Enhancement of NH3-SCR performance of LDH-based MMnAl (M = Cu, Ni, Co) oxide catalyst: influence of dopant M

Abstract

Transition metal (Cu, Ni, Co) doped MnAl mixed oxide catalysts were prepared through a novel method involving the calcination of hydrotalcite precursors for the selective catalytic reduction of NOx with NH3 (NH3-SCR). The effects of transition metal modification were confirmed by means of XRD, BET, TEM, XPS, NH3-TPD, and H2-TPR measurements. Experimental results evidenced that CoMnAl-LDO presented the highest NOx removal efficiency of over 80% and a relatively high N2 selectivity of over 88% in a broad working temperature range (150–300 °C) among all the samples studied. Moreover, the CoMnAl-LDO sample possessed better stability and excellent resistance to H2O and SO2. The reasons for such results could be associated with the good dispersion of Co3O4 and MnOx, which could consequently provide optimum redox behavior, plentiful acid sites, and strong NOx adsorption ability. Furthermore, dynamics calculations verified the meaningful reduction in apparent activation energy (Ea) for the CoMnAl-LDO sample, which is in agreement with the DeNOx activity.