Hydrogen Absorption and Desorption by the Li−Al−N−H System.

Lithium hexahydridoaluminate Li3AlH6and lithium amide LiNH2with 1:2 molar ratio were mechanically milled, yielding a Li−Al−N−H system. LiNH2destabilized Li3AlH6during the dehydrogenation process of Li3AlH6, because the dehydrogenation starting temperature of the Li−Al−N−H system was lower than that of Li3AlH6. Temperature-programmed desorption scans of the Li−Al−N−H system indicated that a large amount of hydrogen (6.9 wt %) can be released between 370 and 773 K. After initial H2desorption, the H2absorption and the desorption capacities of the Li−Al−N−H system with a nano-Ni catalyst exhibited 3−4 wt % at 10−0.004 MPa and 473−573 K, while the capacities of the system without the catalyst were 1−2 wt %. The remarkably increased capacity was due to the fact that the kinetics was improved by addition of the nano-Ni catalyst. [ABSTRACT FROM AUTHOR]