(321i) Computer-Aid Simulation of Gas Solubility and Diffusivity in Room Temperature Ionic Liquids – Initial Progress Report for Computer Aided Design of R T I L-Based Separating Agents

Room Temperature Ionic Liquids (RTILs) are ?green? replacements for volatile organics used in synthesis and separations. RTILs are salts that are liquids at room temperature. RTILs possess a number of properties useful for separating agents including high thermal stability, negligible vapor pressure, and nonflammability. Previous research has shown that RTILs can significantly improve many separation processes including membrane or electrochemical systems. One advantage of RTIL chemistry is the potential for there to be ?trillions? of RTILs to choose from in order to fine tune a required solvent system. This advantage is also a disadvantage since there are also ?trillions? of RTILs to synthesis, prior to testing their thermodynamic and transport properties. Here, we report on the initial stages of a project to develop an efficient and accurate computational tool for screening RTILs for any proposed separation, prior to the RTIL synthesis (akin to computer aided drug design in the pharmaceutical industry). We started with the published models that predict RTIL gas solubility via an RTIL molar volume correlation for molten salt cohesive energies. The published correlation assumes spherical ions with even charge distribution. Our project uses an experimental/computational collaboration to develop computations and simulations for more realistic molecular structures, cohesive energies, and charge distributions. By establishing a correlation between these computed properties and gas solubility (and possibly diffusivity), it will be possible to efficiently screen RTILs prior to their synthesis. The training set for this work is the gas solubilities/diffusivities (CO2 and hydrocarbons), RTIL surface tensions and viscosities for Imidazolium-, phosphonium-, and ammonium-based RTILs.