Extraction process for removal of impurities from mother liquor in the synthesis of carboxylic acid

摘要

A method for removing impurities from a mother liquor comprising a carboxylic acid, a metal catalyst, impurities by (a) evaporating the mother liquor comprising a carboxylic acid, a metal catalyst, impurities and a solvent in a first evaporator zone to produce a vapor stream and a concentrated mother liquor stream;(b) evaporating the concentrated mother liquor stream in a second evaporator zone to form a solvent rich stream and a super concentrated mother liquor stream; (c) mixing in a mixing zone a water-solvent solution and optionally an extraction solvent with the super concentrated mother liquor stream to form an aqueous mixture;(d) optionally separating organic impurities from the aqueous mixture in a solid-liquid separation zone to form a purified aqueous mixture; and (e) extracting the aqueous mixture or purified aqueous mixture with an extraction solvent in an extraction zone to form an extract stream and the raffinate stream.