US 8,026,391 B2Granted

Potassium perfluoroalkanesulfonate and method for producing the same

AssigneesMitsubishi Materials Corporation, Mitsubishi Materials Electronic Chemicals Co., Ltd.

InventorsMasakazu Uotani, Hiroyuki Yatsuyanagi, Tsunetoshi Honda

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Abstract

This method for producing a potassium perfluoroalkanesulfonate includes an electrochemical fluorination step in which an alkanesulfonyl halide compound is subjected to electrochemical fluorination in anhydrous hydrogen fluoride, thereby to generate a production gas containing perfluoroalkanesulfonyl fluoride as the main component. In addition, for example, the methods may include a gas absorption step in which the production gas is reacted with an aqueous solution of potassium hydroxide, thereby to generate a gas absorbed solution containing potassium perfluoroalkanesulfonate, a purification step in which impurities such as potassium fluoride, potassium hydroxide, and potassium sulfate, are removed, and a concentration and collection step in which the aqueous solution from which the impurities are removed is concentrated and dried. In the electrochemical fluorination, for example, it is possible that the proton concentration in the reaction solution is maintained in the range of 150 to 1,500 ppm to suppress the formation of byproducts.

A method for producing potassium perfluoroalkanesulfonate, comprising the steps of:

subjecting an alkanesulfonyl halide compound represented by the general formula:
CnH2n+1SO2X, in which n is an integer of 1 to 3 and X is Cl or F, to electrochemical fluorination in anhydrous hydrogen fluoride, thereby to generate a production gas containing, as the main component, perfluoroalkanesulfonyl fluoride represented by the general formula:
CnF2n+1SO2F in which n is an integer of 1 to 3, (electrochemical fluorination step);
reacting the production gas with an aqueous solution of potassium hydroxide, thereby to generate a gas absorbed solution containing a potassium perfluoroalkanesulfonate represented by the general formula:
CnF2n+1SO3K, in which n is an integer of 1 to 3, (gas absorption step);
removing potassium fluoride, potassium hydroxide, and potassium sulfate which are impurities contained in the gas absorbed solution, (purification step);
and
subjecting the aqueous solution from which the impurities are removed to concentration and drying, thereby to obtain potassium perfluoroalkanesulfonate represented by the general formula:
CnF2n+1SO3K, in which n is an integer of 1 to 3, (concentration and collection step),
wherein, in the purification step, alkali metal hydroxide or alkaline earth metal hydroxide is added to the gas absorbed solution to allow it to react with the potassium fluoride contained in the gas absorbed solution so as to form a fluoride precipitate and potassium hydroxide, and an acid is further added to precipitate the potassium hydroxide in the solution, and these precipitates are removed by filtration, said acid is selected from the group consisting of sulfuric acid, perfluoroalkanesulfonic acid, and a residue of the reaction solution generated in producing perfluoroalkanesulfonic acid by an acid decomposition reaction, and
in the concentration and collection step, the filtrate is subjected to concentration and drying to obtain potassium perfluoroalkanesulfonate.

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Abstract

Claims11