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 invest igated. Ceria was fragile against high temperature calcination, while addit ion of Zr remarkably increased its thermal stability to retain high surface area even at the calcination temperature of 900 degrees C. Rh was supporte d on these oxides and was calcined at 550 degrees C. The Rh supported on th e composite oxide with a Ce/Zr molar ratio of 7/3 which had been calcined a t 900 degrees C exhibited the highest activity. TEM and ESCA analyses revea led that the Rh strongly interacted with the oxide, and there was a possibi lity 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 hi gh catalytic activity. However, when the calcination temperature of the com posite oxide (Ce/Zr molar ratio of 7/3) was increased to 1200 degrees C, it s surface area decreased remarkably and the supported Rh was present in an aggregated state. The Rh in this state had only low catalytic activity desp ite its high surface concentration. (C) 1999 Elsevier Science B.V. All righ ts reserved.