A vanadyl complex grafted to periodic mesoporous organosilica: a green catalyst for selective hydroxylation of benzene to phenol

Selective benzene hydroxylation: A periodic mesoporous organosilica embedded with a vanadyl(IV) acetylacetonate complex has been synthesized through a co-condensation method. This system is a catalyst for direct hydroxylation of benzene to phenol, presenting a selectivity of 100?% towards the phenol formation as well as an excellent catalytic recyclability (see scheme).     

Effect of the Preparation Conditions on the Phase Composition and Texture of Mesoporous Zirconium Dioxide

Changes in the phase composition and textures of zirconium dioxide depending on the composition of the reaction medium and the conditions of the subsequent hydrothemal and thermal treatment have been elucidated. The conditions for preparing uniformly mesoporous zirconium dioxide with pore sizes of 50-64 have been determined. It has been established that treatment of zirconium dioxide hydrogel in alkaline solutions facilitates the formation of nano-sized particles, stable to agglutination.     

NBMAS，AIMCM-41，无定形硅铝和HZSM-5催化裂化性能的比较研究

选取NBMAS（nanometer bimodal mesoporous aluminosilicate，简称为 NBMAS），AlMCM-41，无定形硅铝和HZSM-5几种不同孔结构的硅铝催化剂为研究对 象，以1，3，5-三异丙苯和异丙苯的裂解为探针反应，对其在不同反应温度下和经 水蒸气老化前后的催化裂化性能进行了对比研究。实验结果表明：1.反应物无论是 在新鲜的还是在老化后的催化剂上的裂化转化率均随反应温度的升高而升高；2.1 ，3，5-三异丙苯和异丙苯的裂化产物分布随着反应温度的升高呈规律性变化；3. 比较老化前后分子筛的裂化活性，其它催化剂的裂化活性大大下降，而NBMAS则呈 现出较好的裂化活性及稳定性；4.所选介孔催化剂与HZSM-5对比研究表明：酸性强 的HZSM-5对异丙苯的裂解表现出了较好的裂化活性，而对1，3，5-三异丙苯的裂解 则活性较低。     

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综述了近几年介孔分子筛在催化反应、生物固定吸附和分离、纳米材料制备及环保方面等方面应用研究的进展，并对其在环保方面，尤其是汽油脱硫的应用前景做了展望。     

Preparation and Characterization of Divanadium Pentoxide Nanowires inside SBA-15 Channels

One-dimensional V2O5 nanowires have been synthesized inside the channels of mesoporous silica SBA-15 through chemical approach, which involves aminosilylation of silanol groups on the silica surface, anchoring of isopoly acid, H6V10O28, by neutralization of basic amine groups, and thermal decomposition. The formation and physicochemical properties of the nanowires were monitored and studied by TG-DTA, variable temperature in situ XRD, TEM, N2 sorption measurements and UV-Vis DRS. The results indicate that V2O5 nanowires formed within SBA-15 channels belong to orthorhombic polycrystal domains. The oxygen-to-metal charge transfer band of V2O5 nanowires shows a blue shift in comparison with bulk V2O5, which clearly exhibits the quantum size effect of nanowires.     

Sol–Gel Processed Functional Nanosized TiO2 and SiO2-Based Films for Photocatalysts and Other Applications

Titania and silica-based porous coatings have been produced via sol–gel route in the presence of pore-creating agents PEG and viscous solvent -terpineol, or template agents CTAB, as well as triblock copolimer Pluronic P123. Porous titania films were characterised by HR TEM, UV-Vis, XRD, ellipsometry, ARS methods. The dispersion of the refractive index, the porosity (32–39%) and the thickness of the samples were estimated by integrating sphere transmission and reflection spectra with 3D angular resolved light scattering. The catalytic activity of mesoporous TiO₂ and TiO₂/ZrO₂ as well as SiO₂-benzophenone films in the process of Cr^VI to Cr^III and Ag⁺ to Ag⁰ photoreduction have been studied.     

New hybrid bidentate ligands as precursors for smart catalysts

1-Phosphanorbornadiene derivatives were grafted onto various periodically organized mesoporous powders, including a new zirconia/silica mixed oxide synthesized by aerosol techniques. After complexation with the [Rh(CO)2]+ fragment, these materials were revealed to be more active in olefin hydrogenation than their homogeneous counterparts. The reasons for this higher activity are discussed in the light of theoretical modeling. Various surface treatments, such as esterification, drying, and functionalization with PhSi(OEt)3, provided insights into the nature and mechanism of formation of the active species. Zirconia-based materials were found to be active in internal olefin hydroformylation. Investigation of the mechanism of this reaction shows that the isomerization step is catalyzed by the Lewis acidic support, whereas the hydroformylation step is driven by the rhodium catalyst. Dissociation of these two steps leads to enhancement of activity.     

Hierarchical self-assembly in molecularly ordered phenylene-bridged mesoporous organosilica nanofilaments.

Herein we report on the mechanism of formation of a hybrid phenylene-bridged hexagonally ordered mesoporous organosilica with crystal-like walls (CW-Ph-HMM). Electron microscopy and X-Ray diffraction studies indicate that the formation of CW-Ph-HMM involves the surfactant-mediated hydrothermal transformation of an amorphous organosilica precursor and that the final product is hierarchically ordered. Significantly, the material is in the form of submicrometre-thick sheets that consist of co-aligned aggregates of needle-like particles (up to 500 nm in length and 50 nm in width). The results suggest that preferential growth along the channel direction of the hexagonally ordered mesostructure is coupled with the propagation of molecular periodicity in the pore walls. Together, these factors give rise to the growth of highly anisotropic primary nanofilaments that become co-aligned to produce micrometer-thick sheets consisting of a periodic array of mesoscopic channels oriented perpendicular to the surface of the flake-like particles.     

A NOVEL ALUMINOSILICATE WITH BIMODAL MESOPORE DISTRIBUTION ?a?a SYNTHESIS AND CHARACTERIZATION

A novel aluminosilicate material (denoted as NKF-2) with well defined bimodal mesopore distribution has been hydrothermally synthesized directly using cetyltrimethylammonium chloride and tetraethylammonium hydroxide as mixed templates, in which one mesopore is distributed at around 3.8 nm and the other at 2.6 nm. The synthesized samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy, N2 adsorption, infrared spectroscopy, thermo-gravimetic analysis and solid-state 27Al and 29Si magic-angle-spinning(MAS) NMR spectroscopies to understand both the pore structures and the Local atomic arrangements of these solid products.