Effect of support on methane decomposition for hydrogen production over cobalt catalysts

Cobalt catalysts were tested in methane decomposition reaction at 450 degrees C to evaluate their catalytic properties in non-oxidative methane conversion for hydrogen production via accumulation of carbon. Silica, alumina and niobia supported cobalt catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), H-2 chemisorption and BET surface area measurements. The nature of the support strongly influenced this process. The high initial activity of Co/Al2O3 catalyst reduced at 500 degrees C lead to a large formation of carbon deposits and consequent catalysts deactivation. For Co/SiO2, the activity increased with reaction time due to reduction of cobalt oxide particles that were not reduced during the reduction pretreatment, and this effect was more pronounced for the reduction at 300 degrees C. Co/SiO2 reduced at 500 degrees C was the best catalysts for methane decomposition. For Co/Nb2O5, the Nb2Ox species partially covered cobalt particles even for reduced catalysts at low temperature (300 degrees C) and this effect completely inhibited the reaction after high-temperature reduction (500 degrees C). Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.