不同方法处理的脱铝Y沸石的结构特征研究

用~(29)Si MAS NMR、~(27)Al MAS NMR、XRD及IR等方法对4种不同脱铝方法处理的USY、SSY、US-SSY和DAY的微观结构进行了研究,结合脱铝方法讨论了骨架硅铝的分布以及非骨架硅铝和羟基空穴等的形成和含量不同的原因.发现不同脱铝方法可导致骨架上不同Si(nAl)单元的脱除.XRD结果表明,SSY经进一步高温水蒸汽处理得到的US-SSY的相对结晶度可高达97％.脱铝后,微孔保留愈多,二次孔越少,相对结晶度愈高.最后对~(29)Si MAS NMR、XRD和IR3种测定骨架单胞铝(N_(Al))_F的结果进行了比较.

Studies on Structural Characteristics of Deal uminated Y Zeolites Treated by Different Methods

The microstructure of four kinds of dealuminated Y zeolites (USY,SSY,US-SSY,DAY) were studied by 29Si,27A1 MAS NMR,XRD and IR.The cause of the formation of non-framework Si,Al and Si-OH nests and of difference of their amount were discussed according to the methods of dealumination.It is shown that the different methods of dealumination brings about the removing of different Si(nAl) units on the framework of zeolites.The results of XRD indicate that the relative crystallinity of 97% can be obtained when SSY was further treated by the high temperature steam to US-SSY.After dealumination,if the remains of micropore is more and the secondary mesopore is less,the relative crystallinity of sample is higher.Finally,it was also found that the framework aluminium of unit cell (NAl)F measured by 29Si MAS NMR is less than that measured by XRD and IR,and the reason was also discussed.