氟调变TiO_2载体表面酸性的研究

SURFACE ACIDITY OF FLUORINE MODIFIED TITANIA SUPPORT

采用ＮＨ３－ＴＰＤ，吡啶－ＩＲ和热失重等技术研究了氟对ＴｉＯ２载体表面酸性的调变。ＮＨ３－ＴＰＤ结果表明，引入氟，有消除ＴｉＯ２表面酸中心的作用；随着氟含量的增加，ＴｉＯ２表面酸量逐渐减小，酸强度略有下降。吡啶－ＩＲ光谱证实，氟的引入，主要是消除Ｌ酸中心，并有利于Ｂ酸中心的形成。在氟含量较高时，生成了新的更强的Ｂ酸中心，且使得Ｌ酸酸性增强。

Surface acidity of fluorine modified titania supports with various fluorine contents(0 0%～4 3%)has been characterized by NH 3 TPD,IR etc.The results show that the addition of fluorine decrease the acidity site of titania support.With increasing fluorine content,the surface acidity of titania support decreases.It is further determined that the incorporation of fluorine in titania mainly removes Lewis acid site and is in favour of the formation of Brnsted acid site.While higher fluorine content leads to the formation of stronger Brnsted acid site and Lewis acidity is also strengthened.