DETERMINATION OF SILICON-ALUMINIUM ORDERINGS IN MORDENITE AND ITS ALUMINIUM DEFICIENT FORMS USING HIGH-RESOLUTION MAGIC-ANGLE-SPINNING 29Si-NMR

Abstract

Abstract A series of chemically dealuminated mordenites were investigated by 29Si and 27Al NMR spectroscopy. High-resolution magic-angle-spinning (HRMAS) solid state 29Si NMR lines with varying intensity were observed at δ=−95, −105 and −110 ppm. When it is assumed that the Al atoms are located exclusively in the 4-membered rings of the structure, these variations can be explained by assigning the resonance lines to silicon atoms surrounded by 2, 1 and 0 Al atoms respectively. The 27Al NMR spectrum yields quantitative information on the amount of octahedrally coordinated aluminium formed during various chemical treatments of Na-mordenite.