Process for preparing isocyanates

US8969615B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Vanessa Simone Lehr · Mannheim, DE
• Torsten Mattke · Ludwigshafen am Rhein, DE
• Carsten Knösche · Niederkirchen, DE
• Heiner Schelling · Ludwigshafen, DE
• Gerhard Olbert · Dossenheim, DE

Key dates

• Filing date: Mar 29, 2012
• Grant date: Mar 3, 2015
• Expiry date: Aug 15, 2032

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P20/20
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to gas phase phosgenation of amines for preparation of isocyanates. In the present invention, phosgene is prepared by reacting chlorine with an excess of carbon monoxide in a gas phase. The obtained phosgene-containing reaction mixture is divided into two streams by a thermal and/or a membrane separating process. The first stream is a low-carbon monoxide stream of no more than 1% by weight of carbon monoxide, based on a total weight of the first stream. The second stream is a carbon monoxide-rich stream of more than 10% by weight of carbon monoxide, based on a total weight of the second stream. The first stream is used as the phosgene-containing reactant stream in the gas phase phosgenation of amines to prepare isocyanates. The second stream can be recycled into the phosgene synthesis.