Method for producing nitrobenzene by adiabatic nitriding
AssigneeBayer MaterialScience AG
InventorsThomas Knauf, Alexandre Racoes, Wolfgang Dohmen, Antoni Mairata
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Abstract
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.
Claims15
A continuous adiabatic process for the preparation of nitrobenzene by the nitration of benzene in a nitration unit, comprising:
- a) reacting a benzene-containing stream (a.1), comprising at least 90 wt % of benzene, based on the total weight of (a.1), in a reactor with a mixture of sulfuric acid (a.2) and nitric acid (a.3) under adiabatic conditions, the benzene being used in a stoichiometric excess, based on nitric acid (a.3),
- b) separating the process product obtained in step a) in a phase separation apparatus into an aqueous phase (b.1) comprising sulfuric acid and an organic phase (b.2) comprising nitrobenzene,
- c) concentrating the aqueous phase (b.1) obtained in step b) by evaporation of the water to give an aqueous phase (c.1) having a higher sulfuric acid concentration than (b.1), and recycling all or part of the phase (c.1) into step a) and using the phase (c.1) as a component of (a.2), and
- d) working up the organic phase (b.2) obtained in step b) to pure nitrobenzene (d.1) to give a benzene-containing stream (d.2), all or part of which is used as a component of (a.1) in the nitration unit of step a),
- wherein
- aliphatic organic compounds are specifically removed from the process at at least one point so that only such a benzene-containing stream (a.1) having a content of aliphatic organic compounds of less than 1.5 wt %, based on the total weight of (a.1), is fed into the reactor.
An adiabatic process for the preparation of nitrobenzene by the nitration of benzene in a series of two nitration units (100, 200) each having at least one reactor (1, 1*), comprising:
- a) reacting exclusively benzene (a.1.1) having a content of aliphatic organic compounds of less than 1.5 wt %, based on the total weight of (a.1.1), in the reactor (1) of the first, continuously operating nitration unit (100) with a mixture of sulfuric acid (a.2.1) and nitric acid (a.3.1) under adiabatic conditions, the benzene being used in a stoichiometric excess, based on nitric acid (a.3.1),
- b) separating the process product obtained in step a) in a phase separation apparatus (2) into an aqueous phase (b.1.1) comprising sulfuric acid and an organic phase (b.2.1) comprising nitrobenzene,
- c) concentrating the aqueous phase (b.1.1) obtained in step b) by evaporation of the water to give an aqueous phase (c.1.1) having a higher sulfuric acid concentration than (b.1.1), and recycling all or part of the phase (c.1.1) into step a) and using the phase (c.1.1) as a component of (a.2.1), and
- d) working up the organic phase (b.2.1) obtained in step b) to pure nitro-benzene (d.1.1) to give a benzene-containing stream (d.2.1),
- and reacting the benzene-containing stream (d.2.1) in a reactor (1*) of the second, continuously or discontinuously operating nitration unit (200) with a mixture of sulfuric acid (a.2.2) and nitric acid (a.3.2) under adiabatic conditions to give nitrobenzene, the benzene being used in, a stoichiometric excess, based on nitric acid (a.3.2), of 2.0% to 20%, of theory, and then working up the nitrobenzene formed thereby to pure nitrobenzene.
Dependencies are inferred from the claim text.