Ceria modified FeMnOx-Enhanced performance and sulphur resistance for low-temperature SCR of NOx

- Ce(12.5) possessed the highest activity at 75 °C and lower NH3 adsorption capacity.
- Ceria altered the local surface structure of the catalyst, by partially blocking adsorption sites, while simultaneously altering the amount of chemisorbed surface oxygen.
- Activity enhancement occurred as a result of the fast-SCR reaction.
- Ce(12.5) was found to result in more stable chemisorbed N-containing species in the presence of SO2 leading to a more SO2 resistant catalyst compared to FeMnOx.

Low-temperature NH3-SCR is an environmentally important reaction for the abatement of NOx from stationary sources. In recent years FeMnOx has attracted significant attention as a potential catalyst for this process, however its catalytic activity and SO2 resistance require further improvement. In this contribution FeMnOx has been modified to examine the effect of ceria on catalytic activity and SO2 resistance in the low temperature region. Preparation of catalysts via the citric acid method generate modified materials that exhibit enhanced NO turnover compared to FeMnOx. A reduction in NH3 adsorption (NH3-TPD) and a suitable ratio between NO sites (NO-TPD) and chemisorbed surface oxygen (XPS) are beneficial for the promotion of fast-SCR. A comparative SO2 resistance study of FeMnOx and Ce(12.5) showed that the latter exhibited improved stability in the presence of SO2, as indicated by the retention of pore volume (N2 adsorption) and surface composition (XPS). In-situ DRIFTS demonstrated that chemisorbed N-containing species on Ce(12.5) were much more stable in the presence of SO2 compared to FeMnOx, which resulted in the formation of significantly less metal sulphates and NH4HSO4.

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