Cobalt nanoparticles in hollow mesoporous spheres as a highly efficient and rapid magnetically separable catalyst for selective epoxidation of styrene with molecular oxygen

Uniform rattle-type hollow mesoporous spheres (HMS) with large cavities have been successfully prepared by the colloidal carbon spheres as templates. The spheres are well monodispersed and nearly uniform in dimension with particle size of ca. 150 nm. Co nanoparticles composed of HMS were found to be a highly efficient catalyst for selective epoxidation of styrene under mild reaction conditions. The catalysts can be easily separated from the reaction mixtures by an external magnet, and reused five times without significant loss of catalytic activity.