Effects of reduction temperature and metal-support interactions on the catalytic activity of Pt/γ-AlO and Pt/TiO for the oxidation of CO in the presence and absence of H

TiO- and γ-AlO-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in situ FTIR spectroscopy after activation at various conditions, and their catalytic properties were examined for the oxidation of CO in the absence and presence of H (PROX). When γ-AlOwas used as the support, the catalytic, electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatment conditions. In contrast, the surface properties and catalytic activity of Pt/TiO were strongly influenced by the pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron density on Pt, altering its chemisorptive properties, weakening the Pt-CO bonds, and increasing its activity for the oxidation of CO. The in situ FTIR data suggest that both the terminal and bridging CO species adsorbed on fully reduced Pt are active for this reaction. The high activity of Pt/TiO for the oxidation of CO can also be attributed to the ability of TiO to provide or stabilize highly reactive oxygen species at the metal-support interface. However, such species appear to be more reactive toward H than CO. Consequently, Pt/TiO shows substantially lower selectivities toward CO oxidation under PROX conditions than Pt/γ-AlO. © 2005 American Chemical Society.