Bayer Aktiengesellschaft

Rudolf Hornung

Gunter Lailach

Rudolf Gerken

Karl-Heinz Schultz

Walter Bockmann

Wolfgang Larbig

Wolfgang Dietz

In the production of nitrobenzene by subjecting benzene to nitration with a mixture of nitric acid and sulfuric acid, separating off the nitrobenzene formed, concentrating the sulfuric acid by evaporation and returning the concentrated sulfuric acid to the bezene nitration stage, the improvement which comprises concentrating sulfuric acid to a concentration of from 75 to 92% by evaporation in vacuo at temperatures in the range from 130.degree. to 195.degree. C. Thereby the energy per kg of water evaporated is drastically reduced compared to processes wherein the sulfuric acid is concentrated to a higher level, without a corresponding loss in efficiency or capacity.

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Krefeld, Germany

Rudolf Hornung