Xylene production employing isomerization and transalkylation

摘要

A process is disclosed for the production of high quality benzene (12) and a desired xylene isomer, prefer­ably paraxylene (29), from a mixture of C₇-plus alkylaro­matic hydrocarbons (1). The desired xylene isomer is recovered by separation (28) from a stream (20) of two or three xylene isomers. the resultant isomer-depleted stream (30) is passed into an isomerization/transalkylation zone (6) together with both feed and recycled toluene and C₉ aromatic hydrocarbons (31,27,3) instead of being passed into a xylene isomerization zone. Benzene (12) and xylenes (16) are fractionated (8,11,14) from the iso­merization/transalkylation zone effluent stream (7), with the xylenes (16) being passed into the separation zone (28). A nonmetal catalyst is employed in the isomerizat­ion/transalkylation zone, which must be operated at high severity (high temperature) conditions.