(5am) Development of One-Component Reversible Ionic Liquids for Energy Applications

We have recently reported the synthesis and characterization of one-component reversible ionic liquids, and presented here is the direct application of the novel solvent systems to carbon capture and extraction of crude oil from tar sands/oil shale. We look to develop optimal solvent systems for the given application by examining how the molecular structure of our reversible ionic liquid solvent systems affects their physical and thermodynamic properties, namely the viscosity, equilibrium constant (K), enthalpy of reaction (ΔHrxn), and Gibbs free energy (ΔGrxn). Addition of carbon dioxide (CO2) to a liquid tri-substituted silylpropyl amine causes the conversion of the molecular liquid to a room-temperature ionic liquid, which is easily reversed by stripping with an inert gas or the addition of heat. This molecular-to-ionic liquid conversion results in a drastic change in the chemical and physical properties of the solvent, advantageous for the development of sustainable processes. An example of this switch is seen where non-polar alkanes are soluble in the molecular liquid but insoluble in the ionic liquid, leading to the development of a process for tar sands/oil shale extraction.

We have systematically examined the effect of altering the molecular structure on K by using ATR-FTIR at CO2 pressures up to 70 bar and temperatures up to 150°C. Knowledge of K as a function of temperature and pressure allows for determination of ΔHrxn and ΔGrxn at different processing conditions, critical values for the optimization of solvent systems that can be economically viable for commercial applications. Such reversible ionic liquids have been shown to combine a homogeneous reaction with heterogeneous separation, for facile product purification and catalyst recycle. Another application that we are investigating is the recovery of CO2 from large point-source emitters. Our reversible ionic liquids combine the notable CO2 carrying capacities of conventional ionic liquids with chemical sorption through reaction, and can be optimized for a given feed stream by use of structure-property relationships.