A study on the kinetics of hydriding of the LaNi5 system

Enhancement of hydrogen-storage performance of MgH2 by Mg2Ni formation and hydride-forming Ti addition

“…Stander et al [34] reported that the dehydriding rate of Mg hydride was controlled by the movement of the phase boundary at hydrogen pressures appreciably different from the equilibrium dissociation pressure. We tried to determine a ratecontrolling step for the dehydriding reaction of the hydrided MgH 2 e10Nie4Ti, the rate of which showed strong temperature dependence, by using a spherical moving boundary model [35] on an assumption that particles have a spherical shape with a uniform diameter. Plots for the case in which the rate-controlling step for the dehydriding reaction of the activated MgH 2 e10Nie4Ti is the diffusion of hydrogen atoms through a growing a-solid solution did not show good linearities.…”

Adsorption Characteristics of LaNi5Particles

“…The result of this research shows that the adsorption rate of nitrogen on activated LaNi is roughly proportional linearly to the gas pressure. As mentioned in the Introduction, Park and Lee (16) reported that the hydriding rates of LaNi showed a first-order dependence on hydrogen pressure and that they are controlled by the hydrogen adsorption step on particle surfaces.…”

“…According to the study of Park and Lee on the hydriding kinetics of LaNi (16), the hydriding rate of LaNi shows a first-order dependence on hydrogen pressure in the lower range of fractional conversion, and is controlled by the hydrogen adsorption on the particle surface. However, studies of the adsorption characteristics of LaNi are few.…”

Kinetics of hydrogen absorption and desorption in LaNi5‐xAlx slurries

“…These are crystalline metal alloys which absorb hydrogen in free interstitial sites of the crystal structure, the type of bonding is of a metallic nature (Reilly, 1977). Several mass transfer and reaction steps take place when hydrogen is absorbed in a metal hydride, see for example, Flanagan (1978) and Park and Lee (1982). On the surface of the particles, two different regions have been recognized: Ni and La203/La(OH), (Wallace et al, 1979).…”

“…As soon as the nuclei growth rate has become large enough, either of the two surface processes, chemisorption or dissociation of hydrogen, will be the rate determining step. Park and Lee (1982) presented relations for the hydrogen absorption rate in a hydride ( = dn,/dt) in the case that one of those steps is rate limiting:…”