Separation of m-/p-cresol in mixed phenols by complexation crystallization

Cresol is an important phenolic compound derived primarily from low-temperature coal tar. The presence of m/p-cresol increases the unsaturated bonds in coal tar. This increases the hydrogen consumption in the hydrogenation process. Separation and further purification of m/p-cresol can improve the value of coal tar. The boiling points of m-cresol and p-cresol are similar and therefore difficult to separate. It has become a major problem in the development of crude phenol refining. In this work, a novel complexing agent, hexamethylenetetramine, was used to complex and separate cresols. The effects of crystallization temperature, complexing agent dosage, solvent dosage and crystallization time were investigated. The process was optimized using response the surface methodology. As a result, the purity of m-cresol could reach more than 94.2% and the yield reached more than 30.4%, indicating that the process could effectively separate the mixture of m-cresol and p-cresol.