ISOMERISING OLEFINS

The invention relates to a process for the isomerisation of linear ethylenic hydrocarbons containing 4 to 20 carbon atoms per molecule to branched ethylenic hydrocarbons containing the same number of carbon atoms per molecule as the linear hydrocarbon from which they arise, in which process the hydrocarbon charge consisting at least partly of linear ethylenic hydrocarbons is treated in the presence of steam and of a catalyst containing (a) alumina, (b) 0.5 to 10% by weight of silica and (c) at least one metal or metal compound, the H2O/hydrocarbons of the charge molar ratio being between 0.1 and 10. The process is characterised in that there is used an alumina based on alumina beads manufactured by coagulating as drops.