Patent ID: 7705193

Claim:
A process for conversion of a gasoline-range hydrocarbon feed, comprising 4 to 15 carbon atoms, into a gasoline fraction with a higher octane rating than that of the feedstream and a gasoil fraction with a cetane number higher than 45, the process including the following steps: a) a membrane separation step (B) applied to the hydrocarbon feed under conditions enabling selective separation of the majority of the linear olefins present in said feed, termed β fractions, from the fraction containing the majority of the branched olefins, termed γ fraction constituting a gasoline with a high octane rating greater than that of the feed, b) an oligomerisation step (C) applied to the linear olefins (β fraction) contained in the effluent from the membrane separation step (B) under moderate oligomerisation conditions, c) a distillation separation step (D) applied to the effluent arising from the oligomerisation step in at least two fractions: a δ fraction including hydrocarbons whose end boiling point is below a temperature between 150° C. and 200° C., a η fraction including hydrocarbons whose initial boiling point is above a temperature between 150° C. and 200° C., d) a hydrogenation step (E) applied to the η fraction to obtain a gasoil with a cetane number at least equal to 45, e) a dehydrogenation step (F) applied to said δ fraction to convert at least part of the paraffins into olefins, and to produce a fraction μ which is, at least partially, recycled to the inlet of the membrane separation step (B).