Hydrogen generation from hydrolysis of ammonia-borane using Pd-PVB-TiO2 and Co-Ni-P/Pd-TiO2 under stirred conditions

The employment of Pd-PVB-TiO2 and Co-Ni-P/Pd-TiO2 in hydrogen generation from the hydrolysis of ammonia-borane (H3NBH3, AB) under stirred conditions are reported. Both catalysts are found to be highly active, isolable, and reactivatable in the hydrolysis of ammonia-borane even at low concentrations and temperature. The Arrhenius activation energies were found to be 54.9 and 54.7 kJ mol(-1) for the hydrolysis of ammonia-borane catalyzed by Pd-PVB-TiO2 and Co-Ni-P/Pd-TiO2, respectively. Maximum hydrogen generation rates in the hydrolysis of AB catalyzed by the Pd-PVB-TiO2 catalyst (1.5 mM) are 1910 and 14,800 mL H-2 min (g Pd)(-1) at 25 and 55 +/- 0.5 degrees C, respectively. The maximum hydrogen generation rates are 170 and 1390 mL H-2 min(-1) (g catalyst)(-1) for the hydrolysis of AB catalyzed by Co-Ni-P/Pd-TiO2 (25 mg) at 25 degrees C and 55 +/- 0.5 degrees C, respectively. In comparison to unstirred conditions, these results demonstrate that a significant external mass transfer resistance caused by the desorbed metaborate by-products exist in the under unstirred conditions. (C) 2012 Elsevier B.V. All rights reserved.