Process for the preparation of isocyanates

US8563768B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Rainer Bruns · Leverkusen, DE
• Wolfgang Lorenz · Dormagen, DE
• Friedhelm Steffens · Leverkusen, DE
• Herbert Stutz · Karlsruhe, DE

Key dates

• Filing date: Jun 26, 2010
• Grant date: Oct 22, 2013
• Expiry date: Sep 19, 2030

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B32/80
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

An isocyanate is produced by reacting an amine with a stoichiometric excess of phosgene in the gas phase. This reaction is carried out at a temperature above the amine's boiling point to obtain a liquid stream containing the isocyanate and a gas stream containing hydrogen chloride and phosgene. The gas stream containing hydrogen chloride and phosgene thus produced is separated into a gas stream containing hydrogen chloride and a liquid stream containing phosgene. At least part of the liquid stream containing phosgene is then converted to a gas stream containing phosgene which gas stream is then recycled. The gaseous phosgene stream is maintained at a higher pressure than the liquid phosgene stream.