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Although free hydroxyl radical (·OH) generated on OMS-2-based catalysts during the catalytic ozonation process have been shown as important reactive oxygen species (ROSs) for toluene degradation, improvement of surface ·OH formation ability remains challenging. Here, Na, K, Rb, and Cs-OMS-2-SO 4 2-/ZSM-5 catalysts were prepared, characterized and evaluated for catalytic ozonation of toluene. Both characterizations and DFT calculations showed that the appropriate alkali metal introduction made the catalyst possess with appropriate crystalline, reducibility, and acidity, which was favorable for catalytic ozonation of toluene. Characterizations also showed that alkali metal introduction resulted in water molecule adsorption on Brönsted acid sites of the catalysts, which made water molecule activation by ozone to form ·OH more easily. The introduction of K+ content of ∼ 5.9 wt% yielded K-OMS-2-SO 4 2-/ZSM-5 catalyst with the highest Brönsted acid sites and thus formed the most ·OH among the five prepared catalysts. As a result, the catalyst exhibited excellent toluene conversion and CO x selectivity for catalytic ozonation of toluene at room temperature and ambient humidity. Furthermore, the catalytic activity of deactivated K-OMS-2-SO 4 2-/ZSM-5 catalyst was recovered after regeneration by a combination of water washing and heat treatment. Finally, a complete mechanism for toluene catalytic ozonation, catalyst deactivation, and regeneration was proposed. [Display omitted] • The alkali metal introduction promoted ·OH formation in OMS-2-SO 4 2-/ZSM-5 catalyst. • The increased ·OH facilitated toluene conversion over OMS-2-SO 4 2-/ZSM-5 catalyst. • A complete mechanism for toluene catalytic ozonation and deactivation was proposed. • A strategy for efficient regeneration of K-OMS-2-SO 4 2-/Z catalyst was developed. [ABSTRACT FROM AUTHOR]

A series of MnFe catalysts were prepared by hydrothermal synthesis combined with heat treatment at different temperatures. The characterizations demonstrated that MnFe-120 with both surface -OH and -NO 3 , MnFe-175 with surface -OH, MnFe-300 containing neither surface -OH nor -NO 3 , and MnFe-300-NO 3 containing surface -NO 3 were gained by drying or calcination and impregnation. The activity evaluation showed that the order of catalytic activity was MnFe-120 > MnFe-175 > MnFe-300-NO 3 > MnFe-300. Further, characterizations and experiment results revealed that O 3 adsorbed on the surface of the catalyst can interact with surface -OH and generated hydroxyl radicals (·OH). The presence of surface -NO 3 provided more Lewis acid sites, thereby promoting H 2 O adsorption and conversion to the surface -OH, which supplemented the surface -OH consumed by the interaction with O 3. It was deduced that the coexistence of surface -OH and -NO 3 improved the production of·OH, which synergistically promoted the catalytic ozonation of toluene. [Display omitted] • A series of MnFe catalysts with different amounts of surface -OH and -NO 3 were prepared. • MnFe catalyst containing both surface -OH and -NO 3 had a optimal catalytic ozonation performance for toluene. • O 3 adsorbed on the surface -OH sites and hydroxyl radicals (·OH) to oxidize toluene was produced. • H 2 O adsorbed on the surface -NO 3 sites and was converted to the surface -OH, which supplemented the surface -OH consumed. • The synergistic effect of surface -OH and -NO 3 increased the amount of·OH production. [ABSTRACT FROM AUTHOR]