The development of hierarchical porosity is crucial to overcome the diffusion issue within the zeolite frameworks. Herein, we have successfully developed a sequential mechanochemical treatment and recrystallization in the presence of cetyltrimethylammonium molecules for synthesizing the hierarchically porous ZSM-5 zeolite. The former transforms the large, micron-sized ZSM-5 crystals into nanosized particles with a notable decline in crystallinity due to the high mechanical force. In contrast, the latter converts the nanosized particles into highly crystalline ZSM-5 with preserved size. The products are shown to be aggregates of nanosized ZSM-5 with abundant intercrystalline mesopores. Cetyltrimethylammonium molecules play an inevitable role in preventing excessive coalescence and crystal growth and assemble the nanosized zeolites. In the absence of cetyltrimethylammonium, the recrystallization merely results in the micron-sized ZSM-5 crystals. The hierarchical porosity obtained in this study is proven to relieve the diffusion constraint and improve the catalytic performance in LDPE pyrolysis.
- Hierarchically porous ZSM-5