Fractionation of aromatic streams

Claim 1

A combination xylene separation and a toluene transalkylation process, for producing benzene and orthoxylene comprising the steps of: a. transalkylating a mixture of toluene and C 9 alkylbenzene in a transalkylation zone at transalkylation conditions to produce a transalkylation zone effluent comprising benzene, toluene, C 8 alkylbenzenes, C 9 alkylbenzenes, and C 10 alkylbenzenes; b. fractionating at least a portion of said transalkylation zone effluent in a distillation column wherein benzene and toluene are recovered as an overhead fraction and materials heavier than toluene are recovered as a bottoms fraction; c. fractionating said benzene and toluene fraction in a fractionation column to produce a benzene product and to recover a toluene-rich stream which comprises at least a portion of the charge to the transalkylation zone; d. passing at least a portion of said bottoms fraction, comprising material heavier than toluene, into a xylene fractionator, and recovering overhead a stream comprising orthoxylene and recovering as a bottoms fraction a stream comprising C 9 and C 10 alkylbenzenes; e. passing the C 9 and C 10 alkylbenzene bottoms fraction to a fractionation zone to recover overhead a stream comprising C 9 alkylbenzenes, at least a portion of which C 9 alkylbenzenes stream is charged to the transalkylation zone; f. reboiling the column producing benzene product by indirect heat exchange with vapors from the column producing C 9 alkylbenzenes as an overhead fraction; and, g. reboiling the column producing benzene and toluene as an overhead fraction by indirect heat exchange with a stream comprising orthoxylene vapors obtained as an overhead vapor fraction from the xylene fractionator.