A Study of Permeation of n-Butane through ZSM-5 Membrane by Using Monte Carlo and Equilibrium/Non-Equilibrium Molecular Dynamics Simulations
A Study of Permeation of n-Butane through ZSM-5 Membrane by Using Monte Carlo and Equilibrium/Non-Equilibrium Molecular Dynamics Simulations
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利用蒙特卡罗和平衡/非平衡分子动力学模拟研究正丁烷通过 ZSM-5 膜的渗透
DOI：
10.1252/jcej.36.313
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发表时间：
2003
影响因子：
0.8
通讯作者：
T. Nitta
中科院分区：
文献类型：
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作者：
S. Furukawa;T. Nitta
对正丁烷在ZSM-5分子筛膜中的渗透和吸附进行了分子模拟。在所有的模拟中，一个灵活的潜在模型用于正丁烷，因为渗透分子的最小尺寸几乎是相同的ZSM-5晶体的孔径。正丁烷在ZSM-5分子筛膜上的平衡密度与实验数据吻合较好，符合Langmuir吸附等温模型。用μVT-NEMD方法计算的正丁烷渗透率随温度的变化存在一个极大值，与实验结果定性一致。注意到，在室温下，膜中的整个孔被分子填充。通过与Fick扩散系数、Maxwell-Stefan扩散系数（DF，DMS）和渗透方向自扩散系数（Ds，x）的局部值比较，证实了DMS几乎与膜中的分子负载无关，在高负载时DF > DMS > Ds，x。此外，三个扩散系数几乎相同的零负荷。通过在非线性等温线的情况下提供对分配系数（S）和扩散系数（D）的修改，我们已经清楚地表明，在低温下的渗透由扩散过程控制，其中整个孔被分子填充，然后控制步骤变为在较高温度下的吸附过程，其中孔的特征在于中等负载。
Molecular simulations have been performed on permeation and adsorption of n-butane in a ZSM-5 zeolite membrane. In all simulations, a flexible potential model is used for n-butane since the smallest size of the permeating molecule is almost the same as the pore size of the ZSM-5 crystal. Equilibrium densities of n-butane in the ZSM-5 membrane calculated from the MC method are in good agreement with experimental adsorption data, being represented by the Langmuir adsorption isotherm model. Permeability of n-butane calculated from the μVT-NEMD method has a maximum against temperature, which agrees qualitatively with the experimental results. It is noted that the whole pores in the membrane are filled with molecules at room temperature. As compared with the local values of the Fick and the Maxwell–Stefan diffusion coefficients (DF, DMS) and the self-diffusion coefficients in the permeate direction (Ds, x), we confirm that the DMS is almost independent of molecular loadings in the membrane, and that DF > DMS > Ds, x at high loadings. In addition, the three diffusion coefficients are almost identical at the zero loading. By providing a modification for the distribution coefficient (S) and diffusion coefficient (D) in the case of nonlinear isotherms, we have clearly demonstrated that the permeation at low temperatures is controlled by the diffusion process, where whole pores are filled with molecules, and then the controlling step changes to the adsorption process at higher temperature where the pores are characterized by medium loadings.
J. Teraoka 等人：“Metmyogloblin 氰化物复合物中的异常强烈振动圆二色性”J. Am。
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