One-pot synthesis of hierarchically structured ZSM-5 zeolites using single micropore-template

An easy one-step hydrothermal process has been developed for the first time for the synthesis of hierarchically structured zeolites (HSZs) using a single micropore template of tetrapropylammonium hydroxide. Compared with conventional constructive dual-templating synthesis and destructive post-demetallation methods, this two-in-one process reduces the mass of porogens required and consequent air pollution by combustion of the template, and simplifies the synthesis. The resultant HSZs were characterized by X-ray diffraction, N2 adsorption, scanning electron microscopy, transmission electron microscopy, X-ray fluorescence, 27Al nuclear magnetic resonance, and NH3 temperature programmed desorption. The resultant HSZs with uniform shuttle-type morphology showed high hydrothermal stability and excellent catalytic activity with prolonged life-time in the model reaction of 1,3,5-triisopropylbenzene cracking. A “nucleation/growth-demetallation/recrystallization” mechanism was proposed, which is featured with the integration of zeolite crystallization/growth and basic etching into one hydrothermal process for HSZs production.

Graphical AbstractAn easy one-step low temperature (100 °C) hydrothermal process has been developed for the synthesis of hierarchically structured ZSM-5 zeolites with a single micropore template, and a “nucleation/growth-demetallation/recrystallization” mechanism is discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide