Influence of Mn valence state and characteristic of TiO on the performance of Mn-Ti catalysts in ozone decomposition.

The effects of physicochemical properties of Mn-Ti catalysts on O conversion were examined. The catalysts were prepared by a wet impregnation method that gave manganese supported on various commercial sources of TiO. The properties of the catalysts were studied using physicochemical techniques, including Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), H temperature-programmed reduction (H-TPR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA). The O decomposition tests of Mn-Ti catalysts with various manganese loadings revealed that the 10 wt% manganese catalyst exhibited optimal, excellent activity. The O conversion and Mn valence state of the Mn-Ti catalysts were different, depending on the structure of the TiO source. Increasing the O/Ti surface atomic ratio in TiO increased the Mn ratio. The Mn ratio directly affected the O decomposition activity of the Mn-Ti catalyst. When the Mn ratio was the largest, the catalyst showed the highest activity in O decomposition. The valence state of Mn exposed to the surface was a critical factor in O decomposition by Mn-Ti catalysts.