Consecutive Surfactant-Templating Opens up New Possibilities for Hierarchical Zeolites

Abstract

Intracrystalline mesoporosity can be conveniently introduced in zeolites using cationic surfactants in a mild basic solution –a process known as surfactant-templating. However, this technique is limited to small-headed and single-chain surfactants because they need to diffuse through the narrow micropores of the zeolite, which limits the potential of this approach. Herein, we show that the mesoporosity generated in zeolites with small-headed and single-chain surfactants, such as CTAB, provides enough accessibility to allow the use of bulky surfactants that otherwise cannot enter the structure of the zeolite. Moreover, in this contribution, a USY zeolite has been successively treated with cationic surfactants of different chain lengths (C12 to C22) proving that the mesopores introduced in the zeolite can be efficiently widened and narrowed by consecutive treatments with surfactants of the suitable size. Finally, the use of consecutive surfactant-templating opens up the possibility of using surfactants of different packing parameters to produce new hierarchical architectures in zeolites.