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Transition metal nanoparticle catalysts in releasing hydrogen from the methanolysis of ammonia borane

Ammonia borane (H3N center dot BH3, AB) is one of the promising hydrogen storage materials due to high hydrogen storage capacity (19.6% wt), high stability in solid state as well as in solution and nontoxicity. The methanolysis of AB is an alternative way of releasing H-2 due to many advantages over the hydrolysis such as having high stability against self releasing hydrogen gas. Here we review the reports on using various noble or non-noble metal(0) catalysts for H-2 release from the methanolysis of AB. Ni(0), Pd(0), and Ru(0) nanoparticles (NPs), stabilized as colloidal dispersion in methanol, are highly active and long lived catalysts in the methanolysis of AB. The catalytic activity, lifetime and reusability of transition metal(0) NPs show significant improvement when supported on the surface of solid materials. The supported cobalt, nickel, copper, palladium, and ruthenium based catalysts are quite active in H-2 release from the methanolysis of AB. Rh(0) NPs are highly active catalysts in releasing H-2 from the methanolysis of AB when confined within the void spaces of zeolite or supported on oxide nanopowders such as nanosilica, nanohydroxyapatite, nanoalumina or nanoceria. The oxide supported Rh(0) NPs can provide high activity with turnover frequency values as high as 218 min(-1) and long lifetime with total turnover values up to 26,000 in generation of H-2 from the methanolysis of AB at 25 degrees C. When deposited on carbon the bimetallic AgPd alloy nanoparticles have the highest activity in releasing H-2 through the methanolysis of AB. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.