Understanding the temperature-dependent H2O promotion effect on SO2 resistance of MnOx-CeO2 catalyst for SCR denitration

• Published in: Applied catalysis. B, Environmental Environmental, 2023-05, Vol.324, Article 122263
• Main Authors: Ji, Jiawei, Gao, Ningze, Song, Wang, Tang, Yu, Cai, Yandi, Han, Li, Cheng, Lijun, Sun, Jingfang, Ma, Shenggui, Chu, Yinghao, Tang, Changjin, Dong, Lin
• Format: Article
• Language: English
• Subjects: H2O promotion; MnOx-CeO2 catalyst; SO2 resistance; Sulfite species; Ultra-low temperature denitration
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.122263

Understanding how H2O affects SO2 tolerance of SCR catalysts at different working temperatures is of great importance. Herein, we reported that H2O addition at ultra-low temperature of 100 °C induced a significant promotion on SO2 tolerance of MnOx-CeO2 catalysts. Sole SO2 led to serious activity loss from 100% to 20%, while H2O coexistence alleviated the deactivation and an admirable activity of 60% was reserved. Combining experimental characterizations with DFT calculation, we demonstrated that H2O promoted hydroxyl formed on defect sites, which promoted more sulfite formation and retarded sulfates with strong electron-withdrawing capacity disturbing active Mn sites. In comparison with sulfates, sulfites exhibited less interference in adsorbed species, ensuring the occurrence of Eley-Rideal and Langmuir-Hinshelwood mechanisms. The present study discloses the unique temperature-dependent effect of H2O on SO2 tolerance, which is expected to deepen our understanding on the role of H2O in modulating surface species and catalytic behaviors of SCR catalysts. [Display omitted] •Unusual temperature-dependent H2O promotion effect on SO2 tolerance of SCR catalysts was reported.•The addition of H2O greatly alleviated the SO2 poisoning of MnOx-CeO2 catalysts at ultra-low temperature of 100 °C.•Hydroxyl group derived from H2O disassociation restricted the electron interaction between sulfur species and Mn sites, protecting active Mn via more sulfites forming.•Sulfites showed less interference on surface active adsorbed species and ensured the occurrence of both L-H and E-R mechanism over MnCe-SO2+H2O catalyst.