Immobilization of metalloporphyrin on a silica shell with bimetallic oxide core for ethylbenzene oxidation

Abstract

In this study, metalloporphyrin has been immobilized on a core–shell structured SiO₂@CeO₂ doped with transition metals such as Fe, Cu, Co and Mn. The as-prepared catalysts have been characterized via N₂ adsorption–desorption, XRD, TEM, FT-IR spectroscopy, and UV-vis spectroscopy. It is found that metalloporphyrin is anchored onto a SiO₂ shell with a thickness of about 20 nm and on a MO_x/CeO₂ core (M = Fe, Cu, Co and Mn) with a diameter about 120 nm, which may benefit the diffusion of substrates through the pores in the thin shell into the metal oxide cores and the formation of a synergistic effect between metalloporphyrin and metal oxides. Moreover, CoTPP-(MO_x/CeO₂)@SiO₂ catalysts (M = Fe, Cu, Co and Mn) exhibit different physical and chemical properties, such as surface areas, particle sizes and catalytic performances owing to the addition of transition metals into CeO₂. Moreover, the catalyst doped with Co exhibits a higher catalytic performance than the other catalysts for ethylbenzene oxidation. Thus, the addition of transition metals, such as Co, Cu, Fe and Mn, plays an important role in the catalytic performance of the catalysts for ethylbenzene oxidation via adjusting the physical and chemical properties of the core–shell catalysts.