GB1313441A - Process for preparing chlorine and alkali phosphate solution by electrolysis and electrolytic cell for carrying out the process - Google Patents

Abstract

1313441 Electrolytic production of chlorine and alkali metal phosphate PROGIL 5 May 1971 [15 May 1970] 13194/71 Heading C7B Chlorine, hydrogen and an aqueous solution of alkali metal phosphate are prepared electrolytically in a cell divided by a cationic selectively permeable membrane and having a porous anode of which only the surface(s) not facing the membrane are electro-chemically active, in which alkali metal chloride solution is continuously introduced into the anode compartment from which chlorine and alkali metal chloride solution are continuously withdrawn; and phosphoric acid or alkali metal phosphate solution is continuously introduced into the cathode compartment from which hydrogen and alkali metal phosphate solution (containing a higher alkali metal to phosphate ratio than the solution introduced into the compartment) are continuously withdrawn. The membrane may be a perfluorinated polymer, e.g. a sulphonated polytetra-fluoroethylene. The perforated anode may be of Ti, Ta, Zr, Nb or an alloy thereof; the active surface being coated with a platinum metal or oxide thereof. The cathode may be of perforated metal, e. g. Ni. When using natural phosphate as the catholyte feed, metal cations such as Cr and V present therein as impurities are reduced by the hydrogen evolved to insoluble salts which may be filtered from the phosphate solution withdrawn from the cell.