No abstract

Hydrogen storage properties and reactivity for hydrogenation of acetylene in a series of CeNi 5-x Ga x (x = 0, 0.5, 0.75, 1, 1.25, 1.5) alloys and Mg 2 Ni were determined and compared. The structure of CeNi 5 (CaCu 5 type) was maintained up to CeNi 3.5 Ga 1.5 when Ni was replaced by Ga. The replacement facilitated hydrogenation absorption by creating larger interstitial spaces through expansion of the lattice, allowing CeNi 4.25 Ga 0.75 to absorb the greatest proportion of hydrogen atoms among the alloys under the same conditions. The results showed that the absorbed hydrogen in CeNi 3.75 Ga 1.25 improved reactivity. In contrast, Mg 2 Ni formed a hydride upon hydrogenation of acetylene and thus possessed much lower activity. The difference of the activity of absorbed hydrogen between CeNi 5-x Ga x and Mg 2 Ni was confirmed from transient response tests under reaction gases alternately containing He and H 2 .