Process for preparation of polyisobutylene whose content of terminal double bonds is more than 50% from an industrial c4 hydrocarbon stream comprising 1-butene, 2-butene and isobutene

A process for preparing polyisobutylene having a content of terminal double bonds of more than 50% by polymerizing isobutene using a polymerization catalyst customary therefor from a technical 1-butene-, 2-butene- and isobutene-containing C4 hydrocarbon stream which may comprise up to 3000 ppm by weight of 1,3-butadiene, which comprises reducing the content of oxygenates in the C4 hydrocarbon stream before the polymerization of the isobutene by contacting it with an inorganic adsorbent at a pressure of from 1 to 40 bar and a temperature of from −40 to +220° C.

A process for reducing the content of oxygenates in a technical 1-butene-, 2-butene- and isobutene-containing C4 hydrocarbon stream which may comprise up to 3000 ppm by weight of 1,3-butadiene, which comprises cooling the C4 hydrocarbon stream at a pressure of from 1 to 40 bar to a temperature of less than 20° C., removing water which separates out and then contacting the C4 hydrocarbon stream with an inorganic adsorbent at a pressure of from 1 to 40 bar and a temperature of from −40 to +220° C.