By combining hydrolysis and thermolysis in a single procedure, Arvind Varma and team, Purdue University, USA, have achieved generation of up to 14 wt% H2 from ammonia borane at conditions suitable for use in car fuel cells.
The team report the catalyst-free conditions for maximum hydrogen storage capacity are obtained at 77 wt% ammonia borane and Treactor ~85 °C, along with rapid kinetics. H2 release was reported as 11.6 and 14.3 wt% at pressure 14.7 and 200 psi, respectively.
The U.S. Department of Energy has set a 2015 target of 5.5 wt% for hydrogen storage systems, but as Varma notes, “If you’re only yielding, say, 7 % hydrogen from the material, you’re not going to make this 5.5 % requirement once you consider the combined weight of the entire system, which includes the reactor, tubing, the ammonia borane, water, valves and other required equipment.”
- Hydrogen generation from noncatalytic hydrothermolysis of ammonia borane for vehicle applications
M. Diwan, H. T. Hwang, A. Al-Kukhun, A. Varma
AIChE J. 2010, 56.