Gasoline component mfd. from cracker butene(s) fraction - by selective oligomerisation of isobutene, with isomerisation and recycle of rest

摘要

An olefinic 4C fraction from steam- or catalytic-cracking is upgraded as follows. (a) It is reacted over fluorided Al2O3, boron-contg. Al2O3 or SiO2/Al2O3, converting at least 90% of the isobutene, mainly to dimers and trimers, and less than 10% of the n-butenes. (b) The di- and tri-isobutene are removed by distn., at least partly hydrogenated and then used in gasoline. (c) the remaining prod. from (a) (largely 4C) is extractively distilled, to remove paraffins overhead. (d) The other prod. from (c) (at least 99% n-butenes) is isomerised over fluorided Al2O3 or SiO2/Al2O3, giving substantial conversion of n- to iso-butene. (e) The prod. from (d) is distilled to remove 1-3C by-prods., and the rest is recycled to (a). Most (e.g. 98.85%) of the butenes present are converted to an excellent gasoline component.