Chlorobenzene oxidation using ozone over iron oxide and manganese oxide catalysts

A low-temperature catalytic oxidation of chlorobenzene (CB) has been performed at temperatures of 60-210 degrees C using ozone (O-3) over iron oxide and manganese oxide, respectively. In the absence of ozone. CB conversion achieved with these two catalysts at 200 degrees C was below 10%. However, addition of 1200 ppm ozone results in a remarkable increase in CB conversion and the conversion reaches 91.7% at 150 degrees C for iron oxide, while 81.5% conversion is achieved with manganese oxide at 90 degrees C. The activation energy of manganese oxide (48 kJ mol(-1)) is higher than that of iron oxide (43 kJ mol(-1)) without ozone. However, as ozone is added, the activation energy is significantly reduced to 20.0 kJ mol(-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. (C) 2010 Elsevier B.V. All rights reserved.