Steam reforming of toluene as model compound of biomass tar over Ni-Co/La_2O_3 nano-catalysts: Synergy of Ni and Co

摘要

A series of LaNi1-xCoxO3 (x = 0, 0.2, 0.5, 0.8 and 1) perovskite catalysts were prepared successfully and applied for toluene steam reforming as a model tar molecule. The Ni-Co alloy formation in reduced LaNi1-xCoxO3 was confirmed by TPR, XRD and XPS. The stronginteraction in LaNi0.8Co0.2O3 between Ni and Co produced highly dispersed and smaller metal (8-9 nm), higher reducibility and larger amounts of active sites as well as more abundant oxygen defects and higher surface/lattice oxygen mobility, confirmed by XRD, TEM, TPR, XPS and O-2-TPD. Also, a higher electron density prevented Ni from oxidation and sintering; a more oxidized Co (Co3+) facilitated the dissociation of water and activation of CO2, thus removing the coke. At 600 degrees C, S/C = 3.4 and WHSV = 16.56 ml h(-1) g(cat)(-1), an equilibrium conversion was achieved initially and over 80% conversion after 24 h were obtained for LaNi0.8Co0.2O3 with a high H-2 yield (81.8% at maximum) and 8.0 of H-2/CO ratio. The graphitic/filamentous coke formation was alleviated and no metal sintering was presented after the reaction. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.