COLL 30 |
| Gérard M. Pajonk Sr., LACE UMR 5634, LACE UMR 5634, University Lyon 1- 69650 Villeurbanne-France, Batiment Raulin, Villeurbanne, France |
| Aerogels are ultra-porous solid materials exhibiting large pore volumes (porosities > 90%) high surface areas (hundreds of m2/g) and low bulk densities. They can be prepared as powders, chunks or monoliths,opaque, translucent or transparent to light. Despite their low bulk densities aerogel powder can be fluidized . They are obtained through the sol-gel method and then dried under hypercritical conditions with respect to their liquid phase. When the high temperature supercritical process ( with alcohol, acetone etc..) is applied, the catalysts are hydrophobic and to a some extent aged in-situ the autoclave during the heating step. With the low temperature method ( with liquid CO2 ) they are hydrophilic. But in all cases they can be made hydro-phobic or philic reversibly either by a co-gelation or by derivatization with a hydrophobic reactant in the first case, or by a thermal treatment in the second case. |
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The Science and Engineering of Catalyst Preparation
8:30 AM-11:55 AM, Sunday, March 28, 2004 Marriott -- Orange County 3, Oral
Division of Colloid and Surface Chemistry |