Application of the Aldolization Reaction in Separating the Mixture of Ethylene Glycol and 1,2-Butanediol: Thermodynamics and New Separation Process

The separation of ethylene glycol (EG) and 1,2-butanediol (1,2-BDO) azeotrope is a key technical problem in the synthesis process of EG via dimethyl oxalate (DMO) from syngas. On the basis of systematic investigation, aldolization is expected to be the solution to this industrial problem. Thus, the essential thermodynamics data were determined and correlated well by the corresponding thermodynamic equation, including the vapor pressure of 2-methyl-1,3-dioxolane (2MD) and 4-ethyl-2-methyl-1,3-dioxolane (4EMD), vapor–liquid equilibrium (VLE) data of binary mixture 2MD–4EMD at 101.3 kPa, and liquid–liquid equilibrium (LLE) data of binary system 4EMD–water at atmospheric conditions. The vapor–liquid–liquid equilibrium (VLLE) of binary system 4EMD–water has been successful predicted by LLE experimental data. Finally, the thermodynamics parameters were provided as a reference to design a separation process of the EG and 1,2-BDO mixture. The simulation and optimization results indicate that EG and 1,2-BDO could been separated effectively, which presents the potential of applying aldolization in synthesis of EG basic coal.