One-step synthesis of mesoporous ZSM-11 composites through a dual-template method

Abstract

Hierarchical porous ZSM-11 composites were hydrothermally synthesized through a one-step route using binary templates of cetyltrimethylammonium tosylate (CTATos) and tetrabutylammonium hydroxide (TBAOH). Influences of aluminum content and crystallization temperature on the morphology and structure were investigated. Powder X-ray diffraction (XRD) and N₂ physisorption results show that the mesoporous ZSM-11 composites possess both a considerable mesoporous structure and zeolitic MEL-structure. Moreover, a large amount of aluminum in the gel composition slows the rate of zeolite crystallization, while a high SiO₂/Al₂O₃ ratio is beneficial for the synthesis of mesoporous ZSM-11 without any phase separation. Mesoporous ZSM-11 aluminosilicates were compared to pure ordered mesoporous materials, zeolites and a mechanical mixture of meso and microphases for their catalytic activity in low-density polyethylene (LDPE) pyrolysis. The results suggest that all mesoporous ZSM-11 composites show higher catalytic performance for LDPE cracking.