Hierachical Zeolite-Zeolite Composite Prepared by a Vapor Phase Transport Method

A zeolite-zeolite composite composed of Y and ZSM-5 was successfully prepared by a vapor phase transport (VPT) method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption-desorption and FT-IR. The results display that the synthesis is influenced by the Y content, preparing condition of dry gel and transfering condition for VPT method. FT-IR spectra show the characteristic peaks of MFI framework on ZSM-5 precursor after hydrothermal pre-treatment for 16 h. The result can be attributed to the crystal nucleus or microcrystal of ZSM-5 zeolite, either of which may promote growth of ZSM-5 crystals during the VPT procedure, and depresse formation of ZSM-35 crystals. The mesopores structure, created in as-synthesized zeolite-zeolite composite, can be ascribed to the extracted aluminum from Y zeolite crystals by VPT procedure.