Synthesis of Monolith Hierachical ZSM-5 Zeolite Composed of Nanocrystals by Vapor-phase Transformation Method

A monolith ZSM-5 composed of nano-sized MFI crystals was prepared from a dry gel by a vapor-phase transformation method, in which the dry gel was obtained from a mixture of sodium carboxymethylcellulose and a precursor yielding ZSM-5 zeolite crystals. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N 2 adsorption-desorption, in-situ IR spectra of pyridine and FT-IR. Organic Sior/and Al-species replace the classic inorganic Si-or/and Al-species to take part in the construction of MFI zeolite frameworks. And the long chain organic groups, which connect with the Si-and Al-species, disturb the normal growth of the zeolites crystals in the manner of the so called "bond block". The evenly nano-sized zeolite crystals with the sizes of 100-150 nm are therefore formed and then subsequently self-assembly form a monolith ZSM-5. A mesoporous system which centers around 2-20 nm is therefore introduced into the as-synthesized hierachical zeolites samples.