Synthesis of core-shell structured porous materials and applications as catalysts and precursors for hollow porous materials

Abstract

Ordered porous materials such as zeolites and ordered mesoporous silicas have important physical characteristics based on their high surface area and well-defined pore size. Control of the structure or shape of the ordered porous materials will provide new functions. This review focuses on core-shell structure; especially fabrication methods of core-shell structured zeolites with minimal defects are introduced. As an example of applications, MFI and TON-type zeolites with core-shell structure used as catalysts have high shape selectivity in the methylation of toluene with methanol and skeletal isomerization of tetradecane, respectively. As another application, synthesis of hollow porous materials from core-shell porous materials is also described. Decomposition of silica with dimethyl carbonate catalyzed by an alkali metal salt impregnated in the core was an effective method for selective removal of the core from the core-shell structure. Hollow porous materials show promise as vessels for drug delivery, catalyst vessels and microreactors.