Selective catalytic reduction of NO with NH3 over MnOx-CeO2 catalysts: Unraveling the unusual content-dependent precursor effect

• Published in: Fuel (Guildford) Vol. 376
• Main Authors: Wang, Yan, Cheng, Lijun, Sin, Songil, Zhu, Baiyun, Xu, Lu, Xu, Yun, Tao, Meilin, Ma, Kaili, Zhuang, Ke, Tang, Changjin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.11.2024
• Subjects: Mn content; MnOx-CeO2 catalysts; NH3-SCR; Precursor effect; Reaction mechanism; Reaction mechanism; Mn content; NH3-SCR; MnOx-CeO2 catalysts; Precursor effect
• ISSN: 0016-2361
• DOI: 10.1016/j.fuel.2024.132729

[Display omitted] •Unusual content-dependent precursor effect of MnCe catalysts in NH3-SCR was reported.•Interfacial interaction between MnOx and CeO2 was strengthened via Ce(IV) precursor.•The active sites of MnCe catalysts were different under varied Mn content.•The reaction mechanism of MnCe catalysts was clearly revealed. MnOx-CeO2 catalysts are attractive for low-temperature NH3-SCR. However, the combined effect from diverse influencing factors is still obscure. Herein, we reported an unusual content-dependent precursor effect for MnOx-CeO2 catalysts in NH3-SCR. The 0.33MnCe sample derived from Ce(III) precursor showed inferior NO conversion efficiency (23% vs 56% at 100 °C) as compared to the counterpart from Ce(IV), while an opposite trend was exhibited for high Mn content (3MnCe, 100% vs 74%). Detailed analyses from XRD, Raman, TEM, XPS, ESR and H2-TPR revealed that irrespective of MnOx content, the interaction in terms of surface dispersion and interfacial electron exchange between MnOx and CeO2 was strengthened through Ce(IV) precursor. This exactly played a positive effect in promoting NO conversion for highly dispersed MnOx species. With elevation of Mn content, crystalline MnOx appeared and the weaker interfacial interaction led to generation of more aggregated MnOx. Further characterizations from DFT calculation, NO oxidation and NO/NH3-TPD disclosed the unique capacity of crystalline MnOx species in simultaneously promoting NH3 adsorption/activation and NO oxidation. As a consequence, superior NO conversion was achieved over the catalyst from Ce(III) precursor. The result of present study uncovers the unique content-dependent effect of precursor on the SCR performance, which is expected to provide useful guidance for design of well-performed MnOx-CeO2 catalysts.