Fabrication of uniform 4H-SiC mesopores by pulsed electrochemical etching

In this letter, the uniform 4H silicon carbide (SiC) mesopores was fabricated by pulsed electrochemical etching method. The length of the mesopores is about 19 μm with a diameter of about 19 nm. The introduction of pause time (T_off) is crucial to form the uniform 4H-SiC mesopores. The pore diameter will not change if etching goes with T_off. The hole concentration decreasing at the pore tips during the T_off is the main reason for uniformity.     

Chromium Supported on Mesocellular Silica Foam (MCF) for Oxidative Dehydrogenation of Propane

A series of chromium-containing mesocellular silica foam (MCF) catalysts have been prepared and characterized in the oxidative dehydrogenation (ODH) of propane between 350 and 600 °C. It is demonstrated that the chromium catalysts supported on MCF exhibit much higher catalytic activity in terms of propane conversion and propylene yield than literature results obtained over chromium-supported mesoporous SBA-15 or MCM-41 catalysts during the ODH of propane. Enhanced catalytic performance of the chromium-containing mesoporous MCF catalysts has been attributed to the unique three-dimensional (3D), continuous, ultralarge mesopore structure of the MCF materials, which allow a much faster internal molecular transport during the ODH of propane.     

介孔二氧化硅KIT-6介观单晶微球的合成

以非离子表面活性剂［聚环氧乙烷（PEO）-聚环氧丙烷（PPO）-聚环氧乙烷三嵌段共聚物,P123］和阳离子聚电解质（聚二甲基二烯丙基氯化铵,PAC）形成的复合物胶束为模板,合成了具有球形形貌的介孔二氧化硅KIT-6介观单晶微球。通过扫描电镜（SEM）、透射电镜（TEM）、X射线衍射（XRD）、氮气物理吸附和热重分析（TGA）等手段对合成材料的形貌及孔结构进行了表征分析。结果表明,以有机复合物胶束为模板合成出的介孔KIT-6二氧化硅材料具有较规整的球形形貌,颗粒直径为2~3 μm,具有较大的比表面积和孔体积（747 m²/g和1.3 cm³/g）,介孔孔径为8.5 nm,且在整个颗粒内部介孔保持高度的有序排列。由于长链聚电解质PAC与硅源有着较强相互作用,样品可以在较高水热温度下（160 ℃）合成,有利于提升介观结构的稳定性。该合成方法对于介孔二氧化硅KIT-6单晶微球的合成及其在催化及吸附分离等领域的应用具有一定的启发意义。     

Increasing the adsorption capabilitiy of mordenite and Y zeolites via post‐synthesis chemical/physical treatments in order to remove cationic dyes from polluted water

Different post‐synthesis approaches were used to increase the adsorption abilities of zeolite mordenite and Y in removal of cationic dye molecules as typical dyestuff pollutants. Various methods including acid leaching, alkaline treatment, dealumination with hexafluorosilicate, sonication and combination of them were employed to alter the porous structure of various types of selected zeolites. The dealumination (due to acid leaching), desilication (due to alkaline treatment) and disintegration (due to shear forces generated by ultrasound waves) were responsible for the alteration of pores size and accessibility in mordenite. Acid leaching combined with irradiation of ultrasound was found to be most effective technique in adsorption of rhodamine B as a large dye molecule into mordenite. In the case of zeolite Y, a chemical treatment with ammonium hexafluorosilicate resulted in considerable improvement of adsorption of rhodamine B.     

Synthesis and evaluation of a ruthenium–copper oxide/silica catalyst derived from microemulsion processing

Bimetallic Ru–Cu catalysts supported on SiO₂ have been synthesized in microemulsions using sodium metasilicate (Na₂SiO₃), copper nitrate (Cu(NO₃)_2·3H₂O) and ruthenium chloride (RuCl₃) at 28 °C. The microemulsion system consists of sodium 1,4‐bis(2‐ethylhexyl) sulfosuccinate (AOT) and sodium dodecyl sulphate (SDS), cyclohexane, and an aqueous solution of sodium metasilicate or metal salts. The catalysts have been characterized by XPS, EDX/SEM with line scanning and they possess a very narrow pore size distribution (around 38 Å) and relatively high specific surface areas (around 400 m²/g). The catalytic results of the N₂O decomposition reveal that higher conversions of N₂O can be achieved by the catalysts synthesized from the microemulsion process at lower temperatures (around 400 °C).     

