Effects\nof Zr Doping on Anti-Ca Poisoning of the Ce–Mn/3DOM‑m\nTi–Zr Catalyst for Low-Medium-Temperature NH<sub>3</sub>‑SCR\nof NO<sub><i>x</i></sub>

The development of catalysts with high NH<sub>3</sub>-selective\ncatalytic reduction (SCR) activity in the presence of calcium (Ca)\nis urgently required for cement kiln flue gases at low-medium temperatures.\nHerein, a novel Ce–Mn/3DOM-m Ti–Zr (CMZT-3DOM-m) catalyst\nwas synthesized for low-medium-temperature NH<sub>3</sub>-SCR. Over\n90% NO<sub><i>x</i></sub> conversion can be obtained at\n125–275 °C with over 95% N<sub>2</sub> selectivity, accompanied\nby the excellent wide-temperature NH<sub>3</sub>-SCR performance and\nsuperior resistance to Ca. Through scanning electron microscopy (SEM),\nBrunauer–Emmett–Teller (BET), X-ray diffraction (XRD),\nX-ray photoelectron spectra (XPS), temperature-programmed reduction\nwith H<sub>2</sub> (H<sub>2</sub>-TPR), ammonia temperature-programmed\ndesorption (NH<sub>3</sub>-TPD) and in situ diffuse reflectance infrared\nFourier transform spectroscopy (DRIFTS) characterizations, the results\ndemonstrated that Zr doping could effectively mitigate grain growth\nand enlarge the surface area of the CMZT-3DOM-m catalyst. Furthermore,\nthe surface acidity, redox properties, concentration of surface Ce<sup>3+</sup>, Mn<sup>4+</sup> and chemisorbed oxygen were significantly\nimproved. In situ DRIFTS experiments demonstrated that the adsorption\nand activation of NH<sub>3</sub> and NO are conducive to the excellent\nresistance to Ca poisoning. As a sacrificial site for Ca binding,\nZr protected the active species, thereby enhancing the catalyst’s\nresistance to Ca poisoning and demonstrating excellent anti-Ca properties,\nwhich offered a novel approach to the design of catalysts for the\nprevention of Ca poisoning at low-medium temperatures.