ITQ-3分子筛中二元混合分子扩散性质的模拟

采用平衡分子动力学方法先是模拟研究了纯组分Ar、SF_6以及CF4在ITQ-3分子筛中的扩散行为,结果表明,在窄孔道中Ar的扩散系数随负载的增加呈现先增加再减小的变化趋势,在宽孔道中则随负载逐渐减小。纯组分的大分子SF_6以及CF4只在y方向扩散,扩散系数与小分子在z方向的变化规律一致。随后,又模拟了二元混合组分SF_6和CF4在ITQ-3分子筛中的扩散行为,模拟结果与各自纯组分SF_6和CF4进行了对比,发现二元混合的SF_6和CF4整体变化趋势与其单组分保持一致,在y方向的扩散系数都是随着负载的增加而先增大后减小,但是两者之间还存在一种相互作用,使得在整个负载范围内扩散较快的CF4的扩散系数比纯组分的扩散系数相对小一些,而纯组分时扩散相对缓慢的SF_6在二元混合中的扩散系数则相对增大。

Molecular Dynamics Simulation on DiffusionProperties of the Binary Components in ITQ-3 Zeolite

The equilibrium molecular dynamic simulation was carried out to study the diffusion behavior of pure component and the binary components in the ITQ-3 zeolite. For pure,the diffusion coeffieient along the z direction is an increasing function as the loading increase, after reaching a maximum value at some intermediate loading,the diffusion coefficient decrease at higher loading. But in the y direction ,the diffusion coefficient decreases momotonically as the loading is increased. For and, the diffusion coefficients along the y direction were same as the function of in the z direction. Then the diffusion coefficients of binary components/in ITQ-3 zeolize have been studied using molecular dynamic simulation methods. We noted that the diffusion coefficients of binary components retained the trend of their pure component. But diffused much more slowly in the mixture than as a pure species. Compared to the pure , the diffusion coefficient of in the mixture was increased. This appeared to be due to the influence of coupling effect between diffusing species.