V掺杂的介孔氧化硅材料的合成、表征及应用

采用原位法在弱酸条件下,以不同表而活性剂为模板,水热合成了钒掺杂的介孔氧化硅材料,并用电镜扫描(SEM)、低温氮气吸附、X射线衍射(XRD)、红外光谱(IR)、紫外-可见光谱(UV-Vis)等方法对其结构进行了表征.以罗丹明B的光催化降解反应为探针,研究了催化剂的光催化性能,研究结果表明该方法合成的钒掺杂的介孔氧化硅材料在紫外光下具有理想的光催化活性.     

高活性中孔型纳米二氧化硅粉末制备新工艺的探索

用溶胶－凝胶法制备出SiO2凝胶后，首次结合并采用低温热处理以及球磨工艺制备出高活性中孔型纳米SiO2粉末。利用TEM等手段分析了热处理温度、球磨对其显微结构及其物性的影响。结果表明，选择合适的热处理机制和适当的球磨时间可制备出具有很高表面能和表面活性的中孔型纳米SiO2粉末。本方法设备要求及操作过程简单，是一种具有发展前景的新型工艺。     

Synthesis of mesoporous MOR materials by varying temperature crystallizations and combining ternary organic templates

An approach, which involved perturbations of synthesis conditions in crystallization temperature and organic template composition, has been proposed for derivation of mesopores from bulk structural defects formed in mordenite (MOR) phases, based on the character of intrinsic crystal defects and tensional distortions of two compressed 8-membered rings in MOR framework. Consequently, hierarchically porous materials with MOR structures were prepared by varying temperature synthesis and using ternary organic micelles templates. The synthesized materials were characterized by powder X-ray diffraction, nitrogen adsorption at 77 K and transmission electron microscopy. These crystalline materials combined the advantages of both mordenites with the micropore system and mesoporous materials by featuring an additional intracrystalline mesopore system in MOR single crystals, resulting in a hierarchical pore distribution in range of 1.7-80.0 nm together with the significant specific surface areas. In particular, individual crystal morphologies of typical mesoporous MOR materials showed the defect-rich structures responding essentially to the mesoporosity; the mesoporous materials were substantiated matchable well to normal mordenites in acid capacity and acid strength distribution. Furthermore, several factors acting on intracrystalline mesopore formation were elucidated for explicating the perturbation synthesis approach, and whole reaction routes for synthesizing different solid products under related crystallization conditions were summarized coupling with a demonstration of part TEM micrographs. The overall results suggested that the investigative approach of perturbation imposed on crystal growth provides an alternative route for direct hydrothermal synthesis of mesoporous zeolite materials and implied that bulk structural defects within single crystals lead to the formation of intracrystalline mesopores in various sizes.     

中孔活性炭材料的研究进展

综述了国内外在中孔活性炭材料开发方面的研究进展。着重介绍了催化活化、界面活化、混合聚合物炭化、有机凝胶炭化、铸型炭化等孔径调控方法及其中孔形成机理。为控制活性炭材料孔径大小和分布，提高其中孔容积和吸附性能提供了参考。     

Small angle neutron scattering study of the structure and formation of MCM-41 mesoporous molecular sieves

The nanoscale structure and synthesis mechanisms of the MCM-41 class of inorganic mesoporous materials have been investigated by small angle neutron scattering (SANS). SANS measurements with solvents imbibed in the pores to vary the scattering contrast demonstrate that the low angle diffraction peaks from these materials are entirely due to the pore structure and that the pores are fully accessible to both aqueous and organic solvents. Static and shear flow SANS measurements on the concentrated cationic surfactant and silicate precursor solutions typically used in the synthesis of the mesopore materials indicate that the existence of preassembled supramolecular arrays that mimic the final pore structure is not essential for the synthesis of these materials.