(709d) Experimental Characterization Of Multiply-Substituted Alkylimidazoles As Solvents and Polymeric Membranes 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 multiply-branched 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 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 multiply-branched alkylimidazoles have similar if not improved absorption capacities relative to ionic liquids and 1-n-alkylimidazoles.  In future work, polymeric membranes can be synthesized from these compounds to determine CO₂ permeability and selectivity as a function of ring substitution.  The ultimate goal of this research is to find an imidazole-based solvent with low volatility and high CO₂ absorption capacity or an imidazole-based membrane structure with high CO₂ permeability and selectivity that can be easily manufactured for application in large-scale industry for the reduction of atmospheric CO₂ emissions.