Synthesis Of Hierarchical Porous Zeolite Based On Nanolized ZSM-5 Crystals Dominated With Inter-crystalline Mesoporosity

ZSM-5 zeolite was first synthesized by mobile oil company of USA which has MFI topological structure.It's widely used in the industry as catalysts,adsorbents and ion exchangers.However,due to suffering from the sole microporous structures,which can impose diffusion limitations and increase carbon deposition and further inhibit the effective utilization of the zeolite's functions,therefore,reduce the catalyst life.Nanolized ZSM-5crystals with much small size?<60 nm?have its property changed greatly.The high surface area and shortend pore length benefit the active site of ZSM-5 zeolite to be contacted with reagents and also provide large volumes to speed up the exchange of materials for increase of the catalytic capacity.By controlling of stacking nanolized ZSM-5 crystals,the monoliths with mesopores,namely,the intercrystal porosity dominated meso-zeolites?IPD-mesoZEOs?have been obtained.IPD-mesoZEOs contain rich micro-and meso-pore with high thermal stabilitys that improves ZSM-5 sole microporosity inhibit.In this thesis,we developed a new strategy to construct intercrystal porosity dominated monoliths mesoZeolites?IPD-mesoZEOs?by creating sufficiently small?<60 nm?nanolized ZSM-5,we nominated as IPD-mesoZEO-1.The thesis work has three parts as follows:1.The preparation of IPD-mesoZEO-1:the hierarchical porous zeolite was synthesized by using TEOS and NaSiO₃,NaAlO₂ as silicon and aluminum sources,respectively.Series of IPD-mesoZEO-1?a^e?with various Si/Al ratios of 10,20,30,40,50 were synthesized.2.Characterization of IPD-mesoZEO-1?a^e?:the materials were characterized by various methods:the X-ray powder diffraction?XRD?reveals their MFI topological structure which were identical with ZSM-5.Scanning electron microscope?SEM?evidences the nanolized crystals uniformly stacked with a particle size about 20?50 nm.Nitrogen adsorption and desorption confirm the obtained inter-crystalline mesopores distributed from 12.0?23.7 nm.3.Based on the results of characterization,we summarize the experiment as follows:the porosity of IPD-mesoZEO-1 depends on Si/Al ratio where the time point for adding Al source into the reaction mixture is a key,meanwhile F127 surfactant can help the nanolized ZSM-5crystal monodispersed,favoring to form the IPD-mesoZEO-1 monoliths with narrowly distributed mesopores.