Method for making monolithic metal oxide aerogels
AssigneeThe Regents of the University of California
InventorPaul R. Coronado
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Abstract
Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The containment vessel is enclosed within an aqueous atmosphere that is above the supercritical temperature and pressure of the solvent of the metal alkoxide solution.
Claims37
A method for making monolithic, transparent metal oxide aerogels, said method comprising the steps of:
- (a) hydrolyzing a metal alkoxide in a solution comprising the metal alkoxide, a substoichiometric amount of water, an alcohol solvent, and a catalyst to form a colloidal solution;
- (b) allowing said colloidal solution to gel and form an alcogel;
- (c) containing said alcogel within a containment vessel;
- (d) sealing said containment vessel to produce a sealed containment vessel that is gas permeable;
- (e) supercritically drying the alcogel in said sealed containment vessel by providing a sealed water-containing atmosphere about said sealed containment vessel at above the supercritical temperature and pressure of said alcohol solvent to form a metal oxide aerogel.
A method for producing a metal oxide aerogel, said method comprising:
- extracting an alcohol solvent from an alcogel contained within a sealed containment vessel that is gas permeable, said sealed containment vessel enclosed by water maintained at above the supercritical temperature and pressure of said alcohol solvent,
- unsealing said sealed containment vessel, and
- removing a dried metal oxide aerogel from said containment.
A transparent, monolithic metal oxide aerogel having a density in the range of 0.005 g/cm.sup.3 to 0.05 g/cm.sup.3, comprising a metal selected from the group consisting of tantalum, titanium, zirconium, molybdenum, niobium, tungsten, hafnium, vanadium, chromium, rhenium, the lanthanides (Ce--Lu), boron, aluminum, gallium, indium, germanium, tin, lead, mixtures thereof, and a mixture of at least one metal in the listed group with silicon.
A transparent, monolithic metal oxide aerogel produced by the method comprising the steps:
- (a) hydrolyzing a metal alkoxide in a solution comprising the metal alkoxide, a substoichiometric amount of water, an alcohol solvent, and a catalyst to form a colloidal solution;
- (b) allowing the colloidal solution to gel and form an alcogel;
- (c) containing the alcogel within a sealed containment vessel that is gas permeable;
- and
- (d) supercritically drying the alcogel in the containment vessel to form a metal oxide aerogel.
Dependencies are inferred from the claim text.