CeO2 Nanoparticle-Decorated Co3O4 Microspheres for Selective Oxidation of Ethylbenzene with Molecular Oxygen under Solvent- and Additive-Free Conditions

An ideal catalytic process for the selective oxidation of hydrocarbons should employ an efficient, recyclable, and cost-effective catalyst under solvent- and additive-free conditions with molecular oxygen as the only oxidant. This is an important goal in the catalysis community and remains a significant challenge. In this respect, we report the facile construction of a series of uniform CeO2 nanoparticle-decorated Co3O4 microspheres (CeO2/Co3O4) for the selective ethylbenzene oxidation reaction by molecular oxygen. Among the catalysts with various CeO2 loading levels, CeO2/Co3O4-3 (5 wt % loading of CeO2) obtained by careful composition modulation exhibits the optimum reaction performance, with ethylbenzene conversion of 73.4% accompanied by a selectivity of 78.5% to acetophenone. The yield of acetophenone can achieve 57.6%, while the reaction rate can reach up to 401.3 mmol g(cat)(-1) h(-1). In addition, CeO2/Co3O4-3 presents robust stability and good recycling performance. The tailored CeO2/Co3O4-3 catalyst is superior to the reported catalysts, and it is the state-of-the-art catalyst under the current challenging reaction system. Experimental evidence and mechanism analysis suggest that the interface synergy featured with -Ce-O-V-Co- active sites derived from the intimate connection between the two oxides is the dominant contributor in boosting the catalytic performance. This work can reinvigorate research into the exploitation of catalysts for the sustainable and green catalytic oxidation of ethylbenzene and beyond.