Direct synthesis of hierarchical binder-free ZSM-5 and catalytic properties for MTP

Abstract

Abstract Hierarchical binder-free ZSM-5 zeolites were prepared via directly crystallizing the shaped precursors by a vapor-phase transport method. Shaped precursors were crystallized at 160 °C for different time (0–6 d) or at different temperatures (120, 140, 160, 180 or 200 °C) for identical time 5 d. The experimental results showed that the typical MFI structure formed in 2 d at 160 °C and the hierarchical binder-free ZSM-5 zeolites were obtained in 5 d attributed to alkaline etching; after crystallization at 160 °C or 180 °C full-crystalline ZSM-5 zeolites were obtained and the ZSM-5 zeolites had hierarchical pores, but, after crystallization at 200 °C, no mesopores were observed. The hierarchical binder-free ZSM-5 crystallized at 160 °C for 5 d showed the best catalytic performance in methanol to propylene reaction, attributed to its lowest ratio of B/L, largest mesoporous volume and external surface area.