Effective Utilization of in Situ Generated Hydroperoxide by a Co–SiO₂@Ti–Si Core–Shell Catalyst in the Oxidation Reactions

Abstract

A core–shell catalyst (Co–SiO2@Ti–Si) with cobalt-based SiO2 nanocomposite (Co–SiO2) as the core and Ti-doped mesoporous silica as the shell was designed to catalyze a one-pot reaction of sulfide oxidation with in situ generated hydroperoxide. The catalyst was characterized by SEM, TEM, UV–vis spectroscopy, and XPS, among other methods. Compared to Co–SiO2 and the physical mixture of the two components (Co–SiO2 + Ti–Si), the core–shell catalyst significantly enhanced the reaction rate of the sulfide oxidation. The utilization efficiency of the hydroperoxide was an important factor responsible for the differences in the reaction rates. A further mechanism study showed that the improvement of the efficiency was due to the existence of a coordination pathway. The core–shell structure of a bifunctional catalyst represents a strategy for improving the utilization efficiency of hydroperoxide.