Hierarchical structured Ti-doped CeO2 stabilized CoMn2O4 for enhancing the low-temperature NH3-SCR performance within highly H2O and SO2 resistance

Developing effective and stable catalysts for low-temperature selective catalytic reduction (SCR) of NOx remains challenging. Herein, we constructed a hierarchical structure by loading CoMn2O4 onto Ti-doped CeO2, that CoMn2O4/CeTiOx catalyst has shown superior deNOx activity (>95% at 100~225°C), prominent reaction activation energy (28.8 ± 0.9 kJ·mol-1) and outstanding stability (>75% at 100~200°C within H2O and SO2). The "low-temperature active sites" and "dual anti-poisoning sites" contribute to excellent activity and stability. Firstly, the hierarchical structure boosts generation of active metal-support interface, which is conducive to oxygen migration (including adsorbed oxygen (Oads), lattice oxygen (Olat) and oxygen vacancy (Ov)) and metal charge transfer (Mn2+/3++Ce4+↔Mn3+/4++Ce3+, Ti4++Ce3+↔Ce4++Ti3+). This is the key to breaking through the limits of catalytic activity stability. Secondly, enhanced surface acidity favors NH3 adsorption and activation, which accelerates -NH2/-NH concatenate with NOx through Eley-Rideal mechanism to generate N2 and H2O. Thirdly, the dual strong SO2 affinity sites by Ti-induced CeO2 crystal reconstruction retard the active center affected by the sulfate species, which contributes to striking stability. This work highlights the importance of design of isolated active sites to improve SO2 and H2O endurance.