| Abstract
| - High-surface-area PrOy−ZrO2 mixed oxide, crystallized in the cubic fluorite structure, is synthesized for thefirst time as a single-phase material over a wide range of composition by sol−gel processing. X-ray powderdiffraction shows that the material remains single phase even after thermal treatment in air to 900 °C. Theoxygen storage capacity of PrOy−ZrO2, where praseodymium undergoes Pr3+ ↔ Pr4+ interconversion, isassessed by temperature-programmed reduction with H2. The results show that there is little oxygen storagecapacity unless the PrOy concentration exceeds 25 mol %. A comparison of oxygen storage capacity fromsimilarly prepared single-phase CeO2−ZrO2, PrOy−CeO2, and PrOy−CeO2−ZrO2 materials is presented.Measurements of lattice parameter and reducibility suggest that there are preferred associations that lead toPrOy−ZrO2 and CeO2−ZrO2 rather than PrOy−CeO2 in the ternary mixed oxide. An evaluation of model Pdcatalysts, using PrOy−ZrO2 and CeO2−ZrO2 as support materials, in functional tests approximating warmed-up, steady-state operation of an automotive catalyst, is also reported.
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