Patent ID: 7601311

Claim:
An integrated apparatus for co-producing xylene and pure benzene comprising: a. a transalkylation reaction loop containing at least one transalkylation reaction zone containing transalkylation catalyst, said transalkylation zone being adapted to receive feed comprising lower aromatics comprising at least one of benzene and toluene and higher aromatics comprising C 9 + aromatics and having a reactor effluent port, a benzene column in fluid communication with the reactor effluent port of said transalkylation reactor and adapted to provide a benzene-containing lower boiling fraction and a higher boiling fraction containing toluene and C 8 aromatics, and a fluid communication line from said benzene column to said transalkylation reaction zone adapted to supply at least a portion of the lower boiling fraction to said transalkylation zone; b. a disproportionation loop containing a toluene distillation column being adapted to received said higher boiling fraction from the benzene column of the transalkylation loop, said toluene distillation column adapted to provide a toluene-containing lower boiling fraction and a C 8 aromatics-containing higher boiling fraction, a disproportionation reaction zone containing catalyst for disproportionating toluene to C 8 aromatics and benzene, said disproportionation reaction zone being adapted to receive as feed the lower boiling fraction from said toluene distillation column and containing a reactor effluent port, and a benzene distillation column in fluid communication with the reactor effluent port of said disproportionation reactor, said benzene distillation column being adapted to provide a lower boiling benzene-containing fraction and a higher boiling toluene and C 8 aromatics-containing fraction, in which the benzene distillation column is in fluid communication with the toluene column for supplying the higher boiling toluene and C 8 aromatics-containing fraction to the toluene column; and c. a fluid communication line between the transalkylation loop and the disproportionation loop adapted to supply intermittently or continuously a sufficient portion of the lower boiling toluene-containing fraction from the toluene column of the disproportionation loop to the transalkylation reactor to maintain the content of benzene less than about 15 mass percent and the content of benzene coboilers less than about 10 mass percent in the disproportionation loop.