| 摘要 |
Isocyanates are produced by
a) reacting at least one amine with phosgene, optionally in the presence of a solvent to produce the corresponding isocyanate and a stream containing hydrogen chloride, phosgene and optionally solvent, low-boiling compounds and inert substances is obtained,
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 that includes (1) at least one isothermal absorption step and (2) at least one adiabatic absorption step, to obtain (i) a hydrogen chloride stream containing phosgene in concentrations of at most 0.5 wt.% (based on the weight of the hydrogen chloride stream) and (ii) a liquid phosgene stream, and
c) recycling the liquid phosgene stream (ii) to the reaction of amine with phosgene. |
