High Thermal Stability of La2O3- and CeO2-Stabilized Tetragonal ZrO2

Catalyst support materials of tetragonal ZrO2, stabilized by either La2O3 (La2O3–ZrO2) or CeO2 (CeO2–ZrO2), were synthesized under hydrothermal conditions at 200 °C with NH4OH or tetramethylammonium hydroxide as the mineralizer. From in situ synchrotron powder X-ray diffraction and small-angle X-ray scattering measurements, the calcined La2O3–ZrO2 and CeO2–ZrO2 supports were nonporous nanocrystallites that exhibited rectangular shapes with a thermal stability of up to 1000 °C in air. These supports had an average size of ∼10 nm and a surface area of 59–97 m2/g. The catalysts Pt/La2O3–ZrO2 and Pt/CeO2–ZrO2 were prepared by using atomic layer deposition with varying Pt loadings from 6.3 to 12.4 wt %. Monodispersed Pt nanoparticles of ∼3 nm were obtained for these catalysts. The incorporation of La2O3 and CeO2 into the t-ZrO2 structure did not affect the nature of the active sites for the Pt/ZrO2 catalysts for the water–gas shift reaction.