Encapsulation of a catalytically active core with a nanoporous shell: a new strategy for designing size-selective catalysts

Abstract

A novel strategy to synthesize a size-selective catalyst consisting of a Pd-containing silica core and an outer silica shell with controllable pore size, was developed. Such intended structures were confirmed with N₂ sorption, XRD, TEM and SEM. The pore sizes on the shell could be further tailored through silylation with organosilanes with variable chain lengths. This intriguing nanostructured catalyst showed a high activity in the aerobic oxidation of alcohols. Impressively, when the pores on the shell were tailored to particular sizes the catalyst exhibited size-selective catalysis, and the substrate molecules with only a slight difference in molecular size could be discriminated. This study potentially supplies a new approach for constructing size-selective catalysts.