Novel amorphous aluminum hydroxide catalysts for aluminum-water reactions to produce H-2 on demand

Production of aluminum (Al) through electrolysis is an energy intensive process. Al metal with its very high specific energy density of 28.8 MJ kg(-1) can serve as an excellent energy storage vector. Al reacts with water (reaction (1)) at room temperature producing clean H-2 thus providing an alternative to compressed gas storage. 2Al + 6H(2)O -> 2Al(OH)(3) + 3H(2) (1) Reaction (1) does not proceed easily due to the presence of a 2-4 nm passive alumina surface layer. Aluminum hydroxide (Al(OH)(3)) catalyst disrupts this layer, sustaining reaction (1). The present work focuses on the catalysis aspects of reaction (1) by amorphous Al(OH)(3) produced by urea hydrolysis of aluminum nitrate. H-2 yields of up to 100% were obtained at 45 degrees C. Spent reaction product mixtures are autocatalytic with successive additions of Al micropowder (MP) yielding up to 133 ml H-2/minute and reaction completion within 10 min at pH approximate to 10. There is an induction time initially due to the presence of dissolved ions, followed by production of H-2. Reaction by-products are easily recyclable back to Al metal through subsequent calcining and electrolysis by the Al refining industry, which constitutes the energy storage part of the cycle. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.