PROCESS FOR PREPARING TETRAFLUOROETHYLENE Russian patent published in 1996 - IPC

FIELD: organic chemistry. SUBSTANCE: process comprises pyrolyzing difluorochloromethane in the presence of steam and octafluorocyclobutane and tetrafluorochloroethane which are added to azeotropic boiling mixture in 2-15 wt % ratio with respect to difluorochloromethane, its pyrolysis may be carried out at temperatures of 550-700 C, or at 700-1100 C, or at 1100-1200 C in the presence of catalyst; in this case, difluoromethane may be preliminarily heated to 200-400 C or to 400-600 C, and steam may be heated to 700-1100 C or to 400-700 C. In this case, the azeotropic boiling mixture or octafluorocyclobutane and tetrafluorochloroethane may be added to difluorochloromethane prior to its being heated, or to preheating section or to steam prior to its being fed to the pyrolysis furnace at certain amounts of dithloromethane and steam, and pyrolysis may be carried out at 10-35 %, or 35-55 % or 55-70 % conversion, and as pyrolysis products are herdened, they are mixed with water to give hydrochloric acid after separation of which acid the gases are washed with aqueous sodium hydroxide and into two stages up to 8-12 atm gauge, and drying, separation of high-boiling components and condensation thereof are carried out under rectification conditions in two stages, inhibitor being added at the condensation stage and the first stage condensate being combined with vat fraction of the second rectification stage and this product is further rectified to give difluorochloromethane, hexafluoropropylene and a mixture of octafluorocyclobutane and tetrafluorochloroethane is recovered from the vat fraction. Said mixture is recycled to difluorochloromethane pyrolysis. The invention makes it possible to utilize pyrolysis by- products and cut down specific consumption of energy resources. EFFECT: more efficient preparation process.