Patent ID: 7358414

Claim:
A process for recovering para-xylene from a fluid mixture of aromatic compounds, including at least one other isomer of xylene and ethylbenzene, which process comprises: (1-A) withdrawing from a perm-selective polymeric membrane device a first fluid stream having an enriched content of para-xylene compared to that of a second effluent stream which streams are derived by selective permeation of at least one aromatic compound from a fluid mixture of para-xylene with other aromatic compounds containing 8 carbon atoms, utilizing perm-selective membranes comprising at least one poly(amide)imide material having an average molecular weight between 20,000 and 200,000, which membranes exhibit a permeability of at least 0.1 Barrer for at least one of the isomers of xylene or ethylbenzene; and (1-B) distributing all or portion of the first stream withdrawn from the membrane device into para-xylene concentration unit to extract therefrom a purified product having an enriched content of the para-xylene compared to that of first stream, and a reject stream lean in at least para-xylene.