Shuya Rui,Na Liu,Lingwei Ren,Yang Liu,Zian Liu,Binghui Wu,Hua Pan,Zhiping Ye
Traditional Mn-Ce catalysts for selective catalytic reduction (SCR) of NO with CO (CO-SCR) in iron and steel flue gases are often hindered by competitive adsorption of NO and CO, which compromises catalytic efficiency. In this study, we present a Ni-doped Mn-Ce catalyst that overcomes these challenges, achieving 96 % NO conversion, 98 % N 2 selectivity, and 44 % CO conversion at 175 °C. Comprehensive characterization of the catalyst reveals that Ni doping significantly enhances Mn-Ce interactions, boosting oxygen vacancy density and promoting efficient redox cycling between Mn 3 + /Mn 4+ and Ce 3+ /Ce 4+ . Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirms preferential NO adsorption at oxygen vacancy sites, minimizing CO-NO competition and stabilizing the Langmuir-Hinshelwood mechanism, where both gases co-adsorb and react at oxygen-rich vacancies. Mechanistic insights suggest that Ni facilitates electron transfer, weakening the N–O bond in NO and accelerating its dissociation, resulting in faster NO reduction. This study establishes Ni doping as a promising strategy for improving the low-temperature performance of Mn-Ce-based CO-SCR catalysts, paving the way for more efficient catalytic systems.
A series of 3DOM-Mn x Ce y Ti z catalysts with three-dimensionally ordered macroporous (3DOM) structure were synthesized by a soft template method. The high SCR activity of the 3DOM-Mn 3 Ce 1 catalyst at low temperature was owing to the excellent redox ability and rich Lewis and Brønsted acid sites of the catalysts, which were beneficial to improve the catalytic activity. However, the strong oxidizability of MnO x resulted in the nonselective oxidation of NH 3 and generation of N 2 O, decreasing the N 2 selectivity. After addition of Ti, the redox capacity of the 3DOM-Mn 3 Ce 1 Ti 1 catalyst decreased, and the NH 3 were strongly adsorbed on the acid sites, which enhanced the N 2 selectivity with a broadened temperature window of 240–440 °C and a high GHSV of 120000 h −1 . Furthermore, both the 3DOM-Mn 3 Ce 1 and 3DOM-Mn 3 Ce 1 Ti 1 catalysts showed remarkable tolerance of H 2 O. Finally, through in situ DRIFT analysis, the Langmuir-Hinshelwood (L-H) mechanism was confirmed as the dominant reaction pathway over the 3DOM-Mn 3 Ce 1 Ti 1 catalyst.
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