C,N‐modified TiO2‐supported Mn–Ce–Cox‐based catalyst for low‐temperature NH3‐SCR

• Published in: Journal of chemical technology and biotechnology (1986) 2022-03, Vol.97 (3), p.779-791
• Main Authors: Liu, Shuai, Liu, Shanshan, Sun, Xiaoyi, Liu, Qingjie, Zhang, Xintang
• Format: Article
• Language: English
• Subjects: Acidity; Ammonia; Catalysts; Catalytic activity; Catalytic converters; Cerium; Chemical reduction; cobalt doping; Conversion; Doping; Emissions; Environmental health; low‐temperature selective catalytic reduction; modified support; Nitrogen dioxide; Oxidation; Photoelectron spectroscopy; Photoelectrons; Public health; redox performance; Redox properties; Selective catalytic reduction; surface acidity; Titanium dioxide
• ISSN: 0268-2575; 1097-4660
• DOI: 10.1002/jctb.6983

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–Cox/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 °C; Mn–Ce/Ti–C,N catalyst, 140–320 °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 °C. CONCLUSION Temperature‐programmed reduction (H2‐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–Co0.05/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 (Oα) 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–Co0.05/Ti–C,N catalyst. © 2021 Society of Chemical Industry