Comparison of Extractive Distillation and Pressure-Swing Distillation for Methanol and Acetonitrile Separation

In the present work, a comparative study of the extractive distillation and pressure swing distillation for methanol-acetonitrile separation is performed for the first time. Different separation alternatives, including the conventional extractive distillation, the extractive distillation with vapor or liquid side-stream, the pressure-swing distillation with or without full heat integration, and the heat-pump assisted pressure-swing distillation are rigorously simulated and optimized based on the minimum total annual cost(TAC) via the sequential iterative strategy. The results show that TAC and CO2 emission of the new extractive distillation with vapor side-stream(Vapor-SED) are similar to those of the extractive distillation with liquid side-stream(Liquid-SED). Furthermore, the Vapor-SED and Liquid-SED can achieve 30.01% and 30.56% reduction in TAC and 23.32% and 23.49% reduction in CO2 emission, respectively, over the most competitive fully heat-integrated PSD configuration. Hence, the extractive distillation with vapor or liquid side-stream appears to be a better option economically and environmentally for the separation of methanol and acetonitrile.