Molecular Dynamics Simulation of Diffusion and Structure of Some n-Alkanes in near Critical and Supercritical Carbon Dioxide at Infinite Dilution

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• 作者：Huajie Feng ; Wei Gao ; Zhenfan Sun ; Bingxin Lei ; Gaonan Li ; Liuping Chen
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：October 17, 2013
• 年：2013
• 卷：117
• 期：41
• 页码：12525-12534
• 全文大小：900K
• 年卷期：v.117,no.41(October 17, 2013)
• ISSN：1520-5207

文摘

The diffusion coefficients of n-alkanes (from CH₄ to C₁₄H₃₀) in near critical and supercritical carbon dioxide at infinite dilution have been studied by molecular dynamics simulation. The simulation results agree well with experiment, which suggests that the simulation method is a powerful tool to obtain diffusion coefficients of solutes in fluids at high pressures. The local structures of such fluids are further investigated by calculating radial distribution functions and coordination numbers. Meanwhile, the dihedral, end-to-end distance and radius of gyration, which are calculated to characterize the flexibility of n-alkanes, are used to reasonably explain the abnormal trends on radial distribution functions and coordination numbers. Moreover, it is found that the flexibility effects on diffusion in pure n-alkanes and infinitely dilute n-alkane/CO₂ system are different. The differences in MD simulation results of molecular diffusion in such systems could be qualitatively explained by the flexibility.