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Hydrogen desorption and absorption for activated magnesium hydride

Prendergast, James W. (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

The interaction between MgH2 and LiBH4 was studied to determine the resultant effects on hydrogen desorption and absorption kinetics for potential use as a hydrogen storage material. It is found that the addition of LiBH4 in small molar ratios results in improved kinetics of the same order as those observed for mechanically milled magnesium. The mixture of MgH2 + LiBH4 in ratios at and below 4:1, once reacted, is a highly reversible material at 300°C and it is observed that the kinetics improve upon the process of hydrogen cycling. This improvement is partially attributed to a refinement in microstructure that results in highly porous particle agglomerates and it is this feature that is likely to have a large effect on the kinetics of hydrogenation due to the rate limiting step of the reaction being hydrogen diffusion into the particles of Mg which can be coated in MgH2 phase, through which H2 does not diffuse easily.

Additionally it is observed via Raman spectroscopy that a new bonding structure exists in the H2 cycled mixture after desorption which might improve the rehydrogenation of the sample and reduce the enthalpy of decomposition through an intermediate reaction pathway.

Type of Work:Ph.D. thesis.
Supervisor(s):Anderson, P.A. (Paul Alexander) (1965-)
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Chemistry
Keywords:Hydrogen Storage, Magnesium Hydride, Lithium Borohydride
Subjects:QD Chemistry
Institution:University of Birmingham
Copyright Holders:James Prendergast, Paul Anderson
ID Code:1143
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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