Top-Down Tuning of Nanosized ZSM-5 Zeolite Catalyst by Bead Milling and Recrystallization

Zeolites with high external surface area allow diffusing reactants greater access to catalytically active sites, which has led to interest in the preparation of nanosized zeolites. In this study, a top-down approach has been used for zeolite synthesis by first milling the zeolite to produce nanoparticles. This technique destroys the outer portion of the zeolite framework, causing a significant decrease in its catalytic activity. To remedy this, the damaged part was recrystallized using a dilute silicate solution after bead milling. The combined bead milling and postmilling recrystallization yielded nano ZSM-5 (MFI type zeolite), approximately 60 nm in size, with high crystallinity, and the zeolite powder showed a higher catalytic activity in cumene cracking in comparison with the raw ZSM-5 zeolite. Furthermore, the decrease in crystal size suppresses catalyst deactivation through coke deposition during cumene cracking.