Investigations on the desorption kinetics of Mm-doped NaAlH4

This paper reports mischmetal (Mm) as an effective catalyst for fast desorption kinetics (3.7 wt% in 60 min in which similar to 3.3 wt% observed in 30 min and similar to 5 wt% in 180 min at the desorption temperature of 150 degrees C for the 2 mol% Mm-doped material) and rehydrogenation (up to 35 cycles) of the light weight hydrogen storage material NaAlH4. In fact this catalyst Mm has been shown to be better than the presently known catalyst Ti. For Mm, its presence when admixed in NaAlH4 is discernible. Also the higher reversible hydrogen storage capacity (4.77 wt% which is 86% of the total reversible storage capacity) of the total is achievable in the l2th cycle. The possible modes of catalyst Mm for fast desorption kinetics has been outlined and the most feasible mechanism in terms of weakening of Na and AlH4 bonding has been put forward. (c) 2006 Elsevier B.V. All rights reserved.