Mg-Ni-La based small hydrogen storage tank: kinetics, reversibility and reaction mechanisms.

The improvement of de/rehydrogenation kinetics and reversibility of a Mg-Ni-La based small hydrogen storage tank by doping with TiF 4 and MWCNTs is reported for the first time. During sample preparation, MgH 2 milled with 20 wt% LaNi 5 and 5 wt% TiF 4 and MWCNTs produces Mg 2 NiH 4 and LaH 3 . Two-step dehydrogenation of Mg 2 NiH 4 and MgH 2 is detected at 295 and 350 °C, respectively. Hydrogen desorption and absorption of the tank complete within 150 and 16 min, respectively, together with reversible hydrogen storage capacity up to 4.00 wt% H 2 (68% of theoretical value) upon 16 de/rehydrogenation cycles. Heat release from exothermic hydrogenation is removed effectively at the end of a double tube heat exchanger, where the reaction heat and heat transfer fluid are first in contact. Co-catalytic effects of Mg 2 NiH 4 and LaH 3 as well as good hydrogen diffusion benefit dehydrogenation kinetics and reversibility of the tank.