PRODUCTION OF ALKALI HYDROXIDE

摘要

PURPOSE:To produce alkali hydroxide at a specified concn. with high current efficiency by electrolyzing alkali chloride in the anode chamber of an electrolytic cell with a membrane consisting of a layer contg. a specified cation exchanger on the cathode side and a specified perfluorocarbon polymer layer. CONSTITUTION:A fluorine-contg. cation exchange membrane is composed of a first layer of an alkali-proof cation exchanger having >=5mum thickness and a second layer of a perfluorocarbon polymer having 2-7% water content in 45wt.% aq. NaOH soln., >=5mum thickness and -CO2M groups (M is an alkali metal). The first layer is a porous layer of a cation exchanger contg. dispersed alkali-proof inorg. matter or short fibers, a porous layer of a cation exchange resin having low penetrability of pores or a porous layer of a cation exchanger contg. an embedded alkali-proof polymer having no ion exchange group. The cation exchange membrane is stretched in an electrolytic cell so that the first layer confronts the cathode. Alkali chloride is fed into the anode chamber of the cell and electrolyzed. Alkali hydroxide is efficiently obtd. in the wide concn. range of 20-55%.