Hugo S. MARQUES1, Adilson A. FREITAS 1, José N. CANONGIA LOPES 1, Karina SHIMIZU1
1Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
Global warming and climate change caused by greenhouse gas emissions have become paramount challenges faced worldwide. To help overcome these challenges, several ionic liquids (ILs) will be studied.
The high solubility of polar gases in ILs is related to their large dipole or quadrupole moments and their capacity for specific interactions with the solvent (hydrogen bonding), while the solubility of nonpolar gases is governed by their polarizability. In general, SO2 is the most soluble gas because of its strong interactions with ILs, followed by NH3, CO2 and CH4. In all cases the solubility decreases with temperature increase. The CO2 solubility in [C4C1im] ILs increases with fluorine content of the IL anion, showing that the nature of the anion also has significant effect in gas solubility.
Therefore, in this work ionic liquids in bulk phase with cations based in 1-alkyl-3-methylimidazolium family (alkyl = ethyl, butyl, hexyl and octyl) and different fluorine-containing anions [Ntf2, CnF(2n+1)SO3, CF3CO2, BF4, PF6] were studied by molecular dynamics simulations.
Preliminary results indicate that the density decreases with increasing the amount of CO2. Moreover, the solubility of CO2 increases with increasing the alkyl side chain. The MD trajectories analysis show that the CO2 is in the vicinity of the anion. A close inspection suggest that the CO2 is located near the fluorine atoms.