Incorporation of Ag on Stable Pt/CeO2 for Low-Temperature Active and High-Temperature Stable CO Oxidation Catalyst

Advanced engine technologies and environmental restrictions require new-generation automotive catalysts to be low-temperature (LT) active and high-temperature (HT) stable simultaneously. Here, incorporation of Ag over high temperature (800 degrees C) treated Pt/CeO2 was applied to address the challenge. Strong Pt-O-Ce bonds in Pt/ CeO2 helped improve thermal stability dramatically. Detailed reaction kinetics analysis indicated Eley-Rideal (ER) mechanism for Ag/CeO2 catalysts and Mars-van Krevelen (Mvk) mechanism for both Pt/CeO2 and Ag/ Pt/CeO2 catalyst. After calcined at 800 degrees C, CO adsorbed on ionic Pt site could be readily oxidized by neighbouring oxygen species at a temperature as low as 132 degrees C over Ag/Pt/CeO2, about 60 degrees C lower than Pt/CeO2 and Ag/CeO2. Raman spectroscopy and XPS results suggested that incorporation of Ag created more oxygen defects over Pt/CeO2 and oxygen species on Ag nanoparticles might be more active than bare Pt/CeO2 which would enhance the low-temperature activity for Ag/Pt/CeO2. It might be an effective and cost-efficient approach to develop new catalysts for vehicle emission oxidation.