| abstract |
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, the metal catalyst, impurities, water 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) separating organic impurities with a water-solvent solution from the super concentrated mother liquor in a solid-liquid separation zone to form an aqueous stream and a second aqueous stream; (d) mixing in a mixing zone water and optionally and extraction solvent with the aqueous stream and second aqueous stream to form an aqueous mixture; and (e) adding an extraction solvent to the aqueous mixture in an extraction zone to form an extract stream and a raffinate stream. |