Catalytic oxidation of toluene in contaminant emission control systems using Mn-Ce/gamma-Al2O3.

Toluene, the alkyl benzene, is a common constituent of contaminant streams emitted by hydrocarbon fuel combustion systems. The oxidation of toluene to less toxic compounds can be enhanced through catalysis. The capacity of Mn-Ce/gamma-Al2O3 to catalyze toluene oxidation was investigated using a fixed bed flow reactor, operating within a temperature range of 160-400 degrees C. Mono-metallic catalysts were prepared with the manganese and cerium contents of 1-21 wt% on gamma-Al2O3, support and bi-metallic catalysts were prepared with cerium (0.5-21 wt%/) on 18.2 wt% manganese. The results indicate that the 18.2 wt% Mn-10.0 wt% Ce catalyst combination had the best catalytic efficiency for toluene oxidation. Increase in cerium loading reduces the surface area of catalytic materials measured by BET, but increases catalytic activity. Data obtained through TGA (Thermogravimetric analysis), XRD (X-ray diffraction) and toluene-TPR (Temperature Programmed Reduction) measurements show that the reduction of the catalysts in the process of toluene oxidation is directly proportional to observed weight loss under hydrogen flow. From these results, it is concluded that cerium improves the catalytic role of manganese in toluene oxidation. Oxygen mobility is also promoted in a redox mechanism in which MnO2 serves as the active sites. These results are useful in the development of toluene emission control systems for hydrocarbon fuel combustion systems.