Experimental Characterization of Functionalized Alkylimidazoles As Solvents for CO2 Capture

Previous work has characterized specific physical properties and CO₂ solubility of 1-n-alkylimidazole solvents for use in pre- and post-combustion CO₂ capture during gas treating.  This research project explores the CO₂ solubility and physical properties of functionalized alkylimidazole solvents to determine the effects of functional group position(s) on various chemical and physical attributes.  Using this information, additional correlations between ring substitution and physical properties can be derived to optimize the characteristics best suited for larger-scale pilot testing in industrial applications.  Synthesis and purification of these compounds were followed by tests to determine empirical equations concerning density, viscosity, and vapor pressure as functions of temperature and ring substitution, and these properties were shown to be comparable to previously-tested 1-n-alkylimidazoles.  The solvents in general were found to have low viscosities (<15 cp) and negligible vapor pressures (<0.5 mbar).  CO₂ solubility experiments also showed that functionalized alkylimidazoles have similar if not improved absorption capacities relative to ionic liquids and 1-n-alkylimidazoles.