Supported cobalt oxide nanocrystals: morphology control and catalytic performance for styrene oxidation

Abstract

Metal oxide nanoparticles with controlled size and morphology seem extremely important due to the strong correlation between these parameters and their catalytic properties. Herein supported cobalt oxide nanoparticles with controlled size and different morphologies were successfully synthesized via a facile hydrothermal synthetic route under mild conditions. The size and morphology of the products can be readily tuned by tuning process parameters such as hydrothermal time and hydrothermal temperature. As synthesized supported cobalt oxide nanoparticles, namely Co₃O₄-150, Co₃O₄-550 and Co₃O₄-650, were quite active in the catalytic oxidation of styrene with H₂O₂ as a green oxidant. However, due to the size and morphology differences, these supported cobalt oxide nanoparticles exhibited different activities and selectivities. Co₃O₄-550 resulted in higher activity while Co₃O₄-650 exhibited relatively higher selectivity to epoxide. Moreover, these cobalt catalysts could be recycled, indicating this to be a promising method of fabricating supported cobalt oxide catalysts for the oxidation of olefins in large-scale processes.