Decomposition of N2O on Rh/CeO2/ZrO2 composite catalyst

Nitrous oxide (N2O) was decomposed over Rh supported on ceria/zirconia (Ce/Zr) composite oxide, and the effects of the composition of the oxide and of its calcination temperature on the catalytic performance of Rh were investigated. Ceria was fragile against high temperature calcination, while addition of Zr remarkably increased its thermal stability to retain high surface area even at the calcination temperature of 900 degrees C. Rh was supported on these oxides and was calcined at 550 degrees C. The Rh supported on the composite oxide with a Ce/Zr molar ratio of 7/3 which had been calcined at 900 degrees C exhibited the highest activity. TEM and ESCA analyses revealed that the Rh strongly interacted with the oxide, and there was a possibility that a part of Rh even dissolved into its bulk. The Rh exposed to the surface of the composite oxide in a highly dispersed state exhibited the high catalytic activity. However, when the calcination temperature of the composite oxide (Ce/Zr molar ratio of 7/3) was increased to 1200 degrees C, its surface area decreased remarkably and the supported Rh was present in an aggregated state. The Rh in this state had only low catalytic activity despite its high surface concentration. (C) 1999 Elsevier Science B.V. All rights reserved.