溶析结晶法分离提纯对二氯苯的研究

提出了溶析结晶法从邻、对位二氯苯混合物中分离提纯 地二氯苯的新工艺。选用乙醇作为主溶剂,水作为析出剂,测定了物系的溶解度关系。研究了溶剂配比,结晶温度,投料比等工艺操作条件对产品收率和纯度的影响。实验证明,在温度为5－10℃,溶剂体积比（水：乙醇）为0.25-0.35的条件下,采用溶析结晶法可从对二氯苯含量为77％－85％的原料中,分离出纯度为99.7％以上的对二氯苯产品,收率可达75％－90％。

Separation of p-Dichlorobenzene from Isomer Mixtures by "Solventing-out" Processes

A new separation process of p-dichlorobenzene from isomer mixtures(ODB) by using the "solventing-out" method has been examined to obtain p-dichlorobenzene with high purity. In this process, the mixtures of p-dichlorobenzene (PDCB) and o-dichlorobenzene (ODCB) were first dissolved in the 95% ethanol, and then PDCB were selectively crystallized from ethanol solution by the addition of water. The solubility of PDCB and ODCB in the aqueous ethanol solution was determined respectively. The effects of the feed weight ratio (DCB/ Ethanol), solvent volume ratio (H2O/Ethanol) and temperatures on the yield and purity of the PDCB crystals were observed and studied at different operation conditions. Experimental results showed that the purity of PDCB products can be enhanced up to 99.8% from 77~85% and its yield can be over 76 % under the conditions of the volume ratio of water to ethanol 0.25 ~ 0.30 and temperature 278 ~ 283 K.