On Three-Fold Coordinated Si Sites in Mesoporous MCM-41 Catalysts
نویسندگان
چکیده
Si-NMR, gas adsorption and SAXS results are discussed to determine if the geometry and the electronic properties of Si sites, present in the MCM-41walls, are more similar to threethan to four-fold coordinated sites. The features of Si-MCM-41, SBA-15, Y zeolite and silica (SiO2), characterized by several techniques, are compared. It is shown that the pre-polymer geometries are similar to those of the zeolite secondary building units, but, in the organization-polymerization step, the generation of partially saturated or quite stressed structures is favored.
منابع مشابه
Asymmetric Synthesis of Modafinil and its Derivatives by using the Functionalized Silica-based Mesoporous MCM-41
Modafinil [2-[(diphenylmethyl)sulfinyl]acetamide] is used clinically in the treatment of narcolepsy and sleeping disorders. The synthesis of modafinil, begins with the reaction of benzhydrol and thioglycolic acid in trifluoroacetic acid to afford benzhydrylsulfinyl acetic acid. The reaction of acid with thionyl chloride in benzene followed by treatment with ammonium hydroxide gave acetamide...
متن کاملSelective Preparation of trans-Carveol over Ceria Supported Mesoporous Materials MCM-41 and SBA-15
Ce-modified mesoporous silica materials MCM-41 and SBA-15, namely 32 wt % Ce-Si-MCM-41, 16 wt % Ce-H-MCM-41 and 20 wt % Ce-Si-SBA-15, were prepared, characterized and studied in the selective preparation of trans-carveol by α-pinene oxide isomerization. The characterizations of these catalysts were performed using scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorpti...
متن کاملMesoporous silica-supported zirconocene catalysts for highly isotactic polypropylene.
A new bis(indenyl)zirconocene bearing a pendant Si-Cl anchor has been grafted onto MCM-41, SBA-15, MCM-48 and a disordered mesoporous silica for the polymerisation of ethylene and propylene, producing polymers with very high molecular weights, low polydispersities and, in the case of polypropylene, higher levels of isotacticity than obtainable with analogous homogeneous systems.
متن کاملEffects of the Framework and Mesoporosity on the Catalytic Activity of Hierarchical Zeolite Catalysts in Benzyl Alcohol Conversion
Zeolites are crystalline inorganic porous materials formed by TO4 tetrahedra (T=Si, Al, P, etc.) with ordered microporous structures. As a result of their tunable acidities and framework structures, zeolites have been used widely in catalysis and molecular adsorption/separation as well as several other emerging applications. However, the pore size of a zeolite is usually smaller than 2 nm, whic...
متن کاملCatalytic performance of vanadium incorporated MCM-41 catalysts for the partial oxidation of methane to formaldehyde
The catalytic performance of incorporated V-MCM-41 catalysts for the partial direct oxidation of methane to formaldehyde with molecular oxygen has been investigated. V-MCM-41 catalysts containing 0.56–1.86 wt.% V have been prepared by incorporating the vanadium ions into the framework of mesoporous siliceous MCM-41, resulting in a highly ordered structure with large BET surface area and high su...
متن کامل