US EPA

8096407 

Journal Article 

High-purity purification of indole contained in coal tar fraction - separation of close boiling mixtures of indole by solute crystallization - 

Kim, SJ; Kang, HC; Jeong, HJ 

2010 

21 

2 

238-241 

English; Korean 

The purification of indole from 54.3wt% indole fraction (temperature range of distillate: 250~255 °C) recovered by extraction-distillation combination of coal tar fraction (temperature range of distillate: 240~265 °C) was examined by solute crystallization. The feed consists of eight components such as quinoline, iso-quinoline, indole, quinaldine, 1-methylnaphthalene, 2-methylnaphthalene, biphenyl and phenyl ether. Hexane and an aqueous solution of methanol (50: 50 vol%) were used as the crystallization solvent and the coolant, respectively. A batch stirred tank of glass material was used as a crystallization apparatus. By increasing the operation temperature and the volume ratio of solvent to feed at initial, the purity of indole increased, but yields of indole showed a decreasing tendency. Solute crystallization method using hexane as a solvent was excellent because the purity of 99.3 wt% indole was recovered at the yield of 50% without washing operation. 

Coal tar; High-purity purification; Indole; Solute crystallization