Fe-Modified Mesh-Structured Mn2O3/γ-Al2O3/Al Catalysts: Enriched Surface Active Oxygen and Superior Redox Properties for Enhanced NH3-SCO Performance

Ammonia-selective catalytic oxidation (NH3-SCO) is an effective technology for eliminating NH3 slip; however, the development of catalysts that simultaneously exhibit excellent low-temperature (<350 °C) activity and high N2 selectivity remains a significant challenge. A novel structured monolithic mesh-type Fex-Mn2O3/γ-Al2O3/Al catalyst was developed. XPS, H2-TPR, and O2-TPD results demonstrate that Fe doping markedly increases the concentration of surface-adsorbed active oxygen species and enhances the redox capability. As a result, the optimally doped Fe6.61-Mn2O3/γ-Al2O3/Al catalyst achieved complete NH3 conversion at 210 °C with a 75% N2 selectivity, outperforming previously reported Mn-based catalysts. Density functional theory (DFT) calculations further confirm that Fe modification enhances O2 adsorption energy. In addition, the introduction of Fe significantly improves the catalyst’s resistance to SO2 and H2O. In situ FTIR results indicate that the NH3-SCO reaction over Fe-Mn2O3/γ-Al2O3/Al proceeds predominantly via an internal selective catalytic reduction (i-SCR) pathway.