Abstract: The effect of calcination temperature on the textual structure and catalytic properties of amorphous MnOx for the liquid-phase aerobic oxidation of benzyl alcohol was studied. The amorphous nature of the synthesized MnOx was retained when the calcination temperature was lower than 400 ℃, and calcination temperatures higher than 500 ℃ led to the transformation of amorphous MnOx to crystalline OMS-2 and Mn2O3. Catalytic reaction studies revealed that the amorphous MnOx exhibited higher mass specific activity than OMS-2, Mn2O3, and γ-MnO2, and MnOx calcined at 110 ℃ showed the highest activity. An inverse linear correlation between the onset reduction temperature in H2-TPR and the mass specific activity of the various manganese oxides was observed. This suggested that the reducibility of manganese oxide is the key factor responsible for its activity for the aerobic oxidation of benzyl alcohol.

Key words: amorphous manganese oxide, benzyl alcohol, selective oxidation, reducibility