Core-shell structured mesoporous silica as acid-base bifunctional catalyst with designated diffusion path for cascade reaction sequences

Ping Li, Chang-Yan Cao, Zhe Chen, Hua Liu, Yu Yu and Wei-Guo Song*. Chem. Commun., 2012, 48, 10541-10543.

   A core-shell structured mesoporous silica nanosphere as an acid-base bifunctional catalyst with the acid sites in the inner core and the basic group in the outer shell (MS-A@MS-B) was fabricated. With such a core-shell structure, acid and basic sites were spatially isolated. More importantly, the core-shell structure offered a designated diffusion pathway for the reaction species. For two types of cascade reaction sequences, this catalyst showed superb activity and selectivity, e.g. nearly 100% conversion for the starting substrate and nearly 100% yield for the target product, while no intermediate species were detected.

Scheme 1 Illustration of acid-base bifunctional core-shell mesoporous structured silica catalyst