Catalytic Performance of MnO_x Nanorods in Aerobic Oxidation of Benzyl Alcohol

Various manganese oxide nanorods with similar one-dimensional morphology were prepared by calcination of MnOOH nanorods under different gas atmosphere and at different temper-atures, which were synthesized by a hydrothermal route. The morphology and structure of MnO_x catalysts were characterized by a series of techniques including X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and tempera-ture programmed reduction (TPR). The catalytic activities of the prepared MnO_x nanorods were tested in the liquid phase aerobic oxidation of benzyl alcohol, which follow a sequence as MnO₂>Mn₂O₃≈Mn₃O₄>MnOOH with benzaldehyde being the main product. On the basis of H₂-TPR results, the superior activity of MnO₂ is ascribed to its lower reduction temperature and therefore high oxygen mobility and excellent redox ability. Moreover, a good recycling ability was observed over MnO₂ catalysts by simply thermal treatment in air.