RECOVERY OF HYDROGEN FLUORIDE

PURPOSE:To recover hydrogen fluoride in the reaction of 1,1,1-trichloro-2,2,2- trifluoroethane, etc., with HF to produce 2,2-dichloro-1,1,1,2-tetrafluoroethane by adding 1,1,2-trichloro-1,2,2-trifluoroethane to the effluent gas. CONSTITUTION:In the production of 2,2,-dichloro-1,1,1,2-tetrafluoroethane (C) by the reaction of 1,1,1-trichloro-2,2,2-trifluoroethane (A) or 1,1,2-trichloro-1,2,2- trifluoroethane (B) with HF, the compound B is added to the effluent gas containing the compound A to recovery HF without causing the deposition of the compounds on a separator, etc. A gaseous mixture of the effluent gas of the reactor and the compound B is separated into a gaseous phase composed mainly of the compound C and a liquid phase composed of HF, the compound B, the compound A, etc., by cooling to =0.4.