Process for the purification of a pentafluoroethane azeotrope

The invention generally relates to a process for the purification of a component of a binary azeotrope in which the composition of the azeotrope changes by about 10 mole percent with pressure comprising: (a) subjecting a binary azeotrope to a distillation step in which most of one of the binary components is removed as distillate (distillate 1) with the bottoms (bottoms 1) enriched in the other component; (b) subjecting distillate 1 to at least one additional distillation step conducted at a different pressure in which most of the component recovered as bottoms 1 is removed as distillate 2 with the bottoms 2 enriched in the component enriched in distillate 1; (c) optionally repeating step (b) as many times as desired; and (d) recovering the desired purified component. The invention is particularly useful in the purification of pentafluoroethane in a pentafluoroethane/chloropentafluoroethane azeotrope.