Electrolytic process for preparing hydrogen fluoride

Abstract

Abstract 1,152,073. Preparing hydrogen fluoride electrolytically. P. P.G. INDUSTRIES Inc. March 13, 1967 [March 14, 1966], No. 11603/67. Heading C7B. HF is prepared by electrolyzing an alkali metal and/or ammonium fluoride solution as catholyte separated from an anolyte by an anion exchange membrane so as to produce HF at the anode. The catholyte may be the aqueous reaction product of H 2 SiF 6 and alkali metal (viz. Li, Na, K, Rb or Cs) OH, NH 4 OH or NH 3 , preferably comprising NH 4 F and NH 4 . HF 2 . The anolyte may initially comprise water and (NH 4 ) 2 SO 4 with between 0À5 and 4% HF; alternatively the anolyte may be hydrofluoric acid of initial concentration greater than 38À2% HF (boiling azeotrope with water) to obtain gaseous HF. The membrane may be prepared by chloromethylation of the aromatic nucleus in a styrene-divinylbenzene copolymer matrix, followed by amination to affix thereto, quaternary ammonium groups. The anode may be of impregnated graphite and the cathode of steel, Fe or Ni. The electrolytic cell may be constructed of P.V.C., P.T.F.E. or rubber-lined steel. The current density may range between 10 and 200 A.S. F. and the voltage between 3 and 12 volts.

Inventors

• 👤 William W Carlin

Bibliographic Details