Solid-State NMR Study of Li-Assisted Dehydrogenation of Ammonia Borane

TitleSolid-State NMR Study of Li-Assisted Dehydrogenation of Ammonia Borane
Publication TypeJournal Article
Year of Publication2012
AuthorsKobayashi T, Hlova IZ, Singh NK, Pecharsky VK, Pruski M
Journal TitleInorganic Chemistry
Volume51
Pages4108-4115
Date Published04
Type of ArticleArticle
ISBN Number0020-1669
Accession NumberWOS:000302186600031
Keywordsalkali-metal amidoboranes, angle-spinning, boron-nitride, chemical hydrogen storage, complex hydrides, lithium hydride, mas-nmr, nmr, QUADRUPOLAR NUCLEI, systems, thermal-decomposition
Abstract

The mechanism of thermochemical dehydrogenation of the 1:3 mixture of Li3AlH6 and NH3BH3 (AB) has been studied by the extensive use of solid-state NMR spectroscopy and theoretical calculations. The activation energy for the dehydrogenation is estimated to be 110 kJ mol(-1), which is lower than for pristine AB (184 kJ mol(-1)). The major hydrogen release from the mixture occurs at 60 and 72 degrees C, which compares favorably with pristine AB and related hydrogen storage materials, such as lithium amidoborane (LiNH2BH3, LiAB). The NMR studies suggest that Li3AlH6 improves the dehydrogenation kinetics of AB by forming an intermediate compound (LiAB)(x)(AB)(1-x). A part of AB in the mixture transforms into LiAB to form this intermediate, which accelerates the subsequent formation of branched polyaminoborane species and further release of hydrogen. The detailed reaction mechanism, in particular the role of lithium, revealed in the present study highlights new opportunities for using ammonia borane and its derivatives as hydrogen storage materials.

URL<Go to ISI>://WOS:000302186600031
DOI10.1021/ic202368a
Alternate JournalInorg. Chem.