Ultralow-Temperature NOx Reduction over SmMn2O5 Mullite Catalysts Via Modulating the Superficial Dual-Functional Active Sites

The development of highly efficient catalysts for low-temperature NOx abatement still existed as a scabrous issue. An acid-etched mullite-type SmMn2O5 catalyst (SM-E) was developed and applied in ultralow-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR) to meet the increasingly rigorous demands of emission control in the nonelectric industry, which can convert more than 90% NOx in a wide operating window (90–200 °C). It has been demonstrated that NO can be preferably adsorbed and activated on the unique Mn–Mn dimer sites and further react with the adsorbed NH3 on adjacent Mn–O sites over the SM-E catalyst. The synergistic effects of these abundant exposed dual-functional active sites on the SM-E catalyst contributed to the extraordinary NH3-SCR performance compared to the pristine SmMn2O5 catalyst exposing deficient active sites as well as the Sm–Mn composite oxides containing sole Mn–O sites. This work sheds light on a novel strategy to deeply study the structure–performance relationship and provides deep insights into the rational design of NH3-SCR catalysts for ultralow-temperature NOx abatement.