One-step post-synthesis treatment for preparing hydrothermally stable hierarchically porous ZSM-5

Hierarchically porous ZSM-5 (SiO2/Al2O3 approximate to 120) containing phosphorus was prepared by a one-step post-synthesis treatment involving controlled desilication and phosphorous modification. The hierarchically porous ZSM-5 featured high thermal and hydrothermal stability. The obtained ZSM-5 zeolites were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N-2 adsorption-desorption, NH3 temperature-programmed desorption, and Al-27 and P-31 magic-angle spinning nuclear magnetic resonance spectroscopy. The prepared ZSM-5 displayed enhanced activity and prolonged lifetime toward hydrocarbon cracking. The high activity was attributed to improved coke tolerance owing to the presence of the highly stable mesoporous network of ZSM-5 and acid sites introduced upon phosphorus modification. Additionally a mechanism of the stabilization of the zeolites by phosphorus was proposed and discussed. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.