Synergistic promotion effect of acidity and redox capacity in the simultaneous removal of CB and NOx in NH3-SCR unit

•Fundamental study of structure–activity relationship in simultaneous removal.•The synergistic effect of acid sites and redox sites is clarified.•The activity and mobility of oxygen species is conducive for reaction.•The competition between Cl dissociation and NH3 adsorption is proved.•Oxidation of benzoquinone and nonaromatic species is inhibited by SCR. Exploring the fundamental relationship between catalyst properties (surface acidity and redox capacity) and NOx/chlorobenzene (CB) conversion is a major challenge for developing efficient synergistic catalyst. A series of designed MnOx confined titania nanotubes catalysts with different Mn content were tested and systematically characterized and the catalyst with Mn/Ti = 0.5 exhibited the outstanding collaborative activity·NH3/NOx/CB-TPD results revealed that both the strength of acid sites and the synergistic ability of acid sites and oxidation sites were conducive to the adsorption and activation of reactants. O2-TPD, H2-TPR and XPS results illustrated that abundant oxygen species and excellent oxygen migration capacity were beneficial to the redox cycle in the reaction process, and strong reducibility driven the interface reaction of activated reactants. DRIFTs results showed that the Lewis acid site was the crucial factor to the synergistic reaction because it strongly adsorbed NH3 and was also the sites for the dissociation of C-Cl bond. Furthermore, the introduction of SCR atmosphere inhibited the ring breaking of CB and oxidation of nonaromatic intermediate species, indicating the competition between CB oxidation and NH3/NOx activation in E-R/L-H route and this result proved the importance of redox capacity in simultaneous removal.