Direct synthesis of mesoporous ZSM-5 zeolite by a dual-functional surfactant approach

Mesoporous molecular sieves with crystalline microporous walls of ZSM-5-like frameworks was directly prepared by a dual-functional triquaternary ammonium-type surfactant. Mesopores are generated by surfactant aggregates and crystalline microporous zeolite frameworks within the mesopore walls are directed by quaternary ammonium functional groups of surfactant. The mesoporous zeolite sample was characterized by a complementary combination of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption isotherms, Fourier transform infrared spectroscopy, Al-27 MAS NMR spectra and density functional theory calculation. The results suggest that present method is suitable as a direct synthesis route to highly mesoporous zeolites. Due to the short diffusion routes and strong acidity, the mesoporous ZSM-5 zeolite displayed a clear advantage on catalysis reactions involving large molecules compared to commercial zeolites and mesoporous amorphous materials. The present approach provides an efficient route to synthesize other related mesoporous zeolites in the future. (C) 2012 Elsevier B.V. All rights reserved.