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The Ageing of Silica Gels Affected by Hydrothermal Treatment
Author(s) -
Lutz Wolfgang,
Weber Manfred,
Bertram Rainer,
Kurzhals Rolf,
Kryukova Galina
Publication year - 2011
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201000394
Subject(s) - sorption , hydrothermal circulation , adsorption , chemical engineering , materials science , nitrogen , chemistry , organic chemistry , engineering
Commercial silica gels of the pyrogenic and precipitated types were hydrothermally treated for 72 hours at temperatures between 90 °C and 210 °C in water of autogenous pressure. The samples were characterised by IR spectroscopy, water and nitrogen adsorption. Stability and sorption capacity run similarly. The more Q 4 (Si(OSi) 4 ) building units the framework of a silica gel contained, the lower was its sorption capacity. Sorption capacity increased with rising number of structural defects characterised by the presence of Q 3 (Si(OSi) 3 OH) and Q 2 (Si(OSi) 2 (OH) 2 ) groups. Simultaneously, the hydrothermal stability of the silica material dropped off.