ADSORPTION CHARACTERISTICS OF LANI5 PARTICLES

Nitrogen adsorption on an intermetallic compound, LaNi5, was studied b efore and after activation and after hydriding-dehydriding cycling, Th e specific surface area of activated LaNi5 was 0.271+/-0.004 m(2) g(-1 ). Adsorption and desorption isotherms of activated LaNi5 were obtaine d, The adsorption isotherm was similar to type II among the five types of isotherms classified by S, Brunauer, L, S, Deming, W S, Deming, an d E, Teller (J, Am, Chem. Soc, 62, 1723, 1940), Its hysteresis curve h ad the type B form among de Boer's five types of hysteresis, Desorptio n pore-size analyses showed that the activated LaNi5 had only a few me sopores, the diameters of which were around 20-110 Angstrom. The avera ge adsorption rate of the activated LaNi5 showed a first-order depende nce on nitrogen pressure at 77 K, (C) 1997 Academic Press.