Interaction of hydrogen with an Mg-Al alloy (poster)

A. Andreasen, J.W. Andreasen, R. Burkarl, B. Møller, M. Sørensen, M.M. Nielsen, A. Molenbroek, Allan Schrøder Pedersen, T.R. Jensen

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsResearch

    Abstract

    The properties of magnesium as a hydrogen storage medium may be positively altered by the addition of Al: thermodynamic properties, kinetics and heat transfer of the hydride bed can be improved. The interaction of hydrogen with a Mg-Al alloy pre-exposedto air has been studied with in-situ time resolved powder X-ray diffraction. The experimental setup features acquisition of full diffraction patterns within 150 s allowing structural characterization during kinetic studies. Phase fractions as a functionof time is derived from series of consecutive diffraction patterns. The apparent activation energy for dehydrogenation of the Mg-Al alloy is found to be approx. 160 kJ/mol. This is not significantly higher than for pure and fully activated Mg.Furthermore, it is found that Mg-Al is hydrogenated to MgH2 + Al and upon dehydrogenation a Mg-Al alloy is reformed. Pure Mg is not observed during dehydrogenation, suggesting that the formation of Mg-Al is fast compared to the liberation of hydrogen fromMgH2. From thermodynamical calculations using the semi-empirical Miedema model a slightly lower heat of hydride formation is found. Based on comparison with previous experiments on Mg exposed to air it is suggested that the addition of Al improves theresistance towards oxygen contamination compared to that of pure Mg.
    Original languageEnglish
    Title of host publicationBook of abstracts
    EditorsH. Figiel, P. Mietniowski, A. Paja
    Place of PublicationCracow
    PublisherUniversity of Science and Technology
    Publication date2004
    ISBN (Print)83-921064-0-7
    Publication statusPublished - 2004
    Event9th International Symposium on Metal-Hydrogen Systems: Fundamentals and Applications - Cracow, Poland
    Duration: 5 Sep 200410 Sep 2004
    Conference number: 9

    Conference

    Conference9th International Symposium on Metal-Hydrogen Systems
    Number9
    CountryPoland
    CityCracow
    Period05/09/200410/09/2004

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