Immobilization of metalloporphyrins on CeO2@SiO2 with a core-shell structure prepared via microemulsion method for catalytic oxidation of ethylbenzene

Abstract

CeO2@SiO2 core-shell nanoparticles were prepared by microemulsion method, and metalloporphyrins were immobilized on the CeO2@SiO2 core-shell nanoparticles surface via amide bond. The supported metalloporphyrin catalysts were characterized by N2 adsorption-desorption isotherm (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet and visible spectroscopy (UV-Vis), and Fourier transform infrared spectroscopy (FT-IR). The results show that the morphology of CeO2@SiO2 nanoparticles is core-shell microspheres with about 30 nm in diameter, and metalloporphyrins are immobilized on the CeO2@SiO2 core-shell nanoparticles via amide bond. Especially, the core-shell structure contains multi CeO2 core and thin SiO2 shell, which may benefit the synergistic effect between the CeO2 core and the porphyrin anchored on the very thin SiO2 shell. As a result, this supported metalloporphyrin catalysts present comparably high catalytic activity and stability for oxidation of ethylbenzene with molecular oxygen, namely, ethylbenzene conversion remains around 12% with identical selectivity of about 80% for acetophenone even after six-times reuse of the catalyst.