Hydrolytic dehydrogenation of ammonia borane catalyzed by reduced graphene oxide supported monodisperse palladium nanoparticles: High activity and detailed reaction kinetics

A highly active and stable catalyst for the hydrolytic dehydrogenation of ammonia borane (AB) was prepared by supporting monodisperse palladium nanoparticles (Pd NPs) on reduced graphene oxide (RGO) via a facile method. RGO was prepared via modified chemical route and used as support matrices for monodisperse Pd NPs that were formed by the reduction of palladium(II) acetylacetonate by borane tert-butylamine complex in the presence of oleylamine. RGO supported Pd NPs (RGO@Pd) show high activity and stability in the hydrolytic dehydrogenation of AB. The RGO@Pd catalysts provide the turnover frequency of 26.3 min(-1)-the best among the all Pd-based catalysts and even comparable to Pt-based catalysts tested in the hydrolysis of AB. They are also very stable catalysts providing 11,600 total turnovers in 46 h. The detailed reaction kinetics of catalytic hydrogen generation from the hydrolysis of AB revealed that the reaction proceeds first order with respect to the Pd concentration and zeroth order with respect to the AB concentration. The apparent activation parameters of the catalytic hydrolysis reaction were also calculated; apparent activation energy (E-a(app)) = 40 +/- 2 kJ mol(-1), activation enthalpy (Delta H-#,H-app) = 38 +/- 1 kJ mol(-1) and activation entropy (Delta S-#,S-app) = -134 +/- 1 J K-1 mol(-1). (c) 2012 Elsevier B.V. All rights reserved.