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

Redox and textural/structural properties of low surface area (LS) 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 and buffering 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. Comparison with previously reported high surface area (HS) samples shows that in spire of the initial low surface area of the present samples (approximate to 20 versus approximate to 100 m(2) g(-1)), the reduction occurs at fairly low temperatures when zirconium is incorporated into the CeO2 lattice. Remarkably, the favorable effects of the redox-aging on the reduction behavior are more pronounced in the present LS samples compared to the previously investigated HS ones. Raman and X-ray investigations revealed that important modifications of the structure take place as a consequence of the redox aging, leading to appreciable CeO2 segregation, which could suggest some correlation between these parameters. (C) 2001 Elsevier Science B.V. All rights reserved.