Metal organic framework-templated fabrication of exposed surface defect-enriched Co3O4 catalysts for efficient toluene oxidation.

Exposed surface defect-enriched Co3O4 catalysts derived from metal organic framework (MOF) were fabricated by the promotion of surface Mn species for toluene oxidation. The incorporation of Mn species into Co3O4 surface lattice could give rise to the local lattice distortion in spinel structure, resulting in highly exposed surface defect rather than bulk defect. More Co3+ species were also exposed on the surface of MnOx/Co3O4 samples owing to the electron transfer from Co to Mn species by the occupation of surface Mn in octahedral Co3+ sites. Accordingly, the low-temperature reducibility and high mobility of lattice oxygen were significantly improved in virtue of the highly exposed surface defect and predominately surface Co3+ sites, thus promoting the catalytic activity and stability for toluene oxidation. Moreover, the toluene conversion decreased with the increase of weight hourly space velocity (WHSV). In situ DRIFTS results confirmed the continuous oxidation process for toluene degradation, and the conversion of benzoate into maleic anhydride should be the rate-controlling step.