Basically, the present invention is predicated on the discovery that zeolites that have a high silica to alumina ratio, e.g., a ratio of 20 and above, pore diameters of greater than about 5.0.ANG., and which have substantially no active acid sites, i.e., zeolites which are non-reactive toward olefin isomerization and oligomerization, are especially useful in substantially separating linear olefins and paraffins from hydrocarbon mixtures containing at least linear and branched aliphatic hydrocarbons and optionally containing aromatic and other hydrocarbons.