NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Abstract

Herein, a facile glycine combustion method was utilized to prepare a series of Ni and Mn based single/double metal oxides, which were evaluated as catalysts for low temperature selective catalytic reduction of NO with NH3. The NiMn-T samples presented superior catalytic performance especially for NiMn-400, with ∼100 % NOx conversion, >85 % N2 selectivity within 90-300 °C, and better SO2 resistance. The superior catalytic activity might be related to the coordination of Ni and Mn, which afforded higher Mn4+/Mnn+ ratio, larger SBET, more suitable acid site amounts and redox capacity. The improved SO2 resistance of NiMn-400 catalyst can be ascribed to the less ammonium (bi)sulfate deposition and metal sulfation. In-situ DRIFTS revealed that the Ni doping could deliver more reactive species (NH2, monodentate nitrite, bidentate nitrate), and the surface acidity is less affected by SO2, which can account for the enhanced low temperature activity and SO2 resistance of the NiMn-400 catalyst.