Molecular Thermodynamics and Modelling of Materials Laboratory, Institute of Physical Chemistry, National Center for Scientific Research Demokritos, GR-153 10 Aghia Paraskevi Attikis, Greece.
J Phys Chem B. 2011 Feb 17;115(6):1429-39. doi: 10.1021/jp1063269. Epub 2011 Jan 21.
The self-diffusion and mutual diffusion coefficients of hydrogen (H(2)), carbon monoxide (CO), and water (H(2)O) in n-alkanes were studied by molecular dynamics simulation. n-Alkane molecules were modeled based on the TraPPE united atom force field. NPT molecular dynamics (MD) simulations were performed for n-C(12) to n-C(96) at different temperature and pressure values to validate the accuracy of the force field. In all cases, good agreement was obtained between literature experimental data and model predictions for the density and structure properties of the n-alkanes. Subsequently, the self-diffusion coefficient of the three light components in the various n-alkanes was calculated at different temperatures. Model predictions were in very good agreement with limited experimental data. Furthermore, the Maxwell-Stefan diffusion coefficients of H(2) and CO in two n-alkanes, namely n-C(12) and n-C(28), were calculated based on long MD NVT simulations for different solute concentrations in the n-alkanes. Finally, the Fick diffusion coefficient of the components was calculated as a product of the Maxwell-Stefan diffusion coefficient and a thermodynamic factor. The latter was estimated from the statistical associating fluid theory (SAFT). The Fick diffusion coefficient was found to be higher than the Maxwell-Stefan diffusion coefficient for H(2) and CO in n-C(28). The empirical Darken equation was used to estimate the Maxwell-Stefan diffusion coefficient, and calculations were found to be in good agreement with simulation results.
采用分子动力学模拟研究了氢（H(2)）、一氧化碳（CO）和水（H(2)O）在正构烷烃中的自扩散和互扩散系数。正构烷烃分子基于 TraPPE 一致原子力场建模。在不同温度和压力下对 n-C(12) 至 n-C(96) 进行 NPT 分子动力学（MD）模拟，以验证力场的准确性。在所有情况下，文献实验数据与模型对正构烷烃密度和结构性质的预测之间均具有良好的一致性。随后，在不同温度下计算了三种轻组分在各种正构烷烃中的自扩散系数。模型预测与有限的实验数据非常吻合。此外，基于长 MD NVT 模拟，针对正构烷烃中不同的溶质浓度，计算了两种正构烷烃（即 n-C(12) 和 n-C(28)）中 H(2)和 CO 的 Maxwell-Stefan 扩散系数。最后，通过统计关联流体理论（SAFT）计算组分的 Fick 扩散系数。后者由 Maxwell-Stefan 扩散系数和热力学因子的乘积得出。发现 H(2)和 CO 在 n-C(28)中的 Fick 扩散系数高于 Maxwell-Stefan 扩散系数。采用 Darken 经验方程估算 Maxwell-Stefan 扩散系数，计算结果与模拟结果吻合良好。
