Effect of operating pressure on design of extractive distillation process separating DMC-MeOH azeotropic mixture

Although dimethyl carbonate is defined as a green chemical, separation of dimethyl carbonate-methanol azeotropic mixture is an important issue for many dimethyl carbonate production processes. Extractive distillation process is considered as a favorable method for separating this mixture, but the recovery of entrainer still results in a significant loss of capital and operating costs. On the other hand, operating pressure is an important design variable for distillation columns since it has an important impact on column temperature and phase equilibrium. In this work, the effect of operating pressure is investigated for an extractive distillation process separating the dimethyl carbonate-methanol mixture using methyl isobutyl ketone as entrainer. It is observed that the increase in the operating pressure of extractive distillation column significantly decreases the amount of required entrainer flowrate. As the result, a process with an extractive distillation column operating at 10 bar reduces total annual cost and carbon dioxide emissions by 34.1% and 29.8%, respectively compared to the conventional process with an extractive distillation column operating at atmospheric pressure.