Polymer-immobilized palladium supported on TiO2 (Pd–PVB–TiO2) as highly active and reusable catalyst for hydrogen generation from the hydrolysis of unstirred ammonia–borane solution

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 H2 min−1 (g Pd)−1 was measured by the hydrolysis of AB at 25 °C and 55 ± 0.5 °C, respectively.

Research highlights
► PVB-immobilized Pd is highly active catalyst for hydrolysis of ammonia–borane (AB) for hydrogen production.
► Catalyst demonstrated to be reusable with minimal loss of activity for several cycles.
► In the studied initial AB concentration range of 50–150 mM, the hydrolysis of AB in the presence of Pd–PVB–TiO2 catalyst under no stirring condition was shown to be first order with respect to the AB concentration.
► Arrhenius activation energy of 55.9 kJ/mol was obtained for the PVB-immobilized palladium catalyst catalyzed hydrolysis of unstirred AB.