On the mechanism of selective CO oxidation on nanosized Auγ-Al2O3 catalysts

New findings give further information on the mechanism of carbon monoxide selective oxidation over γ-alumina supported nanoparticle sized gold catalysts. a) CO2 formation, increasing with rising temperature, is observed in the absence of hydrogen and oxygen pointing to a model of active sites consisting of an ensemble of metallic Au atoms and a cationic Au with a hydroxyl group, b) At high temperatures (>200 °C) in excess of H2, reversed water gas shift (RWGS) reaction results in CO2 consumption towards CO and H2O formation. c) Hydrogen strongly influences the interaction of CO on Auγ-Al2O3, by weakening the CO adsorption. The presence of hydrogen plays an important role both decreasing the strength of CO bonding and in the prevention of deactivation and regeneration.