Carbon/chlorinate deposition on MnOx-CeO2 catalyst in chlorobenzene combustion: The effect of SCR flue gas

Abstract NOx and chlorobenzene (CB) generally coexist together in the industrial flue gas, and MnOx-CeO2 catalyst is reported as one of possible candidates to remove them simultaneously. However, the influences of complex gas components on the catalysts are not studied well. Herein, coke deposition and chlorine accumulation are systematically investigated. Compared with coke deposition, the surface chlorine accumulation has a greater impact on the CB oxidation performance. NO and NH3 could reduce the surface coke loading and mitigate the coke deposition extent. The deposited coke mainly consists of various intermediates derived from the nucleophilic and electrophilic substitution of CB, and it could be released in 200–600 °C as CO2. The surface chlorine influences the oxidation state of Mn cations rather than Ce, which restrains the redox property. These species bond to the surface up to 600 °C. DFT results demonstrate that the chlorine anchors on the oxygen vacancies of the MnOx-CeO2 models and hinders the adsorption and activation of O2, which could inhibit the CB oxidation. The adsorbed NH3 weakens the bonding energies of chlorine to the surface, accounting for the mitigation of SCR flue gas on CB oxidation.