Abstract: The subject of the invention is a continuous process for the preparation of 1,1,1,2-tetrafluoroethane (134a) from 2-chloro-1,1,1-trifluoroethane (133a) and hydrofluoric acid in the gaseous phase in the presence of a chromium-based catalysts.According to the invention, the flow of gas leaving the reactor is subjected to a distillation in order to separate at the top a flow containing almost all the HC1 and at least 90% of the 134a produced by the reaction and at the bottom a flow containing at least 90% of the unconverted reactants (133a and HF), and the latter flow is recycled directly to the reactor, without any purifying operation.

Abstract: The invention relates to mass catalysts based on chromium and nickel oxides, obtained from a sol of chromium and nickel hydroxides.These catalysts, in which the Ni/Cr atomic ratio is between 0.05 and 5, may be used from the fluorination of halogenated hydrocarbons by HF in the gas phase.

Abstract: To replace chlorofluorocarbons as refrigerant fluids, the invention proposes to employ mixtures containing, on a mass basis, approximately 25 to 65% of 1,1,1-trifluoroethane, 1 to 70% of perfluoropropane and 5 to 34% of propane.The mixtures according to the invention can also be employed as aerosol propellants or as blowing agents for plastic foams.

Abstract: The invention relates to the separation of hydrogen fluoride (HF) from its mixtures with 1,1,1-trifluoro-2-chloroethane (F133a).By settling of the mixture of HF and F133a in the presence of trichloroethylene at a temperature below 0.degree. C., a lower organic phase which is poor in HF and an upper phase which is rich in HF are obtained. The latter can be directly recycled to the fluorination reactor or subjected to a distillation in order to separate, at the head, the HF/F133a azeotrope which is returned to the settler, and to recover, at the foot, practically pure HF. By distillation of the lower phase, the HF/F133a azeotrope which is returned to the settler is separated at the head and a mixture of F133a and trichloroethylene is recovered at the foot. The latter mixture is subjected to a distillation which makes it possible to separate, at the head, pure F133a from trichloroethylene at the foot.

Abstract: In order to stabilize 1,1-dichloro-1-fluoroethane containing traces of vinylidene chloride, at least one ethylenic hydrocarbon containing at least 4 carbon atoms is added thereto.