METHOD AND SYSTEM FOR PRODUCING NITROBENZENE

摘要

The present invention relates to a process and a plant for the production, in particular the continuous production, of nitrobenzene by means of adiabatic nitration of benzene with nitric acid in the presence of sulfuric acid, in which, following the nitration, a multi-stage concentration of the sulfuric acid is carried out by means of heating at a pressure that is reduced as compared with ambient pressure, and wherein the heating takes place using the heat generated in the adiabatic nitration of benzene.

主权项

1. Process for the production of nitrobenzene by means of adiabatic nitration of benzene with nitric acid in the presence of sulfuric acid, in which
a) the product mixture obtained in the nitration is separated into spent acid and crude nitrobenzene and b) at least the water contained in the spent acid is partially separated from the sulfuric acid contained therein and c) the sulfuric acid so concentrated is fed to the nitration again,which process is characterised in that
i) the separation according to step b) is carried out by evaporation in two stages with an absolute pressure that falls from the first stage to the second stage from 100 mbar to 300 mbar to 50 mbar to 150 mbar, ii) the heat used for the evaporation according to step i) comes substantially from the reaction enthalpy of the nitration and iii) the product mixture obtained in the nitration has a temperature of at least 110° C.