Structure and surface properties of praseodymium modified alumina

Mixed PrO2–Al2O3 oxides with different PrO2 content (1–20 wt.%) were prepared by wetness impregnation of γ-alumina with aqueous solution of praseodymium nitrate. The samples were characterized by different techniques, using surface adsorption–desorption of N2 (SBET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), temperature-programmed reduction (TPR) and temperature-programmed desorption of CO2 (TPD-CO2). TGA and XRD showed the presence of small praseodymium oxide species on the alumina surface. XPS and DRS detected electron deficient interaction between deposited praseodymium oxide and alumina. It was observed a lower reduction temperature for supported Pr oxide species compared to that of the bulk Pr6O11. TPD-CO2 studies suggested that the deposition of Pr oxide on alumina leaded to increase of the basicity of mixed oxides.