Mechanistic insight into the dynamic transformation of acid sites on ceria supported molybdenum oxide catalyst for NOx reduction. Issue 5 (October 2022)

• Record Type: Journal Article
• Authors: Ma, Nan; Hao, Zhifei; Liu, Guoquan; Zhang, He; Zhan, Sihui
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 5(2022)
• Publication Date: 2022-10
• Subjects: NOx removal -- MoOx/P-CeO2 -- Electronic interaction -- Acid sites -- Dynamic transformation; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.108114
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Acidity is a crucial factor limiting the application of ceria-based catalyst for selective catalytic reduction (SCR) of NOx with NH3 . Unravelling the participation mechanism of acid sites on ceria-based catalyst is imperative but still lacking. Herein, by tuning the electronic interaction between MoOx and CeO2 nanosheet with numerous pits (P-CeO2 ) via controlling the number of surface pits of P-CeO2, we demonstrate that electronic interaction strongly determines the acidity properties of catalyst to modulate the catalytic performance. The MoOx /P-CeO2 exhibits much better catalytic activity, N2 selectivity and tolerance to SO2 and H2 O than MoOx /CeO2 with few pits in a temperature range of 250–400 °C with a gas hourly space velocity (GHSV) of 60, 000 h −1, which is due to the highly dispersion of Mo-O-Mo structure over P-CeO2 as determined by Raman. Furthermore, XPS and DFT calculations demonstrate that electrons transfer from P-CeO2 to MoOx result in a unique dynamic transformation from Brønsted acid site to Lewis acid site, enhancing the catalytic activity. This work increases the acidity sites on the catalyst by regulating the electron oxide-support interaction, which provides a new strategy for designing highly efficient ceria-based SCR catalysts. Graphical Abstract: ga1 Highlights: Mo/P-CeO2 with abundant unsaturated cerium sites was prepared for NH3 -SCR. The Mo(0.01)/P-CeO2 exhibited best activity and H2 O and SO2 resistance. The pits on Mo/P-CeO2 regulate electronic interaction and affect acid sites. A dynamic transformation from Brønsted to Lewis acid appeared on Mo/P-CeO2 .