Promoting effects of ceria on the catalytic performance of gold supported on TiO2 for low-temperature CO oxidation

Abstract

The La or Ce-doped TiO₂ prepared by a sol–gel method was used as the support, and supported gold catalysts for CO oxidation were prepared by the deposition–precipitation method. These Au catalysts were characterized by N₂ adsorption–desorption, ICP, XRD, TEM, H₂-TPR, and in situ FT-IR. It was found that doping Ce or La in the TiO₂ support obviously improved the catalytic activity and stability of the Au catalysts for CO oxidation. The promoting effect of CeO₂ on its catalytic activity is much larger than La₂O₃. The presence of Ce not only increases the surface area of TiO₂ and restrains the growth of TiO₂ crystallites, but it also enhances the microstrain of TiO₂ and reinforces the interaction between TiO₂ and Au. As a result of the redox efficiency of CeO₂, the synergistic interaction between the Au particles and support, the activity of the active sites and the reactivity of the surface oxygen species, are remarkably improved. Moreover, the effortless decomposition of carbonates and the quick recovery of oxygen vacancies on the Au/Ce–TiO₂ surface might be responsible for the high stability of the Au catalyst, compared with the Au/TiO₂ catalyst.