高等学校化学学报

高等学校化学学报 ›› 2011, Vol. 32 ›› Issue (4): 800.

• 研究论文 • 上一篇    下一篇

OFF沸石中锂离子在骨架外的分布及可接近性

吕新春1,2,赵荣1,吴泰琉1,孙尧俊1,唐颐2   

  1. 1. 复旦大学分析测试中心,
    2. 化学系, 上海 200433
  • 收稿日期:2010-10-18 修回日期:2011-01-05 出版日期:2011-04-10 发布日期:2011-03-09
  • 通讯作者: 吕新春 E-mail:lvxinchun@fudan.edu.cn
  • 基金资助:

    国家自然科学基金(批准号: 20890122, 20721063)资助.

Siting and Accessibility of Lithium Cations in Zeolite Li-OFF

LÜ Xin-Chun1,2*, ZHAO Rong1, WU Tai-Liu1, SUN Yao-Jun1, TANG Yi2   

  1. 1. Center for Analysis and Measurement,
    2. Department of Chemistry, Fudan University, Shanghai 200433, China
  • Received:2010-10-18 Revised:2011-01-05 Online:2011-04-10 Published:2011-03-09
  • Contact: Lü Xin-Chun E-mail:lvxinchun@fudan.edu.cn
  • Supported by:

    国家自然科学基金(批准号: 20890122, 20721063)资助.

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摘要： 对OFF沸石进行离子交换制备出NH4-OFF沸石，然后通过Li2CO3/NH4-OFF体系的固态反应制备了不同锂离子交换度的Li-OFF沸石。对吸附氮气和氧气的Li-OFF样品进行了7Li MAS NMR表征。研究发现，所有吸附氧气样品的部分7Li MAS NMR共振峰均发生了顺磁位移。通过对实验谱的拟合，得知Li-OFF沸石中的锂离子可分布在三类阳离子位置（A、B和C）上，对应于三个不同位移的谱峰。Li+离子并非等比例地进入三个可交换的位置，而是优先占据主孔道中的A位置，随着交换度的升高，位能较高的C和B位置上的Li离子占有率逐渐增加。在100％固态交换度样品中，Li+离子在不同离子位的占有率分别为17％(位置B)、29％(位置C)和54％(位置A)。其中，位置B是O2分子不可接近的，所以Li-OFF沸石中有83％的阳离子是可以接近的。

关键词: OFF沸石, 可接近性, 顺磁位移效应

Abstract: NH4-OFF zeolite was obtained by cations exchange of OFF zeolite.The Li-OFF zeolite with different exchange degree of Li+ cations was prepared through solid-state reaction of Li2CO3/NH4OFF system. Paramagnetic shift effect of adsorbed O2 was observed in the 7Li MAS NMR spectra of all O2 containing Li-OFF samples. By simulation of the 7Li MAS NMR spectra, it was found that Li+ cations are located in three types of cationic sites, corresponding to three simulated peaks. Li+ cations prefer the site A in the center of the channel. With the growth of exchange degree, Li+ cations appears more gradually in site B and C where need higher potential energy. As for the 100% Li+ exchanged OFF, Li+ cations occupy the three locations with a constant ratio: 54% site A, 17% site B and 29% site C, and approximately 83% of Li+ cations are accessible to O2 molecules.

Key words: OFF, Accessibility, Paramagnetic shift effect

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