Samarium oxide catalyst; formation, characterization and activity towards propan-2-ol decomposition. An IR spectroscopic study

Abstract

IR spectroscopy has been used to study the gas-phase reaction products from the dehydrogenation–dehydration of propan-2-ol over Sm₂O₃ at temperatures between room temperature and 400 °C. Sm₂O₃ was shown to be a selective dehydration catalyst at 250 °C with decomposition of propan-2-ol to propene (ca. 90%). The Sm₂O₃ catalyst was obtainied as a final decomposition product of Sm(CH₃CO₂)₃· 4H₂O. The thermal decomposition processes up to 800 °C were characterized by the thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD) and IR spectroscopy. The compound dehydrates in two steps at 125 and 170 °C and recrystallizes at 195 °C. AT 350 °C, the anhydrous acetate decomposes to SmO(CH₃CO₂)via the intermediate Sm(OH)(CH₃CO₂)₂. AT 450 °C two different phases of Sm₂O₂(CO₃) are obtained which when further heated to 675 °C form Sm₂O₃. Surface area measurement and scanning electron microscopy showed that the final product, Sm₂O₃, at 800 °C has a surface area of 35 m² g^–1 and is a crystalline porous material.