Browsing by Author "Kalu, E.E."

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Cobalt-Nickel Supported on Pd-Activated Tio2 (co-ni-p/Pd-tio2) as Cost-Effective and Reusable Catalyst for Hydrogen Generation From Hydrolysis of Alkaline Sodium Borohydride Solution
(2011) Rakap, M.; Kalu, E.E.; Özkar, S.
Catalytically active, low-cost, and reusable transition metal catalysts are desired to develop on-demand hydrogen generation system for practical onboard applications. Electrolessly deposited Pd-activated TiO2-supported Co-Ni-P ternary alloy catalyst (Co-Ni-P/Pd-TiO2) is employed as catalyst in the hydrolysis of alkaline sodium borohydride solution. The catalyst is found to be isolable, redispersible, and reusable in the hydrolysis of alkaline NaBH4. The reported work also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy (Ea = 57.0 kJ/mol) and effects of the amount of catalyst, amount of substrate, and temperature on the rate for the catalytic hydrolysis of NaBH4. Maximum H2 generation rate of ∼460 mL H2 min-1 (g catalyst)-1 and ∼3780 mL H2 min-1 (g catalyst)-1 was measured by the hydrolysis of NaBH4 at 25 °C and 55 °C, respectively. © 2011 Elsevier B.V.
Hydrogen Generation From Hydrolysis of Ammonia-Borane Using Pd-Pvb 2 and Co-ni-p/Pd-tio 2 Under Stirred Conditions
(2012) Rakap, M.; Kalu, E.E.; Özkar, S.
The employment of Pd-PVB-TiO 2 and Co-Ni-P/Pd-TiO 2 in hydrogen generation from the hydrolysis of ammonia-borane (H 3NBH 3, 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-TiO 2 and Co-Ni-P/Pd-TiO 2, respectively. Maximum hydrogen generation rates in the hydrolysis of AB catalyzed by the Pd-PVB-TiO 2 catalyst (1.5 mM) are 1910 and 14,800 mL H 2 min -1 (g Pd) -1 at 25 and 55 ± 0.5 °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-TiO 2 (25 mg) at 25 °C and 55 ± 0.5 °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. © 2012 Elsevier B.V. All rights reserved.
Hydrogen Generation From the Hydrolysis of Ammonia Borane Using Cobalt-Nickel (co-Ni Catalyst Supported on Pd-Activated Tio 2 by Electroless Deposition
(2011) Rakap, M.; Kalu, E.E.; Özkar, S.
Catalytically active, low-cost, and reusable transition metal catalysts are desired to develop on-demand hydrogen generation system for practical onboard applications. By using electroless deposition method, we have prepared the Pd-activated TiO2-supported Co-Ni-P ternary alloy catalyst (Co-Ni-P/Pd-TiO2) that can effectively promote the hydrogen release from ammonia-borane aqueous solution. Co-Ni-P/Pd-TiO2 catalysts are stable enough to be isolated as solid materials and characterized by XRD, SEM, and EDX. They are isolable, redispersible and reusable as an active catalyst in the hydrolysis of AB. The reported work also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy (Ea = 54.9 kJ mol-1) and effects of the amount of catalyst, amount of substrate, and temperature on the rate for the catalytic hydrolysis of AB. Maximum H2 generation rate of ∼60 mL H2 min-1 (g catalyst)-1 and ∼400 mL H 2 min-1 (g catalyst)-1 was measured by the hydrolysis of AB at 25 °C and 55 °C, respectively. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
Polymer-Immobilized Palladium Supported on Tio2 (pd-Pvb 2) as Highly Active and Reusable Catalyst for Hydrogen Generation From the Hydrolysis of Unstirred Ammonia-Borane Solution
(2011) Rakap, M.; Kalu, E.E.; Özkar, S.
Herein we report the preparation, characterization and the catalytic use of the polymer-immobilized palladium catalyst supported on TiO2 (Pd-PVB-TiO2) in the hydrolysis of unstirred ammonia-borane solution. The polymer-immobilized palladium catalyst is stable enough to be isolated as solid materials and characterized by XRD, SEM, and EDX. The immobilized palladium catalyst supported on TiO2 is found highly active, isolable, and reusable in the hydrolysis of unstirred ammonia-borane even at low concentrations and temperature. The work reported here also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy (Ea = 55.9 kJ/mol) and the effects of catalyst and substrate concentration on the rate for the hydrolysis of unstirred ammonia-borane solution. Maximum H2 generation rate of ∼642 mL H2 min-1 (g Pd)-1 and ∼4367 mL H 2 min-1 (g Pd)-1 was measured by the hydrolysis of AB at 25 °C and 55 ± 0.5 °C, respectively. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.