The hydrogen desorption reaction of magnesium hydride (MgH2), MgH2 Mg + H2, is accelerated by mixing catalytic metal oxides (e.g., Nb2O5). This catalytic effect is evaluated quantitatively using the atomization energy concept. The measured hydrogen desorption rate increases monotonously with increasing y × ΔE O values of metal oxides, MxOy. Here, ΔEO, is the atomization energy for the oxide ion in M xOy. This indicates that the oxide ion interacts mainly with hydrogen atom in MgH2, in agreement with the observation of the O-H stretching mode in the FT-IR spectra during the dehydrogenation of the Nb2O5-catalyzed MgH2. This approach is also proved to be useful for the catalytic analysis of metal chlorides (e.g., TiCl3) on the decomposition reaction of NaAlH4 expressed as, NaAlH4 (1/3)Na3AlH6 + (2/3)Al + H 2.
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