C,N modified TiO 2 supported Mn‐Ce‐Co x ‐based catalyst for low‐temperature NH 3 ‐SCR

BACKGROUND The emission of NOx can causes serious environmental pollution and endangers human health. In recent years, the selective catalytic reduction of NO with NH3 (NH3-SCR) technology has been widely studied and adopted to reduce the production and emissions of NOx during many technologies. RESULTS A series of Mn-Ce-Co-x/Ti-C,N catalysts were prepared by the impregnation method, and low-temperature NH3-SCR was studied. The results show that support modification (Ti-C,N) can broaden the operation temperature window of the catalyst (NO conversion >95%: Mn-Ce/TiO2 catalyst, 160-320 degrees C; Mn-Ce/Ti-C,N catalyst, 140-320 degrees C). The doping of Co further improves the low-temperature NH3-SCR of the catalyst. When n(Co):n(Ti) = 0.05, the catalyst has the best catalytic performance with the NO conversion reaches 100% at 100 degrees C. CONCLUSION Temperature-programmed reduction (H-2-TPR) and temperature-programmed desorption (NH3-TPD) results showed that Ti-C,N can improve the redox ability but reduces the surface acidity. Co-doping has no effect on surface acidity, but the redox ability is further improved. A suitable amount of Co-doping is beneficial to the optimal catalytic activity of Mn-Ce-Co-0.05/Ti-C,N catalyst. This suggests a balance between redox properties and surface acidity. Especially for the strong redox ability, it can promote the oxidation of NO to NO2, and promote low-temperature NH3-SCR through the 'fast SCR' pathway. X-ray photoelectron spectroscopy results of the highest chemisorbed oxygen (O-alpha) concentration and relative atomic ratio (Mn4+/Mnn+, Ce3+/Cen+ and Co3+/Con+) confirmed the above conclusion. Both the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms occurred in the NH3-SCR reaction over the Mn-Ce-Co-0.05/Ti-C,N catalyst. (c) 2021 Society of Chemical Industry