Patent ID: 7553998

Claim:
A process for the production and recovery of one or more high-purity xylene isomers from a catalytic reformate, comprising the sequential steps of: (a) fractionating the catalytic reformate to obtain a light reformate and a heavy-reformate feed stream comprising alkylaromatic hydrocarbons and containing about 1.0 wt.-% or more of C 9 and heavier hydrocarbons including about 0.5 wt.-% or more of methylethylbenzenes; (b) contacting the feed stream in the presence of hydrogen with a heavy-aromatics-conversion catalyst in a heavy-aromatics-conversion zone at heavy-aromatics-conversion conditions to obtain a de-ethylated stream having a lower content of methylethylbenzenes than the content in the feed stream; (c) fractionating the de-ethylated aromatic stream to separate a light product comprising C 7 and lighter hydrocarbons and a heavy product comprising C 9 and heavier hydrocarbons from a intermediate stream comprising C 8 aromatics; (d) subjecting the light reformate stream to an aromatics-extraction and fractionation step to separate benzene, toluene and a toluene-bottoms stream from a non-aromatic raffinate; (e) contacting the heavy product comprising C 9 and heavier hydrocarbons and at least a portion of the toluene in a transalkylation zone with a transalkylation catalyst at transalkylation conditions to obtain a transalkylation product; (f) fractionating the transalkylation product to separate a C 7 and lighter stream, an intermediate stream and a C 9 and heavier stream; (g) subjecting at least a portion of the intermediate stream, along with an isomerized stream, to an isomer-recovery process to recover at least one high-purity xylene isomer and yield a C 8 -aromatic raffinate stream comprising non-recovered C 8 -aromatic isomers; and, (h) contacting at least a portion of the C 8 -aromatic raffinate stream with an isomerization catalyst in an isomerization zone at isomerization conditions comprising substantially less than 0.05 moles of hydrogen/mole of feed to obtain the isomerized stream comprising a concentration of at least one xylene isomer that is higher than the concentration in the C 8 -aromatic raffinate stream.