Surface characterization of zirconia-coated alumina as support for Pt particles

ZrO2/Al2O3 samples were prepared by impregnation of the alumina powder with a solution of zirconium hydroxide in nitric acid, containing ZrO2 in the r ange of 1-20 wt%. Platinum was impregnated by incipient wetness technique, using an aqueous solution of H2PtCl6. The surface coverage of zirconia on a lumina, as probed by XPS and ISS, increased up to 10 wt% of ZrO2 and above this concentration crystallites of zirconia nucleated, which decreases the BET surface area. XRD measurements indicated that the average size of these crystallites was about 1 nm. ISS data of Pt/ZrO2 and Pt/10%ZrO2/Al2O3 cata lysts, after reduction at 773 K indicated an increase in the surface popula tion of Zr atoms which are able to catch CO. This interaction was also prob ed by FTIR spectra of CO adsorbed on Pt/ZrO2 catalyst, where an intense ban d at 2130 cm(-1), associated to CO adsorption on Pt-ZrOx interface, was obs erved.