| Abstract
| - TiO2- and γ-Al2O3-supported Pt catalysts were characterized by HRTEM, XPS, EXAFS, and in situ FTIRspectroscopy after activation at various conditions, and their catalytic properties were examined for the oxidationof CO in the absence and presence of H2 (PROX). When γ-Al2O3 was used as the support, the catalytic,electronic, and structural properties of the Pt particles formed were not affected substantially by the pretreatmentconditions. In contrast, the surface properties and catalytic activity of Pt/TiO2 were strongly influenced bythe pretreatment conditions. In this case, an increase in the reduction temperature led to higher electron densityon Pt, altering its chemisorptive properties, weakening the Pt−CO bonds, and increasing its activity for theoxidation of CO. The in situ FTIR data suggest that both the terminal and bridging CO species adsorbed onfully reduced Pt are active for this reaction. The high activity of Pt/TiO2 for the oxidation of CO can also beattributed to the ability of TiO2 to provide or stabilize highly reactive oxygen species at the metal−supportinterface. However, such species appear to be more reactive toward H2 than CO. Consequently, Pt/TiO2 showssubstantially lower selectivities toward CO oxidation under PROX conditions than Pt/γ-Al2O3.
|
