically oxidizing the chloride or the chloric acid compound to synthesize the perchloric acid compound, and a method for electrolytically synthesizing a perchloric acid compound.

Description

FIELD OF THE INVENTION [0001] This invention relates to an electrolysis cell of which an object is to obtain a perchloric acid compound effectively as a high purity product, which is an industrially important oxidant and used as a feedstock for an explosive and a reaction synthesis reagent, and a producing method of the perchloric acid compound with the electrolysis cell. BACKGROUND OF THE INVENTION [0002] Each of perchloric acid and perchlorate is one of useful materials for electrolytic synthesis and used for a rocket fuel, an explosive, and a reaction catalyst. Sodium perchlorate is obtainable by oxidizing, concentrating, and crystallizing sodium chlorate through electrolysis. Perchloric acid is synthesized by heat cracking distillation of sodium perchlorate with sulfuric acid and put on market and transported as a 60% to 70% aqueous solution to avoid risk of explosion. Potassium perchlorate is synthesized by adding potassium chloride to a solution synthesized by electrolysis, fo...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25B11/12C25B1/28
CPCC25B1/28
Inventor UNO, MASAHARUNARA, MIWAKONISHIKI, YOSHINORIFURUTA, TSUNETO
Owner DE NORA PERMELEC LTD
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