Efficient Separation of 1,3,5-Trioxane by the Ionic Liquid Heat Integration Extraction Distillation Process: Quantum Chemical Calculation and Multiperformance Evaluation

As a crucial raw material in the chemical industry, 1,3,5-trioxane (TOX) has an irreplaceable value. However, the synthesis liquid of TOX contains numerous impurities and various azeotropes that are challenging to separate through conventional distillation methods. Therefore, there is an urgent need to develop a new process for the efficient separation of high-purity TOX. In this study, 1,3-dimethylimidazolium dimethyl phosphate ionic liquid ([MIMM][DMP]) was used as an entrainer for the extractive distillation of the TOX mixture. We performed quantum chemical calculations, including electrostatic potential analysis, RDG analysis, and intermolecular interaction energy, to study the extractive distillation mechanism at the molecular level. Meanwhile, an ionic liquid extractive distillation process (IL-EDP) was developed using [MIMM][DMP], and the developed process was then optimized using a sequential iterative procedure to ensure that the optimum parameters for the process were obtained. Four process integration flows were developed with a vapor recompression heat pump and heat integration technology. The results showed that the ionic liquid heat integration extractive distillation process-II (IL-HI-EDP-II) reduced the total annual cost by 29.95%, the total operation cost by 37.38%, the total capital cost by 12.90%, and the total acid gas emission and energy consumption by 42.01% compared with the IL-EDP. IL-HI-EDP-II has an outstanding economic, environmental, and energy impact and is of great value in advancing TOX separation technology.