A comparative study of MOx (M = Mn, Co and Cu) modifications over CePO4 catalysts for selective catalytic reduction of NO with NH3.

Graphical abstract Highlights • The NOx conversion of the MnO x /CePO 4 catalyst was above 80% even at 180 °C. • The MnO x /CePO 4 catalyst exhibits an excellent water tolerance and N 2 selectivity. • The process of NO oxidation to NO 2 over the catalyst plays a key role during the NH 3 -SCR process. • Monodentate nitrates were the major active species for the NO removal. • The reaction process of the MnO x /CePO 4 catalyst was majorly conducted via the Langmuir–Hinshelwood mechanism. Abstract The MO x (M = Cu, Mn, Co)/CePO 4 support was firstly prepared via the hydrothermal and impregnated method. Selective catalytic reduction of NO with NH 3 (NH 3 -SCR) results showed that the MnO x modifications greatly improved the SCR activities at low temperatures. The NOx conversion of the MnO x /CePO 4 catalyst was above 80% even at 180 °C. In-situ DRIFTS results suggest that the SCR reaction is majorly conducted between the absorbed monodentate nitrate and NH 3 species (i.e., the Langmuir–Hinshelwood mechanism). MOx (M = Cu, Mn, Co) exists in the formation of nano-size particles obtained by SEM and TEM directly. These nano-size particles can provide active surface adsorbed oxygen and thus improve the NO oxidation ability as indicated by the O 2 -TPD and NO oxidation tests. The process of NO oxidation to NO 2 plays a key role to produce the absorbed monodentate nitrate as indicated by the In-situ DRIFTS. The support CePO 4 acts as the acid sites to form highly active NH 4 + species. The synergic effect between the MnO x and CePO 4 contributed to the high SCR activity over the MnO x /CePO 4 catalyst. Additionally, the MOx/CePO 4 catalyst exhibits an excellent water tolerance and N 2 selectivity. Consequently, the MnO x /CePO 4 catalyst becomes the potential catalyst for the practical process. [ABSTRACT FROM AUTHOR]