Continuous process for the gaseous-phase preparation of trichlorotrifluoroethane, dichlorotetrafluoroethane and monochloropentafluoroethane in controlled proportions

A continuous catalytic gaseous-phase process for the preparation of trichlorotrifluoroethane, dichlorotetrafluoroethane and monochloropentafluoroethane, in predetermined proportions, from tetrachloroethylene, chlorine and hydrofluoric acid comprising the steps of:

• (a) reacting a mixture of chlorine, hydrofluoric acid and recycled products comprising tetrachloroethylene, hexachloroethane, pentachlorofluoroethane, tetrachlorodifluoroethane and trichlorodifluoroethane to produce a molar ratio of chlorine to recycled tetrachloroethylene of between about 1.1 and 5.0, in the gaseous phase in a first chlorination-fluorination reaction zone:
• (b) mixing the gases leaving the first chlorination-fluorination reaction zone with fresh tetrachloroethylene to produce a molar ratio of chlorine to fresh tetrachloroethylene of between about 0.95 and 1.05;
• (c) further reacting the effluent gases from the first chlorination-fluorination reaction zone with fresh tetrachloroethylene in a second gaseous-phase chlorination-fluorination reaction zone maintained at a lower temperature;
• (d) feeding the effluents from the second reaction zone into a separation unit where the desired amounts of trichlorotrifluoroethane and dichlorotetrafluoroethane are extracted and from which excess dichlorotetrafluoroethane is sent to a fluorination-dismutation reaction zone;
• (e) reacting in the fluorination-dismutation reaction zone a mixture of hydrofluoric acid and dichlorotetrafluoroethane that has been recycled from the separation unit, in a molar ratio of between about 0.1 and 1 to produce chloropentafluoroethane;
• (f) sending the effluents from the fluorination-dismutation reaction zone into the separation unit;
• (g) treating the gaseous products in the separation unti to recover the unused hydrofluoric acid and extract predetermined quantities of chloropentafluoroethane, dichlorotetrafluoroethane and trichlorotrifluoroethane;
• (h) recycling the untransformed tetrachloroethylene, hexachloroethane, pentachlorofluoroethane, tetrachlorodifluoroethane and the excess trichlorotrifluoroethane to the first reaction zone;
• and
• (i) recycling the excess dichlorotetrafluoroethane to the fluorination-dismutation reaction zone.