单一微孔模板剂一锅法制备多级结构ZSM-5沸石

摘要

An easy one-step hydrothermal process has been developed for the first time for the synthesis of hierarchically structured zeolites (HSZs) using a single micropore template of tetraprop-ylammonium hydroxide. Compared with conventional constructive dual-templating synthesis and destructive post-demetallation methods, this two-in-one process reduces the mass of porogens required and consequent air pollution by combustion of the template, and simplifies the synthesis. The resultant HSZs were characterized by X-ray diffraction, N2 adsorption, scanning electron microscopy, transmission electron microscopy, X-ray fluorescence, 27Al nuclear magnetic resonance, and NH3 temperature programmed desorption. The resultant HSZs with uniform shuttle-type morphology showed high hydrothermal stability and excel-lent catalytic activity with prolonged life-time in the model reaction of 1,3,5-triisopropylben-zene cracking. A “nucleation/growth-demetallation/recrystallization” mechanism was pro-posed, which is featured with the integration of zeolite crystallization/growth and basic etch-ing into one hydrothermal process for HSZs production.%以微孔模板剂四丙基氢氧化铵为单一模板剂,采用一种温和的低温水热一锅法工艺,成功制备出多级结构ZSM-5沸石(HSZs)。与传统的双模板法和后处理法相比,这种结合了沸石生长与后刻蚀于一体的新方法,不仅减少了模板剂的用量及二次酸/碱刻蚀、煅烧造成的环境污染,同时也极大地简化了合成工艺。利用XRD, N2吸附, SEM, TEM, XRF,27Al NMR与NH3-TPD等测试手段对合成的HSZs进行了全面表征,并提出了一种“成核/生长-刻蚀/再晶化”的形成机理。与传统ZSM-5沸石相比,这种具有均一梭型形貌的HSZs具有高的水热稳定性,并在三异丙苯催化裂解的探针反应中表现出优异催化性能和较长使用寿命。