Paper Citing NAMD - Abstract
Shi, Wei; Sorescu, Dan C.; Luebke, David R.; Keller, Murphy J.; Wickramanayake, Shan
Molecular Simulations and Experimental Studies of Solubility and Diffusivity for Pure and Mixed Gases of H-2, CO2, and Ar Absorbed in the Ionic Liquid 1-n-Hexyl-3-methylimidazolium Bis(Trifluoromethylsulfonyl)amide ([hmim][Tf2N])
JOURNAL OF PHYSICAL CHEMISTRY B, 114:6531-6541, MAY 20 2010
Classical molecular dynamics and Monte Carlo simulations are used to calculate the self-diffusivity and solubility of pure and mixed CO2, H-2, and Ar gases absorbed in the ionic liquid 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]). Overall, the computed absorption isotherms, Henry's law constants, and partial molar enthalpies for pure H-2 agree well with the experimental data obtained by Maurer et al. [J. Chem. Eng. Data 2006, 51, 1364] and the experimental values determined in this work. However, the agreement is poor between the simulations and the experimental data by Noble et al. Find. Eng. Chem. Res. 2008, 47, 3453] and Costa Gomes [J. Chem. Eng. Data 2007, 52, 472] at high temperatures. The computed H-2 permeability values are in good agreement with the experimental data at 313 K obtained by Luebke et al. [J. Membr. Sci. 2007, 298, 41; ibid, 2008, 322, 28], but about three times larger than the experimental value at 573 K from the same group. Our computed H-2 solubilities using different H-2 potential models have similar values and solute polarizations were found to have a negligible effect on the predicted gas solubilities for both the H-2 and Ar. The interaction between H-2 and the ionic liquid is weak, about three times smaller than between the ionic liquid and Ar and six times smaller than that of CO2 with the ionic liquid, results that are consistent with a decreasing solubility from CO2 to Ar and to H-2. The molar volume of the ionic liquid was found to be the determining factor for the H-2 solubility. For mixed H-2 and Ar gases, the solubilities for both solutes decrease compared to the respective pure gas solubilities. For mixed gases of CO2 and H-2, the solubility selectivity of CO2 over H-2 decreases from about 30 at 313 K to about 3 at 573 K. For the permeability, the simulated values for CO2 in [hmim][Tf2N] are about 20-60% different than the experimental data by Luebke et al. [J. Membr. Sci. 2008, 322, 28].
