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 degrees 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.