物理化学学报 >> 1994, Vol. 10 >> Issue (03): 247-253.doi: 10.3866/PKU.WHXB19940311

研究论文 上一篇    下一篇

锌在ZnZSM-5沸石中的形态及其催化作用

佘励勤, 王多才, 李宣文, 刘兴云, 韩明   

  1. 北京大学化学系,北京 100871
  • 收稿日期:1992-07-30 修回日期:1993-02-16 发布日期:1994-03-15
  • 通讯作者: 佘励勤

The States of Zinc in ZnZSM-5 Zeolites and their Catalysis

She Li-Qin, Wang Duo-Cai, Li Xuan-Wen, Liu Xing-Yun, Han Ming   

  1. Department of Chemistry, Peking University, Beijing 100871; Department of Chemistry, Sichuan Normal College, Nanchong 637002
  • Received:1992-07-30 Revised:1993-02-16 Published:1994-03-15
  • Contact: She Li-Qin

摘要:

采用NH_3-TPD和吡啶吸附红外光谱法,研究了不同含Zn量ZnHZSM-5沸石中Zn的存在状态.结果表明,用浸渍方式将Zn引入到HZSM-5沸石后,在NH_3-TPD谱上产生两个新的NH_3脱附峰.峰位分别在原HZSM-5沸石的低温峰与高温峰之间和比高温峰较高温区处,其相应的吸附中心分别以L_1、L_2表示.L_1可能与ZnHZSM-5沸石上ZnO物种相对应; L_2与吡啶吸附红外光谱的L_(1616)吸收带有关,可能与ZnHZSM-5上的ZnOH~+物种相对应.丙烷芳构化反应结果表明,芳烃收率随L_2的脱附NH_3量的增加有一最宜值,而活性的稳定性则随之降低。

关键词: ZnZSM-5, 丙烷, 芳构化, NH3-TPD, 吡啶吸附红外光谱, 沸石

Abstract:

NH_3-TPD and pyridine adsorption IR spectroscopy techniques have been used to study the zinc states in ZnHZSM-5 zeolite containing various zine content. The results indicate that, in addition to two desorption peaks for HZSM-5 zeolite located at about 533 and 733 K, two new peaks located at about 573 and 873 K were observed. These new peaks are believed to be associated with two kinds of zinc sites designated by L_1, L_2. The adsorbed ammonia amount of L_2 corresponds to the amount of L_(1616) acid characterized by pyridine adsorption IR spectra for ZnHZSM-5 zeolite with various zinc contents. It is possible that there are two kinds of zinc states in ZnHZSM-5 zeolite. One kind of them is ZnO species with weak acidity, the other is ZnOH~+ species with strong acidity which can promote the activity and has an effect on stability of activity for aromatization of propane.

Key words: ZnZSM-5, Propane, Aromatization, NH3-TPD, Pyridine adsorption IR spectra, Zeolite