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

• Published in: Journal of hazardous materials 2019-02, Vol.363, p.439-446
• Main Authors: Liu, Cheng, Li, Fei, Wu, Jing, Hou, Xin, Huang, Wei, Zhang, Yong, Yang, Xiangguang
• Format: Article
• Language: English
• Subjects: CePO4; Langmuir–Hinshelwood (LH) mechanism; Monodentate nitrates; NO oxidation; Selective catalytic reduction
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.09.054

[Display omitted] •The NOx conversion of the MnOx/CePO4 catalyst was above 80% even at 180 °C.•The MnOx/CePO4 catalyst exhibits an excellent water tolerance and N2 selectivity.•The process of NO oxidation to NO2 over the catalyst plays a key role during the NH3-SCR process.•Monodentate nitrates were the major active species for the NO removal.•The reaction process of the MnOx/CePO4 catalyst was majorly conducted via the Langmuir–Hinshelwood mechanism. The MOx (M = Cu, Mn, Co)/CePO4 support was firstly prepared via the hydrothermal and impregnated method. Selective catalytic reduction of NO with NH3 (NH3-SCR) results showed that the MnOx modifications greatly improved the SCR activities at low temperatures. The NOx conversion of the MnOx/CePO4 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 NH3 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 O2-TPD and NO oxidation tests. The process of NO oxidation to NO2 plays a key role to produce the absorbed monodentate nitrate as indicated by the In-situ DRIFTS. The support CePO4 acts as the acid sites to form highly active NH4+ species. The synergic effect between the MnOx and CePO4 contributed to the high SCR activity over the MnOx/CePO4 catalyst. Additionally, the MOx/CePO4 catalyst exhibits an excellent water tolerance and N2 selectivity. Consequently, the MnOx/CePO4 catalyst becomes the potential catalyst for the practical process.