| 摘要 |
The reaction of aromatic amines with phosgene takes place in the mixing zone of a plug flow reactor to form both the product isocyanate as well as the intermediate carbamyl chloride. The aromatic amine dissolved in an inert diluent is fed to the center portion of the plug flow reactor while the phosgene is fed to the annular space. The reactor is designed so as to eliminate back-mixing at the feed zone and thus to avoid reaction of any isocyanate formed with the incoming aromatic amine which produces in turn undesirable by-products such as urea and tar. Cold phosgene that is fed into the annular space cools the wall sufficiently to inhibit the reaction to TDI. By heating the wall such as with the installation of a heating jacket to counteract the cooling effect of phosgene, the wall of the reactor is maintained above 90 DEG C. and thus any solid carbamyl chloride that migrates to the wall is reacted to the isocyanate, eliminating pluggage of the reactor from solids build-up. |
