Enhanced extraction of methanol and dimethyl carbonate by hydrogen bond breaking-reconstruction with deep eutectic solvents

Abstract

The separation of methanol and dimethyl carbonate (DMC) is of great significance in industry. Extraction separation can be used for methanol-DMC separation due to simple operation and low energy consumption. The ionic liquid (IL) extractants can achieve good separation efficiency, but there is a problem of large loss of DMC entrainment. In this work, in order to reduce DMC entrainment, we introduced hydrogen bond donors into ILs to form deep eutectic solvents (DESs), so as to weaken the interaction between extractant and DMC. The characterization results indicated that the introduction of hydrogen bonding donors significantly reduces the viscosity of the system. Further extraction experimental results demonstrated that this strategy can effectively reduce the entrainment of DMC by 30 % while maintaining an extraction efficiency of up to 80 %. By conducting interaction energy calculations, electrostatic potential (ESP) charge analysis, interaction region indicator (IRI) analysis, and quantum theory of atoms in molecules (QTAIM) analysis for each system, the mechanism of hydrogen bond breaking and hydrogen bond reconstruction between DESs and components in methanol-DMC system was discovered, thus elucidating the mechanism of reducing DMC entrainment at the molecular level.