Abstract: A combination isomerization and liquid phase adsorptive separation process has been developed. In this arrangement, a C5+ naphtha stream is split into a heavy hydrocarbon stream comprising normal heptane and higher boiling hydrocarbons, an isomerization and adsorption zone feed stream comprising pentanes and lower boiling hydrocarbons, and a desorbent stream containing hexanes. The isomerization and adsorption zone feed stream is combined with an isomerization section effluent to form a combined feed to an adsorptive separation section. In the adsorption separation section, normal pentanes are selectively adsorbed on an adsorbent material, and a raffinate stream comprising hexanes and isoparaffins is recovered and passed to a deisohexanizer column. A desorbent stream containing normal hexane is recovered as a sidecut from the deisohexanizer column and is combined with the desorbent stream containing the hexanes from the naphtha splitter to supply the desorbent for the adsorptive separation section.

Abstract: A combination isomerization and liquid phase adsorptive separation process is given increased efficiency and cost effectiveness while also improving the product quality by eliminating the columns for the separation of desorbent material from extract and raffinate streams. In this arrangement a C.sub.5 + naphtha stream is split into a heavy hydrocarbon stream comprising normal hexane and higher boiling hydrocarbons and an isomerization zone feedstream comprising isohexane and lower boiling hydrocarbons. The heavy hydrocarbon stream goes directly to a deisohexanizer column. The isomerization zone feedstream is combined with an excess desorbent stream and the extract stream from an adsorptive separation section to form a combined feed. Hydrocarbons in the combined feed are isomerized and after stabilization pass directly into the adsorption section.

Abstract: A combination isomerization-reforming process provides additional liquid volume yields of gasoline without significant increase in utilities expense by recycling the isomerization zone effluent to an extended feed fractionation zone from which an isomerization product is also withdrawn. The feed fractionation zone receives a C.sub.5 -plus boiling range naphtha feed. The fractionation zone provides a relatively heavy bottoms stream for a reformer feed and a relatively lighter sidecut stream for feed to an isomerization zone. Effluent from the isomerization zone is recycled to the feed fractionation zone at a midfractionation entry point. A net overhead stream withdrawn from the feed fractionation zone and containing principally C.sub.6 isoparaffins and lighter boiling hydrocarbons provides a relatively high octane blending component.