物理化学学报 >> 1994, Vol. 10 >> Issue (07): 628-634.doi: 10.3866/PKU.WHXB19940710

研究论文 上一篇    下一篇

镓改性ZSM-5沸石中镓活性中心的形成与表征

佘励勤, 朱高忠, 温瑞武, 张昌军, 李宣文, 刘兴云   

  1. 北京大学化学系,北京 100871
  • 收稿日期:1993-03-09 修回日期:1993-11-30 发布日期:1994-07-15
  • 通讯作者: 佘励勤

Formation and Characterization of Ga Active Site in GaZSM-5 Zeolite

She Li-Qin, Zhu Gao-Zhong, Wen Rui-Wu, Zhang Chang-Jun,  Li Xuan-Wen, Liu Xing-Yun   

  1. Department of Chemistry, Peking University, Beijing 100871
  • Received:1993-03-09 Revised:1993-11-30 Published:1994-07-15
  • Contact: She Li-Qin

摘要:

采用脉冲微反体系研究了经不同程度还原和不同镓含量的GaZSM-5沸石的芳构化性能与吡啶吸附红外光谱特征谱带吸收度的关联,证实了1458 cm~(-1)吸收带的用于表征与Ga物种有关的活性中心,并研究了沸石的硅铝比对Ga中心形成和Ga的价态对芳构化性能的影响。结果表明,对Ga含量相同的样品来说,硅铝比愈低,起始Ga中心生成量愈多,高价态与低价态的Ga中心对丙烷芳构化反应都有促进作用。

关键词: GaZSM-5沸石, 丙烷芳构化, 吡啶吸附红外光谱

Abstract:

The process of the formation of the Ga active site in GaZSM-5 zeolite (prepared by impregnation) and the enhancement of the aromatization activity following successive increasing extent of reduction of Ga species were observed by the IR spectra of pyridme adsorption and pulse microreaction system respectively. The results show that absorbance of the band near 1458 cm~(-1) can be correlated with the aromatization activity and Ga content of GaZSM-5 zeolite, so it can be assigned to a pyridine complex with Ga active site. The effect of SiO_2/Al_2O_3 ratio on the formation of Ga active site was also studied. It was found that the sample with lower SiO_2/Al_2O_3 ratio could form more Ga active sites. After measuring the aromatzation activity by pulse microreaction and determining the valence state of Ga sites by TPR, the authors suggest that both the high and the low valence Ga active sites can play the role of the active sites in C_3H_8 aromatization.

Key words: GaZSM-5 zeolite, C3H8 aromatization, IR spectra of pyridine adsorption