|
|
|
|
|
Silica-aluminaSilica-alumina, also known as alumino-silicate(s). Oxide-like combination of aluminium, silicon and oxygen. Major component of kaolin and clays. When amorphous silica-alumina is treated with strong acids such as hydrochloric and hydrofluoric acids, the material acts as a solid acid and becomes capable to promote reactions that require acid catalysis. Under other circumstances, when trivalent aluminum is forced by surrounding tetravalent silicon to crystallize in a tetrahedral symmetry, a partial electron deficiency occurs at the aluminum site allowing it to act as a Lewis acid, or to react with a water molecule and form a conjugated Brnsted. Natural and synthetic zeolites can be such crystalline alumino-silicates if aluminum precursors are added in the synthesis process. See also: acid site, catalysis, catalyst, active site,
|
 |
|
| Copyright 2005-2009 OnPedia.com. All Rights Reserved |
|
|