Impacts of Decomposition Atmosphere on Surface Properties and Crystal Structure Characteristics of Praseodymia

Praseodymia or praseodymium oxide PrO1.83 was prepared from praseodymium nitrate hydrate in different atmospheres of gases oxygen, argon, and a mixture of oxygen and argon (1:1). The crystal structure and surface characteristics of praseodymium oxide (PrO1.83 and PrO2) obtained as the final decomposition product were characterized by different techniques, using surface adsorption–desorption of N2 (SBET), thermogravimetric analysis (TGA), and X-ray diffraction (XRD), the acidic properties of praseodymium oxide PrO1.83 were tested by FTIR spectroscopy of adsorbed CO as a probe molecule. The results indicate that the decomposition atmosphere affects the surface area, porosity, and crystal structure of the obtained oxides. Oxygen atmosphere promotes the formation of PrO2, whereas Argon and Argon/oxygen atmosphere promote the formation of PrO1.833 with larger surface area and improved mesoporosity. The non-stoichiometric oxide PrO1.833 displays different types of surface hydroxyl groups and two different types of Lewis acid sites as indicated by CO adsorptions.