Promotional mechanism of activity of CeEuMnOx ternary oxide for low temperature SCR of NOx

Abstract

Due to strong synergistic effect of the elements, a series of XEuMnOx ternary oxides (X = Ce, Ni, Co, Sb, Sn, Mo) were synthesized by one-pot co-precipitation method, and composite components were identified and optimized to maintain high activity and superior SO2 and H2O endurance in selective catalytic reduction of NOx with NH3 (NH3-SCR). NOx conversion of CeEuMnOx ternary oxide catalysts attains more than 90% at 100–250 °C, and finally achieves 74% under existence of 50 × 10−6 SO2 and 10 vol% H2O at 230 °C. The facile electron transfer through redox cycle of Mn3+ + Ce4+ ↔ Mn4+ + Ce3+ and enhanced oxygen mobility can promote formation of more Mn species in high oxidation state and chemisorbed oxygen, accelerating oxidation of NO and the adsorbed NO2 formed can facilitate “fast SCR” reaction to improve low-temperature activity. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study reveals that addition of Ce to EuMnOx catalyst boosts adsorption of NH3 and NOx species. NH3 species are activated as crucial intermediate (NH2) to promote NH3-SCR reaction. This research provides a novel material for practical deNOx application of stationary source combustion flue gas in the future.