Membrane electrolytic process for producing concentrated caustic
US4900408A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 17, 1989 |
| Grant date | Feb 13, 1990 |
| Priority date | — |
| Expiry date | May 17, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2371/12
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Process for the manufacture of sodium hydroxide in a sustained manner, tolerant of upsets in sodium hydroxide concentration, by electrolysis of sodium chloride at about 70.degree.-110.degree. C. in an electrolysis cell separated into a cathode compartment and an anode compartment by a cation exchange membrane, wherein the membrane is made of a copolymer of tetrafluoroethylene with a perfluoro monomer Z having a defined structure and a carboxyl end group, the mole ratio of tetrafluoroethylene to the monomer Z in the copolymer being about 7.6 to 8.2, the membrane material on the side exposed to the catholyte being nonporous but having a porous catholyte diffusion layer in direct contact therewith or in close proximity thereof. The sodium chloride feed solution is about equal to the concentration of saturated brine at the operating temperature, and the concentration of sodium chloride solution leaving the anode compartment is about 18-24%, no water being added to the catholyte during steady state operation. In this manner, 42-54% sodium hydroxide can be made with current efficiencies of about 90-97%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.