镓改性ZSM-5沸石中镓活性中心的形成与表征

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。

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

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 1458cm-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 SiO2/Al2O3 ratio on the formation of Ga active site was also studied. It was found that the sample with lower SiO2/Al2O3 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 C3H8 aromatization.