Reduced energy alcohol separation process having controlled pressure

摘要

The present invention is directed to processes for the recovery of ethanol from a crude ethanol product obtained from the hydrogenation of acetic acid using a low energy process. The crude ethanol product is separated in one or more columns. At least one of the columns is operated at a controlled pressure to enhance separation of ethanol and organics. In one embodiment, there are at least two columns that operate at controlled pressures.

主权项

1. A process for producing ethanol, comprising:
hydrogenating acetic acid and/or an ester thereof in a reactor in the presence of a catalyst to form a crude ethanol product; separating a portion of the crude ethanol product in a first distillation column to yield a first distillate comprising acetaldehyde and a first residue comprising ethanol, acetic acid, ethyl acetate and water; separating a portion of the first residue in a second distillation column to yield a second residue comprising acetic acid and water and a second distillate comprising ethanol and ethyl acetate; and separating at least a portion of the second distillate in a third distillation column to yield a third distillate comprising ethyl acetate and a third residue comprising ethanol, wherein the first distillation column and the third distillation column are operated at a lower pressure than the second distillation column.