Abstract: A method is provided to improve the quality of recycle of certain residues by modifying the separation of alkanes and alkane-like materials and carbonyl-containing impurities from the recycle during the manufacture of acetic acid by the carbonylation of methanol. The improvement comprises partitioning the residues by the addition of water obtained from aqueous streams containing up to 50 wt. % acetic acid and which have been treated in a catalytic distillation unit to react the acetic acid with methanol to form recyclable methyl acetate and water and wherein the water is separated from the organics by distillation.

Abstract: Esters such as methyl acetate which contain carbonyl impurities including aldehydes are purified by adding to the esters an amino compound which reacts with the carbonyls to form water soluble nitrogenous derivatives, separating an organic ester phase from an aqueous derivative phase, and distilling the ester phase to further remove heavier impurities. The formation of nitrile from the nitrogenous derivative is minimized by adding water to the distillation column or washing the aqueous bottoms from distillation with water to further remove the derivatives from any ester contained in the bottoms. The organic phase recovered from the bottoms can be recycled to the distillation to recover ester.

Abstract: Acetic acid produced by the low water carbonylation of methanol and containing iodide, unsaturates and carbonyl impurities is purified by treatment with ozone.

Abstract: Acetic acid containing iodide, unsaturates and carbonyl impurities is purified by treatment with ozone and thereafter contacted with activated carbon and/or an ion-exchange resin for removal of impurities.

Abstract: Acetic acid containing iodide, unsaturates and carbonyl impurities is purified by treatment with ozone in the presence of an oxidation catalyst. The acetic acid product may be further contacted with activated carbon or ion-exchange resins for additional removal of impurities.