| 摘要 |
A process for preparing 1,1,1,2,2-pentafluoropropane (245cb), the process comprising gas phase catalytic dehydrochlorination of a composition comprising 1,1,1-trifluoro-2,3-dichloropropane (243db) to produce an intermediate composition comprising 3,3,3-trifluoro-2-chloro-prop-1-ene (CF3CCl=CH2, 1233xf), hydrogen chloride (HCI) and, optionally, air; and gas phase catalytic fluorination with hydrogen fluoride (HF) of the intermediate composition to produce a reactor product composition comprising 245cb, HF, HCI and air; wherein the process is carried out with a co-feed of air. The two stages of the reaction are preferably carried out in separate reactors, and the reaction is preferably carried out continuously. Addition of air to the second reaction reduces the rate of deactivation of the catalyst(s) by coking. Preferred catalysts for the dehydrochlorination include activated carbon, a zero-valent metal, a metal oxide, a metal oxyhalide, a metal halide or mixtures thereof, particularly preferred is a zinc/chromic catalyst. Hydrogen fluoride may be provided for the dehydrochlorination. The reactor product may also comprise 2,3,3,3-tetrafluoropropene (1234yf). 245cb may also be catalytically dehydrofluorinated to 1234yf in the gas phase. |
