Characterization of Silica Gels by 29Si MAS NMR and IR Spectroscopic Measurements

Wolfgang Lutz (1) , Dirk Täschner (2) , Rolf Kurzhals (2) , Detlef Heidemann (3) , Cornelia Hübert (4)

1 Süd-Chemie Zeolites GmbH
2 Süd-Chemie Zeolites GmbH
3 HU Berlin - Humboldt-Universität zu Berlin = Humboldt University of Berlin = Université Humboldt de Berlin
4 Brandenburgische Technische Universität Cottbus-Senftenberg

The solubility of commercial and synthesized silica gels in a solution of Tetra-Ethyl-Ammonium-Hydroxide (TEAOH) was investigated at room temperature. The state of parent silica frameworks was characterized by BET and SEM. The structural defects were identified both by the Qn group analysis in 29Si MAS NMR and IR spectroscopic investigation. It was found that the dissolution rate of the samples shows a tendency for growing up with an increasing BET surface. The increase of the internal surface was accompanied by formation of Si(OSi)3(OH) (Q3) and Si(OSi)2(OH)2 (Q2) structural units. The higher the number of Q3 and Q2 groups observed, the faster the samples were dissolved in TEAOH solution due to the attack of the hydroxide ions on the terminal OH groups of the framework. The asymmetrical TOT valence vibration of the IR spectra was systematically shifted to lower values with increase in the number of Q3 and Q2 structure groups.

Mots clés: Physical Sciences

Wolfgang Lutz, Dirk Täschner, Rolf Kurzhals, Detlef Heidemann, Cornelia Hübert. Characterization of Silica Gels by 29Si MAS NMR and IR Spectroscopic Measurements. Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (13-14), pp.2191. ⟨10.1002/zaac.200900237⟩. ⟨hal-00509231⟩