On the Kinetics of ALH3 Decomposition and the Subsequent AL Oxidation

Metal hydrides are used for hydrogen storage. AlH3 shows a capacity of about 10wt%2and the hydrogen is split-off in the temperature interval of 400-500K. On dehydrogenation a nano- structured Al material emerges which is oxidized on air access up to 25%2 forming a 3-4 nm alumina layer. The heat released from this Al oxidation induces a high risk to this type of hydrogen storage if the containment might be destroyed, accidentally. The kinetics of the dehydrogenation and the subsequent oxidation is investigated by methods of thermal analysis. A reaction scheme is confirmed which consists of a starting Avrami-Erofeev mechanism followed by formal 1st order oxidation. The kinetic parameters are evaluated and can be used to calculate the reaction progress together with heat of reaction of Al oxidation.