VERFAHREN ZUR GEWINNUNG VON REINEM TETRAFLUORETHYLEN.

摘要

Process is claimed for the prepn. of pure tetrafluoroethylene (TFE) by pyrolysis of organofluorine cps. with 1-4C atoms contg. H and one Cl atom, whereby after removal of HCl or HF and drying, a liq. contg. 20-70 wt.% TFE is distilled under pressure by passage through a series of fractionating columns in the following manner: in the first column, low-boiling contaminants are removed whilst in the second, TFE is distilled from higher-boiling contaminants with the help of an entrainment medium, pref. chlorodifluoromethane, added in the proportion of 0.6-2.0 kg per kg of TFE. Chlorotetrafluoroethane, trifluoromethane or perfluorocyclobutane may be used as alternative entrainment media. The distns. are carried out pref. at 0.4-0.5 MPa according to the following procedures: (i) 3-5 kg distillate from the second column is collected per kg of TFE isolated and may be returned to this column; (ii) 6-15 kg distillate from the first column is collected per kg of TFE isolated and may be returned to this column.