| abstract |
Disclosed are processes for the production of fluorinated olefins, preferably adapted to commercialization of CF 3 CF=CH 2 (1234yf). Three steps may be used in preferred embodiments in which a feedstock such as CCl 2 =CClCH 2 Cl (which may be purchased or synthesized from 1,2,3-trichloropropane) is fluorinated (preferably with HF in gas-phase in the presence of a catalyst) to synthesize a compound such as CFaCCl=CH2, preferably in a 80-96% selectivity. The CF 3 CCl=CH 2 is preferably converted to CF 3 CFClCH 3 (244-isomer) using a SbCl 5 as the catalyst which is then transformed selectively to 1234yf, preferably in a gas-phase catalytic reaction using activated carbon as the catalyst. For the first step, a mixture of Cr2O3 and FeCl 3 /C is preferably used as the catalyst to achieve high selectivity to CF 3 CCl=CH 2 (96%). In the second step, SbCl 5 /C is preferably used as the selective catalyst for transforming 1233xf to 244-isomer, CF 3 CFClCH 3 . The intermediates are preferably isolated and purified by distillation and used in the next step without further purification, preferably to a purity level of greater than about 95%. |