Modeling and analyzing the hydriding kinetics of Mg-LaNi5 composites by Chou model |
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Authors: | Yan-Biao PanYu-Feng Wu Qian Li |
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Affiliation: | Shanghai Key Laboratory of Modern Metallurgy & Materials Processing, Shanghai University, Shanghai 200072, China |
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Abstract: | Chou model was used to analyze the influences of LaNi5 content, preparation method, temperature and initial hydrogen pressure on the hydriding kinetics of Mg-LaNi5 composites. Higher LaNi5 content could improve hydriding kinetics of Mg but not change hydrogen diffusion as the rate-controlling step, which was validated by characteristic reaction time tc. The rate-controlling step was hydrogen diffusion in the hydriding reaction of Mg-30 wt.% LaNi5 prepared by microwave sintering (MS) and hydriding combustion synthesis (HCS), and surface penetration was the rate-controlling step of sample prepared by mechanical milling (MM). Rising temperature and initial hydrogen pressure could accelerate the absorption rate. The rate-controlling step of Mg-30 wt.% LaNi5 remained hydrogen diffusion at temperatures ranging from 302 to 573 K, while that of Mg-50 wt.% LaNi5 changed from surface penetration to hydrogen diffusion with increasing initial hydrogen pressure ranging from 0.2 to 1.5 MPa. Apparent activation energies of absorption for Mg-30 wt.% LaNi5 prepared by MS and MM were respectively 25.2 and 28.0 kJ/mol H2 calculated by Chou model. Kinetic curves fitted and predicted by Chou model using temperature and hydrogen pressure were well exhibited. |
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Keywords: | Hydrogen storage materials Mg-LaNi5 composites Kinetics Model |
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