Catalytic Ozonation of Low Concentration Toluene over MnFeO-USY Catalyst: Effects of Interactions between Catalytic Components and Introduction of Gas Phase NO.

A series of Mn and Fe metal oxide catalysts loaded onto USY, as well as single metal oxides, were prepared and characterized. The effects of interactions between the catalytic components and the introduction of gas phase NO on the catalytic ozonation of toluene were investigated. Characterization showed that there existed strong interactions between MnO, FeO, and USY, which enhanced the content of oxygen vacancies and acid sites of the catalysts and thus boosted the generation of reactive oxygen species and the adsorption of toluene. The MnFeO-USY catalyst with MnO and FeO dimetallic oxides exhibited the most excellent performance of catalytic ozonation of toluene. On the other hand, the presence of NO in reaction gas mixtures significantly promoted both toluene conversion and mineralization, which was attributed to the formation of nitrate species on the catalysts surface and thus the increase of both acid sites and toluene oxidation sites. Meanwhile, the reaction mechanism between O and CH was modified in which the strong interactions between MnO, FeO, and USY accelerated the reaction progress based on the L-H route. In addition, the formation of the surface nitrate species not only promoted reaction progress following the L-H route but also resulted in the occurrence of the reaction via the E-R route.