Improved activity of Rh/CeO2-ZrO2 three-way catalyst by high-temperature ageing

The effect of high-temperature ageing on the activity of Rh/CeO2-ZrO2 for the NO-C3H6-O-2 reaction was quite different depending on the Ce/Zr molar ratio of CeO2-ZrO2 support. The activity of Rh/CeO2-ZrO2 with a Ce/Zr molar ratio of 74/26 (Rh/CZ-74/26) was significantly enhanced by high-temperature ageing, whereas that of the other Rh/CeO2-ZrO2 was decreased. The promotion of the activity of Rh/CZ-74/26 by high-temperature ageing was considered to be due to the formation and stabilization of active reduced Rh species as well as the change in the surface properties of CeO2-ZrO2 to inhibit the formation of formate species poisoning the catalytically active sites. (C) 2009 Elsevier B.V. All rights reserved.