Nano-crystallite oriented self-assembled ZSM-5 zeolite and its LDPE cracking properties: Effects of accessibility and strength of acid sites

• Nano-crystallite oriented-assembled ZSM-5 zeolite is prepared by seed-induced route.
• Morphology and external surface are regulated by co-effects of KF, template, and seed.
• Crystallinity and intrinsic acidity are preserved when decreasing crystallite size.
• Fine accessibility and high acid strength lead to notable LDPE cracking activity.
• Fast and low-cost preparation opens a possibility for large-scale production.

Nano-crystallite oriented self-assembled ZSM-5 zeolite (NS-Z5) is successfully synthesized with high yield of 85% by a facile salt-aided seed-induced method within 1.5 h at TPABr (tetrapropylammonium bromide)/SiO2 ratio of 0.1. The systematic and thorough characterizations, involving morphology, textural/structure property, and acidity, indicate that NS-Z5 particle is composed of oriented-assembled high-crystalline zeolite MFI nano-crystallites and possesses abundant accessible strong acid sites due to its large/rough external surface. The strong acidity of NS-Z5 sample results from its high crystallinity and few framework defects benefiting from the introduction of seeds. The catalytic evaluations both in batch and in thermogravimetric reactors demonstrate the important roles of the accessibility and strength of acid sites on low-density polypropylene cracking. This paper provides a facile method for preparation of hierarchical high-crystalline ZSM-5 nano-zeolite and confirms the significance to synchronously maintain large amount and high strength of accessible acid sites on large molecule conversion.

Nano-crystallite oriented self-assembled ZSM-5 zeolite has been synthesized by a salt-aided seed-induced route; this catalyst exhibits notable activity of LDPE cracking reaction for the well maintaining fine accessibility and high strength of acid sites.Figure optionsDownload high-quality image (87 K)Download as PowerPoint slide