Detection of Distorted Tetrahedral-Coordinate Aluminum in Dealuminated Mordenite by 27Al 3Q MAS NMR
脱铝丝光沸石中扭曲四配位铝的27Al 3Q MAS NMR研究

Al MAS and 3Q MAS NMR spectroscopy was applied to study the aluminum coordination in dealuminated zeolite mordenite and amorphous silica-alumina A signal ascribed to distorted tetrahedral-coordinate Al (DTA) was detected By comparison with amorphous silica-alumina, it was found that the presence of distorted tetrahedral-coordinate species is a typical feature in crystalline zeolites after activation and dealumination From these experimental results we suggest that the DTA species, which are absent in amorphous silica-alumina, locate at the interface between the crystalline framework lattice and the extra-framework species formed by dealumination