Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes
Phase 1. Hydrolysis of borohydride compounds offer the potential for significant hydrogen storage capacity, but most work to date has focused on one particular anion, BH4-, which requires high pH for stability. Other borohydride compounds, in particular polyhedral borane anions offer comparable hydrogen storage capacity without requiring high pH media and their long term thermal and hydrolytic stability coupled with non-toxic nature make them a very attractive alternative to NaBH4. The University of Missouri project provided the overall program focal point for the investigation of catalytic hydrolysis of polyhedral borane anions for hydrogen release. Due to their inherent stability, a transition metal catalyst was necessary for the hydrolysis of polyhedral borane anions. Transition metal ions such as cobalt, nickel, palladium and rhodium were investigated for their catalytic activity in the hydrolysis of nido-KB11H14, closo-K2B10H10, and closo-K2B12H12. The rate of hydrolysis follows first-order kinetics with respect to the concentration of the polyhedral borane anion and surface area of the rhodium catalyst. The rate of hydrolysis depends upon a) choice of polyhedral borane anion, c) concentration of polyhedral borane anion, d) surface area of the rhodium catalyst and e) temperature of the reaction. In all cases the yield of hydrogen was 100% which corresponds to ~7 wt% of hydrogen (based on material wt%). Phase 2. The phase 2 of program at the University of Missouri was focused upon developing aluminum ammonia-boranes (Al-AB) as chemical hydrogen storage materials, specifically their synthesis and studies of their dehydrogenation. The ammonia borane molecule (AB) is a demonstrated source of chemically stored hydrogen (19.6 wt%) which meets DOE performance parameters except for its regeneration from spent AB and elemental hydrogen. The presence of an aluminum center bonded to multiple AB residues might combine the efficiency of AB dehydrogenation with an aluminum mediated hydrogenation process leading to reversibility. The Al-AB complexes have comparable hydrogen capacity with other M-AB and have potential to meet DOE’s 2010 and 2015 targets for system wt%.
- Research Organization:
- University of Missouri, Columbia, MO
- Sponsoring Organization:
- USDOE Assistant Secretary for Energy Efficiency and Renewable Energy (EE); USDOE Office of Hydrogen, Fuel Cells, and Infrastructure Technologies Program (EE-2H)
- DOE Contract Number:
- FC36-05GO15058
- OSTI ID:
- 990217
- Report Number(s):
- DOE/GO/15058; TRN: US201020%%517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
25 ENERGY STORAGE
ALUMINIUM
AMMONIA
ANIONS
BORANES
BOROHYDRIDES
CATALYSTS
COBALT
DEHYDROGENATION
HYDROGEN
HYDROGEN STORAGE
HYDROGENATION
HYDROLYSIS
KINETICS
NICKEL
PALLADIUM
REGENERATION
RESIDUES
RHODIUM
STABILITY
SURFACE AREA
SYNTHESIS
TRANSITION ELEMENTS
Polyhedral Boranes
Aluminum Amido-boranes
Hydrogen storage