Promotion of NH 3 -SCR activity by sulfate-modification over mesoporous Fe doped CeO 2 catalyst: Structure and mechanism

• Published in: Journal of hazardous materials 2021-03, Vol.414, p.125565
• Main Authors: Wang, Hui, Qu, Zhenping, Liu, Lianlian, Dong, Shicheng, Qiao, Yujie
• Format: Article
• Language: English
• ISSN: 1873-3336

The mesoporous Fe doped CeO catalyst after modifying organic sulfate functional groups show an excellent activity with above 80% NO conversion in a temperature range of 250-450 °C. These organic-like sulfate groups bound to the Fe-O-Ce species leads to the strong electron interaction between Fe -O-Ce species and sulfate groups, which modifies the acidity and redox properties of catalyst. The strong ability of S˭O/S-O in sulfate groups to accommodate electrons from a basic molecule is a driving force in the generation of acidic properties, and thus promotes to produce new Brønsted acid sites. The bondage of Fe-O-Ce species obviously inhibits the creation of thermostable bidentate NO species. Besides, the redox cycles between Fe and Ce are disrupted, thus inhibiting NH oxidation at medium-high temperatures and resulting in the increase of NO conversion. Furthermore, the in situ DRIFTS results show that for the fresh samples, the coordinate NH reacts not only with NO through L-H mechanism, but also with oxygen species to form NO . Differently for sulfated sample, the coordinate NH might react with achieved NO instead of the oxygen species through E-R mechanism, meanwhile the NH could react with the NO species through L-H mechanism.