HYDRIDE DEVELOPMENT FOR HYDROGEN STORAGE K. J. Gross, G. J. Thomas and G. Sandrock Sandia National Laboratories Livermore, CA 94550 Abstract The hydrogen storage properties of NaAlH 4 mechanically catalyzed with 2 mol % each of the liquid alkoxides Ti(OBu n ) 4 + Zr(OPr) 4 have been studied using a small (1.5 g sample) reactor and a 100 g “scaleup” reactor. The aim was to assess the potential for using this new hydride family for fuel-cell vehicle applications and to identify potential problems. Studies included low temperature equilibrium thermodynamic measurements, discharging and recharging kinetics and thermal effects, cyclic capacity, room temperature desorption kinetics, H 2 purity analysis and other practical properties. For the first time, low temperature equilibrium pressure measurements were made which showed that a hydrogen pressure of 1 atm can be obtained at 33°C by desorbing NaAlH 4 to Na 3 AlH 6 . Also, recharging was possible at lower temperatures and pressures than generally reported. Cycling tests, however, indicated a much lower than expected capacity after the first desorption. The use of alkoxide-based Ti and Zr catalysts introduces oxygen and hydrocarbon impurities into the sample which were still present after several cycles and may contribute to the observed low reversible capacity. For this reason we have started to investigate inorganic catalysts as well as dry doping processes. Our latest results show reversible capacities close to the theoretical value of 5.6 wt.% (note added in proof).