Economically Viable Process for Synthesizing and Purifying Ionic Liquids: 1-Butyl-3-methyl Imidazolium Tetrafluoroborate

Ionic liquids (ILs) have been utilized in a variety of applications owing to their nonflammability, low volatility, and tunable chemical properties. However, removing impurities during the synthesis process is complex and costly. In this work, we introduce a novel and cost-effective method to purify [bmim][BF4], an IL, by inducing phase separation using a halocarbon refrigerant such as chlorodifluoromethane (Rf-22). The technique utilizes a ternary phase diagram consisting of [bmim][BF4], water, and halocarbons to achieve a purity greater than 99% and simplify the purification process. Large-scale process simulations based on experimental data were performed using the ASPEN Plus process simulator. The minimum [bmim][BF4] sales price of the developed process was estimated to be $12,004 per metric ton, making it an economically viable option for [bmim][BF4] production.