混合多氯苯中对二氯苯的回收工艺研究

Study on the recovery process of P-dichlorobenzene from mixed polychlorinated benzene

系统地研究从副产多氯苯中回收对二氯苯(p-DCB)工艺路线,通过分馏-甲醇/水结晶-过滤-气流干燥,制得精品对二氯苯。通过对溶剂/水结晶中纯溶剂、丙酮/水、甲醇/水、表面活性剂/水等结晶工艺进行了比较,以甲醇/水为最佳,其结晶母液可多次直接套用,为本工艺的一大突破。p-DCB的综合回收率可达90%,p-DCB含量≥99.6%,水分≤0.035%,工艺简单,可操作性好。

The process of recovering p-dichlorobenzene(p-DCB)from the by-product polychlorinated benzene was systematically studied.Fine p-dichlorobenzene was prepared by fractional distillation-methanol/water crystallization-filtering-air drying.The crystallization processes with pure solvent,acetone/water,methanol/water and surfactant/water were compared.The best crystallization process was using methanol/water,it’s mother liquid could be directly recycled for many times.The comprehensive recovery of P-DCB is 90%,the content of p-DCB is≥99.6%,the moisture is≤0.035%,the technology is simple and the operability is easy.