Magic angle spinning29Si and27Al NMR study of mordenite dealumination |
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Authors: | J. A. Ripmeester A. Majid R. E. Hawkins |
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Affiliation: | 1. Division of Chemistry, National Research Council of Canada, K1A OR9, Ottawa, Ontario, Canada
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Abstract: | Magic angle spinning29Si NMR presents a rapid qualitative method of assessing the degree of dealumination of sodium mordenite modified by acid leaching and heat treatment. A quantitative determination of the29Si coordination sphere is hampered by the overlap of chemical shift ranges for Si?O?Al and Si?O?H species. MAS27Al NMR indicates the presence of octahedrally coordinated Al in interstitial sites in all treated samples. On treating mordenite samples at high temperatures (~700°C) much of the Al becomes invisible to the NMR experiment because of its location in sites of low symmetry and large quadrupole coupling constant. |
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