Activity and kinetics of ruthenium supported catalysts for sodium borohydride hydrolysis to hydrogen

Abstract

Ru–RuO₂/C prepared by galvanic replacement has high catalytic activity for sodium borohydride hydrolysis. In the present study, a series of Ru–RuO₂/C catalysts, Ru–RuO₂/C reduced, RuO₂/C and Ru supported on Ni foam (Ru/Ni foam) are prepared and characterized. Results show that RuO₂ on Ru–RuO₂/C is formed from both the consumption of the parent Ni and NiO nanoparticles and the disproportionation of RuCl₃ with epitaxial growth of Ru species. The quantity of RuO₂ with oxygen vacancies in Ru–RuO₂/C determines the hydrolysis activity for sodium borohydride. In contrast to Ru–RuO₂/C, Ru/Ni foam without oxygen vacancies has the lower hydrolysis activity. Results of kinetics calculation further confirm that without mass transfer limitation, Ru–RuO₂/C has lower intrinsic activation energy and correspondingly higher catalytic activity due to existence of oxygen vacancies than those from Ru–RuO₂/C reduced, RuO₂/C, Ru/Ni foam and catalysts from the literature.