Catalytic decomposition of N2O over Au/Co3O4 and Au/ZnCo2O4 catalysts

Au/Co3O4 catalysts with different gold loadings were prepared by the deposition-precipitation method using HAuCl4 solution through adjustment of the pH value to 7, 9 or 11. Their catalytic properties for N2O decomposition in the presence of oxygen were investigated. 0.29%Au/Co3O4 catalyst prepared at the pH value of 9 exhibited higher catalytic activity than 0.31%Au/ZnCo2O4 prepared under optimal conditions although ZnCo2O4 was more active than Co3O4. AES, BET, XRD, SEM, XPS and H2-TPR characterization results indicated a synergistic effect existed between gold and cobalt species in Au/Co3O4, which is, however, absent in the Au/ZnCo2O4. Despite that N2O was completely decomposed at 500?C in oxygen atmosphere for both the samples, the N2O conversion was decreased to 92% and 63% after the reaction was carried out for 10 h in the presence of both oxygen and steam over the 0.29%Au/Co3O4 and the 0.31%Au/ZnCo2O4, respectively.