Graphene supported CoO nanoparticles as an advanced catalyst for aerobic oxidation of cyclohexane

Transition metals are commonly employed as catalysts for the oxidation of cyclohexane. However, the harsh reaction conditions and the low efficiency hinder their further application. In this work, to further improve the reaction efficiency, transition metal oxide (CoO and MnO)/graphene composites are fabricated as heterogeneous catalysts for the oxidation of cyclohexane. Among the as synthesized catalysts, CoO/graphene (CoO/G) exhibits the best catalytic efficiency. The structure characterization illustrated that the transition metal oxides are well anchored on the graphene sheets, thus leading to the fine distribution of the catalyst. To demonstrate the synergistic catalytic activity of CoO and graphene in the oxidation process of cyclohexane, CoO loaded on other supports, pure CoO and pure graphene were also adopted as the catalyst for the oxidation reaction under the same conditions. The results show that CoO or graphene solely exhibits relatively low catalytic activity, but their hybrid efficiently improves the conversion and selectivity. By optimizing the experimental conditions, 32.4% conversion of cyclohexane and 75.4% selectivity to K/A oil could be achieved.