Molecular Simulation Studies on Membrane Permeation and Molecular Design of Membranes

膜渗透的分子模拟研究和膜的分子设计

基本信息

批准号：
09450286
负责人：
NITTA Tomoshige
金额：
$ 7.74万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450286/
关键词：
Inorganic Membrane Carbon Membrane Molecular Dynamics Non-Equilibrium Zeolite Membrane Quantum Chemistry Wave function

项目摘要

The objectives of the present work are twofold : molecular simulation studies of gas permeation mechanisms through inorganic membranes and an attempt of surface modification method by use of ab initio quantum chemical calculations. Followings are important results : (1) The gammaVT-NEMD method has been effectively used to simulate permeation of pure and mixed gases through carbon membranes ; it is found that the separation mechanism of mixed gases through a membrane composed of heterogeneous surfaces of belt-like potential barrier changes from adsorption-control to diffusion-control as the potential barrier increases. (2) One of interesting observations is a blocking phenomenon where ethane molecules, which are strongly adsorbed on carbon surfaces, cover outer mouths of slit pores, resulting in preventing small methane molecules to enter. (3) Simulations of permeation of helium, nitrogen, carbon dioxide, methane, ethane through the pure silica ZSM-5 membrane have been carried out and d … More ensity profiles of gases are found to provide quantitative estimations of permeation-resistance through the entrance, inside and exit of the membrane. (4) A wavepacket analysis method was firstly. introduced to investigate the statistical behavior of molecules that penetrate a slit-shaped micropore ; the effect of kinetic energy vertical to the wall surface on gas permeation from inside to outside was investigated by the new method.A strategy has been suggested to modify surface atoms through ab initio quantum chemical calculations : the GAUSSIAN is used to optimize the geometry of a molecule and a cluster imitating a surface and the GAMESS is used to decompose the molecular interaction energy into various energy terms : electrostatic, exchange, polarization, charge-transfer and others. It is found that the charge-transfer term is the largest in the above interaction terms for molecular interactions between CO^2 and a cluster of MgO (electron charge is transferred from the surface to the CO^2 molecule) ; therefore, Ca atoms, which have smaller electronegativity than Mg atoms, are selected to enhance the charge-transfer effect from surface to the CO^2 atom. A partial exchange of Mg atoms with Ca atoms resulted in lower potential energy for adsorption of CO^2 on the modified surface as expected, which suggests that the proposed method will be a rational tool for the evaluation of atoms to be modified. Less

本工作的目标是双重的：通过无机机制对气体渗透机制进行分子模拟研究，并尝试通过使用量子量子化学计算来尝试进行表面修饰方法。以下是重要的结果：（1）Gammavt-Nemd方法已被有效地用于模拟通过碳膜的纯净和混合气体的渗透；发现通过膜的混合气体的分离机理（2）有趣的观察结果之一是一种阻止现象，在这种现象中，在碳表面上强烈吸附，覆盖缝隙孔的外口，导致防止小甲烷分子进入。（3）已经进行了氦气，氮，二氧化碳，甲烷，蚀刻液的渗透模拟，通过纯硅ZSM-5膜进行了模拟，D…更多的气体能量曲线可提供通过膜内部和膜的渗透性抑制的定量估计。（4）首先是波袋分析方法。引入的是为了研究穿透裂变微孔的分子的统计行为。通过新方法研究了动能垂直到壁表面对从内部到外部气体渗透的影响。已经提出了一种策略通过量子量子化学计算来修饰表面原子：使用高斯来优化分子的几何形状，并使用表面和gamess模仿的群集和gamess的群集用于分解了偏离能量的能量，并分解了分解分子互动，并将各种互动化为各种电源：电动互动，并将各种分解为电源，并将各种互动化为各种互动。发现电荷转移项是上述相互作用项中的最大值，用于CO^2和一组MGO之间的分子相互作用（电子电荷从表面转移到Co^2分子）；因此，选择比Mg原子的电性较小的Ca原子被选择以增强从表面到Co^2原子的电荷转移效应。与CA原子的部分交换的Mg原子会根据预期在修饰的表面上增加CO^2的势能较低，这表明该方法将是评估要修改原子的合理工具。较少的