Dynamics of Water in Hierarchical Mesoporous H-ZSM-5 by Fast Field-Cycling NMR Relaxometry

Autor:	Bharat S. Rana, Yu-Wen Chen, Chia-Wei Hsu, Anil K. Sinha, Rohit Kumar, Dennis W. Hwang
Rok vydání:	2014
Předmět:	Relaxometry education.field_of_study Phase transition Chemistry Population Analytical chemistry Surfaces Coatings and Films Electronic Optical and Magnetic Materials General Energy Adsorption Molecule Physical and Theoretical Chemistry ZSM-5 Zeolite education Mesoporous material
Zdroj:	The Journal of Physical Chemistry C. 118:20481-20487
ISSN:	1932-7455 1932-7447
DOI:	10.1021/jp506859h
Popis:	The dynamics of water molecules adsorbed in hierarchical mesoporous H-ZSM-5 was investigated by fast field-cycling NMR relaxometry. Three distinct sites in H-ZSM-5 that can host water molecules, designated a, b, and c, have been identified; no significant exchange of water molecules among these sites was observed. Investigations into the relative populations of molecules confined at sites c (Pc) and b (Pb) revealed that the population ratio (Pc/Pb) does not change significantly over the temperature and water-content ranges investigated. Furthermore, the motion of water at site b is very slow and shows almost no dependence on temperature. While H-ZSM-5 has pores of two different sizes (mesopores and micropores), the low population and observed slow motion of water at site b indicates a strong interaction between water molecules and the zeolite materials, which is possible only when water is adsorbed on the surface. The temperature of the phase transition of water provides insight into the properties of wat...
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::4da55ce4db0b24b6e22e491b4caddb13 https://doi.org/10.1021/jp506859h Zobrazit plný text záznamu