摘要 |
Disclosed are processes for the production of fluorinated olefins, preferably adapted to commercialization of CF<SUB>3</SUB>CF-CH<SUB>2 </SUB>(1234yf). Three steps may be used in preferred embodiments in which a feedstock such as CCl<SUB>2</SUB>-CClCH<SUB>2</SUB>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 CF<SUB>3</SUB>CCl-CH<SUB>2</SUB>, preferably in a 80-96% selectivity. The CF<SUB>3</SUB>CCl-CH<SUB>2 </SUB>is preferably converted to CF<SUB>3</SUB>CFClCH<SUB>3 </SUB>(244-isomer) using a SbCl<SUB>5 </SUB>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 Cr<SUB>2</SUB>O<SUB>3 </SUB>and FeCl<SUB>3</SUB>/C is preferably used as the catalyst to achieve high selectivity to CF<SUB>3</SUB>CCl-CH<SUB>2 </SUB>(96%). In the second step, SbCl<SUB>5</SUB>/C is preferably used as the selective catalyst for transforming 1233xf to 244-isomer, CF<SUB>3</SUB>CFClCH<SUB>3</SUB>. 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%.
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