SCHEDULED MAINTENANCE
Ammonia borane–metal alanate composites: hydrogen desorption properties and decomposition processes
Abstract
Hydrogen desorption properties and decomposition processes of NH3BH3–MAlH4 (M = Na, Li) composites were investigated by using thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS), powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. We prepared the composites by ball-milling and the mixtures by hand-milling. The ball-milled composites desorbed 4–5 wt% hydrogen at three exothermic steps below 260 °C. The emissions of by-product gases, NH3, B2H6 and B3H6N3, were effectively suppressed. From XRD analysis, the formation of a mixed-metal (Na(Li), Al) amidoborane phase was suggested. Very different results were obtained using hand-milling. They showed only one exothermic reaction at 80–90 °C. The emission of by-product gases was not suppressed. By comparing the differences between ball-milled composites and hand-milled mixtures, the importance of mixed-metal amidoborane in this system was proposed.
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