Facile synthesis of ZSM-5 mesocrystal via novel pathway of crystallization: Fast precipitation, deconstruction and reorganization

Abstract

Mesocrystal zeolite with well-defined morphology owns mesoporous channels and single crystal characteristics, which could promote diffusion efficiency, stability and catalytic activity. Thus, we performed the controllable synthesis of ZSM-5 mesocrystal without special additives and complex methods. Selected area electron diffraction (SAED) and fast Fourier transform (FFT) showed diffraction spots regardless of crystallization time, which indicated the well oriented feature of synthesized ZSM-5 zeolites. The crystallization process was further investigated. The oriented particle attachment (OPA) effectively guided the synthesis process of mesocrystals, which followed the nonclassical crystallization mechanism. The crystallinity curve exhibited valley-like shape, which manifested that the crystallization pathway went through three stages: fast precipitation, deconstruction and reorganization. The plausible formation mechanism was proposed, which might be useful for the fabrication of ZSM-5 mesocrystal. The prepared zeolites showed superior catalytic performance in aldol condensation reaction between benzaldehyde and 2-hydroxyacetophenone, obtaining 93% of the conversion. The fast precipitation gave rise to perfect oriented feature. Then, the synthesized zeolites deconstructed due to OH − ions, the lighter bule indicated imperfect crystallized crystal due to the damage of OH − ions. Finally, the reorganization happened due to further ripening of deconstructed nanoparticles. The planar graph embedded in the circle demonstrated the structure of inter domain. •ZSM-5 mesocrystal with tunable Si/Al ratio was synthesized without special additives and complex methods. •The synthesis of ZSM-5 mesocrystal underwent unusual crystallization pathway: fast precipitation, deconstruction and reorganization. •ZSM-5 mesocrystal showed excellent catalytic performance in the Claisen‐Schmidt condensation reaction.