Synthesis and properties of MFI zeolites with microporous, mesoporous and macroporous hierarchical structures by a gel-casting technique

Abstract

The comparatively small micropore dimensions of bulk ZSM-5 zeolites often limit both the adsorption and catalytic conversion of large organic molecules. Here, we report that ZSM-5 zeolites were prepared by a gel-casting technique with microporous, mesoporous and macroporous hierarchical structures. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, temperature-programmed-desorption of ammonia (TPD-NH₃) and Fourier transform infrared spectroscopy (FTIR) measurements. The hierarchical structured ZSM-5 zeolites were used to carry out catalytic cracking of 1,3,5-triisopropyl benzene and n-hexadecane. The results show that, compared with traditional ZSM-5, Beta or Al-MCM-41, this modified ZSM-5 displayed preferable catalytic activity and selectivity.