Stability of Catalyzed Magnesium Hydride Nanocrystalline During Hydrogen Cycling. Part I: Kinetic Analysis

Magnesium hydride is widely recognized as a promising material for hydrogen storage and thermal energy storage. Cyclic stability of the kinetics of catalyzed MgH 2 was systematically investigated in this study. Three systems including MgH 2 –TiH 2, MgH 2 –TiMn 2, and MgH 2 –VTiCr were prepared by high energy ball milling. Volumetric hydrogen desorption and absorption cycles were performed using the pressure–composition–isothermal (PCI) method. Results show that the kinetics of high-temperature (300 °C) hydrogenation and dehydrogenation maintained a good stability during 100 hydrogen cycles. However, when testing the hydrogenation kinetics at the low-temperature range from 25 to 150 °C, a severe degradation was observed after hydrogen cycles. Among the three materials, the MgH 2 –VTiCr system shows better cyclic performance. The degradation of low-temperature kinetics can be mainly related to the hydrogenation–dehydrogenation cycling reactions.