| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve problems wherein, when phosgenation is carried out on a large scale, the amount of unreacted phosgene gas discharged into exhaust gas to be disposed together with waste gas and the amount of catalysts used are unnegligibly large and that complete recovery and effective utilization thereof are required. <P>SOLUTION: The exhaust gas generated by phosgenation is introduced into an exhaust phosgene-trapping tank, in which reaction raw materials for the next batch have been charged, and phosgene gas in the exhaust gas is completely absorbed thereby permitting effective utilization while the catalyst, VM reagent, is subjected to recycle use at least four times. Thus, the phosgenation method is environmentally friendly and efficient. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
