The Separation of Catechol from Carbofuran Phenol by Extractive Distillation

In this study, extractive distillation has been applied to separate catechol (CAT) from carbofuran phenol (CFP) with high purity and yield. The relative volatility of CFP to CAT was measured, and the choice of separating agents was investigated. The experimental results indicated that CFP/CAT is an azeotropic system with an azeotropic point at 93.40 degrees C/0.400 kPa and an azeotropic mixture containing 49.96% of CFP and 50.04% of CAT. Data from the determination of the relative volatility have shown that separating agents such as diglycol and 4-butylcatechol (4-TBC) are able to increase the relative volatility up to 1.90. In one shot process batch extractive distillation of CFP mixture with 3% (by mass) diglycol as separating agent, the purity and yield of the obtained CFP was 99.0% and 95.0%, respectively, while the distillation without separating agent provided a purity and yield of only 98.0% and 90.0%, respectively. There was no residual separating agent found in the product.