Characterization of incorporated gallium in beta zeolite

[[abstract]]Framework and nonframework gallium species in beta zeolites were characterized by n.m.r., XPS, and i.r. spectroscopic methods. The isomorphous substitution of Al+3 by Ga+3 in the framework of beta zeolite gives 1 and 3 ppm downfield shifts of Si(1M) and Si(2M) peaks (M = Ga instead of Al) in Si-29 MAS n.m.r. spectra, such shifts have been confirmed by SCF-GIAO theoretical calculation. During heat treatment, the framework Ga and AI of beta zeolites can change into nonframework species, as were detected by Ga-71- and Al-27-MAS n.m.r., and XPS, and such change shifts the binding energy of Ga-3d XPS from 20.7 to 21.4 eV and gives an i.r. band of extraframework hydroxyl groups at 3,685 cm(-1) (GaOH) or 3,655 cm(-1) (AIOH) with the i.r. band of bridging hydroxyl groups at 3,619 cm(-1) (Ga(OH)Si) or 3,607 cm(-1) (Ai(OH)Si). The extraframework Ga species probably exist in cation-like state.[[fileno]]2010323010067[[department]]化學