Propene and CO oxidation on Pt/Ce-Zr-SO 4 2– diesel oxidation catalysts: Effect of sulfate on activity and stability

Platinum/cerium-zirconium-sulfate (Pt/Ce-Zr-SO 4 2– ) catalysts were prepared by wetness impregnation. Catalytic activities were evaluated from the combustion of propene and CO. Sulfate (SO 4 2– ) addition improved the catalytic activity significantly. When using Pt/Ce-Zr-SO 4 2– with 10 wt% SO 4 2– , the temperature for 90% conversion of propene and CO decreased by 75 °C compared with Pt/Ce-Zr. The conversion exceeded 95% at 240 °C even after 0.02% sulfur dioxide poisoning for 20 h. Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO 4 2– support, and the increased number of Pt particles built up more Pt &+ -(SO 4 2– ) &– couples, which resulted in excellent activity. The increased total acidity and new Brönsted acid sites on the surface provided the Pt/Ce-Zr-SO 4 2– with good sulfur resistance. Support sulfation improved catalytic activity and sulfur resistance of Pt/Ce-Zr-SO 4 2– catalyst significantly, as their Pt dispersity and total acidity increased, and new active sites (Pt &+ -(SO 4 2− ) &− couples) were generated.