Manganese supported on Sr-induced AlO₄ and AlO₆ catalyst for complete oxidation of propene: effect of preparation methods

The complete oxidation of propene was done by using a series of MnAl and Sr-doped MnAl catalysts prepared by deposition precipitation followed by the coprecipitation method. The concentration of Mn₂O₃ and SrAl₂O₄ active phases increases with the relative content of reactive oxygen species. These species enhance the reducibility of catalysts, which further increases the activity of C₃H₆ oxidation at relatively low temperatures. Characterization techniques like X-ray diffraction, FTIR, BET, X-ray photoelectron spectroscopy, temperature-programmed reduction, high-resolution transmission electron microscopy and ²⁷Al NMR were used to determine the physicochemical characteristics of the catalysts. The complete propene oxidation activity was observed on MnSr_0.3Al at 237°C. The effect of preparation methods indicates that the coprecipitation followed by the deposition precipitation approach strengthens the interaction between Sr and Mn. It also improved the dispersion of Sr and Mn on the surface of Al₂O₃ compared to the successive impregnation and deposition precipitation method.