Method for operating a gas-phase phosgenation plant

US9840461B2 · kind B2 · utility

Assignee

• Covestro Deutschland AG · DE

Inventors

• Thomas Knauf · Dormagen, DE
• Wolfgang Lorenz · Dormagen, DE
• Friedhelm Steffens · Leverkusen, DE
• Rainer Bruns · Leverkusen, DE
• Wolfgang Taube · Neuss, DE

Key dates

• Filing date: Mar 24, 2015
• Grant date: Dec 12, 2017
• Expiry date: Mar 24, 2035

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C263/20
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

This invention relates to a process for operating a gas phase phosgenation plant (100) to form an isocyanate (4) by reacting an amine (2) with phosgene (1), in which the gas phase phosgenation plant is started up by first charging the plant with phosgene. At the same time as, or after the first charge of phosgene, the amine supply devices are rendered inert using a hot inert gas stream (30). Then, amine is admixed for the first time. In this way and by maintaining a pressure drop in the amine and phosgene devices to the mixing zone, the back mixing of phosgene into the amine-containing reactant stream during start-up is prevented.