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 Ni_xMn bimixed metal oxides (Ni_xMn-LDO) were prepared via calcining Ni_xMn layered double hydroxides (Ni_xMn-LDHs) precursors at 400 °C and applied as catalysts in the selective catalytic reduction (SCR) of NO_x with NH₃. The DeNO_x performance of catalysts was optimized by adjusting the Ni/Mn molar ratios of Ni_xMn-LDO precursors, in which Ni₅Mn-LDO exhibited above 90% NO_x 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 DeNO_x property.