On the reversibility of hydrogen storage in Ti- and Nb-catalyzed Ca(BH4)2 |
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Authors: | Jae-Hun Kim Jae-Hyeok Shim Young Whan Cho |
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Affiliation: | aMaterials Science and Technology Research Division, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea |
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Abstract: | The hydrogen sorption properties of calcium borohydride (Ca(BH4)2) catalyzed with a small amount of TiF3, TiCl3, NbF5 or NbCl5 are investigated using thermal analyses and X-ray diffraction. NbF5 exhibits the best performance among all the catalysts; it causes a decrease in the hydrogen desorption temperature which leads to hydrogen absorption at practical temperature and pressure conditions. The hydrogen content of Ca(BH4)2 with NbF5 reaches about 5.0 wt.% after hydrogen absorption at 693 K for 24 h under 90 bar of hydrogen. The main dehydrogenation product of Ca(BH4)2 with NbF5 is a CaH2−xFx solid solution with a CaF2 (C1) structure, while pure Ca(BH4)2 produces CaH2 after hydrogen desorption. |
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Keywords: | Hydrogen storage Calcium borohydride Catalyst Ball milling Thermal analysis Fuel cell |
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