Effect of boric acid on thermal dehydrogenation of ammonia borane: Mechanistic studies

Hyun Tae Hwang, Arvind Varma

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Ammonia borane (AB, NH3BH3) is a promising hydrogen storage material for use in proton exchange membrane (PEM) fuel cell applications. In this study, the effect of boric acid on AB dehydrogenation was investigated. Our study shows that boric acid is a promising additive to decrease onset temperature as well as to enhance hydrogen release kinetics for AB thermolysis. With heating, boric acid forms tetrahydroxyborate ion along with some water released from boric acid itself. It is believed that this ion serves as Lewis acid which catalyzes AB dehydrogenation. Using boric acid, we obtained high H2 yield (11.5 wt% overall H2 yield, 2.23 H 2 equivalent) at 85 °C, PEM fuel cell operating temperatures, along with rapid kinetics. In addition, only trace amount of NH3 (20-30 ppm) was detected in the gaseous product. The spent AB solid product was found to be polyborazylene-like species. The results suggest that the addition of boric acid to AB is promising for hydrogen storage, and could be used in PEM fuel cell based vehicles.

Original languageEnglish
Pages (from-to)1925-1931
Number of pages7
JournalInternational Journal of Hydrogen Energy
Volume38
Issue number4
DOIs
StatePublished - Feb 12 2013

Keywords

  • Ammonia borane
  • Boric acid
  • Dehydrogenation
  • Hydrogen
  • Hydrogen storage

ASJC Scopus subject areas

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

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