核壳MFI/CHA分子筛的合成及催化性能

采用二次生长法(外延法)在ZSM-5(MFI型)晶体颗粒表面外延生长SAPO-34(CHA型)磷酸硅铝分子筛壳层,合成了MFI/CHA型核壳分子筛材料。并利用X射线衍射(XRD)、扫描电镜(SEM)、能量色散射线光谱(EDS)和傅里叶变换红外(FTIR)光谱对其进行了表征。结果表明,核相ZSM-5的预处理步骤对于成功合成此核壳型分子筛材料十分关键。通过研究晶化温度和晶化时间对MFI/CHA核壳型沸石分子筛合成的影响推测出MFI/CHA壳层生长的晶化机理,并考察在甲醇芳构化中的择形催化作用。

Synthesis and Catalytic Activity of Core-Shell MFI/CHA Zeolites

MFI/CHA core-shell zeolites were synthesized by a two-step hydrothermal synthesis strategy (epitaxial growth). The growth of silicoaluminophosphate SAPO-34 fabricates crystalline layers over ZSM-5 nanocrystal crystallites. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and Fourier transform infrared (FTIR) spectroscopy. The analyses indicate that the pretreatment step of the core phase was an important step during the synthesis. The growth kinetics of the MFI/CHAcore-shell zeolites were investigated by analyzing the products obtained with different secondary crystallization times and temperatures. The core-shell zeolite shows good shape-selective catalytic performance for converting methanol to aromatic compounds.