摘要
通过分子模拟方法获得NaY沸石中晶内扩散系数,进而采用Maxwell-Stefan(MS)方程描述晶内扩散、主体扩散和努森扩散特性,建立沸石膜及支撑层区域内的一维定态扩散模型,模型化预测苯在NaY沸石膜中的渗透特性。预测结果与文献实验值比较,定量证实苯在NaY沸石中的扩散机制主要是经SⅡ-W-SⅡ笼间跳跃而发生的长程运动;对本文计算体系,支撑层阻力使苯的渗透通量减小1个数量级,阻力的大小与支撑层结构及吹扫气体性质等因素有关,大孔和规则孔道可减小支撑层阻力,增大苯通量,小分子吹扫气体产生阻力相对较小。
By incorporating diffusion parameters derived from atomistic Kinetic Monte Carlo （KMC） simulations a mass transfer model for predicting permeation fluxes of benzene in NaY zeolite membrane and supports has been developed, in which surface diffusion in the membrane and the bulk and Knudsen diffusion are described by applying the Maxwell-Stefan theory. Comparison with experimental data suggests that the dominant mechanism for diffusion of benzene in NaY zeolite is SⅡ -W-SⅡ cage to cage jumps, and that the existence of the support layer results in a one order of magnitude decrease in flux. The support resistance was found to be related to the structure of the support layer and the properties of the sweep gas. Using larger pores, more regular channels and lower molecular weight sweep gases leads to larger fluxes. Our analysis indicates that combination of molecular simulations with transport models is a useful tool in the predictive design of such separators.
出处
《北京化工大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2007年第4期341-345,共5页
Journal of Beijing University of Chemical Technology(Natural Science Edition)
基金
国家重点基础研究发展规划项目(2004CB217804)
