Influence of the noble metal on the properties as oxygen exchanger of Rh/LnOx systems (Ln: Ce,Tb):: Application of the oxygen buffering capacity (OBC) technique

Ceria-based mixed oxides are being used as key components in TWC formulations, especially to widen the temperature range where ceria can be an effective oxygen exchanger. In TWC formulations, supported noble metals can modify the redox properties of the oxide acting as support. In this work, oxygen exchange properties of a set of oxides and mixed oxides have been studied with and without noble metal. The temperature range where the samples are effective has been studied by OBC (oxygen buffering capacity) measurements. This technique allows us to study the ability of a sample to buffer fast oscillations in the composition of the environment, and thus, to evaluate in a wide range of temperatures its ability as fast oxygen exchanger. Some interesting synergic effects can be found for noble metal-supported oxides. (C) 2002 Elsevier Science B.V. All rights reserved.