A Multifactor Study Of Catalyzed Hydrolysis Of Solid Nabh_4 On Cobalt Nanoparticles: Thermodynamics And Kinetics

摘要

In the present work, hydrogen generation through hydrolysis of a NaBH_(4(s))/catalyst_(s) solid mixture was realized for the first time as a solid/liquid compact hydrogen storage system using Co nanoparticles as a model catalyst. The performance of the system was analysed from both the thermodynamic and kinetic points of view and compared with the classical catalyzed hydrolysis of a NaBH_4 solution. The kinetic analysis of the NaBH_(4(s))/catalyst_(s)/ H_2O_(1) system shows that the reaction is first order with respect to the catalyst concentration, and the activation energy equal to 35 kJ mol_(NaBH4)~(-1). Additionally, calorimetric measurements of the heat evolved during the hydrolysis of NaBH_4 solutions evidence the global process energy (-217kJ mol_(NaBH4)~(-1)). Characterization of the cobalt nanoparticles before and after the hydrolysis associated with the calorimetric measurements suggests the "in situ" formation of a catalytically active Co_χB phase through "reduction" of an outer protective oxide layer that is regenerated at the end of reaction.