ABSTRACT
Fluorine was isolated by Moissan in 1886 by electrolysis of anhydrous hydrogen fluoride containing a small amount of potassium fluoride to render HF con ducting. H2 was liberated at the cathode and F2 at the anode. Potassium fluoride does not appear in the overall reaction:
Three different types of fluorine cells have been developed, depending on their operating temperature. All three are based on KF • wHF electrolytes. Lowtemperature cells (15 to 50°C) employed HF-rich melts (n > 3) and hightemperature cells (245 to 310°C) KF • HF melts. Medium-temperature cells (80 to 120°C), using KF • 2HF melts, are now the main practical source of fluorine. Hereafter, most discussions will refer to the latter electrolyte.
