Method for producing isocyanates

US9376377B2 · kind B2 · utility

Assignee

• Covestro Deutschland AG · DE

Inventors

• Friedhelm Steffens · Leverkusen, DE
• Jan Busch · Düsseldorf, DE
• Markus Hollaus · Bedburg, DE

Key dates

• Filing date: Jul 21, 2014
• Grant date: Jun 28, 2016
• Expiry date: Jul 21, 2034

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C263/10
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a method for producing an isocyanate by reacting the corresponding primary amine with phosgene in a reactor (100) which comprises at least one reaction zone (110) and a quenching zone (120) arranged below said reaction zone, having the following steps: (i) introducing a gaseous amine flow (1) and a gaseous phosgene flow (2) into the reactor (100) and reacting the flows in the reaction zone (110) into a product gas flow (3) comprising isocyanate and hydrogen chloride and optionally excess phosegene; (ii) introducing the product gas flow (3) into the quenching zone (120), in which the product gas flow is cooled by injecting a quenching liquid (4) via at least one quenching nozzle (200) such that a liquid flow (5) comprising the quenching liquid (4) and isocyanate and a gaseous flow (6) comprising hydrogen chloride and optionally phosgene are obtained; and (iii) separating the isocyanate from the liquid flow (5) obtained in step (ii); wherein the temperature Tw*, of the wall of the reaction zone (110) directly above the quenching zone (120) is kept at a value which lies maximally 4.0%, preferably maximally 2.0%, below the maximum temperature, Twmax, of the wal…