On the reversibility of hydrogen storage in Ti- and Nb-catalyzed Ca(BH4)2

✍ Scribed by Jae-Hun Kim; Jae-Hyeok Shim; Young Whan Cho

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 548 KB
• Volume: 181
• Category: Article
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2008.02.094

✦ Synopsis

The hydrogen sorption properties of calcium borohydride (Ca(BH 4 ) 2 ) catalyzed with a small amount of TiF 3 , TiCl 3 , NbF 5 or NbCl 5 are investigated using thermal analyses and X-ray diffraction. NbF 5 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(BH 4 ) 2 with NbF 5 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(BH 4 ) 2 with NbF 5 is a CaH 2-x F x solid solution with a CaF 2 (C1) structure, while pure Ca(BH 4 ) 2 produces CaH 2 after hydrogen desorption.