Carbon dioxide capture is of great importance for chemical research due to carbon dioxide’s potential as a greenhouse gas. Ionic liquids have been suggested as possible alternatives to traditional aqueous amine solutions currently used for capture because ionic liquids can absorb more CO2 per mole and because lower desorption energies can be achieved. Previous computational work has shown that the presence of electron-withdrawing substituents on phenolate and cyclohexanolate ions decreases the interaction energy of CO2 . Using density functional theory, we sought to understand what effect other electron-withdrawing or electron-donating substituents would have on the interaction energy of phenolate- and cyclohexanolate-derived anions. We calculated the energies associated with the interactions between CO2 and various substituted cyclohexanolates and phenolates to observe the correlation between ring structure, bond length, and reaction energy. Partway through our research, we became intrigued by other research on SO2 capture showing high molar ratios of SO2 to ionic liquid. Thus, we calculated the energies of a CO2 -anion interaction for various amine- and phosphinefunctionalized anions, in an attempt to understand the possibilities of greater than a 1:1 molar capture ratio of CO2 to ionic liquid.
Timothy Pavlik, ’16
Sponsor: Craig Teague