Low temperature oxidation of toluene by ozone over MnOx/γ-alumina and MnOx/MCM-41 catalysts

Ozonation of toluene catalyzed by manganese oxides supported on gamma-alumina and siliceous MCM-41 was studied at temperatures from 22 to 100 degrees C. Nitrate and acetate precursors of manganese were used to compare structure and activity of dispersed manganese oxides on gamma-alumina and MCM-41. Catalysts were characterized by X-ray diffraction, Raman spectroscopy, BET and ICP-MS. Catalysts became deactivated at room temperature due to accumulation of carbon species. A minimum reaction temperature of 65 degrees C was required to achieve steady state oxidation of toluene with ozone. Alumina supported catalysts prepared from the nitrate and acetate precursors had comparable activity. MCM-41 supported catalyst resulted in lower toluene and ozone conversion in comparison to gamma-alumina catalysts above 40 degrees C. CO and CO2 were the main reaction products while oxalic acid, acetic acid, benzene and maleic anhydride were also detected as the minor reaction byproducts. (C) 2012 Elsevier B.V. All rights reserved.