PRODUCTION OF OLEFINS

1332328 Preparing alpha-olefines ETHYL CORP 26 Aug 1970 [27 Aug 1969] 41166/70 Heading C5E Olefines in the range C 0 to C 16 are made by a stepwise adding, growing or polymerizing reaction of an olefine of lower molecular weight in the presence of a metal alkyl growth adjuvant, and the product worked up by: (a) flashing off olefines of product range and lower, (b) transalkylating organometallics in the residue with molecules of lower olefine, (c) converting the product from (b) to a mixed vapour-mist system with C 16 + olefines in the mist phase and more volatile materials in the vapour phase, (d) separating the vapour and mist phases in an inertial separator, and (e) recycling vapour from (d) to the initial reaction system. As shown, ethylene and trialkylaluminium are fed to a growth system (10), the product is distilled at 18, the lightest fraction (ethylene) being recycled (20), whereas other distillate fractions (olefines from C 4 to C 14 ) are taken off, and the bottoms, containing higher olefines and trialkyaluminium passed to 11, where they are transalkylated with ethylene, to convert other trialkylaluminiums to triethylaluminium. The transalkylated material is again distilled at 19, the lightest fraction (ethylene) being recycled (20) while other distillate fractions (olefines up to C 8 ) are taken off, and the bottoms heated at 27 to vaporize lower olefines and triethylaluminium, but leave higher olefines in mist form. The two phases are separated in a centrifugal separator 12, and passed through pressure controls 28 and 29, e.g. throttling valves. Part or all of either of the resulting streams (13 and 14) may be further distilled, or stream 13 (containing the triethylaluminium) may be recycled to 10 without distillation. A small proportion of the stream passing from 18 to 11 may be bled off to prevent the build-up of undesirable materials. This bleed stream can be combined with the stream 14 and processed to alcohols.