Patent ID: 7268263

Claim:
A process for isomerizing xylenes comprising: (a) providing a naphtha stream to a hydrotreating zone, wherein the naphtha stream is contacted with a hydrotreating catalyst under hydrotreating conditions to produce a hydrotreated naphtha stream; (b) passing the hydrotreated naphtha stream to a reforming zone, wherein said hydrotreated naphtha is contacted with a reforming catalyst under reforming conditions to produce a reformate stream comprising aromatic components and light-end hydrocarbons; (c) introducing all of the reformate stream, a transalkylation product stream, and an isomerization zone effluent, in individual streams or a combined stream, to a transalkylation stripper zone and separating a toluene and lighter hydrocarbons enriched stream and a xylene and heavier hydrocarbons enriched stream; and (d) removing light ends and LPG from the toluene and lighter hydrocarbons enriched stream to form a feed stream comprising benzene, toluene, and C 5 -C 8 aliphatic hydrocarbons; (e) introducing the feed stream comprising benzene, toluene, and C 5 -C 8 aliphatic hydrocarbons into an extractive distillation zone to separate a bottoms aromatic hydrocarbons stream comprising benzene and toluene, a sidecut aliphatic hydrocarbons stream comprising C 7 -C 8 aliphatic hydrocarbons, and an overhead aliphatic hydrocarbons stream comprising C 5 -C 7 aliphatic hydrocarbons; (f) treating the sidecut aliphatic hydrocarbons stream comprising C 7 -C 8 aliphatic hydrocarbons to generate a substantially solvent-free sidecut aliphatic hydrocarbons stream; (g) introducing the substantially solvent-free sidecut aliphatic hydrocarbons stream comprising C 7 -C 8 aliphatic hydrocarbons, hydrogen, and a non-equilibrium xylene stream comprising a non-equilibrium mixture of xylenes into an isomerization zone to contact an isomerization catalyst at isomerization conditions and generate the isomerization zone effluent.