Low-temperature NOx reduction over hydrothermally stable SCR catalysts by engineering low-coordinated Mn active sites

Abstract

Low-temperature selective catalytic reduction (SCR) of NOx over hydrothermally stable metal oxide catalysts is still a great challenge in heavy-duty diesel exhaust purification. Herein, hydrothermally stable MnOx/Al2O3 catalysts with highly dispersed low-coordinated Mn active sites were originally demonstrated for low-temperature NOx reduction. The catalyst exhibited greater than 90 % NOx conversion within 200–360 °C even after a 24 h aging treatment at 650 °C with a flow of 10 % H2O. A series of characterization revealed that the developed catalysts with more active low-coordinated Mn species possessed reactive redox sites and Lewis acid sites. Thus, the successive adsorption and activation of NH3 and NOx species would be efficiently accelerated and proceeded with the subsequent SCR reaction over hydrothermally stable MnOx/Al2O3 catalysts. This work discovered hydrothermally stable manganese oxide catalyst for low-temperature NOx reduction which would provide new opportunities for the application of metal oxide catalysts among diesel engine exhaust emission control.