Nature and centers of localization of extraframework particles in Y zeolite dealuminated by silicon tetrachloride

Abstract

X-ray diffraction, XPS, and NMR have been used to investigate the nature and centers of localization of nonframework particles in Y zeolite dealuminated by silicon tetrachloride. It has been established that the reaction products formed upon dealumination consist mainly of aluminum compounds that migrate from the volume of the zeolite to the surface and are also partially localized in internal supercages and small cages (sodalite cells). Water washing removes the particles localized in the supercages but does not affect the particles localized in sodalite cells. It has been shown that, by plotting maps of electron density on the basis of x-ray powder diffraction patterns, the sites of localization of extraframework particles can be determined. The results are consistent with those obtained by other methods, and the maps of electron density give a graphic picture of changes in internal structure of the Y zeolite.