物理化学学报2012，Vol.28Issue(9)：2115-2121,7.DOI:10.3866/PKU.WHXB201206141
晶种导向干凝胶法制备成型ZSM-5分子筛
Synthesis of Shaped ZSM-5 Zeolites by Dry-Gel Conversion with Seed Gel as Directing Agent
摘要
Abstract
Shaped binderless ZSM-5 zeolites were prepared via a rapid dry-gel conversion technique from aluminosilicate extrudate.Silica gel and boehmite were well mixed and extruded into cylindrical shaped extrudates with diameter of 2 mm with the aid of silica sol,ZSM-5 zeolite seed gel,and/or tetrapropylammonium hydroxide (TPAOH) solution.The total molar ratio of TPAOH to SiO2 was fixed at 0.025.With same amounts of structure directing agent (TPAOH),the addition of seed gels accelerated the crystallization of the zeolite.The seed gel directing agent composition was 0.35TPAOH:1SiO2:20H2O:4C2H5OH.The seed gel not only provided crystal nuclei for rapid crystallization but also controlled the size of the ZSM-5 crystals.Especially,the morphology of these extrudates was well maintained in the crystallization process.The crystallization processes of zeolite were characterized by X-ray diffraction (XRD),thermogravimetric (TG) analysis,and Fourier transform infrared (FTIR) spectroscopy.The results showed that the growth of the zeolite was accompanied by the occupation of the zeolite channels by TPAOH.When the TPAOH/SiO2 molar ratio was 0.025,the sample achieved 100％ relative crystallinity after 3 h crystallization.The morphology and textural properties were characterized by scanning electron microscopy (SEM) and nitrogen sorption isotherms.The obtained shaped zeolites comprised nanosized crystals (200 nm) and exhibited a hierarchical structure with high mesopore volume (0.28 cm3· g-1).The temperature-programmed desorption of ammonia (NH3-TPD) was used to assess the acidity of these shaped zeolites.The results showed that this shaped zeolite possessed an acidity similar to that of a commercial H-ZSM-5 catalyst.关键词
成型ZSM-5分子筛/干凝胶法/多级孔结构/晶种导向剂/纳米分子筛Key words
Shaped ZSM-5zeolite/ Dry-gel conversion/ Hierarchicalstructure/ Seed structure directing gel/ Nanoscalezeolite分类
化学化工引用本文复制引用
岳明波,杨娜,王一萌..晶种导向干凝胶法制备成型ZSM-5分子筛[J].物理化学学报,2012,28(9):2115-2121,7.基金项目
国家自然科学基金(20890124,21003083)和山东省博士科研奖励基金(BS2009CL031)资助项目 （20890124,21003083）
The project was supported by the National Natural Science Foundation of China (20890124,21003083) and Doctoral Foundation of Shandong Province,China (BS2009CL031). （20890124,21003083）
