Atomization energy approach to the quantitative evaluation of catalytic activities of metal oxides during dehydrogenation of MgH2

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 × ΔEO values of metal oxides, MxOy. Here, ΔEO, is the atomization energy for the oxide ion in MxOy. 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 + H2

Research highlights▶ Study of catalytic reaction on MgH2 and NaAlH4 using atomization energy concept. ▶ Quantitative evaluation of catalytic activities of metal oxide for MgH2. ▶ Quantitative evaluation of catalytic activities of metal chlorides for NaAlH4. ▶ Observation of the O–H stretching mode on Nb2O5-catalyzed MgH2 in FT-IR.