Acta Phys. -Chim. Sin. ›› 1994, Vol. 10 ›› Issue (03): 247-253.doi: 10.3866/PKU.WHXB19940311

• ARTICLE • Previous Articles     Next Articles

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

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