Process for obtaining pure aniline

摘要

A process for obtaining pure aniline contains
catalytically hydrogenating nitrobenzene, to obtain a reaction mixture,separating the reaction mixture into a gas phase containing hydrogen and a liquid phase,liquid/liquid phase separating the liquid phase to obtain an aqueous phase and also crude aniline containing water as an organic phase,distillatively pre-purifying the crude aniline by removing the water via an overhead stream of a first distillation column to obtain a first bottom stream,feeding the first bottom stream as a feed stream to a pure column from which a pure aniline stream is taken off at the top and a second bottom stream containing high boilers is taken off, andpassing the second bottom stream to incineration, by pumping the second bottom stream through heated pipelines and by adding methanol, ethanol, propanol, and/or acetone to the second bottom stream.

主权项

1. A process for obtaining pure aniline, the process comprising:
catalytically hydrogenating nitrobenzene, to obtain a reaction mixture, optionally partially condensing the reaction mixture, separating the reaction mixture or the partially condensed reaction mixture into a gas phase comprising hydrogen and a liquid phase, liquid/liquid phase separating the liquid phase to obtain an aqueous phase which is passed to a further work-up or discharged and also crude aniline as an organic phase, where the crude aniline comprises 90-95% by weight of aniline, 4-9% by weight of water and a remainder comprising components having boiling points higher than that of aniline, in each case based on the total weight of the crude aniline, and the sum of the components of the crude aniline is 100% by weight, distillatively prepurifying the crude aniline by partially or completely removing the water via an overhead stream of a first distillation column to obtain a first bottom stream, feeding the first bottom stream as a feed stream to a pure column from which a pure aniline stream comprising at least 99.9% by weight of aniline, based on the total weight of the pure aniline stream, is taken off at the top and a second bottom stream comprising high boilers is taken off, wherein a proportion by weight of the second bottom stream is not more than 0.8%, based on the weight of the feed stream, and passing the second bottom stream to incineration, by pumping the second bottom stream through one or more heated pipelines wherein a temperature of the second bottom stream is 45° C. or higher, and by adding methanol, ethanol, propanol, acetone or a mixture thereof to the second bottom stream in a proportion by weight of 5-30%, based on the weight of the second bottom stream.