Oxidative degradation of m-cresol using ozone in the presence of pure γ-Al2O3, SiO2 and V2O5 catalysts

Abstract

The oxidative degradation of a potential pollutant, m-cresol with ozone was investigated both in the absence and presence of a catalyst. The oxidation reaction was studied as a function of time, where aliquots were drawn in every reaction from 3 to 24 h and dissolved in an absolute ethanol. The resultant product mixtures were analyzed using FT-IR and GC–MS spectroscopy for the identification of oxidation products. A hypothesis had been made that ethanol may affect the oxidation products as they are commonly carboxylic acids, ketones, and aldehydes, which was proved to be correct. The ethanol-mediated esterification of maleic and oxalic acid is thus reported. The oxidation products that were identified included 2,3-dihydroxy toluene and m-tolyl acetate. The catalyst materials were characterized using XRD, FT-IR, SEM and TEM techniques. Activated charcoal served as a reference catalyst to study and compare the activity to that of the metal oxides, where the order of catalytic activity was found to be SiO2 > γ-Al2O3 > activated charcoal >V2O5. However, activated charcoal resulted in higher selectivities towards products and lower substrate conversion.