Enhancement of NH 3 -SCR performance of LDH-based MMnAl (M = Cu, Ni, Co) oxide catalyst: influence of dopant M.

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 NO x with NH 3 (NH 3 -SCR). The effects of transition metal modification were confirmed by means of XRD, BET, TEM, XPS, NH 3 -TPD, and H 2 -TPR measurements. Experimental results evidenced that CoMnAl-LDO presented the highest NO x removal efficiency of over 80% and a relatively high N 2 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 H 2 O and SO 2 . The reasons for such results could be associated with the good dispersion of Co 3 O 4 and MnO x , which could consequently provide optimum redox behavior, plentiful acid sites, and strong NO x adsorption ability. Furthermore, dynamics calculations verified the meaningful reduction in apparent activation energy ( E a ) for the CoMnAl-LDO sample, which is in agreement with the DeNO x activity.