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

US7344650B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Thomas Knauf · Dormagen, DE
• Franz-Ulrich Von Gehlen · Krefeld, DE
• Wolfgang Dohmen · Duisburg, DE
• Jörg Schmiedler · Duisburg, DE

Key dates

• Filing date: Apr 7, 2005
• Grant date: Mar 18, 2008
• Expiry date: Jan 28, 2026

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S210/919
• WIPO field: Environmental technology
• WIPO sector: Chemistry

Abstract

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° C. under excess pressure with the exclusion of oxygen.