K_(2)O修饰γ－Al_(2)O_(3)的表面性能研究

STUDY ON SURFACE PROPERTIES OF γ-Al_(2)O_(3) MODIFIED BY K_(2)O

本文利用ＥＰＭＡ、ＸＰＳ和ＦＴＩＲ等物理方法，研究了浸渍Ｋ２Ｏ以后的γ－Ａｌ２Ｏ３的表面组成、表面羟基性质、表面酸碱性以及表面各元素电子结合能的变化。实验结果表明，γ－Ａｌ２Ｏ３经Ｋ２Ｏ修饰以后，表面Ｋ／Ａｌ比大于本体Ｋ／Ａｌ比，Ｋ２Ｏ富集在γ－Ａｌ２Ｏ３的表面上；Ｋ２Ｏ在表面上起到了抑制酸性，增强碱性包括羟基碱性的作用；表面碱性中心种类增多、碱性增强、分布增宽的主要原因是表面氧的电负性增强和铝在一定程度上的还原。

By using EPMA, XPS and FTIR etc.,the surface composition,the properties of surface hydroxyls,the acidity and basicity of the adsorption sites and the electron binding energies of surface elements of γ-Al_2O3 modified by K_2O are studied. The measurements in dicate that for the modified samples the K/Al ratio on the surface is larger than that in the bulk,showing most of K_2O are deposited on the surface,The structure of the surface lattice is not greatly changed because the Al/O ratioes both for γ-Al2O3 and the modified samples are kept unchanged. K_2O plays a role of decreasing the acidity and increasing the basicity of the surface species and hydroxyls.However,it does not alter the Lewis acidic sites.The number and kinds of basic sites become more and their dictributions broader, which benefits to the catalytic properties of COS hydrolysis and also to its adsoption.