Total oxidation of propane over Cu-Mn mixed oxide catalysts prepared by co-precipitation method

The catalytic activity of Cu-Mn mixed oxides with varying Cu/Mn ratios prepared by co-precipitation method was examined for the total oxidation of propane. The nature and phase of the metal oxide species formed were characterized by various methods such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H₂ temperature-programmed reduction (TPR) as well as BET surface area measurement. The co-precipitation method provides highly interdispersed copper and manganese metallic elements forming Cu-Mn mixed oxide of spinel structure (Cu_1.5 Mn_1.5O₄). Besides the spinel-type Cu-Mn mixed oxide, CuO or Mn₂O₃ phases could be formed depending on the Cu/Mn molar ratio of their precursors. The catalytic activity of Cu-Mn mixed oxide catalyst for propane oxidation was much higher than those of single metal oxides of CuO and Mn₂O₃. The higher catalytic activity likely originates from a synergic effect of spinel-type Cu-Mn mixed oxide and CuO. The easier reducibility and BET surface area seems to be partially responsible for the high activity of Cu-Mn mixed oxide for total oxidation of propane.