Copper-cobalt Bimetallic Oxides-doped Alumina Hollow Spheres: A Highly Efficient Catalyst for Epoxidation of Styrene

Copper-cobalt bimetallic oxides-doped alumina hollow spheres(CuCo/AHS) were fabricated through the sacrificial carbonaceous template strategy. The dependence of the physicochemical properties and morphologies of CuCo/AHS on the composition of copper and cobalt in CuxCoy/AHS(x/y=9/1, 7/3, 5/5, and 3/7) were characterized by X-ray powder diffraction, nitrogen physisorption, atomic adsorption spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Among these catalysts, Cu7Co3/AHS catalyst exhibited perfect hollow sphere structure, thin wall, and big pore size. The calcined catalysts were examined for the epoxidation of styrene with tert-butyl hydroperoxide as oxidant. Compared with the monometallic counter-parts(Cu/AHS and Co/AHS) and other CuxCoy/AHS catalysts, Cu7Co3/AHS catalyst showed higher performance, yielding a styrene conversion of 64.6% with 93.0% selectivity toward styrene oxide. In addition, the strong interaction of Cu2+ or Co2+ with AHS ensured the good stability after four consecutive reactions.