Process combining hydroisomerisation and separation using a zeolitic adsorbent with a mixed structure for the production of high octane number gasolines

For producing a gasoline stock with a high octane number, employed are at least one hydroisomerisation section and at least one section for adsorptively separating multibranched paraffins contained in a constituted by a C5 to C8 cut. The separation section contains at least one zeloitic adsorbent with a mixed structure with principal channels with openings defined by a ring containing 10 oxygen atoms and secondary channels with openings by a ring of at least 12 oxygen atoms, the secondary channels only being accessible to the feed to be separated via the principal channels.