Bayer Materialscience Ag

Covestro Deutschland Ag

Wolfgang Dohmen

Thomas Knauf

Alexandre Racoes

Andreas Karl Rausch

Antoni Mairata

Franz-Ulrich Von Gehlen

Jörg Schmiedler

Andreas Rausch

The invention relates to an adiabatic process for producing nitrobenzene by nitrating benzene with sulphuric acid mixtures and nitric acid mixtures using a stoichiometric excess of benzene and reusing non-reacted benzene, the content of the aliphatic organic compounds in the feed benzene being limited, by the targeted evacuation of aliphatic organic compounds to at least one step in the process, to a content of less than 1.5 mass-%, in relation to the total amount of feed benzene.

Method for producing nitrobenzene by adiabatic nitriding

The invention relates to a continuous process for the manufacture of nitrobenzene. This process comprises the nitration of benzene with nitrating acid that contains at least 3.0 wt. % of nitric acid and at least 67.0 wt. % of sulfuric acid, in a reaction space in which the start temperature of the reaction is above 100.0&#xb0; C. but below 102.0&#xb0; C. In addition, this process requires that the benzene and the nitrating acid are dispersed in one another several times.

Continuous process for the manufacture of nitrobenzene

Alkaline waste waters formed in the washing of crude nitrobenzene which has been prepared by the adiabatic nitration of benzene with nitrating acid, washed in an acidic washing process, and then washed in an alkaline washing process are treated. The alkaline waste water being treated generally contains benzene in a concentration of from about 100 to about 3000 ppm and nitrobenzene in a concentration of from about 1000 to about 10,000 ppm. In the process of the present invention, undissolved benzene and/or nitrobenzene are separated from the alkaline waste water, residual benzene and/or nitrobenzene is/are then optionally stripped out of the alkaline waste water, and the alkaline waste water from which benzene and/or nitrobenzene has been removed is heated to a temperature of from 150 to 500&#xb0; C. under excess pressure with the exclusion of oxygen.

Process for the working-up of waste waters containing aromatic nitro compounds

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Duisburg, Germany

Wolfgang Dohmen