Modification of the redox behaviour of CeO{sub 2} induced by structural doping with ZrO{sub 2}
- Universita di Trieste (Italy); and others
Reduction/oxidation behaviour of high surface area CeO{sub 2} and Ce{sub 0.5}Zr{sub 0.5}O{sub 2} mixed oxide is compared. It is shown that introduction of ZrO{sub 2} into the CeO{sub 2} framework with formation of a solid solution strongly modifies the reduction behaviour in comparison to that seen with CeO{sub 2} alone. Remarkably, upon repetitive reduction/oxidation processes, the temperature of the reduction of the solid solution decreases from 900 to 700 K. Conversely, in the aged CeO{sub 2} sample, almost no reduction occurs below 900 K. Textural characterisation shows that the redox process favours a large sintering of both the samples and, unexpectedly, induces formation of a new mesoporosity centered at about 20 nm. The expansion/contraction of the lattice parameter upon, respectively, reduction/oxidation, detected by X-ray diffraction, is suggested to be responsible for the textural modification. The suppression of the redox capacities of CeO{sub 2} at moderate temperature is associated with the decrease of the surface area. The sintering process induces a structural modification of Ce{sub 0.5} Zr{sub 0.5}O{sub 2} which promotes the reduction in the bulk, resulting in a high efficiency of the Ce{sup 4+} {r_equilibrium} Ce{sup 3+} redox cycle at moderate temperatures. 44 refs., 6 figs., 4 tabs.
- OSTI ID:
- 486386
- Journal Information:
- Journal of Catalysis, Vol. 164, Issue 1; Other Information: PBD: Nov 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
The influence of the processing parameters on the reactive flash sintering of ZrO2-CeO2
Effects of Zr/Ce molar ratio and water content on thermal stability and structure of ZrO{sub 2}–CeO{sub 2} mixed oxides prepared via sol–gel process