物理化学学报 >> 2006, Vol. 22 >> Issue (02): 198-202.doi: 10.3866/PKU.WHXB20060214

研究论文 上一篇    下一篇

无胺法合成高硅丝光沸石的表征

祁晓岚; 王战; 李士杰; 李斌; 刘希尧; 林炳雄   

  1. 北京大学化学与分子工程学院物理化学研究所, 北京 100871; 中国石油化工股份有限公司上海石油化工研究院, 上海 201208; 北京燕山石油化工公司研究院, 北京 102500
  • 收稿日期:2005-08-17 修回日期:2005-10-10 发布日期:2006-01-22
  • 通讯作者: 祁晓岚 E-mail:qixl@sript.com.cn

Characterization of High Silica Mordenite Synthesized from Amine-free System Using Fluoride as Structure-directing Agent

QI Xiao-lan; WANG Zhan; LI Shi-jie; LI Bin; LIU Xi-yao; LIN Bing-xiong   

  1. Institute of Physical Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R.China; Shanghai Research Institute of Petrochemical Technology, SINOPEC, Shanghai 201208, P.R. China; Research Institute of Beijing Yanshan Petrochemical Corporation, Beijing 102500, P. R. China
  • Received:2005-08-17 Revised:2005-10-10 Published:2006-01-22
  • Contact: QI Xiao-lan E-mail:qixl@sript.com.cn

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摘要： 采用XRD、SEM、FT-IR、MAS NMR等表征手段, 对以氟离子为结构导向剂无胺法合成的高硅丝光沸石进行了表征. 结果表明: 高硅丝光沸石结构属立方晶系, 晶胞参数小于传统低硅丝光沸石, 但b、c值要比相近硅铝比非氟体系合成的丝光沸石样品的大; 样品形貌及粒径与其硅铝比有关, 表明晶化条件对产物形貌及粒径均有影响; 随硅铝比的增大, FT-IR光谱中450、544、1053 cm-1谱带向高频移动, 720 cm-1谱带强度减弱, 表明骨架中铝减少而硅增多; 采用含氟无胺体系合成高硅丝光沸石时基本上不会产生非骨架铝.

关键词: 氟离子, 高硅丝光沸石, 表征

Abstract: A series of high silica mordenite samples synthesized from amine-free system using fluoride as structure-directing agent were characterized by XRD, SEM, FT-IR, and MAS NMR. The results confirmed that the samples were truly mordenite with high SiO2/Al2O3 molar ratio. The unit cell constants a, b, c and the unit cell volume (a×b×c) of M-36 sample were smaller than those of mordenite with silica alumina molar ratio(SAR)=10 reported in the literature, which indicated the unit cell contraction caused by the replacement of Al atoms by smaller Si atoms. However, compared with the sample with SAR=31.5 synthesized from free-fluoride system, the lattice parameters of M-36 were somewhat increased in the a and c directions, but elongated obviously in b direction, which indicated some influences on 8-membered ring parallel to the b axis of mordenite structure should be brought by using fluoride as structure-directing agent. As the SAR of mordenite samples increased, a variety of crystal morphologies (cuboids, hexagonal prismatic crystals, rectangular parallelepiped crystals) was observed and a wide variation in the crystallite size was presented. As the SAR changed from 14 to 55, in the infrared spectra of the samples, the band attributed to T—O bending vibration shifted from 434 cm-1 to 450 cm-1, and its absorption intensity also increased. The band at 720 cm-1 which corresponded to the internal symmetric stretching vibration of the AlO4 tetrahedral in the mordenite from a weak band developed into a broad band and nearly disappeared at last, indicating that the number of SiO4 in the framework was increased. In 27Al MAS NMR spectra, almost all high silica mordenite samples presented a peak at δ(55.6) and no non-framework Al species peak at about δ(0), which was different from steamed or acid-leached siliceous mordenite.

Key words: Fluoride anion, High silica mordenite, Characterization