Patent ID: 6376733
Filing Date: 2002-04-23
Classification: C07C,Y02P

Abstract:
A process for recovering paraxylene from a C8 aromatics stream containing paraxylene and at least one other isomer of xylene, ethylbenzene, or mixtures thereof which process comprises:(a) recovering by means of a paraxylene separation process in a paraxylene recovery unit a portion of said paraxylene from at least a portion of said C8 aromatics stream to produce a first stream having a reduced paraxylene content and containing a portion of said other isomers of xylene, said ethylbenzene, or mixtures thereof; (b) passing at least a portion of said first stream to an isomerization unit to produce an isomerate having an enriched paraxylene content compared to that of said first stream; (c) passing at least a portion of said isomerate directly or indirectly to a membrane unit comprising a molecular sieve membrane and optionally isomerization catalyst under isomerization conditions, such that the permeate withdrawn through the molecular sieve membrane and from the molecular sieve membrane unit is enriched in paraxylene when compared to the feed to the membrane unit; and (d) feeding the permeate directly or indirectly back to the paraxylene separation process.