化学学报 ›› 2009, Vol. 67 ›› Issue (15): 1765-1770. 上一篇    下一篇

研究论文

MFI/MFI核壳分子筛的合成及催化性能研究

孔德金*,a,b 邹 薇b 童伟益a 房鼎业a

  

  1. (a华东理工大学化工学院 上海 200237)
    (b中国石油化工股份有限公司上海石油化工研究院 上海 201208)

  • 收稿日期:2008-05-14 修回日期:2009-01-13 出版日期:2009-08-14 发布日期:2009-08-14
  • 通讯作者: 孔德金

Synthesis and Catalytic Behaviors of MFI/MFI Core-shell Zeolite

Kong, Dejin *,a,b Zou, Wei b Tong, Weiyi a Fang, Dingye a   

  1. (a College of Chemical Engineering, East China University of Science and Technology, Shanghai 200237)
    (b Shanghai Research Institute of Petrochemical Technology, China Petroleum & Chemical Corporation, Shanghai 201208)
  • Received:2008-05-14 Revised:2009-01-13 Online:2009-08-14 Published:2009-08-14
  • Contact: Kong, Dejin

通过对核相ZSM-5的预处理步骤和在温和水热条件下的二次生长, 合成了壳层硅铝比高、核相硅铝比低、纳米晶壳层致密的MFI(核)/MFI(壳)型核壳分子筛材料. 考察了晶化温度和晶化时间对高硅壳层MFI/MFI核壳型沸石分子筛的合成的影响, 其适宜的合成条件为晶化温度高于130 ℃, 晶化时间19 h. 核相ZSM-5的预处理步骤对于成功合成此特殊核壳型分子筛材料十分关键. 与普通ZSM-5沸石分子筛相比, MFI/MFI核壳分子筛在催化甲苯甲基化反应时的失活效率显著降低.

关键词: 沸石分子筛, 核壳结构, 合成, 甲苯甲基化

Hierarchical core/shell structures with low Si/Al ratio core and continuous shell of high Si/Al ratio ZSM-5 were successfully fabricated by a novel two-step procedure. The final products were characterized by X-ray diffraction and scanning electron microscopy (SEM) methods to determine the morphologies and structural properties of the core/shell nanostructures. It was shown that MFI/MFI core-shell zeolite with high Si/Al shell could be synthesized by using ethylamine rather than TPAOH as organic template under mild hydrothermal conditions. It was achieved by in situ pre-seeding step on ZSM-5 cores and secondary growth of ZSM-5 shell on the modified ZSM-5 crystals, in which the pre-seeding step is a determining strategy during the synthesis. The MFI/MFI core-shell zeolite exhibited much lower deactivation rate than the core zeolite in the toluene methylation reaction.

Key words: zeolite, core-shell structure, synthesis, toluene methylation