Remarkable low temperature catalytic activity for SCR of NO with propylene under oxygen-rich conditions over Mn0.2La0.07Ce0.05Ox/ZSM-5 catalyst

Unlike NH3-SCR systems, even in oxygen-poor conditions, SCR of NO with propylene traditionally exhibited good catalytic activity only at high temperature (>300 ?C) due to the reduction properties of propylene. Most of the researches of low temperature HC-SCR are still focused on the development of noble metal (Ag, Pt, Pd, Rh etc.) catalysts. Herein, a series of rare earth metals LayCez co-doped Mn-based microporous zeolite ZSM-5 (MnxLayCez/ ZSM-5) were prepared by co-impregnation method. Under the simulated oxygen-rich condition of actual diesel engines, we first reported a non-noble metal catalyst that exhibited high activity (>90%) and selectivity (>90%) for low temperature (180?270 ?C) C3H6-SCR. The excellent low temperatures catalytic performance could be attributed to the more Br?nsted acid sites, the higher superficial dispersion of manganese species, the more oxygen vacancy and the larger pore size (4.42 nm) characterized by XRD, SEM, HR-TEM, HAADF-STEM, NH3TPD, H2-TPR and FT-IR. Moreover, the XPS results showed that the introduction of La could effectively enhance the oxygen vacancies of manganese oxide and cerium oxide, which significantly increase the chemical adsorption of NO, reducing the reaction activation energy, and promoting the conversion of NO under low-temperature. These advantages suggest the material has huge application potential in the deNOX process.

Automated summary

This study developed a non-noble metal catalyst with high activity and selectivity for NO-SCR reaction at low temperatures. The catalyst's success can be attributed to more Br?nsted acid sites, higher surface dispersion of manganese species, increased oxygen vacancies, and larger pore size.