Patent ID: 7371912

Claim:
A process for making xylene isomer comprising: (a) separating at least one xylene isomer from a separation feed stream that contains para-xylene, ortho-xylene, meta-xylene and ethylbenzene and up to about 500 ppm-mass C 9 + aromatics, to provide a product fraction containing at least about 90 mass-percent of said at least one xylene isomer and a depleted fraction containing ethylbenzene, C 9 + aromatics and at least one other xylene isomer; (b) withdrawing at least a portion of the product fraction; (c) isomerizing at least a portion of the depleted fraction to provide an isomerate containing lower boiling, by-product hydrocarbons, para-xylene, meta-xylene, ortho-xylene, ethylbenzene and C 9 + aromatics; (d) fractionating by distillation at least a portion of the isomerate to provide a lower boiling fraction containing said lower boiling, by-product hydrocarbons and at least one mid-boiling fraction containing para-xylene, meta-xylene, ortho-xylene, ethylbenzene and C 9 + aromatics, and at least one higher boiling fraction containing para-xylene, meta-xylene, ortho-xylene, ethylbenzene and C 9 + aromatics wherein said at least one higher boiling fraction contains a greater mole percent of C 9 + aromatics than said at least one mid-boiling fraction; (e) recycling at least a portion of said at least one mid-boiling fraction as a recycle stream to step (a); and (f) providing to step (a) at least one C 8 aromatic feed stream that contains between about 15 to 25 mass-percent para-xylene, ortho-xylene, meta-xylene and ethylbenzene and C 9 + aromatics, wherein the separation feed stream comprises the recycle stream of step (e) and the at least one C 8 aromatic feed stream.