PURIFICATION METHOD OF PARA-PHENYLENEDIAMINE CAPABLE OF FREELY REDUCING THE PRESSURE OF TOTAL DISTILLATION PROCESS TO LOW PRESSURE BY PREVENTING THE BLOCKAGE OF A CONDENSER AND VACUUM SYSTEM

摘要

PURPOSE: A purification method of para-phenylenediamine is provided to prevent clogging phenomenon of distillation apparatus, to prevent the loss of para-phenylenediamine, and to obtain para-phenylenediamine with high purity which is not discolored.;CONSTITUTION: A purification method of para-phenylenediamine comprises: a first step separating raw para-phenylenediamine to high-boiling-point impurities, para-phenylenediamine, and low-boiling point impurities through distillation process in a first distillation tower, and transferring the para-phenylenediamine and the low-boiling point impurities to a second distillation tower; a second step adding N-methylpyrrolidone to the outcome in the second distillation tower, obtaining low-boiling point impurities and purified para-phenylenediamine through distillation process, and transferring the low-boiling point impurities to the third distillation tower, transferring the purified para-phenylenediamine to a storage tank, and a part of the same to the circulating liquid of the first distillation tower; a third step separate-extracting the normal-methylpyrrolido and para- phenylenediamine, and transferring the low-boiling point impurities to a waste storage tank, and transferring the normal-methylpyrrolido to circulating liquid of the second distillation tower.;COPYRIGHT KIPO 2012