Patent ID: 7504533
Filing Date: 2009-03-17
Classification: C01B,C07C

Abstract:
1. A process for the production of an isocyanate comprising: a) reacting at least one amine with phosgene, optionally in the presence of a solvent, to produce a corresponding isocyanate and a stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances, b) separating the stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances in an at least two-stage sequence of absorption steps comprising (1) at least one isothermal absorption step and (2) at least one adiabatic absorption step to obtain (i) a hydrogen chloride stream containing no more than 0.5 wt. % phosgene, based on total weight of the hydrogen chloride stream and (ii) a liquid phosgene stream, and c) recycling the liquid phosgene stream (ii) to step a).