Experimental and simulation studies on the simultaneous removal of methanol and water from dimethyl ether crude gas by choline-based deep eutectic solvents

This study examines the viability of utilizing deep eutectic solvents for the separation of methanol and water from crude dimethyl ether. To begin with, the COSMO-SAC model is employed to screen various deep eutectic solvents, The results indicate that deep eutectic solvents formed by choline chloride as the hydrogen bond acceptor and glycerol as the hydrogen bond donor exhibit excellent selectivity. Additionally, the non-ideal nature of the system is initially assessed using the σ-profile and excess enthalpy. Subsequently, the vapor–liquid equilibrium data for dimethyl ether /methanol/water and deep eutectic solvents are determined through model predictions and saturation vapor pressure experiments. Furthermore, Quantum computation is used to generate the electrostatic potential surfaces and distribution of extremum points of the van der Waals surface of molecules, explaining the interaction sites between molecules. Molecular dynamics simulations are employed to analyze the spatial distribution functions and radial distribution functions of multi-molecular systems. Lastly, a process flow for the removal of methanol and water from dimethyl ether is established. Under the optimal operating conditions, the combined concentration of methanol and water in dimethyl ether is successfully reduced to below 50 ppm, thus demonstrating the feasibility of this approach.