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US 7,118,653 B2Granted
Process for the purification of mixtures of toluenediisocyanate incorporating a dividing-wall distillation column
AssigneeBayer Aktiengesellschaft
InventorsBill Brady, Friedhelm Steffens, Berthold Keggenhoff, Kai Verkerk, Gerhard Ruffert
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Abstract
Process for the purification of toluenediisocyanate from a crude distillation feed which includes toluenediisocyanate, an organic solvent and less than 2% by weight phosgene by separating the crude distillation feed in a dividing-wall distillation column into at least four product fractions P1–P4. P1 is a phosgene enriched low-boiler product, P2 is a solvent-enriched product, P3 is a high boiler enriched bottoms and P4 is a toluenediisocyanate product stream.
Claims9
A process for the production of toluenediisocyanate comprising the steps of:
- a) reacting toluene diamine with phosgene resulting in a crude distillation feed,
- b) separating the phosgene from the crude distillation feed from step a) when the crude distillation feed from step a) comprises 2% by weight or more of phosgene, resulting in a crude distillation feed comprising less than 2% by weight phosgene,
- c) separating the crude distillation feed comprising toluene-diisocyanate, an organic solvent and less than 2% by weight phosgene in a dividing-wall distillation column into at least 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 a toluenediisocyanate product stream.
4 more elements
Dependencies are inferred from the claim text.