Redox behavior of CeO2-ZrO2 mixed oxides I.: Influence of redox treatments on high surface area catalysts

Redox and textural/structural properties of high surface area ceria-zirconia mixed oxides with composition ranging from 0 to 85 mol% of ZrO2, have been studied using Raman spectroscopy, X-ray diffraction, textural characterization, magnetic susceptibility measurements, temperature-programmed reduction and oxidation, oxygen storage and buffering capacity measurements. Special attention was given to the effects of aging under redox conditions. Correlation between chemical composition, textural, structural and redox properties of the oxides is reported. While for pure ceria almost no reducibility occurs below 773 K, mixed oxides, independently of their composition, exhibit an oxygen storage and buffering capacity at low temperature, which remains stable even after several oxidation/reduction cycles. This improvement with respect to CeO2 is remarkably high in the oxides with high zirconia content and is not affected by worsening of textural properties induced by redox-aging. Phase transformation and/or structural modification are detected as a consequence of the redox treatments, which could be at the origin of such effects. (C) 2000 Elsevier Science B.V. All rights reserved.