Acta Phys. -Chim. Sin. ›› 1992, Vol. 8 ›› Issue (05): 586-594.doi: 10.3866/PKU.WHXB19920504

• ARTICLE • Previous Articles     Next Articles

Hydrogen Absorption Kinetics of LaNi5 Alloy

Hong Cun-Mao; Lin Qiu-Zhu; Han De-Gang   

  1. Department of Chemistry, Peking University, Beijing 100871
  • Received:1991-04-25 Revised:1991-09-23 Published:1992-10-15
  • Contact: Hong Cun-Mao

Abstract: Hydrogen absorption kinetics of LaNi_5-H system in α and α+β phases has been investigated. Taking the reversibility of hydrogen absorption and desorption into account, an analytical solution has been obtained for the α phase. In a temperature range of 20—50 ℃, the rate constant of hydrogen absorption, k_a, was found to be 0.08—0.41 s~(-1) and that of hydrogen desorption, k_a, 4.8—25 MPa·s~(-1) respectively. The apparent activation energy of hydrogen absorption was 35 kJ(mol H_2)~(-1). Hydrogen absorption in α+β phase was slower than that of the α-phase. The initial rate of hydrogen absorption is in first order with the hydrogen pressure used. The reaction is controlled by the dissociation of hydrogen on the alloy surface. With increasing of the reaction depth, the controlling step will shift to the reaction occuring on the α-β interface. The rate constants are weakly dependent on the temperature. The hydrogen absorption rates on the initial and final stage of the pressure plateau in α-β phase are obviously different.

Key words: Hydrogen, Alloy, Kinetics