Chlorobenzene oxidation using ozone over iron oxide and manganese oxide catalysts

Abstract

A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60–210°C using ozone (O3) over iron oxide and manganese oxide, respectively. In the absence of ozone, CB conversion achieved with these two catalysts at 200°C was below 10%. However, addition of 1200ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at 150°C for iron oxide, while 81.5% conversion is achieved with manganese oxide at 90°C. The activation energy of manganese oxide (48kJmol−1) is higher than that of iron oxide (43kJmol−1) without ozone. However, as ozone is added, the activation energy is significantly reduced to 20.0kJmol−1 for iron oxide. CO and CO2 are the only carbon-containing products detected in the effluent gas stream. For the long-term test, no obvious deactivation was found in iron oxide and ozone. However, in the case of manganese oxide and ozone, 3% reduction of CB conversion was observed. Slight deactivation might be attributed to a small amount of reaction byproducts (carboxylic acid species) and residual chloride (MnCl2) being deposited on the active sites of the catalysts.