NH3-SCR performance and mechanism of Mn-Fe-doped SO42--CeCO3F-CePO4 catalysts: Effect of Mn-Fe-Ce synergy and sulfuric acid concentration

Abstract

Iron (Fe) and manganese (Mn) were integrated as active elements onto the surface of the pre-acidified CeCO₃F-CePO₄ catalyst using sulfuric acid through the impregnation method. The study examined the impact of the doping sequence of iron and manganese and sulfuric acid acidification on the catalyst's performance. It was determined that the catalyst, with an iron-first and then manganese doping sequence (Fe: Mn = 2: 10) and a sulfuric acid concentration of 1 mol/L (10%Mn–2%Fe/SO₄^2--CeCO₃F-CePO₄), exhibited optimal reactivity. The denitration efficiency consistently exceeded 94 % in the temperature of 150 °C–400 °C, while the N₂ selectivity remained above 90 %. SEM and XRD analyses revealed that the prioritized doping of iron facilitated the dispersion of active substances on the catalyst surface, thereby enhancing the adsorption and activation of reaction gases. The improved reaction activity resulting from the preferential introduction of iron and sulfuric acid acidification was linked to the generation of a greater abundance of Ce³⁺, Mn⁴⁺, Fe³⁺, and an increase in atomic adsorbed oxygen. DRIFTS results indicated that the NH₃-SCR reaction primarily adhered to the L-H and E-R mechanisms.