Calorimetric investigations on kinetics of the dehydrogenation process in the system lanthanum-magnesium-hydrogen

A kinetic study of the dehydrogenation of several magnesium-based alloys/compounds with lanthanum is presented and the results are referred to the kinetics of the dehydrogenation process of pure magnesium hydride. Measurements were performed in a differential scanning calorimeter (DSC) by applying various pressure steps to the samples at isothermal conditions. Different thermokinetic models were fitted to the experimental obtained DSC curves as well as the power curves, calculated from the DSC curves, to evaluate the kinetic parameters. The derived dehydrogenation rate is discussed in terms of their dependence on hydrogen pressure and temperature. Under certain conditions, it is possible to visualise individual rate-determining steps. Considering these results first mechanistic considerations on the dehydrogenation reaction of the magnesium-based alloys/compounds can be drawn. (C) 2002 Elsevier Science B.V. All rights reserved.