Chia-Min Yang

Large pore ordered mesoporous silica materials with 3D cubic Ia3d structure: a comprehensive gas adsorption study

The paper deals with the systematic gas adsorption investigation and structural characterization of novel ordered mesoporous silica materials with three-dimensional (3-D) cubic Ia3d structure (KIT-6). The pore condensation and hysteresis behavior of nitrogen (at 77.4 K) and argon (at 77.4 K and 87.3 K) was studied in KIT-6 silicas of different porosities and various mean pore diameters (from 5 nm up to 11 nm). We compared the sorption and phase behavior of nitrogen and argon confined to these 3-D cubic porous systems with their behavior in pseudo 1-D pore systems (e.g. SBA-15). Our results provide information on how pore connectivity and network effects influence pore condensation and hysteresis, and the validity of the single pore model for the pore size analysis of materials consisting in pore networks is discussed.

Exploring the catalytic activity of metal nanoparticles in functionalized mesoporous silica

Abstract The catalytic activitiy of highly dispersed metal nanoparticles in functionalized mesoporous silica SBA- 15 prepared by a solution technique is demonstrated. The surface of SBA-15 was functionalized with positively charged groups, and anionic metal species were subsequently incorporated into the channel system via ion exchange. The anionic metal precursors were then reduced by either H 2 flow or by NaBH 4 solution. Among the as-synthesized Au catalysts, two of them show activity for CO oxidation at room temperature. The most active Au catalyst was found to catalyse the reaction with a rate of 2.7x10 4 mmol g cat 1 s 1 , which is more active than any other silica-supported system made by a solution technique. On the other hand, supported Pd and Pd-Au nanoparticles in SBA-15 show capabilities as catalysts for Heck reactions. Buchwald-Hartwig-aminations and Suzuki-reactions are catalysed as well, but the yields, turn-over-numbers (TONs) and turn-over-frequencies (TOFs) in these transformations are substantially lower than those of standard solution phase systems.

Beckmann rearrangement on microporous and mesoporous silica

Crosslinked Silicalite-1 and SBA-15 have been investigated as solid acid catalysts in the vapour phase Beckmann rearrangement reaction of cyclohexanone oxime to e-caprolactam. The catalytic activity of crosslinked colloidal Silicalite-1 is strongly dependent on the used amount of linker. With increasing amount of linker the external surface area increases as well as the catalytic activity. Surface modified SBA-15 was investigated to study the influence of pore dimensions, acid sites and catalytic activity in micro-and mesopores. A combination of these studies allows making suggestions concerning the location of the catalytic reaction.

Structural characterization and systematic gas adsorption studies on a series of novel ordered mesoporous silica materials with 3D cubic Ia-3d structure (KIT-6)

We present the results of systematic gas adsorption experiments and an advanced structural characterization of novel ordered mesoporous silica materials with 3-D cubic Ia-3d structure (KIT-6). The pore condensation and hysteresis behavior of nitrogen (at 77.4 K) and argon (at 77.4 and 87.3 K) was studied in KIT-6 materials of different porosities and various mean pore diameters (ranging from ∼ 5 nm up to 12 nm). We compare further the sorption and phase behavior of nitrogen and argon confined to this 3D cubic porous system with their behaviour in pseudo-lD pore systems (e.g. SBA-15 silica). Our results also shed light on the extent to which the so-called single pore model can be used for the pore size analysis of materials consisting of ordered pore networks.