Process for isomerization of a C7 fraction with co-production of a cyclic molecule-rich fraction

A process for the production of an isomerate that is at least equal to 80 and for co-production of a naphthenic fraction comprising mostly methylcyclohexane and optionally toluene, starting from a fresh C7 hydrocarbon feedstock containing paraffins, naphthenes and aromatic compounds, said process comprising at least one distillation column, at least one isomerization unit, and at least one unit for separating normal paraffins from cyclic molecules, wherein an isomerate is produced containing less than 1% by weight of aromatic compounds, and fresh feedstock is introduced into said distillation column from which are extracted a) a top flow that contains said isomerate, b) a lateral flow that feeds into an isomerization unit, and c) a bottom flow that is introduced into said unit for separating normal paraffins from cyclic molecules, and said normal paraffins are introduced in a mixture with the lateral flow into said isomerization unit and the resultant naphthenic fraction is produced with a purity level that is at least equal to 90% by mass.