Positive Effect of Water Vapor on CO Oxidation at Low Temperature over Pd/CeO2–TiO2 Catalyst

CO oxidation at low temperature over Pd/CeO 2 –TiO 2 catalyst was carried out in the feed containing different contents of water vapor (H 2 O). A positive effect of H 2 O was observed on the catalytic performance of Pd/CeO 2 –TiO 2 in CO oxidation at low temperature. The extent of this effect depends on the content of H 2 O in the feed; with a H 2 O content being 2.5 vol%, the catalyst Pd/CeO 2 –TiO 2 exhibits the highest stability (longest life time for CO oxidation at 80 °C). The results of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature-programmed reaction (TPReaction) reaction illustrated that H 2 O in the feed supplies sufficient OH groups in the presence of O 2 , which can react with adsorbed CO on Pd species to produce CO 2 . Moreover, H 2 O may also enhance the adsorption of CO and suppress the formation of some carbonate species.