Synthesis and catalytic properties of multilayered MEL-type titanosilicate nanosheets

Abstract

Multilayered MEL-type titanosilicate nanosheets (MTS-2) were hydrothermally synthesized through a dual-template method, using cetyltrimethylammonium tosylate (CTATos) and tetrabutylammonium hydroxide (TBAOH) as templates for mesopores and micropores, respectively. The mismatch of nanocrystals and mesophase was minimized by decreasing the size of primary zeolite particles, taking advantage of MEL-type zeolite that tends to form nano-sized crystallites. The titanosilicate nanosheets possess both MEL zeolitic structure and large volume of intersheet mesopores without the formation of a physical mixture of bulky zeolites and mesoporous materials. Moreover, it exhibited improved catalytic activities for bulky molecules compared to those of other ordered mesoporous materials and conventional MFI- and MEL-type titanosilicates, where post-treatment of as-made MTS-2 samples using NH₄F could reduce the silanols, and thus enhance their hydrophobicity and epoxidation activity.