Patent ID: 7153394
Filing Date: 2006-12-26
Classification: C07C,Y10S

Abstract:
1. A system for dianhydride isolation comprising an extraction column operated at a first temperature and pressure sufficient to form an extracted aqueous phase comprising water, exchange catalyst and dianhydride precursor; a flash vessel that receives the extracted aqueous phase from the extraction column and forms a molten phase wherein the flash vessel is operated at a second temperature and pressure sufficient to produce a molten phase; a falling film evaporator in fluid communication with a first outlet of the flash vessel, wherein the falling film evaporator receives the molten phase from the flash vessel and the falling film evaporator is operated at a third temperature and pressure sufficient to form an isolation mixture having an exchange catalyst to dianhydride precursor ratio of about 0.4 to about 0.8; and a wiped film evaporator in fluid communication with a first outlet of the falling film evaporator and operated at a fourth temperature and pressure wherein the wiped film evaporator receives the isolation mixture from the falling film evaporator and further wherein the wiped film evaporator comprises a first outlet for collection of isolated dianhydride and further falling film evaporator is operated at a temperature less than the temperature of the wiped film evaporator.