Tunable preparation of highly dispersed NixMn-LDO catalysts derived from NixMn-LDHs precursors and application in low-temperature NH3-SCR reactions

Abstract

A series of NixMn bimixed metal oxides (NixMn-LDO) were prepared via calcining NixMn layered double hydroxides (NixMn-LDHs) precursors at 400 °C and applied as catalysts in the selective catalytic reduction (SCR) of NOx with NH3. The DeNOx performance of catalysts was optimized by adjusting the Ni/Mn molar ratios of NixMn-LDO precursors, in which Ni5Mn-LDO exhibited above 90% NOx conversion and N2 selectivity at a temperature zone of 180-360 °C. Besides, Ni5Mn-LDO possessed considerable SO2 & H2O resistance and outstanding stability. Multiple characterization techniques were used to analyze the physicochemical properties of the catalysts. The analysis results indicated that all catalysts had the same active species Ni6MnO8, while their particle sizes showed significant differences. Notably, the uniform distribution of active species particles in the Ni5Mn-LDO catalyst provided the rich surface acidity and suitable redox ability which were the primary causes for its desirable DeNOx property.