{{Chembox | ImageFile = Silicalite MFI framework.png | ImageSize = 284px | ImageAlt = | IUPACName = | OtherNames = |Section1={{Chembox Identifiers | CASNo = | PubChem = | SMILES = [Si].[O].[O] }} |Section2={{Chembox Properties | Si=1|O=2 | MolarMass = | Appearance = white solid | Density = 1.76 g/cm<sup>3</sup> | MeltingPtC = 1300 | MeltingPt_notes = decomposition | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }} '''Silicalite''' is an inorganic compound with the formula SiO<sub>2</sub>. 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)<sub>10</sub> rings that allow sorption of hydrophobic molecules of diameter 0.6 nm.<ref>{{cite journal|title=Silicalite, a New Hydrophobic Crystalline Silica Molecular Sieve|author=E. M. Flanigen |author2=J. M. Bennett |author3=R. W. Grose |author4=J. P. Cohen |author5=R. L. Patton |author6=R. M. Kirchner |author7=J. V. Smith |journal=Nature|volume=271|pages=512–516|year=1978|issue=5645|doi=10.1038/271512a0|bibcode=1978Natur.271..512F|s2cid=4266556}}</ref>
A commercially important modification of silicalite is titanium silicalite. With the formula Si<sub>1−x</sub>Ti<sub>x</sub>O<sub>2</sub>, 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.<ref>{{cite journal|title=Structural and Physicochemical Features of Titanium Silicalites|author=Georgi N. Vayssilov|journal=Catalysis Reviews|volume=39|pages=209–251|year=1997|issue=3|doi=10.1080/01614949709353777}}</ref>
==References== <references />
{{Silica minerals}}
Category:Polymorphism (materials science)
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