Preparation of 1,1,1-trifluoroethane by catalytic fluorination of 1,1,1-trichloroethane and 1-fluoro-1,1-dichloroethane

Preparation of 1,1,1-trifluoroethane by catalytic gas phase fluorination of 1,1,1-trichloroethane and 1-fluoro-1,1-dichloroethane was studied. Mixtures of chromium fluoride and magnesium fluoride were found to be active fluorinating catalysts for preparing 1,1,1-trifluoroethane. Molar ratio of chromium to magnesium in the active catalysts was determined to be in the range of 0.2/1 to 4/1. Optimal conditions of reaction temperature, contact time and feed composition as well as the extent of the catalyst temperature increase by the exothermic reactions were also studied. Two stage fluorination reaction was proposed for producing a high yield of 1,1,1-trifluoroethane and for lengthening the catalyst lifetime: 1,1,1-trichloroethane to 1-fluoro-1, 1-dichloroethane at a low temperature first and 1-fluoro-1,1-dichloroethane to 1,1,1- trifluoroethane at a high temperature later.