铁的化学形态对Au/Fe-O催化剂甲醛催化氧化性能的影响

采用溶胶沉积法、共沉淀法制备了负载型Au/Fe-O催化剂,运用X-射线粉末衍射(XRD)、透射电镜(TEM)、电感耦合等离子原子发射光谱(ICP-AES),比表面和X射线光电子能谱(XPS)技术对其进行了表征,考察了Au/Fe-O催化剂对甲醛的催化氧化活性.金负载量相同的条件下,溶胶沉积法制备的样品甲醛催化氧化活性好于共沉淀法制备的样品.实验结果表明:六面体的FeOOH载体担载了较多活性组分纳米金,是影响甲醛催化氧化活性的主要原因.     

以开孔的二维MFI纳米片为构筑单元制备沸石片膜

以食人鱼溶液(体积比为3∶1的95%～98%(w/w)H_2SO_4和30%(w/w)H_2O_2混合液)处理多层MFI(ML-MFI)除去有机结构导向剂(OSDA),经超声剥离和沉降纯化后得到了开孔的MFI沸石纳米片。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N_2吸附-脱附、傅立叶变换红外光谱(FT-IR)和热重分析(TGA)等手段对得到的MFI沸石纳米片进行表征,发现食人鱼溶液处理可移除ML-MFI中的OSDA,再经超声剥离得到可分散、开孔的MFI沸石纳米片。将MFI沸石纳米片用简单抽滤的方式沉积到自制Al_2O_3载体上,不经二次生长得到了连续的沸石纳米片膜。单组分气体渗透性能测试结果表明,制备的MFI沸石纳米片膜对正/异丁烷的理想选择性为4.1～5.8,正丁烷的渗透速率为2.2×10~(-7)～4.1×10~(-7) mol·m~(-2)·s~(-1)·Pa~(-1)。     

Microporous Metal–Organic Frameworks for Gas Separation

Microporous metal–organic frameworks (MOFs) are comparatively new porous materials. Because the pores within such MOFs can be readily tuned through the interplay of both metal‐containing clusters and organic linkers to induce their size‐selective sieving effects, while the pore surfaces can be straightforwardly functionalized to enforce their different interactions with gas molecules, MOF materials are very promising for gas separation. Furthermore, the high porosities of such materials can enable microporous MOFs with optimized gas separation selectivity and capacity to be targeted. This Focus Review highlights recent significant advances in microporous MOFs for gas separation.     

经过吸附处理的Ti-Si沸石的IR和UV-Vis光谱研究

用IR和UV-Vis光谱对Ti-Si沸石吸附H₂O、H₂O₂、烯丙基氯后的变化情况进行了研究。观察到H₂O₂的吸附将引起Ti-Si沸石IR光谱中960cm^-1谱带的减弱,同时一个弱带在880cm^-1处形成;而在UV-Vis光谱中,吸附H₂O₂将导致一个新的电子跃迁带在425nm处形成。这时若吸附烯丙基氯,则可发现880cm^-1的弱带及UV-Vis425nm的宽带会进一步减弱,同时一个新的IR带重又出现在980cm^-1处。吸附H₂O₂后导致的IR880cm^-1弱带的出现及UV-Vis425nm宽带的出现均证实此时在沸石表面形成了过氧钛物种。推测骨架晶格钛可能在H₂O₂参加的氧化反应中起活性中心作用。     

Stability analysis of a model equilibrium for a gravito-electrostatic sheath in a colloidal plasma under external gravity effect

The present contribution tries to find a scientific answer to the question of stability of an equilibrium plasma sheath in a colloidal plasma system under external gravity effect. A model equilibrium of hydrodynamical character has been discussed on the basis of quasi-hydrostatic approximation of levitational condition. It is found that such an equilibrium is highly unstable to a modified-ion acoustic wave with a conditional likelihood of linear driving of the so-called acoustic mode too. Thus, it is reported (within fluid treatment) that a plasma-sheath edge in a colloidal plasma under external gravity effect could be highly sensitive to the acoustic turbulence. Its consequential role on possible physical mechanism of Coulomb phase transition has been conjectured. However, more rigorous calculations as future course of work are required to corroborate our phenomenological suggestions.     

