Process for upgrading a gasoline fraction and transforming in gasoils with additional treatment for increasing the efficiency of the gasoil fraction

摘要

Process for the adjustment of the relative productions of petrol and gasoil from a petrol cut comprsing 4 - 15 C hydrocarbons to obtain a petrol with an improved octane index and a gasoil fraction with a high cetane index. The process is carried out in the following stages (1) membrane separation, B, of the hydrocarbon charge to obtain a selective separation of most of the linear olefins,cut beta , from the branched chain olefins, cut gamma , comprising petrols of higher octane index than the original charge; (2) (b) oligomerisation, C, of the linear olefins, beta cut, in the effluents from the membrane separation; (c) (3) separation by distillation, D, of the effluents from oligomerisation to give two cuts ; cut delta comprises hydrocarbons of final boiling points lower than 150 - 200[deg]C, and a cut , comprising hydrocarbons of initial boiling points greater than 150 - 200[deg]C; (4) (d) hydrogenation, E, of the cut to obtain a gasoil of cetane index of at least 45; (5) (e) dehydrogenation, F, of the cut delta to convert paraffins to olefins, producing a cut mu which is partly recycled to the membrane separation stage.