Marc Doyle

A Novel Fluorine Production Process in a Proton Exchange Membrane Reactor

Fluorine production was demonstrated in a Nafion 115 membrane-separated electrochemical reactor. Direct oxidation of anhydrous HF from the gas-phase did not occur. Instead, the bifluoride ion (HF 2 -) abundant in KF• xHF molten salt was a necessary reactant for sustained fluorine evolution. Transport of bifluoride ion to catalyst-coated ELAT or membrane electrode assembly electrodes was hindered by electrostatic exclusion from the perfluorinated ionomer solution catalyst binder and membrane. The anode was flooded with KF•xHF molten salt to circumvent transport restrictions by providing HF 2 directly to the anode surfaces. Galvanostatic operation at 0.5 kA/m 2 yielded fluorine at 7.2 V with 62% current efficiency.