Synergetic Effect of Oxides on Hydrogen Reaction Kinetics of Magnesium Hydride
The kinetics of hydrogen reaction (absorption and desorption) on the MgH2 have been reported to be improved significantly by addition of transition metal oxides as catalysts. Among the oxides reported previously, Cr2O3 seems to improve hydrogen absorption kinetics and Nb2O5 for desorption kinetics. The catalytic effect of addition of more than one oxide, however, has not been reported yet. We investigated the hydrogen reaction kinetics of ball milled MgH2 powders added with either Cr2O3 or ZnO together with Nb2O5. In absorption reaction, the hydrogen contents reached 6 wt% and 5.3 wt% in 5 min for the powders added with 1 mol% ZnO + 1 mol% Nb2O5 and with 1 mol% Cr2O3 + 1 mol% Nb2O5, respectively. Those powders desorbed hydrogen up to about 4.5 wt% in 20 min. The significant improvement was not expected if one of the oxides was added separately. The combination of two kinds of oxides might play an important role for improvement of reaction kinetics.
Young Won Chang, Nack J. Kim and Chong Soo Lee
A. Patah et al., "Synergetic Effect of Oxides on Hydrogen Reaction Kinetics of Magnesium Hydride", Materials Science Forum, Vols. 561-565, pp. 1605-1608, 2007