Fluids in nanospaces: Molecular simulation studies to find out key mechanisms for engineering

被引:24
作者
Miyahara M.T. [1 ]
Numaguchi R. [1 ]
Hiratsuka T. [1 ]
Nakai K. [2 ]
Tanaka H. [1 ]
机构
[1] Department of Chemical Engineering, Kyoto University, Katsura, Nishikyo
[2] BEL Japan Inc., Toyonaka, Osaka 561-0807, 1-9-1, Harada-naka
来源
Miyahara, M.T. (miyahara@cheme.kyoto-u.ac.jp) | 1600年 / Kluwer Academic Publishers卷 / 20期
基金
日本学术振兴会; 日本科学技术振兴机构;
关键词
Capillary condensation; Critical point depression; Fluids in nanospaces; Pore size distribution; Porous coordination polymers;
D O I
10.1007/s10450-013-9588-2
中图分类号
学科分类号
摘要
We have analyzed various phenomena that occur in nanopores, focusing on elucidating their key mechanisms, to advance the effective engineering use of nanoporous materials. As ideal experimental systems, molecular simulations can effectively provide information at the molecular level that leads to mechanistic insight. In this short review, several of our recent results are presented. The first topic is the critical point depression of Lennard-Jones fluid in silica slit pores due to finite size effects, studied by our original Monte Carlo (MC) technique. We demonstrate that the first layers of adsorbed molecules in contact with the pore walls act as a "fluid wall" and impose extra finite size effects on the fluid confined in the central portion of the pore. We next present a new kernel for pore size distribution (PSD) analysis, based entirely on molecular simulation, which consists of local isotherms for nitrogen adsorption in carbon slit pores at 77 K. The kernel is obtained by combining grand canonical Monte Carlo (GCMC) method and open pore cell MC method that was developed in the previous study. We show that overall trends of the PSDs of activated carbons calculated with our new kernel and with conventional kernel from non-local density functional theory are nearly the same; however, apparent difference can be seen between them. As the third topic, we apply a free energy analysis method with the aid of GCMC simulations to investigate the gating behavior observed in a porous coordination polymer, and propose a mechanism for the adsorption-induced structural transition based on both the theory of equilibrium and kinetics. Finally, we construct an atomistic silica pore model that mimics MCM-41, which has atomic-level surface roughness, and perform molecular simulations to understand the mechanism of capillary condensation with hysteresis. We calculate the work required for the gas-liquid transition from the simulation data, and show that the adsorption branch with hysteresis for MCM-41 arise from spontaneous capillary condensation from a metastable state. © 2013 Springer Science+Business Media New York.
引用
收藏
页码:213 / 223
页数:10
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