Monte Carlo Simulations of Carbon Dioxide Dissolved in Imidazolium-Based Ionic Liquids
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In this thesis, we first report a molecular simulation study of the liquid-vapor phase behavior of 1-octyl-3-methylimidazolium tetrafluoroborate, [C 8 mim][BF 4 ]. We calculate the liquid-vapor saturation properties of [C 8 mim][BF 4 ] for temperatures spanning from 250K to 1100K. Simulations are completed with a realistic united-atom force field. Monte Carlo simulations are performed using a combination of direct grand canonical simulations and isothermal-isobaric temperature expanded ensemble simulations, which has been developed by our group. Next we examine the solubility of carbon dioxide dissolved in 1-butyl-3-methylimidazolium tetrafluoroborate (C4mim][BF 4 ]), 1-octyl-3-methylimidazolium tetrafluoroborate ([C 8 mim][BF 4 ]), and homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C n mim][NTf 2 ]) ( n = 2, 4, 8), at select temperatures. Monte Carlo simulations are performed in a N 1 , μ 2 , P,T ensemble with a TraPPE force field for carbon dioxide and a realistic united-atom force field for the ionic liquids. The predicted carbon dioxide solubility in these ionic liquids consists with experimental data. Our results show that the increase in the alkyl chain length on the cation of the ionic liquids increases the carbon dioxide solubility; the solubility of carbon dioxide is strongly dependent on the choice of anion; and the solubility of CO 2 decreases as temperature increases.