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Solid solutions of CeO2 with Yb2O3, Y2O3, Sm2O3, Gd2O3, La2O3, Nb2O5, Ta2O5, and Pr6O11 were prepared by sol-gel methods. All of the samples exhibited a single, cubic phase in x-ray diffraction and the lattice parameters were consistent with formation of the solid solutions. Surprisingly, all of the mixed oxides exhibited a much lower catalytic activity for n-butane oxidation than that of pure CeO2 at 650 K, with Sm0.2Ce0.8O1.9, Gd0.2Ce0.8O1.9, La0.2Ce0.8O1.9, Nb0.1Ce0.9O2.05, and Ta0.1Ce0.9O2.05 showing rates less than 10-2 that of pure ceria. Lower dopant levels with Sm+3 and Gd+3 affected the rates proportionately less. The implications of these results for use of ceria as an oxidation catalyst are discussed.
ceria, doped ceria, butane oxidation, ionic conductivity, samaria, gadolinia, lanthana, niobia, praeseodymia, tantala
Date Posted: 09 February 2006
This document has been peer reviewed.