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Investigation on specific adsorption of hydrogen on lithium-doped mesoporous silica.

Authors :
Kubo, Masaru
Ushiyama, Hiroshi
Shimojima, Atsushi
Okubo, Tatsuya
Source :
Adsorption; Feb2011, Vol. 17 Issue 1, p211-218, 8p, 10 Diagrams, 5 Graphs
Publication Year :
2011

Abstract

This paper reports the synthesis, structure, and hydrogen adsorption property of Li-doped mesoporous silica (MPS) with a 2D hexagonal structure. The Li-doping is achieved by impregnation of the cylindrical mesopores with an ethanol solution of lithium chloride followed by heat treatment. Detailed characterization by solid-state NMR, TG-MS, and FT-IR suggests that, during the heat treatment, lithium chloride reacts with surface ethoxy groups (≡Si-OEt) to form ≡SiOLi groups, while ethyl chloride is released into the gas phase. The hydrogen uptake at 77 K and 1 atm increases from 0.68 wt% for the undoped MPS to 0.81 wt% for Li-doped MPS (Li-MPS). The isosteric heat of adsorption is 4.8 kJ mol, which is consistent with the quantum chemistry calculation result (5.12 kJ mol). The specific hydrogen adsorption on Li-MPS would be explained by the frontier orbital interaction between HOMO of hydrogen molecules and LUMO of ≡SiOLi. These findings provide an important insight into the development of hydrogen storage materials with specific adsorption sites. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09295607
Volume :
17
Issue :
1
Database :
Complementary Index
Journal :
Adsorption
Publication Type :
Academic Journal
Accession number :
57642304
Full Text :
https://doi.org/10.1007/s10450-010-9316-0