Publications in Scientific Journals:
L. Lukashuk, K. Föttinger, E. Kolar, Ch. Rameshan, D. Teschner, M. Hävecker, A. Knop-Gericke, N. Yigit, H. Li, E. McDermott, M. Stöger-Pollach, G. Rupprechter:
"Operando XAS and NAP-XPS studies of preferential CO oxidation on Co3O4 and CeO2-Co3O4 catalysts";
Journal of Catalysis,
Co3O4 is a promising catalyst for removing CO from H2 streams via the preferential CO oxidation (PROX).
A Mars-van-Krevelen redox mechanism is often suggested but a detailed knowledge especially of the oxidation
state of the catalytically active surface under reaction conditions is typically missing. We have
thus utilized operando X-ray absorption spectroscopy to examine structure and oxidation state during
PROX, and near atmospheric pressure-XPS at low photoelectron kinetic energies and thus high surface
sensitivity to monitor surface composition changes. The rather easy surface reduction in pure CO (starting
already at 100 C) and the easy reoxidation by O2 suggest that molecularly adsorbed CO reacts with
lattice oxygen, which is replenished by gas phase O2. Nevertheless, the steady state concentration of oxygen
vacancies under reaction conditions is too low even for XPS detection so that both the bulk and surface
of Co3O4 appear fully oxidized during PROX. Furthermore, the effect of adding CeO2 (a less active
material) to Co3O4 was studied. Promotion of Co3O4 with 10 wt% CeO2 increases the reduction temperatures
in CO and H2 and enhances the PROX activity. Since CeO2 is a less active material, this can only be
explained by a higher activity of the Co-O-Ce interface.
Cobalt oxide PROX Hydrogen Operando XAS NAP-XPS Ceria promoter Oxidation state
Electronic version of the publication:
Created from the Publication Database of the Vienna University of Technology.