A superior Mn5CeTi5Ox catalysts for synergistic catalytic removal of chlorobenzene and NOx: Performance enhancement and mechanism studies

Abstract

The transition metal titanium-doped Mn-Ce-O_x catalysts catalyst were employed to achieve synergetic removal of NO and CB at 180–220 °C. The Mn₅CeTi₅O_x catalyst with a molar ratio of Mn/Ce/Ti = 5:1:5 exhibits excellent activity, and the NO_x and CB removal efficiencies reach 96 % and 89 % at 160–220 °C, respectively. The selectivity for N₂ and CO₂ are 93 % and 78 %, respectively. The N₂-physisorption, NH₃-TPD, H₂-TPR and XPS results show that Ti doping makes the catalyst possess a mesoporous structure, suitable particle sizes, and excellent redox and Lewis site properties. All of these features contribute to the observed high NO and CB removal efficiency. The synergetic removal of CB and NO over Mn₅CeTi₅O_x results from the synergistic catalysis between the redox and the solid acid. On the one hand, in the synergistic removal process, CB and NH₃ are competitively adsorbed on the catalyst surface, resulting in a decrease in the NH₃-SCR activity. On the other hand, the removal of NO and CB has a synergetic effect. The byproduct NO₂ produced by the NH₃-SCR reaction promotes the oxidation of CB, which is beneficial for CB removal. Moreover, the consumption of NO₂ indirectly promotes the NH₃-SCR reaction, which partially compensates for the decrease in the NO removal efficiency caused by competitive adsorption between NH₃ and CB. Ti doping promotes the participation of the SCR byproduct NO₂ in the CBCO reaction and promotes the formation of maleic acid, an intermediate product of CB oxidation. In summary, the Mn₅CeTi₅O_x catalyst exhibits good activity for the synergistic removal of NO_x and CB and is a promising candidate for the effective and economical removal of NO and CB during waste incineration.