Generation of halogens by electrolysis of hydrogen halides in a cell having catalytic electrodes bonded to a solid polymer electrolyte
AssigneeGeneral Electric Company
InventorsRussell M. Dempsey, Thomas G. Coker, Anthony B. La Conti
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Abstract
A halogen such as chlorine is produced by the electrolysis of an aqueous solution of a hydrogen halide such as hydrochloric acid in an electrolysis cell having anolyte and catholyte chambers separated by a solid polymer electrolyte in the form of a stable, selectively permeable, hydrated ion exchange membrane. Catalytic electrodes in the form of fluorocarbon bonded, thermally stabilized, reduced oxides of platinum group metals are bonded to at least one surface of the membrane and an aqueous hydrochloric acid solution is brought in contact with the bonded anode to generate chlorine at the anode and hydrogen at the cathode.
Claims22
A process for the continuous production of chlorine from hydrochloric acid which comprises:
- (a) continuously providing an aqueous solution of hydrochloric acid to the anode compartment of an electrolytic cell which is separated from the cathode compartment by a cation selective ion exchange membrane, bringing the solution into contact with a catalytic, bonded, graphite anode electrode activated with reduced platinum group metals and oxides thereof bonded to and embedded in the membrane on the side facing the anode compartment said anode being opposite to a catalytic cathode bonded to and embedded in the other side of the membrane forming a unitary electrode-membrane structure whereby catalytic sites in the electrodes are in contact with the ion exchanging sites of the membrane so that electrolysis takes place directly at the membrane-electrode interface,
- (b) applying a potential to the electrodes through separate electron conductive current collectors in physical contact with the bonded electromechanically active electrodes to electrolyze the aqueous hydrochloric acid solution to produce chlorine at the anode electrode and hydrogen ions which are transported across said membrane to produce hydrogen at the cathode electrode,
- (c) continuously removing chlorine from the anode compartment and hydrogen from the cathode department.
A process for generating a halogen which comprises electrolyzing an aqueous solution of a hydrogen halide between a pair of electrodes separated by an ion permeable membrane, the improvement which comprises conducting the electrolysis with at least one of the electrodes including an electronconductive platinum group metal catalyst bonded to the membrane at a plurality of points forming a unitary electrode membrane structure exposed to an aqueous electrolyte wherein electrolysis of the aqueous solution is effected to keep oxygen evolution at the halogen evolving electrode below 5% by volume.
A process for generating a halogen which comprises electrolyzing an aqueous solution of a hydrogen halide between a pair of electrodes separated by an ion permeable membrane, the improvement which comprises conducting the electrolysis with at least one of the electrodes, including an electroconducting, thermally stabilized, reduced oxide of a platinum group metal bonded to the membrane at a plurality of points to form a unitary electrode-membrane structure, supplying potential to the electrodes by electron conductive current distributors the surface of which is in contact with the electrode and is exposed to the electrolyte, said electrodes having lower hydrogen or chlorine overvoltages than the electron current distributors in physical contact therewith.
Dependencies are inferred from the claim text.