Quantum-chemical calculation on models of hydroxy-containing zeolite fragments

Ethyleneimine Anchored on Thiol-Modified Silica Gel Surface—Adsorption of Divalent Cations and Calorimetric Data

“…The yielded product (≡Sil-SH) was dried in vacuum for 8 h at 373 K and the reaction involved is represented by Eq. [1]. In the next step, 5.0 g of this modified silica was suspended in 30.0 cm 3 of xylene.…”

“…The systematic use of organofunctional molecule immobilization has increased in the past three decades, mainly on silica, because this support offers pronounced advantages over the organic supports, such as: (a) immobilization on silica resulting in a great variety of silylating agents, allowing myriad pendant functional groups in the inorganic framework; (b) attachment being easier on silica surface than on organic supports, which have a high number of crosslinking bonds, requiring hours to reach equilibrium; (c) silica gel being the most popular substrate for surfaces studies because it was the first commercially available high specific surface area substrate with constant composition, enabling analysis and interpretation of results; (d) inorganic supports not swelling in organic solvents; (e) great resistance to organic solvents, and (f) particularly, silica having high thermal resistance (1).…”

Secondary crystallization of SBA-15 pore walls into microporous material with MFI structure

“…On the other hand, the dehydroxylation of the silica surface may increase the Lewis acidity by the formation of tricoordinated silica cations [24] on the wall surface. The influence of silica dehydroxylation on the electron-acceptor properties of the wall surface was observed by Lygin [25]. Although an o/p ratio of more than one is expected for a bimolecular isomerization mechanism, the o/p molar ratio observed in jH + (1Ày) j[Si y Al (1Ày) O 2 ]-SBA-15/MFI (OH À /48 h) was very low, indicating the presence of geometrical constraints for the formation of the bimolecular transition state on the mesopore walls.…”

Polystyrene‐Supported 2‐Arylindenyl Zirconocene Catalysts for Propylene Polymerization

“…This reaction can be monitored by FTIR by observing the disappearance of the Si-H stretch at 2100 cm -1 and an ~4 ppm downfield shift of the methylene carbons bonded to the silanol silicon (resonances at 3.0 ppm and 10.5 ppm for PS-DES-SiH shift to 7.0 ppm and 14.5 ppm for the silanol (2)). The resulting silanolsubstituted polystyrene resin provides an analogue to lone hydroxyl groups found on the surface of partially dehydroxylated silica, 28 allowing the cross-application of silane bonding chemistry from silica supports to polystyrene.…”