Abstract: Process for preparing pentafluoroethane (HFC-125) wherein 1,1,1-trifluorodichloroethane (HFC-123) is reacted with HF at a temperature from 310° to 380° C., in the presence of a catalyst comprising Cr2O3 supported on preformed AlF3. HFC-125 is obtained with high yields (up to 60-70% and over), high conversions (over 80%) and high selectivity, i.e. formation of by-product in very low amounts (5% by moles at most) Moreover, the catalyst maintains a high activity for a long time also with high organic charges.

Abstract: 1,1,1,2-tetrafluoroethane (134a) is prepared by reacting, in the gas phase, trichloroethylene with 1,1,1-trifluorochloroethane (133a) and hydrofluoric acid with trichloroethylene/133a molar ratios ranging from 5/95 to 50/50, in the presence of a catalyst consisting of Cr.sub.2 O.sub.3 carried on AlF.sub.3.The process provides 134a yields higher than 90% and permits an exceptionally long life of the catalyst. In this way it is possible to realize a continuous process by recycling the unreacted trichloroethylene and 133a, thereby making up for the relatively low global conversion of the reagents.

Abstract: 1,1,1,2-tetrafluoroethane (134a) is prepared by reacting, in the gas phase, trichloroethylene with 1,1,1-trifluorochloroethane (133a) and hydrofluoric acid with trichloroethylene/133a molar ratios ranging from 5/95 to 50/50, in the presence of a catalyst consisting of Cr.sub.2 O.sub.3 carried on AlF.sub.3.The process provides 134a yields higher than 90% and permits an exceptionally long life of the catalyst. In this way it is possible to realize a continuous process by recycling the unreacted trichloroethylene and 133a, thereby making up for the relatively low global conversion of the reagents.

Abstract: 1,1,1,2-tetrafluoroethane (134a) is prepared by reacting, in the gas phase, trichloroethylene with 1,1,1-trifluorochloroethane (133a) and hydrofluoric acid with trichloroethylene/133a molar ratios ranging from 5/95 to 50/50, in the presence of a catalyst consisting of Cr.sub.2 O.sub.3 carried on AlF.sub.3.The process provides 134a yields higher than 90% and permits an exceptionally long life of the catalyst. In this way it is possible to realize a continuous process by recycling the unreacted trichloroethylene and 133a, thereby making up for the relatively low global conversion of the reagents.

Abstract: 1,1,2-trifluoro-1,2-dichloroethane (Al23a) is isomerized to 1,1,1-tri-fluoro-2,2-dichloroethane (Al23) by contacting it with AlF.sub.3 at temperatures ranging from 180.degree. to 400.degree. C. Advantageously, it is operated with mixtures of Al23a with Al23 and/or other chlorofluorocarbons coming from the preparation of Al23 by hydrofluorination of perchloroethylene.

Abstract: 1,1,1-trifluoro-2-fluoroethane (CFC 134a) is purified from 1,1-difluoro-2-chloroethylene (CFC 1122) by reacting a mixture comprising said compounds with hydrofluoric acid, at temperatures from 200.degree. C. to 450.degree. C., in one presence of chrome oxide (Cr.sub.2 O.sub.3) in substantially crystalline form.

Abstract: 1,1,1-trifluoro-2-fluoroethane (CFC 134a) is purified from 1,1-difluoro-2-chloroethylene (CFC 1122) by reacting a mixture comprising said compounds with hydrofluoric acid, at temperatures from 200.degree. C. to 450.degree. C., in the presence of chrome oxide (Cr.sub.2 O.sub.3) in substantially crystalline form.

Abstract: 1,1,1,2-tetrafluoroethane (134a) is prepared by reacting, in the gas phase, trichloroethylene with 1,1,1-trifluorochloroethane (133a) and hydrofluoric acid with trichloroethylene/133a molar ratios ranging from 5/95 to 50/50, in the presence of a catalyst consisting of Cr.sub.2 O.sub.3 carried on AlF.sub.3.The process provides 134a yields higher than 90% and permits an exceptionally long life of the catalyst. In this way it is possible to realize a continuous process by recycling the unreacted trichloroethylene and 133a, thereby making up for the relatively low global conversion of the reagents.

Abstract: The 1,1,2-trifluoro-1,2-dichloroethane content is reduced or removed from 1,1,1-trifluoro-2,2-dichloroethane by contacting a gaseous mixture comprising said compounds with chrome oxide (Cr.sub.2 O.sub.3) either as such or supported, at temperatures from 180.degree. to 400.degree. C.