摘要
在不同的准等温和变化的压力条件下,对LaNi4.7Al0.3贮氢合金的氢化/脱氢动力学进行了PCT模型的模拟研究。一个理想的合金氢化/脱氢反应动力学方程是设计反应过程单元的重要工具。根据多项式PCT方程与形核成长模型得到适合于LaNi4.7Al0.3贮氢合金氢化/脱氢动力学的模型方程。该合金PCT平台区斜率较大,将平台区按氢化/脱氢量划分为3个区域,利用Vant’Hoff方程计算出各区域反应焓变和熵变。模拟研究结果表明,该模型方程中活化能Ea=32kJ/mol,Avrami指数n的取值范围为1.1～1.33时,计算曲线与实验结果能较好地吻合,氢化/脱氢过程由反应初期的一维形核长大控制向后期的低维扩散控制转变。
The PCT properties and hydriding/dehydriding kinetics were simulated for LaNi4.7Al0.3 under quasi-isothermal and variable pressure conditions.An ideal kinetic expression for the hydriding/dehydriding reaction is an important tool in the designing process of reaction unit.This paper is based on PCT polynomial equation and nucleation and growth model,and appropriate model equations were obtained for hydriding/dehydriding reaction of LaNi4.7Al0.3 hydrogen storage alloy.There was a large slope in the PCT plateau of the alloy.The plateau was divided into three regions according to hydrogen content of hydriding/dehydriding,and enthalpy and entropy values are calculated for each regions using Van＇t Hoff equation.The results show that the activation energy value was Ea=32kJ/mol,and the Avrami index n were within the narrow range of 1.1-1.33 in the model equation.The theoretical curves and the experimental data show a good agreement.The mechanism of hydriding/dehydriding changes from one-dimensional nucleation and growth in the prior period to lower diffusion in the later period for controlling reaction process.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2013年第7期1053-1058,共6页
Journal of Functional Materials
基金
国家自然科学基金资助项目(51106118)
西安市科技局技术转移促进工程资助项目(CX1254-7)
西安市碑林区科技计划资助项目(GX1204)
