Promoting the NH3-SCR performance of Fe2O3-TiO2 catalyst through regulation of the exposed crystal facets of Fe2O3

Iron oxide (Fe2O3)-based catalysts have garnered significant attention in the field of selective catalytic reduction with NH3 (NH3-SCR) due to their high thermal stability, N2 selectivity, low cost, and environmental friendliness. In this study, Fe2O3 catalysts with exposed {0 1 2}, {0 1 4}, and {1 1 3} facets were successfully synthesized using a hydrothermal method. Subsequently, TiO2 was loaded to construct Fe2O3-TiO2 catalysts with different crystal facets of Fe2O3. The results demonstrated that TiO2 was uniformly distributed on three different morphologies of Fe2O3. Among the catalysts, the Fe2O3{1 1 3}-TiO2 exhibited superior NOx removal capacity and a broader temperature operating range than Fe2O3{0 1 2}-TiO2 and Fe2O3{0 1 4}-TiO2. The promotion mechanism of NH3- SCR performance was determined by regulating the crystal facets of Fe2O3 in Fe2O3-TiO2 catalysts. The mech-anism can be attributed to the improved redox properties, as well as the presence of additional active oxygens, surface acid sites, and adsorbed nitrate species on the Fe2O3{1 1 3}-TiO2 catalyst. In situ DRIFTS results indicated that the SCR reactions of Fe2O3-TiO2 catalysts with different crystal facets of Fe2O3 followed both the Langmuir-Hinshelwood and Eley-Rideal mechanisms. Furthermore, the Fe2O3{1 1 3}-TiO2 catalyst exhibited the improved reaction efficiency at both the Langmuir-Hinshelwood and Eley-Rideal pathways. This study provides novel insights on the influence of crystal planes on Fe2O3, which is important for optimizing Fe2O3-based NH3-SCR catalysts.