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dc.contributor.authorBenge, Kathryn Ruthen_NZ
dc.date.accessioned2008-02-19T08:55:36Z
dc.date.available2008-08-07T16:17:34Z
dc.date.issued2008en_NZ
dc.identifier.citationBenge, K. R. (2008). Hybrid Solid-State Hydrogen Storage Materials (Thesis, Master of Science (MSc)). The University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/2320en
dc.identifier.urihttps://hdl.handle.net/10289/2320
dc.description.abstractThis thesis investigates the chemistry of ammonia borane (NH3BH3) relevant to the development of hydrogen storage systems for vehicular applications. Because of its high hydrogen content and low molecular weight ammonia borane has the potential to meet stringent gravimetric hydrogen storage targets of gt;9 wt%. Two of the three moles of H2 in ammonia borane can be released under relatively mild conditions, with the highest gravimetric yield obtained in the solid-state. However, ammonia borane does not deliver sufficient H2 at practical temperatures and the products formed upon H2 loss are not amenable to regeneration back to the parent compound. The literature synthesis of ammonia borane was modified to facilitate large scale synthesis, and the deuterated analogues ND3BH3 and NH3BD3 were prepared for the purpose of mechanistic studies. The effect of lithium amide on the kinetics of dehydrogenation of ammonia borane was assessed by means of solid-state reaction in a series of specific molar ratios. Upon mixing lithium amide and ammonia borane, an exothermic reaction ensued resulting in the formation of a weakly bound adduct with an H2N...BH3-NH3 environment. Thermal decomposition at or above temperatures of 50eg;C of this phase was shown to liberate gt;9 wt% H2. The mechanism of hydrogen evolution was investigated by means of reacting lithium amide and deuterated ammonia borane isotopologues, followed by analysis of the isotopic composition of evolved gaseous products by mass spectrometry. From these results, an intermolecular multi-step reaction mechanism was proposed, with the rates of the first stage strongly dependent on the concentration of lithium amide present. Compounds exhibiting a BN3 environment (identified by means of solid-state sup1;sup1;B NMR spectroscopy) were formed during the first stage, and subsequently cross link to form a non-volatile solid. Further heating of this non-volatile solid phase ultimately resulted in the formation of crystalline Li3BN2 - identified by means of powder X-ray diffractometry. This compound has been identified as a potential hydrogen storage material due to its lightweight and theoretically high hydrogen content. It may also be amenable to hydrogen re-absorption. The LiNH2/CH3NH2BH3 system was also investigated. Thermal decomposition occurred through the same mechanism described for the LiNH2/NH3BH3 system to theoretically evolve gt;8 wt% hydrogen. The gases evolved on thermal decomposition were predominantly H2 with traces of methane detected by mass spectrometry.en_NZ
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherThe University of Waikatoen_NZ
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectammonia boraneen_NZ
dc.subjectHydrogen storageen_NZ
dc.subjectHydrogenen_NZ
dc.subjectmethylamine boraneen_NZ
dc.subjectlithium amideen_NZ
dc.subject11B NMRen_NZ
dc.subjectsolid-state NMRen_NZ
dc.titleHybrid Solid-State Hydrogen Storage Materialsen_NZ
dc.typeThesisen_NZ
thesis.degree.disciplineChemistryen_NZ
thesis.degree.grantorUniversity of Waikatoen_NZ
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (MSc)en_NZ
uow.date.accession2008-02-19T08:55:36Zen_NZ
uow.date.available2008-08-07T16:17:34Zen_NZ
uow.identifier.adthttp://adt.waikato.ac.nz/public/adt-uow20080219.085536en_NZ
uow.date.migrated2009-06-09T23:30:37Zen_NZ
pubs.place-of-publicationHamilton, New Zealanden_NZ


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