Newsome David A, Sholl David S
Department of Chemical Engineering, Carnegie-Mellon University, Pittsburgh, Pennsylvania 15213, USA.
J Phys Chem B. 2006 Nov 16;110(45):22681-9. doi: 10.1021/jp063287g.
The net mass transfer resistance for gas molecules permeating through zeolite membranes includes contributions from intracrystalline diffusion and contributions from interfacial effects. These interfacial effects can arise either from gas-zeolite interfaces or from interfaces that exist within zeolite crystals due to grain boundaries. We present the first atomically detailed simulations that examine interfacial mass transfer resistance due to internal grain boundaries in zeolites that are relevant for membrane applications. Our calculations examine twinned silicalite crystals in crystallographic configurations that have been identified in previous experiments. We used the dual control volume grand canonical molecular dynamics method to simulate the permeance of CH(4) and CF(4) through thin twinned silicalite crystals. The magnitudes of the grain boundary resistances are quite substantial, at least for the thin crystals that are accessible in our simulations.
气体分子透过沸石膜的净传质阻力包括晶内扩散的贡献和界面效应的贡献。这些界面效应可能源于气体与沸石的界面，也可能源于由于晶界而存在于沸石晶体内部的界面。我们首次进行了原子尺度的详细模拟，研究了与膜应用相关的沸石内部晶界引起的界面传质阻力。我们的计算考察了在先前实验中已确定的晶体结构中的孪晶硅沸石晶体。我们使用双控制体积巨正则分子动力学方法来模拟CH(4)和CF(4)透过薄孪晶硅沸石晶体的渗透率。晶界阻力的大小相当可观，至少对于我们模拟中可及的薄晶体是这样。
