Method for producing nitrobenzene by adiabatic nitriding

US9260377B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Thomas Knauf · Dormagen, DE
• Michael Merkel · Hof, DE
• Antoni Mairata · Düsseldorf, DE

Key dates

• Filing date: Jul 23, 2013
• Grant date: Feb 16, 2016
• Expiry date: Jul 23, 2033

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C201/08
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention provides a continuous adiabatic process for the preparation of nitrobenzene by nitrating benzene with mixtures of sulfuric and nitric acids using a stoichiometric excess of benzene, wherein the content of organic compounds in the circulating sulfuric acid, at least during the start-up period of the production plant, is always kept below 1.0 mass percent, based on the total mass of circulating sulfuric acid. This is preferably achieved by a procedure in which, either after the end or before the beginning of a production cycle, the circulating sulfuric acid is circulated at elevated temperature so that the organics contained in the sulfuric acid, preferably comprising nitrobenzene and traces of benzene, dinitrobenzene and nitrophenols, are separated off in the evaporation apparatus for concentrating the sulfuric acid.