Process for the recovery of mixtures of chlorotetrafluoroethane and octafluorocyclobutane

Claim 1

A process for recovering mixtures of chlorotetrafluoroethane and octafluorocyclobutane from pyrolysis products of chlorodifluoromethane, wherein the pyrolysis has been conducted at a temperature above 600° C., and wherein hydrogen chloride, tetrafluoroethylene, hexafluoropropylene and unreacted chlorodifluoromethane have been substantially removed from the pyrolysis products, said process comprising: distilling in a rectifying column the remaining pyrolysis products, which remaining pyrolysis products comprise chlorotetrafluoroethane, octafluorocyclobutane, perfluorobutenes, compounds which boil at a temperature higher than the perfluorbutenes, and compounds which boil at a lower temperature than chlorotetrafluoroethane, and withdrawing a mixture of chlorotetrafluoroethane and octafluorocyclobutane from the rectifying column as a side fraction ,the withdrawal of the side fraction being carried out in a region of the rectifying column which includes 5 to 90% of its total length, calculated from the top of the column, the perfluorobutenes and the compounds which boil at a higher temperature than the perfluorobutenes remaining in a bottom product withdrawn from the rectifying column, and the compounds which boil at a lower temperature than chlorotetrafluoroethane being included in a top product withdrawn from the rectifying column