Separation of azeotropes in the dimethoxymethane production process using deep eutectic solvents: Liquid–liquid extraction experiments and molecular insights

• The application of DESs to the separation of the DMM-MEOH azeotropic system was proposed for the first time. • The extraction mechanism was explored by MD simulations and QC calculations. • The liquid–liquid equilibrium data of MEOH-DMM-DMS1/DES2/DES3 were obtained. This study proposes a liquid–liquid extraction strategy that integrates thermodynamic screening, molecular simulations, and experimental validation to assess the potential of deep eutectic solvents (DESs) for separating the dimethoxymethane (DMM)–methanol (MEOH) azeotrope. Firstly, the COSMO-RS model was employed to predict the thermodynamic properties of various DESs to screen the optimal extractant. Then, quantum chemical calculations (QC) and molecular dynamics (MD) simulations were conducted to elucidate the separation mechanism of DESs in the DMM–MEOH system. Finally, liquid–liquid equilibrium experiments confirmed the consistency with theoretical predictions. Among the tested systems, DES1 (ChCl:EG = 1:3) demonstrated the best stability and recyclability, followed by DES2 (ChCl:EG = 1:4) and DES3 (ChCl:EG = 1:5). This work not only verifies the potential application of DESs in separating DMM–MEOH azeotropic mixtures, but also provides theoretical guidance and data support for the development of green separation processes in this system.