Enhanced Low-Temperature NH 3 –SCR Activity of MIL-100(Fe) Catalysts via Calcination Atmosphere Engineering: Structure Regulation and Reaction Mechanism

Iron-based metal–organic framework (MOFs) catalysts show promising potential in the NH3–SCR denitrification. Rational regulation of calcination processes is crucial for optimizing the low-temperature NH3–SCR performance of MIL-100(Fe) catalysts. This study systematically investigated the effects of four calcination atmospheres (N2, Air, N2 → Air, Air → N2) on its structure and denitrification activity, with the calcination atmosphere regulating the catalyst structure via ligand decomposition, Fe species dispersion/valence, acid site distribution, and pore structure adaptability. The MIL-100(Fe)-NA (N2 → Air) catalyst exhibited 94% NOx conversion at 300 °C, near-100% N2 selectivity, an ultralow apparent activation energy (12.93 KJ·mol–1), as well as excellent SO2 promotion effect and stability. Its superiority stems from a uniform cubic cluster structure, high Fe content, strong redox capacity, and abundant medium-strong acid sites. Quantitative structure–property-activity correlation analysis confirms that Lewis acid site content, lattice oxygen ratio, and redox capacity are the key factors governing catalytic activity, rather than physical properties like specific surface area. In situ DRIFTS verified that the catalyst follows both Langmuir–Hinshelwood and Eley–Rideal mechanisms. This work provides a green pathway for innovating the preparation processes of Fe-MOFs-derived catalysts and offers a reference for high-efficiency catalytic materials in industrial NOx advanced treatment.