Effects of the Incorporation of Sc2O3 into CeO2-ZrO2 Solid Solution: Structural Characterization and in Situ XANES/TPR Study under H2 Atmosphere

Abstract

Nanostructured CeO2-rich samples cosubstituted with ZrO2 and Sc2O3 are studied. The effects of the combined additions of both oxides on structural, morphological, and, especially, redox properties of the substituted lattice are assessed. In situ near edge X-ray absorption (XANES) experiments with synchrotron light were performed to study oxygen exchange capacity in a reducing environment for these ternary oxides. Structural characterization revealed that up to 8 at. % Sc was successfully incorporated into the CeO2-ZrO2 lattice without phase segregation. Increased scandia solubility was achieved through a soft chemical route synthesis involving citrate complexation which gave rise to porous powders with crystallite sizes in the nanometer range. In situ XANES experiments in 5 mol % H2/He atmosphere demonstrated that adding Sc3+ to the CeO2-ZrO2 mixed oxide leads to a ternary system (Ce0.9ScxZr0.1-xO2-δ) with faster reduction kinetics and enhanced reducibility in the whole temperature range analyzed (25-800 °C) compared to both binary materials: Ce0.9Zr0.1O2 and Ce0.9Sc0.1O1.95.