PROCESS FOR THE MANUFACTURE OF 1,1,1,2-TETRAFLUOROETHANE

1. A process for the preparation of 1,1,1,2-tetrafluoroethane which comprises: a) conducting a first reaction step comprising vaporizing a first recycled composition comprising hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane at a hydrogen fluoride to 1,1,1-trifluoro-2-chloroethane mole ratio of at least about 1:1, and reacting the composition under suitable conditions in the presence of a fluorination catalyst to thereby form a first reaction product mixture comprising 1,1,1,2-tetrafluoroethane; and b) conducting a second reaction step comprising vaporizing a second composition comprising hydrogen fluoride, trichloroethylene and the first reaction product mixture from step (a) such that the mole ratio of hydrogen fluoride to trichloroethylene is at least about 3:1 and wherein the second reaction step is conducted in the presence of a fluorination catalyst and at a temperature which is higher than the first reaction step, to thereby form a second reaction product mixture comprising 1,1,1,2-tetrafluoroethane, 1,1,1-trifluoro-2-chloroethane, hydrogen fluoride, trichloroethylene and hydrogen chloride. 2. The process of claim 1 further comprising the subsequent step of recovering 1,1,1,2-tetrafluoroethane. 3. The process of claim 1 further comprising the subsequent steps of: c) recovering hydrogen chloride by a first distillation from the second reaction product mixture product of step (b); d) recovering a product comprising 1,1,1,2-tetrafluoroethane by a second distillation from the mixture resulting from step (c), and obtaining a recycling mixture of 1,1,1-trifluoro-2-chloroethane, trichloroethylene and hydrogen fluoride from the second distillation and adding the recycling mixture as a feed to step (a); and e) recovering substantially pure 1,1,1,2-tetrafluoroethane from the product of step (d). 4. The process of claim 1 wherein the second reaction step (b) is conducted at a temperature which is at least about 5 degree C higher than first reaction step (a). 5. The process of claim 3 further comprising adding a portion of the recycling mixture of 1,1,1-trifluoro-2-chloroethane, trichloroethylene and hydrogen fluoride from the second distillation as a feed to the second reaction step (b). 6. The process of claim 1 comprising the further step of removing HCl from the first reaction product mixture prior to step (b). 7. The process of claim 1 wherein the fluorination catalyst used in steps (a) and (b) is selected from the group consisting chromium, aluminum,