| Abstract
| - ITQ-1, a microporouspure-silica polymorph isomorphous to zeolite MCM-22, forms uponcalcination of a layered precursor obtained by hydrothermal synthesis.Calcined ITQ-1 contains a remarkably small concentration ofconnectivity defects (≅7 Si(OSi)3OH mol %) incontrast to uncalcined ITQ-1 (≅30%). 29Si NMRspectra, which are in good agreement with the structure proposed forMCM-22, demonstrate the defects are not randomly distributed in thelayered precursor but arise mostly from unconnected T1−O−T1 andT2−O−T3 bonds.
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