摘要
利用动力学MonteCarlo(KMC)模拟方法计算了苯在Y沸石中扩散的自扩散系数,并考察了3种不同W W位间跳跃扩散机制下的自扩散系数及其对温度和浓度的依赖关系.实验测量结果表明,苯在Y沸石中的长程运动主要是经SⅡW SⅡ笼间的跳跃,基本不发生W W之间的跳跃.相应得到的自扩散系数对温度的依赖关系较接近实验值;自扩散系数浓度依赖变化趋势为:先随覆盖量的增加而减小,到覆盖量大于S位的饱和覆盖量(每个超笼中4个分子)后,则随覆盖量增加先增后减,但也不会大于零覆盖量时扩散系数值,该情形与考虑W W之间跳跃时完全不同.此外,模拟结果表明,使用正确的跳跃机制是KMC方法能正确模拟客体分子在沸石内扩散行为的关键.
Kinetic Monte Carlo （KMC） simulations of self-diffusivities of benzene in zeolite Y were performed for three possible jump diffusion mechanisms of the diffusant, and the corresponding dependence of self-diffusivity on loadings and temperature was investigated. It was demonstrated that different jump mechanisms resulted in significantly different temperature and concentration dependence relationships of self-diffusivity in zeolite Y. It was found and verified by comparison with literature data that SⅡ-W -SⅡ cage to cage jump was the dominant mechanism for diffusion of benzene in zeolite Y, while W-W jump played no role in the process. In this case, simulated temperature and concentration dependence relationships were closer to the experimental results than that predicted by the other two mechanisms.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2006年第5期1147-1152,共6页
CIESC Journal
基金
教育部科学技术研究重点项目(02017)
国家重点基础研究发展规划项目(2004CB217804).~~
关键词
苯
Y沸石
KMC模拟
跳跃频率
benzene
zeolite Y
KMC simulation
jump frequency
