Au/Y-TiO2 Catalyst: High Activity and Long-Term Stability in CO Oxidation

Gold catalysts supported on TiO 2 doped with Y (1, 3, and 6 wt % of Y) were prepared by the deposition-precipitation with urea method. Two yttrium precursors were used: yttrium acetylacetonate and yttrium nitrate. The Y-TiO 2 supports prepared by the sol–gel method allowed the formation of solids with high specific surface area. The incorporation of yttrium restricted the growth of TiO 2 anatase crystals and hindered the transformation to the rutile phase. The average gold particle size was very similar in all the prepared catalysts (∼3 nm). Au/Y-TiO 2 catalysts showed higher activity and stability at room temperature than Au/TiO 2 in the CO oxidation reaction. This behavior is related to the strong anchoring of the gold particles on the structural defects and oxygen vacancies of the support caused by the doping of the anatase with yttrium. The variation of the yttrium precursor (acetylacetonate or nitrate) did not have an important effect on the catalytic activity or the temporal stability of the catalysts. In the samples with a high content of Y, High Resolution Transmission Electron Microscopy (HRTEM) results suggest the segregation of yttrium as Y 2 O 3 on the surface of TiO 2 . The presence of Y 2 O 3 crystals on the TiO 2 surface had a detrimental effect on the catalytic activity.