Surface cobalt silicate and CoO _x cluster anchored to SBA-15: Highly efficient for cyclohexane partial oxidation

The present investigation showed that the surface cobalt silicate and CoO _x cluster anchored to SBA-15 are highly efficient heterogeneous catalysts for the cyclohexane partial oxidation with air-like O₂ (20%)-N₂ (80%) mixture as oxidant in the continuously stirred tank reactor at 413 K and 1.0 MPa. Typically, selectivity of 84.6% at cyclohexane conversion of 14.5% can be achieved in a period of 2 h reaction. The performance of Co-catalyst is affected by the nature of Co species introduced to SBA-15. The surface cobalt silicate with higher proportion of "isolated" Co²⁺ sites shows better result than the well dispersed CoO _x clusters mainly on the internal surface of SBA-15. Furthermore, different preparation method also influences the porosity of SBA-15 and accessibility to Co sites, which may in turn affect on the reaction performance. Graphical Abstract: The surface cobalt silicate and CoOx cluster anchored to SBA-15 are highly efficient for the cyclohexane partial oxidation with air-like O₂(20%)-N₂(80%) mixture as oxidant in the continuously stirred tank reactor at 413 K and 1.0 MPa. Typically, selectivity of 84.6% at cyclohexane conversion of 14.5% can be achieved in a period of 2 h reaction. The catalyst performance is dependent on the nature of Co species introduced to SBA-15.