Oxidation of Toluene on γ-Al 2 O 3 Supported Copper–Manganese Catalysts

Abstract

Abstract

Catalytic incineration of toluene over γ-Al₂O₃-supported copper–manganese oxide catalysts in the temperature range of 433 K–553 K was investigated using a fixed-bed flow reactor. Catalysts were characterized using Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, temperature-programmed reduction, temperature-programmed oxidation, X-ray photoelectron spectroscopy, and X-ray diffraction. Incineration of toluene was achieved at temperatures up to 553 K and it was found that the weight ratio of reactants (Cu:Mn) was optimized to be 15:10. Brunauer-Emmett-Teller surface area results had no correlation with the activity of the catalysts. Results of temperature-programmed reduction/temperature-programmed oxidation and X-ray photoelectron spectroscopy showed that the redox peak of the 15Cu-10Mn catalyst shifted at lower temperatures and the binding energy shifted toward higher oxidation levels. These results show that high binding energy and high redox capacity are the causes of high activity. It was assumed that Cu_1.5Mn_1.5O₄ forms the active sites of the catalysts, as confirmed by X-ray diffraction. It seems that the redox activities and the high oxidation state of the catalysts are responsible for catalytic activity.