水合八面沸石型沸石的分子动力学研究

Molecular dynamics study of hydrated faujasite-type zeolites.

作者信息

Shirono Katsuhiro, Endo Akira, Daiguji Hirofumi

机构信息

Institute of Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 113-0033, Japan.

出版信息

J Phys Chem B. 2005 Mar 3;109(8):3446-53. doi: 10.1021/jp047293t.

DOI:10.1021/jp047293t

PMID:16851378

Abstract

Molecular dynamics (MD) simulations of hydrated zeolite NaX (Si/Al = 1.0) and NaY (Si/Al = 2.0) were done at a temperature of 300 K. The calculation results show that the adsorption of water occurs via a three-step mechanism in zeolite NaX: (1) adsorption around Na, (2) formation of a monolayer on the walls, and (3) pore filling in the supercage during which adsorbed water molecules are localized around the 12-membered rings. Zeolite NaY adsorbs in a similar manner. However, at intermediate hydration states, cluster formation occurs around Na instead of monolayer formation. The calculated energy distribution functions suggest that in zeolite NaX, the water vapor adsorption can be expressed by using the Langmuir model with two adsorption sites, but in zeolite NaY, it is not Langmuir-type adsorption.

摘要

在300 K的温度下对水合沸石NaX（硅铝比=1.0）和NaY（硅铝比=2.0）进行了分子动力学（MD）模拟。计算结果表明，在沸石NaX中，水的吸附通过三步机制发生：（1）在Na周围吸附，（2）在壁上形成单层，（3）在超笼中进行孔填充，在此期间吸附的水分子定位于12元环周围。沸石NaY以类似的方式吸附。然而，在中等水合状态下，在Na周围发生团簇形成而不是单层形成。计算得到的能量分布函数表明，在沸石NaX中，水蒸气吸附可以用具有两个吸附位点的朗缪尔模型来表示，但在沸石NaY中，它不是朗缪尔型吸附。