Abstract: Excellent performances promoted by lattice oxygen have attracted wide attention for catalytic degradation of volatile organic compounds (VOCs). However, how to control the continuous regeneration of lattice oxygen from the support is seldom reported. In this study, we selected sepiolite supported manganese-cobalt oxides (Co_xMn_100-xO_y) as model catalysts by tuning Co/(Co + Mn) mass ratio (x = 3%, 10%, 15%, and 20%) to enhance toluene degradation efficiency, owing to lattice oxygen regeneration by redox cycle existing at the interface and Mn species with high valence state, initiated by cobalt catalytic performance under the role of crystal field stability phase. The results of activity test show that the sepiolite-Co₁₅Mn₈₅O_y catalyst exhibit outperformances at 193 ℃ with 10,000 h^-1 GHSV. In addition, the catalyst existed at the bottom of the “volcano” curve correlated T₅₀ or T₉₀ with Co/(Co + Mn) weight ratio is sepiolite-Co₁₅Mn₈₅O_y, conforming its outperformance. Further characterized by investigating active sites structural and electronic properties, the essential of superior catalytic activity is attributed to the grands of lattice oxygen continuous formation resulted from redox engineering based on the high atomic ratio of surface lattice oxygen with continuous refilled from the support and that of Mn⁴⁺/Mn³⁺ cycle initiated by cobalt catalytic behaviors. All in all, redox engineering, not only promotes grands of active species reversible regeneration, but supplies an alternative catalyst design strategy towards the terrific efficiency-to-cost ratio performance.

Key words: Redox engineering, Crystal field stability phase, Lattice oxygen, Toluene degradation

摘要： Excellent performances promoted by lattice oxygen have attracted wide attention for catalytic degradation of volatile organic compounds (VOCs). However, how to control the continuous regeneration of lattice oxygen from the support is seldom reported. In this study, we selected sepiolite supported manganese-cobalt oxides (Co_xMn_100-xO_y) as model catalysts by tuning Co/(Co + Mn) mass ratio (x = 3%, 10%, 15%, and 20%) to enhance toluene degradation efficiency, owing to lattice oxygen regeneration by redox cycle existing at the interface and Mn species with high valence state, initiated by cobalt catalytic performance under the role of crystal field stability phase. The results of activity test show that the sepiolite-Co₁₅Mn₈₅O_y catalyst exhibit outperformances at 193 ℃ with 10,000 h^-1 GHSV. In addition, the catalyst existed at the bottom of the “volcano” curve correlated T₅₀ or T₉₀ with Co/(Co + Mn) weight ratio is sepiolite-Co₁₅Mn₈₅O_y, conforming its outperformance. Further characterized by investigating active sites structural and electronic properties, the essential of superior catalytic activity is attributed to the grands of lattice oxygen continuous formation resulted from redox engineering based on the high atomic ratio of surface lattice oxygen with continuous refilled from the support and that of Mn⁴⁺/Mn³⁺ cycle initiated by cobalt catalytic behaviors. All in all, redox engineering, not only promotes grands of active species reversible regeneration, but supplies an alternative catalyst design strategy towards the terrific efficiency-to-cost ratio performance.

关键词: Redox engineering, Crystal field stability phase, Lattice oxygen, Toluene degradation