Alumina hollow microspheres supported gold catalysts for low-temperature CO oxidation: effect of the pretreatment atmospheres on the catalytic activity and stability

Hierarchically organized γ-Al₂O₃ hollow microspheres were prepared via a hydrothermal method using potassium aluminum sulfate and urea as reactants. The corresponding Au/Al₂O₃ catalysts were obtained using a deposition-precipitation (DP) method. The effect of the pretreatment under different atmospheres (N₂, air, and H₂) on the activity and stability of the Au/Al₂O₃ catalysts in CO oxidation was investigated. The results showed that the pretreatment under H₂ atmosphere improved the low-temperature CO oxidation activity. Furthermore, a 50?h long-term test at 30?°C showed no significant deactivation for the H₂-pretreated catalyst. Moreover, the catalytic activity was promoted by H₂O vapor in all cases, and the H₂-pretreated catalyst exhibited a good tolerance in the co-presence of CO₂ and H₂O. Finally, oxygen temperature-programmed desorption (O₂-TPD) and in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) revealed that the reductive atmosphere pretreatment greatly improved the CO adsorption capacity and facilitated the oxygen activation.