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Hydrogen storage in zeolites: activation of the pore space through incorporation of guest materials

Turnbull, Matthew Simon (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

Solid state hydrogen storage materials have become a key area of research over the past 20 years. In this work, the potential of zeolites to occlude hydrogen storage materials as guests to make composite materials was explored. Lithium borohydride was successfully loaded in zeolites NaA, NaX and NaY; showing a two phased system. Desorption of hydrogen from the occluded lithium borohydride was 5\(^\circ\)C lower than that of bulk lithium borohydride, but with slower kinetics, implying diffusion effects of occlusion into the host. Adsorption showed reduced uptakes of hydrogen at 77 K compared with the host zeolite, which was consistent with the degree of loading. Limited hydrogenation was achieved with milder conditions at 350\(^\circ\)C at 15 bar hydrogen of the desorbed lithium borohydride. Heats of adsorption were estimated for the samples both before and after high temperature desorption of hydrogen. Lithium borohydride was also loaded into zeolitic carbons and lithium, copper (II) and ammonium ion-exchanged zeolites. Copper exchanged zeolite catalysed desorption of hydrogen from lithium borohydride was most promising and occurred at room temperature. Lithium and ammonium exchanged zeolite showed a 10\(^\circ\)C reduction in desorption temperature, the ammonium system showing the best diffusion kinetics, with a sharp desorption similar to the bulk lithium borohydride. NaA and NaX were occluded with ammonia borane and lithium borohydride amide [Li\(_4\)BH\(_4\)(NH\(_2\))\(_3\)]. NaY containing occluded sodium was found to hydrogenate at room temperature at pressures up to 15 bar. This was accompanied with trapping of hydrogen and an increased adsorption of hydrogen at low temperature, exceeding the gravimetric absorption value for zeolite NaY.

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
Subjects:QD Chemistry
Institution:University of Birmingham
ID Code:1034
This unpublished thesis/dissertation is copyright of the author and/or third parties.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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