摘要
研究了LaNi_5-H体系的吸氢反应动力学。在吸放氢可逆反应同时考虑的情况下,求得了速度方程的解析解。在α相区20—50℃的温度范围内,吸氢速度常数k_α为0.08—0.41s^(-1);脱氢速度常数k_d为4.8—25MPa·s^(-1)。吸氢反应的表观活化能E_α为35kJ(molH_2)^(-1)。在α+β相区的吸氢较α相区慢得多。起始阶段吸氢速度对氢压为一级,反应受氢化物表面上氢分子解离控制。随着吸氢反应深度的增大,吸氢速度变为固相中的界面反应控制。速度常数受温度的影响很小。α+β相区的压力平台前半段和后半段有着不同的吸氢速度。
Hydrogen absorption kinetics of LaNi_5-H system in α and α+β phases has beeninvestigated. Taking the reversibility of hydrogen absorption and desorption into ac-count,an analytical solution has been obtained for the α phase.In a temperature rangeof 20--50℃, the rate constant of hydrogen absorption, k_a, was found to be 0.08-0.41s^(-1) and that of hydrogen desorption, k_a, 4.8--25 MPa·s^(-1) respectively.The ap-parent activation energy of hydrogen absorption was 35kJ(mol H_2)^(-1). Hydrogen ab-sorption in α+β phase was slower than that of the α-phase.The initial rate of hydrogenabsorption is in first order with the hydrogen pressure used.The reaction is controlledby the dissociation of hydrogen on the alloy surface. With increasing of the reactiondepth, 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 absorptionrates on the initial and final stage of the pressure plateau in α+β phase are obviou-sly different.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1992年第5期586-594,共9页
Acta Physico-Chimica Sinica
基金
国家科委资助863项目
