Comparative Investigation on Chlorobenzene Oxidation by Oxygen and Ozone over a MnOx/Al2O3 Catalyst in the Presence of SO2

Catalytic oxidation of volatile organic compounds (VOCs) usually encounters complicated components in flue gas causing severe deactivation that restrict its application in specific conditions. The Cl substitution in chlorobenzene further increases poisoning risks. Ozone assistance has unique superiority that can overcome these bottleneck problems. Herein, this study performs a comparative investigation of CB oxidation by oxygen and ozone over a simple Mn/Al2O3 catalyst. CB conversion suffered from slight deactivation in oxygen atmosphere (from 90 to 70%) and more severe deactivation in the presence of SO2 (from 90 to 45%) at 480 °C. Introduction of ozone successfully attained high CB conversion at low temperature (120 °C) with excellent stability and less byproducts. Especially, CB oxidation by ozone maintained its original conversion in the presence of SO2. The deactivation process was simulated by synthesizing several sulfated catalysts. Direct sulfation on Mn/Al2O3 attained more severe deactivation in CB conversion and CO2 formation than sulfation on the Al2O3 support. Ozone with a strong oxidation property promoted the CB oxidation cycle, facilitated desorption of carbonaceous intermediates, and protected MnOx species from severe erosion, thus exhibiting high and stable performance in CB oxidation.