NbF 5 additive improves hydrogen release from magnesium borohydride

Ahmad Al-Kukhun, Hyun Tae Hwang, Arvind Varma

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The dehydrogenation properties of Mg(BH 4) 2 with various additives (SiO 2, VCl 3, CoCl 2 and NbF 5) were investigated. The addition of NbF 5 significantly improved the extent of hydrogen release as well as the kinetics. While neat Mg(BH 4) 2 starts to release hydrogen >270 °C, Mg(BH 4) 2 with NbF 5 begins hydrogen release ∼75 °C, as confirmed by mass spectrometry and thermogravimetry. The maximum hydrogen yield of Mg(BH 4) 2, obtained in the presence of 15 wt% NbF 5, was 3.7, 7.4, 10.0, 11.4 wt% for 150, 250, 300 and 350 °C, respectively. Using pXRD, we confirmed that the final crystalline product at 300 °C from Mg(BH 4) 2 + 15 wt% NbF 5 was Mg, while it was MgH 2 for neat Mg(BH 4) 2. Solid state 11B NMR analysis of Mg(BH 4) 2 with 15 wt% NbF 5 at 300 °C showed significant selectivity toward the formation of Mg(B 12H 12) as intermediate, while neat Mg(BH 4) 2 showed β-Mg(BH 4) 2, Mg(B 2H 6) as well as some Mg(B 12H 12). Our results demonstrate that NbF 5 is a promising additive to provide high hydrogen yield values from Mg(BH 4) 2 at moderate temperatures <300 °C.

Original languageEnglish
Pages (from-to)17671-17677
Number of pages7
JournalInternational Journal of Hydrogen Energy
Volume37
Issue number23
DOIs
StatePublished - Dec 2012

Keywords

  • Dehydrogenation
  • Hydrogen storage
  • Magnesium borohydride
  • Metal complex hydrides
  • Niobium fluoride

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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