Separation of the cresol isomers by a new technique combining distillation and crystallization

A new separation technology, called stripping crystallization (SC) or distillative freezing (DF) is developed to separate the mixtures with close boiling temperatures, including the mixed xylenes and the benzene/cyclohexane mixture. SC is operated at a triple-point condition, in which the liquid mixture is simultaneously vaporized and crystallized due to the three-phase equilibrium. Thus, SC combines distillation and crystallization to produce pure crystals. The SC operation can be applied to purify p-cresol from the cresol isomer. In the purification of p-cresol by SC, the recovery rate increases with increasing operating pressure while the final purity of the product decreases with increasing operating pressure. This is an abstract of a paper presented at the 2012 AIChE Spring National Meeting and 8th Global Congress on Process Safety (Houston, TX 4/1-5/2012).