Synthesis of Hierarchical Pore Zsm-5 on Silica Gel and Its Catalytic Performance for Fcc Reaction

ZSM-5 zeolite is a preferred active component for low-carbon alkene production during fluidized catalytic cracking (FCC). However, during industrial catalyst preparation, ZSM-5 is inevitably mixed with binder, thereby reducing the contact with the feedstock and lowering the efficiency of ZSM-5. It is interesting to grow a layer of ZSM-5 zeolite on the mother-support. Here we report a method for the direct in-situ crystallization of ZSM-5 on the surface of hollow silica gel microspheres. The objective of using such composite materials is to improve mass transfer and the FCC product distribution. In this study, ZSM-5 zeolite has been synthesized hydrothermally using n-butylamine on silica gel microspheres as the template. The composite materials were characterized by X-ray diffraction (XRD), Scanning Electronic Microscope (SEM), and BET surface area via liquid N2 adsorption. The effects of initial gel composition (Na+/SiO2, OH-/SiO2, H2O/ SiO2, BuNH2/SiO2), crystallization time, and crystallization temperature on crystallinity, morphology and pore structures were systematically investigated. Different morphologies and crystal sizes of ZSM-5 were obtained. Hierarchical ZSM-5 on the surface of silica gel microsphere will be synthesized by various methods, such as surfactants addition and steam treatment. Composite materials ZSM-5/SiO2 with different pore distributions will be obtained. Finally, the effects of crystal morphology, pore distribution, and acidity on the selectivity/yield for FCC products will be investigated.