Aerobic oxidation of cyclohexane over metal-organic framework-derived Ce, Ni-modified Co3O4

Abstract

The heterogeneous interface in materials, due to its crucial role in catalytic reactions, has attracted much attention. Herein, we report the facile synthesis of Co3O4 and Ce/Ni-modified Co3O4 catalysts derived from ZIF-67 and their application in the aerobic oxidation of cyclohexane. The catalytic performance of the catalysts was greatly affected by the calcination temperature and molar ratio of the second metal (Ce, Ni) to Co. The catalytic performance of Co3O4 improved with the increase of the calcination temperature and reached a plateau at 400 °C due to the small-sized Co3O4 crystallites and developed pore structures. The introduction of the second metal improved the dispersion of Co3O4 and induced the creation of the oxygen vacancies at Co3O4-CeO2/NiO interface. The highest catalytic activity with 12.8% conversion and 95.5% selectivity were achieved over the Ce-Ni-modified Co3O4 catalyst with the molar ratio of Ce/Ni/Co=0.11/0.21/1.00. The superior catalytic performance of the Ce-Ni-modified catalyst can be ascribed to the highly dispersed Co3O4 crystallites and the activation of the oxygen molecules by the oxygen vacancies.