| abstract |
This invention relates to a method of producing polyisobutenes from a feedstock comprising a mixture of C4 hydrocarbons and containing isobutene and at least 5% by weight of 1-butene using a cationic polymerisation catalyst, characterised in that prior to polymerisation, the feedstock is subjected to a pre-treatment step in order to reduce the 1-butene content thereof to a level which is at least 20% lower than that of the 1-butene content in the initial mixed C4 hydrocarbon feedstock prior to the pre-treatment thereof and the polyisobutene so formed is (a) very high in its vinylidene group content and (b) substantially free of halogen. |