Anti-K salt poisoning of MnO_xcatalyst via X (X = Ce, Sm and Er) oxides for low-temperature NH₃-SCR of NO and oxidating CO

Manganese oxide (MnOx) serves as an effective catalyst for the simultaneous elimination of NO and CO pollutants in low-temperature flue gas. However, potassium salts present in industrial flue gas severely compromise the catalytic performance by altering surface physicochemical properties, leading to deactivation and reduced pollutant removal efficiency. To address this limitation, several rare earth (Ce, Sm and Er) oxides were incorporated into MnOx catalyst to enhance active site under potassium (K) exposure in this work. Catalytic activities of NO and CO removal both followed the order of K-Sm/MA > K-Er/MA > K-Ce/MA > K/MA. Especially, Sm/MA enhanced the considerable conversion of NO and CO at 175°C. Characterization revealed that Sm optimized the ration of Mn4 + and Oα, which showed higher active sites than other rare earth oxides modification. Moreover, in situ DRIFTS analysis confirmed the enhanced fast SCR process and the stronger interaction between CO and active sites on K-Sm/MA catalyst, which contributed to its superior K resistance and improved the removal efficiency. The K-Sm/MA catalyst accumulated more nitrate species and exhibited good reactivity, sustaining continuous NO conversion through the Langmuir-Hinshelwood (L-H) mechanism. Finally, a pathway model of Sm oxide on MnOx catalyst for the simultaneous NH3-SCR coupling CO oxidation at K poisoned situation.