Mineral-derived catalysts optimized for selective catalytic reduction of NOx with NH3

A type of novel mineral-derived catalyst (MDC) composed vanadium–titanium magnetite and sintering ore was prepared via calcination or acid modification for selective catalytic reduction nitrogen oxides (NOx) with ammonia (NH3) to reduce the production cost simplify preparation process. Characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) mapping, photoelectron spectroscopy (XPS) temperature-programmed hydrogen (H2–TPR) characterizations were performed observe evolution physicochemical properties mineral during modification, which corelated their activity. The in-situ DRIFTS also investigated discuss reaction mechanism different catalysts. results show that catalysts sulfuric exhibit high NOx conversion (above 90% at 350 °C) sulfur resistance due formation ferric sulfate species presence Fe3+/Fe2+ V5+/V4+ couples in abundant Brønsted sites promotes redox indicate modified calcination-pretreatment primarily follow Langmuir-Hinshelwood (L–H) where gaseous NO is more easily adsorbed on ?-Fe2O3 form stable nitrates react a small number NH3 ?-Fe2O3, leading decreased On other hand, mainly Eley-Rideal (E–R) less thermal stability large amount directly NO, resulting higher