Holly A. E. Dole

Ethylene Oxidation in an Oxygen‐Deficient Environment: Why Ceria is an Active Support?

Pt/CeO2, Ru/CeO2, Ir/CeO2 and the corresponding unsupported nanoparticles (Pt, Ru and Ir) were evaluated for their performance in the complete oxidation of ethylene in the presence and absence of oxygen. The lattice oxygen and oxygen storage capacity (OSC) of CeO2 had a significant influence on the interaction with the supported metal nanoparticles, which caused different catalytic behaviours in the absence of oxygen. Overall, Ru/CeO2 was more stable than Ir/CeO2 and Pt/CeO2, which results in transient promotional rate enhancement ratio (ρMSI; MSI=metal–support interaction) values that reach 200 in the first 25 min. These results were attributed to the corresponding interaction with CeO2 and negligible carbon deposition. A proposed relationship between ρMSI and the O2− consumed from CeO2 is discussed, which was suggested as a possible tool to estimate the extent of the MSI. In general, an increase in ρMSI corresponded to an increase in O2− consumed from ceria.

Catalytic CO Oxidation over Au Nanoparticles Supported on Yttria-Stabilized Zirconia

Gold nanoparticles supported on yttria-stabilized zirconia (YSZ) were synthesized using a modified alcohol method which involves the stabilizing agent, polyvinylpyrrolidone (PVP). Two different average sizes (13.1 and 17.1 nm) of Au nanoparticles were synthesized. These catalysts were tested for gas phase CO oxidation. Since PVP is known to block the active Au sites, the catalysts were calcined at 300°C and 600°C in order to remove the PVP. Overall, higher catalytic activity was found for the smaller Au nanoparticles. It was also found that calcination is required in order to achieve activity, even though the particle size increases with this treatment. The effect of calcination temperature did not prove to be significant. It is demonstrated that O 2- ionically conductive YSZ is a promising catalyst support that can finely disperse and stabilize Au nanoparticles for CO oxidation.