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Influence of the SiO2/Al2O3 ratio on the synthesis and physicochemical characteristics of levyne-type zeolite |
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| Authors: | CV Tuoto A Regina JB Nagy A Nastro |
| Affiliation: | aDept. of Chemical Engineering and Materials, University of Calabria, Arcavacata di Rende, 87030 Rende, (CS), Italy bUnité de R.M.N., University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium |
| Abstract: | Levyne-type zeolites were synthesized from gels of initial compositions 4.5Na2O-6MeQI-xAl2O3 30SiO2-500H2O, with MeQ = methylquinuclidinium and 0.6 ≤ x ≥ 3 at 150 ≤ t ≥ 190 °C. The 29Si NMR spectra show the presence of two crystallographically different sites in the structure. The 27Al NMR spectra also suggest the presence of two different tetrahedral Al atoms incorporated in the structure. A rather high amount of defect groups SiOM and Si(OM)2 with M = MeQ, Na and/or H are present in the precursor samples. The Si(OM)2 groups are eliminated during calcination, and a certain amount of SiOM still persists after calcination. The combined 13C NMR and thermal analysis data allowed one to interpret the nature of the two different types of MeQ+ ions occluded in the levyne channels. |
| Keywords: | Levynite Synthesis 29Si NMR 27Al NMR 13C NMR |
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