Insight into structure defects and catalytic mechanism for NO oxidation over Ce0.6Mn0.4Ox solid solutions catalysts: Effect of Manganese precursors

The effects of Mn precursors on structure defects and NO catalytic mechanism over Ce0.6Mn0.4Ox catalysts were fully investigated. The Ce0.6Mn0.4Ox-Ac catalyst, synthesized by using MnAc2 as a Mn precursor, showed the best catalytic activity for NO conversion (86.9%) at 250 degrees C under high space velocity (40,000 mL g(-1) h(-1)). Detailed structure-activity relationship reveals that the abundant oxygen vacancies and the highly migratory oxygen species formed on Ce0.6Mn0.4Ox are the crucial factors that leading to the better NO oxidation activity than that of the other Ce0.6Mn0.4Ox-Y (Y=NO3,SO4, Cl) catalysts. In situ DRIFTS technique confirms that the differences in formation mode and desorption ability of N-based (nitrates, nitrites, and dimer nitroso) intermediate species are the vital factors for NO high-efficiency catalytic oxidation. The highly reactive surface intermediate species, like monodentate nitrates, were observed particularly on Ce0.6Mn0.4Ox-Ac catalyst, so that the NO oxidation performance on Ce0.6Mn0.4Ox-Ac catalyst was more active comparing with other Ce0.6Mn0.4Ox-Y catalysts. This study can broaden the horizons for understanding NO catalytic oxidation mechanism on serial Ce0.6Mn0.4Ox catalysts and serve as a reference guide in design of structure defects for functional materials by modulating precursor species. (C) 2019 Elsevier Ltd. All rights reserved.