Aniline purification process

Abstract

The present invention concerns a process for the preparation of pure aniline, comprising the steps of a) providing a crude aniline fraction containing up to 20.000% by weight of phenol; b) dividing the crude aniline fraction from step a) into a first partial stream and a second partial stream; c) distilling the first partial stream from step b) in a first distillation column and distilling the second partial stream from step b) in a second distillation column, wherein the first distillation column is operated at a higher head pressure than the second distillation column, with the proviso that each of the first distillation column and the second distillation column is operated at a head pressure in the range from 1.0 mbar(abs.) to 500 mbar(abs.), and wherein from each of the first distillation column and the second distillation column, (i) a gaseous aniline distillate (=purified aniline) is removed as the overhead product and subsequently condensed, wherein a first partial stream of the condensed aniline distillate is returned to the first and/or the second distillation column as a reflux stream and a second partial stream of the condensed aniline distillate is removed as the product stream, and (ii) a liquid bottom stream which is concentrated in phenol is removed, from which a first portion is partially or completely vaporised and is returned to the respective distillation column, and from which a second portion is discharged; d) using the heat released during the condensation of the aniline distillate from the first distillation column in order to provide the heat necessary for vaporising the first portion of the bottom stream from the second distillation column.

Dependencies are inferred from the claim text.