Method for separating toluene diisocyanate from the post-reaction mixture in the toluene diamine phosgenation process in the gas phase

摘要

The present invention relates to the method for separating toluene diisocyanate from the post-reaction mixture in the toluene diamine phosgenation process in the gas phase. More specifically the solution concerns obtaining a higher TDI concentration in the liquid reaction product. The method is based on the fact that cooling and condensation of the reaction product - toluene diisocyanate - (TDI) is carried out by the application of spraying in the cooling and condensation zone, directly after the reactor, wherein this operation is carried out at a temperature elevated enough to obtain a low concentration of the solvent, i.e. within 5-30% by weight, in relation to TDI obtained, and thus a high concentration of (within 70-95% by weight) TDI obtained.