Au/Rutile Catalysts: Effect of the Activation Atmosphere on the Gold-Support Interaction

Au/rutile catalysts were activated in hydrogen and in air, and their catalytic activity for the oxidation of CO was analyzed as a function of time. The catalysts were characterized with X-ray powder diffraction, the refinement of the crystalline structures, transmission electron microscopy, and infrared spectroscopy. The activation atmosphere determined the interaction between the gold atoms and the support, which in turn determined the mobility of the gold particles with time and, with that, the gold particle dimensions and, consequently, their catalytic activity for the oxidation of CO. This catalytic activity was also affected by the adsorption, with time, of carbonate species on the active sites, species that were eliminated by heating the aged catalysts in air at 200 degrees C, recovering the catalytic activity.