(381b) Hydrogen Generation From Ammonia Borane for PEM Fuel Cell Applications

Ammonia borane (NH₃BH₃, AB) is a promising hydrogen storage material because it contains 19.6 wt% hydrogen. To release hydrogen from ammonia borane, thermolysis, catalytic hydrolysis and heat generated by additional reactive mixtures have been employed. All the current methods, however, have disadvantages which decrease the efficiency of hydrogen storage systems. In this work, we report new approaches to release hydrogen from AB, which do not require any catalyst and provide relatively high hydrogen yield and environmentally benign byproducts. One approach involves nano-aluminium (nAl)/water combustion reaction, which provides heat for AB dehydrogenation and releases additional hydrogen from water [1]. The second approach thermally activates AB hydrolysis in aqueous AB solutions and slurries under modest inert gas pressure [2-3]. The third approach involves AB thermolysis alone, with effective reaction heat management. The combustion-based methods could be used in compact power sources for portable electronic devices, while AB hydrothermolysis or thermolysis are attractive for vehicle transportation applications. For the latter case, we also conducted systematic experiments to compare the various approaches in terms of highest hydrogen yield, lowest ammonia formation, and moderate operating temperature [4], and details will be presented in this work.

References

1. Diwan, M., Hanna, D. and Varma, A., “Method to Release Hydrogen from Ammonia Borane for Portable Fuel Cell Applications,” International Journal of Hydrogen Energy, 35, 577-584 (2010).
2. Hwang, H. T., Al-Kukhun, A. and Varma, A., “Hydrogen for Vehicle Applications from Hydrothermolysis of Ammonia Borane: Hydrogen Yield, Thermal Characteristics, and Ammonia Formation,” Ind, Eng. Chem. Res, 49, 10994-11000 (2010).
3. Diwan, M., Hwang, H. T., Al-Kukhun, A. and Varma, A., “Hydrogen Generation from Noncatalytic Hydrothermolysis of Ammonia Borane for Vehicle Applications,” AIChE Journal, 57, 259-264 (2011).
4. Al-Kukhun, A., Hwang, H. T. and Varma, A., “A Comparison of Ammonia Borane Dehydrogenation Methods for Proton-Exchange-Membrane Fuel Cell Vehicles: Hydrogen Yield, Ammonia Formation and Its Removal,” Ind, Eng. Chem. Res (in press, 2011, DOI 10.1021/ie102157v).