US Patent 7381858 Xylene process using perm-selective separations

Processes are disclosed for production of purified products from a fluid mixtures of C8 aromatics by means of integration of perm-selective separations with purified product recovery operations. The perm-selective separations of the invention comprise of one or more devices using polymeric perm-selective membrane devices to separate a meta-xylene enriched stream from fluid mixtures of C8 aromatics thereby producing a fluid comprising the remaining aromatic compounds which advantageously includes para-xylene. Processes of the invention are particularly useful for recovery of very pure meta-xylene and para-xylene co-products from liquid mixtures even containing ethylbenzene as well as the three xylene isomers.