物理化学学报 >> 2008, Vol. 24 >> Issue (11): 2128-2132.doi: 10.3866/PKU.WHXB20081132

研究简报 上一篇    下一篇

分子在纯硅β分子筛内扩散的随机行走模型

杨晓峰; 秦张峰; 王建国   

  1. 中国科学院山西煤炭化学研究所, 煤转化国家重点实验室, 太原 030001; 中北大学物理系, 太原 030051; 中国科学院研究生院, 北京 100049
  • 收稿日期:2008-07-02 修回日期:2008-07-31 发布日期:2008-11-10
  • 通讯作者: 王建国 E-mail:iccjgw@sxicc.ac.cn

A Random Walk Model for Molecular Anisotropic Diffusion in Siliceous β-Zeolites

YANG Xiao-Feng; QIN Zhang-Feng; WANG Jian-Guo   

  1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R. China; Department of Physics, North University of China, Taiyuan 030051, P. R. China; Graduate University of the Chinese Academy of Sciences, Beijing 100041, P. R. China
  • Received:2008-07-02 Revised:2008-07-31 Published:2008-11-10
  • Contact: WANG Jian-Guo E-mail:iccjgw@sxicc.ac.cn

摘要: 建立了一个β分子筛上分子扩散的模型. 该模型中, 分子在β分子筛中运动是在不同吸附点位上作无规行走. β孔道的拓扑结构和在两种孔道吸附位上不同的跃迁几率导致分子沿两个主轴方向扩散, 扩散系数存在一个关联关系; 分子动力学对不同温度下苯分子在β分子筛上扩散模拟证实了这一关联关系. 氩原子在不同作用半径下的动力学模拟表明, 分子作用半径大小是满足随机行走假设的重要条件, 即该模型要求扩散分子作用半径足够大, 与分子筛孔径相近.

关键词: 分子动力学, β分子筛, 扩散系数, 随机行走

Abstract: A model of molecules diffusion in β-zeolite was proposed by assuming that the movement of molecules was a random walk on different adsorption sites. Owing to the topological structures and differences of transition probabilities between adsorption sites through two type of pores, there existed a correlation between diffusion coefficients along two principal axes, which was proved by molecular dynamics simulation of benzene diffusion in β zeolite at different temperatures. The diffusions of argon with different interaction radii showed that the interaction radius was crucial to the fitness of the randomwalk model; the interaction radius must be large enough (near the size of zeolite pores).

Key words: Molecular dynamics, β-zeolite, Diffusion coefficient, Random walk

MSC2000: 

  • O642