Silicon is an extremely common element found in rock, gravel, and dust in the form of complex silicates or silica. Silicon is the second most abundant element in the earth's crust. Now, the silicon catalyst has obtained considerable development, each kind of contains silicon catalyst to be invented unceasingly, has the quite widespread application in the inorganic chemical industry and the organic synthesis.
Aluminosilicate
Acid catalysis plays an important role in petroleum refining and petrochemical industry. Many organic reactions, such as alkylation, isomerization, esterification, and cracking of unsaturated hydrocarbons, require the use of acidic materials as catalysts. Over the past decades, aluminosilicate has received wide attention as a solid acid catalyst to catalyze Friedel-Crafts alkylation. Compared with the traditional homogeneous acid catalyst, the catalytic process has the advantages of simple production process, no corrosion, no pollution wastewater, high yield. Mesoporous aluminosilicate molecular sieve (MASM) is widely used in catalytic reactions, especially in macromolecular reactions, and can be used as a catalyst and catalyst carrier.
In addition, silicon modified γ-Al2O3 catalyst also has applications. The γ-Al2O3 can increase its acidity after doping with different proportions of silicon, so as to catalyze the dehydration of methanol synthesis of dimethyl ether.
Silica gel supported catalyst
Supported catalysts using silica gel and silica aerogel as carriers have important application values and prospects in fine chemical fields such as alcohol dehydrogenation to ketone, aldehyde and acid. Among them, Cu/SiO2 catalyst has been used on a large scale in industry. It can catalyze the dehydrogenation of ethanol into acetaldehyde, the hydrogenation of diethyl oxalate into ethylene glycol, and the epoxidation of propylene.
In addition, the composite carrier catalyst containing Mg-Si has the advantages of high catalytic efficiency, good flow dispersion performance and good particle morphology, which can be used in the gas-phase polymerization of ethylene.
Carbosilane dendritic catalyst
Novel carbosilane dendritic molecular catalysts have unique structure and performance characteristics, and their volume, shape, functional groups and molecular weight can be precisely controlled at the molecular level. Therefore, it has great application prospects in organic synthesis, supramolecular chemistry, biomedicine and other fields. Among them, trihexylsilane and trimethylsilyl trifluoromethanesulfonate are widely used. The trihexylsilane can catalyst for hydrodefluorination leading to the synthesis of hydrocarbons while trimethylsilyl trifluoromethanesulfonate is a highly effective silylation reagent and strong lewis acid catalyst.
Carbosilane dendritic molecules can also be used as a carrier to form complexes with palladium or cobalt. This new homogeneous supported catalyst can be used for Heck reaction and epoxidation of olefin. Among them, platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution is a powerful hydrosilanization catalyst, which can be used to prepare trans-β-silane.
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