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US 2008/0302135 A1Published application
Method for the Production of Shaped Silica Aquagels
AssigneeDegussa AG
InventorsLorenzo Costa, Giulio Boara
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Abstract
It has been discovered that aquagels, formed from acid catalized composite sols, survive to conditions of high-tension when they are prepared by a process that hydrolyzes the silicon alkoxides in presence of fumed silica. The aquagel can be used for the production of monoliths of glass.
Claims2
Method for the production of formed aquagels for the production of monoliths by means of the sol-gel process, comprising the following steps:
- a. Dispersing a pyrogenically prepared silicondioxide in water or a water containing solvent, to form an aqueous or water containing dispersion.
- b. Adding of an acid in order to reach a pH-value of 2±0.5.
- c. Adding of tetraethylorthosilicate (TEOS).
- d. Hydrolyzing the tetraethylorthosilicate (TEOS) in order to produce a sol containing the pyrogenically produced oxide of a metal and/or metalloid.
- e. Evaporating the liquid from the sol.
- f. Adding to the remaining sol an aqueous solution of ammoniumhydroxide in order to reach a pH-value of 4±0.5.
- g. Filling the sol into a mould.
- h. Gelling the sol to the corresponding aquagels.
5 more elements
Dependencies are inferred from the claim text.