Study On The Synthesis Of Nano-sized ZSM-5 Zeolite

Nano-sized ZSM-5 zeolite has been widely used in the fields of petrochemical and fine chemical industry because of its higher specific surface area and shorter pore structure.As zeolite catalyst,the number of center of surface acid,adsorption capacity,molecular diffusion capacity,and anti carbon ability have been greatly improved.In this paper,nano-sized ZSM-5 zeolite was synthesized by adding nucleation gel instead of crystal seed and template in template-free system,using industrial water glass as silicon source,aluminum sulfate as aluminum source.The influence factors of the amount of water,crystallization temperature and crystallization time in the synthesis system of nucleation gel,and the influence factors of the ratio of Si O2 to Al2O3,basicity,the addition amount of nucleation gel and surfactant,crystallization temperature and time in the synthesis system of zeolite were investigated.The method and process conditions for the synthesis of nano-sized ZSM-5 zeolite were determined.The method of separating zeolite from mother liquor after crystallization and the recycled utilization of mother liquor were explored.The obtained zeolite products were characterized by X-ray diffractometer(XRD),Scanning electron microscopy(SEM),Fourier transform infrared spectrometer(FI-IR),High performance specific surface and aperture analyzer and Energy spectrometer(EDS),the following conclusions are obtained:Well crystallized and well dispersed dispersed ZSM-5 zeolite can be synthesized,when the ratio of silicon to aluminum in the synthetic system is within the range of 30~120.Under the optimum conditions,the size of the ZSM-5 zeolite is less than 100 nm and the specific surface area is 452 m2/g.The cost and environmental pollution of synthesizing for ZSM-5 zeolite are reduced by the nucleation gel method.In the process of research,it is found that the aggregation of particles can be effectively decreased for synthesis process of zeolite by adding surfactant and washing with anhydrous ethanol in the synthesis system.The particle size of the zeolite can be effectively reduced and the yield of the product can be increased by recycling the crystallization mother liquor of zeolite in the synthesis process.