硼、钾改性KX沸石上甲苯和甲醇的侧链烷基化反应

研究了硼、钾改性ＫＸ沸石催化剂的甲苯侧链烷基化反应性能。结果表明,硼和钾同时改性可显著地提高甲苯侧链烷基化反应活性,Ｈ３ＢＯ３和ＫＯＨ在催化剂样品浸渍过程中形成了不同化学计量比的碱金属硼酸盐,该硼酸盐在沸石上作为新的碱性中心而有利于醇的催化脱氢。实验发现,各样品的甲苯侧链反应产物收率与异丙醇分解产物丙酮选择性之间有较好的关联。此外,酸碱中毒试验也进一步证实碱性位在反应中起主要作用     

Colloidal stability and drug incorporation aspects of micellar-like PLA–PEG nanoparticles

The drug delivery properties of a series of poly(lactic acid)–poly(ethylene glycol) (PLA–PEG) micellar-like nanoparticles have been assessed in terms of their colloidal stability and their ability to incorporate a water soluble drug. These studies have focused on a range of PLA–PEG copolymers with a fixed PEG block (5 kDa) and a varying PLA segment (3–110 kDa). In aqueous media, these copolymers formed micellar-like assemblies following precipitation from water miscible solvents. There was a controlled increase in the particle size as the molecular weight of the PLA block was increased. The characteristics of the PEG corona were also highly dependent on the PLA moiety. Copolymers with a low molecular weight PLA block (3–15 kDa) formed highly colloidally stable dispersions, with a complete PEG surface coverage. However, increasing the molecular weight of the PLA block resulted in significantly less colloidally stable nanoparticle dispersions, which flocculated in solvents that were significantly better than θ-solvents for the stabilising PEG chains. This can be attributed to a reduced PEG surface coverage and the probable presence of naked PLA ‘patches’ on the particle surface. These larger PLA–PEG nanoparticles (30:5–110:5) were found to be stabilised in the presence of serum components, which are thought to adsorb into the gaps on the particle surface and prevent flocculation. All of the dispersions were found to be stable under physiological conditions and therefore suitable for in vivo administration. A reasonable loading (3.1% w/w) of the micellar-like PLA–PEG 30:5 nanoparticles with the water soluble drug procaine hydrochloride was achieved. The incorporated drug was found to have no effect on the nanoparticle structure or recovery, which can be attributed to the micellar character of these assemblies and the presence of the stabilising PEG chains.     

新型氧化铝空心球的制备及表征

以胶体碳球为模板, 廉价的硝酸铝为铝源, 成功制备出了新型的大小可控的氧化铝空心球. 通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)、能量扩散X射线(EDX)、X射线粉末衍射(XRD)等手段对合成产品进行了表征, 并考察了不同合成条件对空心球形貌的影响. 实验结果表明, 合成的氧化铝空心球大小均一, 粒径及壁厚均可调节. 在该实验条件下, 硝酸铝浓度及吸附时间的改变对产品结果没有明显的影响, 而吸附温度的改变引起了产品表面光滑度及壁厚的改变.     

紫外/臭氧法在脱除沸石有机模板剂中的应用

选取LTA, FAU, BETA, MFI和MEL型沸石, 研究紫外/臭氧法在沸石有机模板剂脱除中的应用, 并与传统高温焙烧法比较, 考察两种方法对有机模板剂的脱除能力. 采用XRD, FT-IR, BET等方法对脱除模板剂前后的沸石样品进行表征, 结果表明紫外/臭氧法是一种低温有效除去沸石模板剂的方法. Beta, silicalite-1和silicalite-2沸石在紫外光照后相应的模板剂四乙基氢氧化铵、四丙基氢氧化铵和四丁基氢氧化铵已彻底脱除, A和Y型沸石中分别有27.5和6.2 wt%的四甲基氢氧化铵模板剂残留, 这主要是受其特殊β笼结构的限制而引起的.