Method for producing isocyanates

US10858311B2 · kind B2 · utility

Assignee

• Covestro Deutschland AG · DE

Inventors

• Wolfgang Taube · Neuss, DE
• Rainer Bruns · Leverkusen, DE
• Artur Mausbach · Dormagen, DE

Key dates

• Filing date: Jun 6, 2018
• Grant date: Dec 8, 2020
• Expiry date: Jun 6, 2038

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C2601/14
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a method for preparing an isocyanate by phosgenating the corresponding primary amine in the gas phase, wherein the gaseous reaction product mixture is cooled by being brought into contact with at least one flow stream of a quenching liquid in a quenching zone, wherein the quenching liquid used in total comprises, based on the total mass, organic solvents in a proportion of maximally 50.0% by mass, and the remainder of up to 100% by mass consists of at least the isocyanate to be produced, thereby obtaining a mixture of the reaction product mixture and the quenching liquid. Furthermore, the mixture obtained in this manner of the reaction product mixture and the quenching liquid is separated into a liquid and a gaseous phase in a collection zone, and a liquid solvent intermediate flow comprising more than 50.0% by mass of organic solvents, based on the total mass of the liquid solvent intermediate flow, is conducted into the collecting zone and/or into a collecting tank arranged fluidically downstream of the collection zone for the liquid phase obtained in the collection zone.