Iron-Based Composite Oxide Catalysts Tuned by CTAB Exhibit Superior NH3–SCR Performance

Iron-based oxide catalysts for the NH3–SCR (selective catalytic reduction of NOx by NH3) reaction have gained attention due to their high activity and structural adjustability. In this work, iron–niobium, iron–titanate iron–molybdenum composite oxides were synthesized a co-precipitation method with or without assistance hexadecyl trimethyl ammonium bromide (CTAB). The CTAB (FeM0.3Ox-C, M = Nb, Ti, Mo) showed superior SCR performance in an operating temperature range from 150 °C 400 compared those addition (FeM0.3Ox, Mo). To reveal such enhancement, characterized N2-physisorption, XRD (Powder X-ray diffraction), NH3-TPD (temperature-programmed desorption ammonia), DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy), XPS (X-ray Photoelectron H2-TPR (H2-Total Physical Response). It was found that crystalline phase Fe2O3 formed influenced presence preparation process, which favored formation ?-Fe2O3. Owing changed structure, redox-acid properties FeM0.3Ox-C modified, higher exposure acid sites improved ability NO oxidation NO2 at low-temperature, both also contributed improvement conversion. addition, weakened redox Fe prevented over-oxidation NH3, thus accounting greatly high-temperature as well N2 selectivity.