Activity and deactivation of Au/Al2O3 catalyst for low-temperature CO oxidation

Au/Al2O3 catalyst was investigated with respect to its activity for low-temperature CO oxidation. The activity changes of the catalyst were examined after separate treatment in the following different atmosphere: (i) O2 + N2 + CO; (ii) O2 + N2 heated above 100 °C and (iii) O2 + N2 + H2O vapor. The results show that each of the treatments above may deactivate the catalyst to the different degree. The deactivation by CO oxidation is mainly due to the accumulation of carbonate-like species on the catalyst surface. The addition of H2O vapor may inhibit the deactivation effectively. The removal of hydroxyl groups at active sites during heating may be responsible for the deactivation by thermal treatment. These two kinds of deactivations are reversible. The irreversible deactivation by H2O vapor treatment is mainly caused by the growth of gold particles size.