Ionic Liquids for the Dehydration Process of 1,3,5-Trioxane: From Molecular Insights to Process Design

1,3,5-Trioxane (TOX) is an important organic synthetic intermediate, but the separation of water (H2O)/TOX, which can form an azeotrope, is the main challenge of the synthesis of TOX. Consequently, developing an innovative approach to efficiently recover TOX has become critically important. This study presents vapor–liquid equilibrium (VLE) measurements of TOX/H2O incorporating the ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM][Br]) conducted at atmospheric pressure. The results show that the addition of [EMIM][Br] can effectively break the azeotropic effect of the original components. Correlation of the acquired ternary VLE data sets was performed employing four distinct thermodynamic models: the Wilson, d-Wilson, NRTL, and e-NRTL equations. Comparative assessment demonstrated that the NRTL model achieved optimal consistency with the empirical observations. Furthermore, the mechanism of [EMIM][Br] separation of TOX/H2O was explored through electrostatic potential (ESP) analysis, calculation of binding energy, and COSMO-RS. Subsequently, the extractive distillation process (EDP) was designed by the Aspen Plus V11 software, and the NSGA-II algorithm was written to optimize the parameters of EDP. Finally, process intensification design was carried out using heat integration to reduce the total annual cost (TAC). This method provided a new idea for the design of extractive distillation for TOX/H2O and promoted the practical application of the ionic liquid in advancing TOX separation technology.