Effect of Confinement On Ionic Liquid Properties for Carbon Capture Processes

Work in our laboratory has focused for a number of years on examining the potential of room temperature ionic liquids for post combustion carbon capture processes. Experimental work has involved measurements of carbon dioxide solubility and diffusivity in different ionic liquids as well as on gas permeation measurements through supported ionic liquid membranes (SILMs) prepared using anodic alumina films as the support membrane.

Results from these studies have raised questions about the impact of a solid interface on the properties of ionic liquids.  Gas permeation through SILM systems with different pore size indicates both carbon dioxide and nitrogen permeation is larger when the ionic liquid is confined within a 20 nm pore size membrane when compared to a 100 nm pore size membrane. Ideal selectivity values are generally the same in the two membrane systems.  A comparison of measured membrane permeation to values predicted from bulk solubility and diffusivity values shows higher carbon dioxide permeance in the membranes compared to values predicted from bulk properties of the ionic liquids.

Gas uptake into confined ionic liquids have also been experimentally measured, with solubility and diffusivity of carbon dioxide in the confined ionic liquids compared to bulk phase characteristics. To date, results have been mixed with results from some ionic liquids showing no impact of the solid interface whereas others indicate a significant difference in ionic liquid properties when confined. In this presentation.  Results from these studies will be presented and discussed.