Molecular simulation and optimization of extractive distillation for separation of dimethyl carbonate and methanol

Dimethyl carbonate, an important green solvent, has garnered substantial attention in recent years. The routes for dimethyl carbonate synthesis include transesterification, alcoholation of urea by methanol, and oxidative carbonylation of alcohols. The transesterification process accounts for the largest proportion of dimethyl carbonate synthesis because it affords a high conversion rate of the raw materials, easy separation of the products, and is the most mature process. The azeotrope of dimethyl carbonate and methanol in the top of the columns used for preparing dimethyl carbonate by transesterification needs to be further separated. Herein, the optimal ionic liquid ([BMIM] [OTF]) for the separation of dimethyl carbonate and methanol via extractive distillation was determined by applying a molecular dynamics simulation algorithm and utilized in the separation process. As an efficient and green energy-saving process, pervaporation-assisted extractive distillation was further evaluated for the separation of dimethyl carbonate and methanol. The results showed that the pervaporation-assisted extractive distillation process offers economic benefits and has less environmental impact, and its total annual cost is 17.28% lower than that of the common extractive distillation process. Environmental analysis showed that carbon dioxide emissions, sulfur dioxide emissions, and nitric oxide emissions were reduced by 49.09% with this process. Therefore, this research has important guiding significance for the realization of the high-efficiency, energy-saving, and green separation of dimethyl carbonate and methanol in industries.