High-purity 1-butene recovery from mixed butene streams - by isobutene polymerisation to gasoline and fractionation

摘要

Recovery of 1-butene from C4 olefinic feeds is effected by (a) subjecting the feed to selective polymerisation to convert isobutene to gasoline; (b) fractionating the effluent from (a) to separate the gasoline from a fraction (I) comprising isobutane, n-butane, 1-butene, 2-butenes and a small amt. of isobutene; (c) deisobutanising (I); and (d) fractionating the deisobutanised stream to recover a fraction comprising mainly 2-butenes and n-butane and a fraction comprising at least 99 wt.% 1-butene. The process can be applied to C4 streams from catalytic or steam cracking units, giving high-purity 1-butene suitable for use as a comonomer in the mfr. of high-density polyethylene.