PRODUCING AN ALKALI METAL HYDROXIDE IN ELECTROLYTIC CELL WITH PERFLUOROCARBON MEMBRANE

摘要

A method for producing an alkali metal hydroxide by electrolysis in an electrolytic cell comprising an anode compartment and a cathode compartment, which comprises supplying an alkali metal chloride to the anode compartment and water or a dilute alkali metal hydroxide to the cathode compartment, wherein a fluorine-containing cation exchange membrane comprising a first outer layer of a perfluorocarbon polymer having -SO3M groups (wherein M is an alkali metal) with a thickness of at least 5 .mu. m, and a second layer of a perfluorocarbon polymer having -CO2M groups (wherein M is an alkali metal) and a water content of from 2 to 7% by weight in a 45 wt% NaOH aqueous solution with a thickness of at least 5 .mu.m, the water content of the first layer being higher than that of the second layer, is disposed with the first layer facing the cathode compartment.