Patent ID: 8575403

Claim:
A process for purifying a crude ethanol product, comprising the steps of: hydrogenating acetic acid in a reactor in the presence of a catalyst to form the crude ethanol product; separating at least a portion of the crude ethanol product in a first column into a first distillate comprising ethanol, water and ethyl acetate, and a first residue comprising acetic acid; separating at least a portion of the first distillate in a second column into a second distillate comprising ethyl acetate and less than 30 wt. % ethanol, and a second residue comprising ethanol and water; optionally separating at least a portion of the second residue in a third column into a third distillate comprising ethanol and a third residue comprising water; optionally separating at least a portion of the second distillate in a fourth column into a fourth distillate comprising acetaldehyde and a fourth residue comprising ethyl acetate; hydrolyzing at least a portion of one of the first distillate, the second distillate, or the fourth residue to form a hydrolyzed stream; and feeding at least a portion of the hydrolyzed stream to the first column.