Process for the purification of mixtures of toluenediisocyanate incorporating a dividing-wall distillation column

摘要

The invention is directed to a process for the purification of toluenediisocyanate from a crude distillation feed comprising less than 2% by weight phosgene by separating the crude distillation feed in a dividing-wall distillation column into four product fractions P1 - P4, whereby P1 is a phosgene enriched low-boiler product, P2 is a solvent -enriched product, P3 is a high boiler enriched bottoms and P4 is an isocyanate product stream.