Silicalite
Chemical compound / From Wikipedia, the free encyclopedia
Silicalite is an inorganic compound with the formula SiO2. It is one of several forms (polymorphs) of silicon dioxide. It is a white solid. It consists of tetrahedral silicon centers and two-coordinate oxides. It is prepared by hydrothermal reaction using tetrapropylammonium hydroxide followed by calcining to remove residual ammonium salts. The compound is notable in being ca. 33% porous. It is useful because the material contains (SiO)10 rings that allow sorption of hydrophobic molecules of diameter 0.6 nm.[1]
Identifiers | |
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Properties | |
O2Si | |
Molar mass | 60.083 g·mol−1 |
Appearance | white solid |
Density | 1.76 g/cm3 |
Melting point | 1,300 °C (2,370 °F; 1,570 K) decomposition |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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A commercially important modification of silicalite is titanium silicalite. With the formula Si1−xTixO2, it consists of silicalite with Ti doped into some Si sites. Unlike conventional polymorphs of titanium dioxide, the Ti centers in titanium silicalite have tetrahedral coordination geometry. The material is a useful catalyst for the reaction of hydrogen peroxide with propylene to give propylene oxide.[2]