Condensable vapor permeation through miroporous silica membranes studied with molecular dynamics simulation
Condensable vapor permeation through miroporous silica membranes studied with molecular dynamics simulation
复制标题
用分子动力学模拟研究微孔二氧化硅膜的可冷凝蒸汽渗透
DOI：
10.1016/s1383-5866(03)00059-5
复制
发表时间：
2003
影响因子：
8.6
通讯作者：
M. Asaeda
中科院分区：
文献类型：
--
作者：
Tomohisa Yoshioka;T. Tsuru;M. Asaeda
对通过熔融淬火程序制备的虚拟无定形二氧化硅膜进行了可冷凝蒸气通过亚纳米级孔隙渗透的分子动力学（MD）模拟。 C2H6(TC=305 K)类LJ颗粒通过直径8 Å孔径的模拟渗透率在相对较高的温度区域(400-800 K)表现出类似表面扩散的温度依赖性，而在300 K左右，渗透率随着温度的降低而降低。即，在磁导的温度依赖性曲线中观察到最大值。渗透可冷凝蒸汽的临界温度 TC 可能是微孔渗透性能的影响因素。 260 K 时模拟的 C2H6 渗透率随着平均压力的增加而降低。在低压下，预计不会发生微孔填充，即使在低于TC的温度下也观察到几乎像气体一样的渗透，而在相对高压的微孔填充条件下，渗透率突然下降。在同一晶胞上也进行了吸附模拟，微孔填充相中吸附分子的迁移率小于低密度相中的吸附分子的迁移率。通过对渗透率的温度和压力依赖性的研究，可以得出结论，微孔填充相的发展导致渗透率下降，并且由于凝结填充相通过微孔的传输是一个激活的过程。
Molecular dynamics (MD) simulations of condensable vapor permeation through sub-nano scale pores were conducted for a virtual amorphous silica membrane, prepared by melt–quench procedures. The simulated permeance of C2H6(TC=305 K)-like LJ particles through an 8 Å in diameter pore showed a surface diffusion-like temperature dependency in the relatively high temperature region (400–800 K), while at around 300 K, the permeance decreased with decreasing temperature. That is, a maximum was observed in the temperature dependency curve for permeance. The critical temperature, TCof the permeating condensable vapor could be a contributing factor in the permeation properties through the micropore. The simulated permeance of C2H6at 260 K decreased with increasing mean pressure. At low pressure, where micropore filling would not be expected to occur, an almost gas like permeation was observed even at temperatures below the TC, while under micrpore filling conditions at a relatively high pressure, the permeance abruptly decreased. Adsorption simulations were also conducted on the same unit cell, and the mobility of the adsorbed molecules in the micropore filling phase were smaller than those in the lower density phase. Through this investigation of temperature and pressure dependency of permeance, it can be concluded that the development of the micropore filling phase led to a decrease in permeance, and transport as the condensed filling phase through the micropore was an activated process.