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51.
The reactions of various aldehydes with CH3NO2 catalyzed by Et3N, n-C6H13NH2, and Me2N(CH2)2NH2 were accelerated by the addition of silica gel to give aromatic (aliphatic) β-nitroalcohols, aromatic nitroalkenes, and aromatic 1,3-dinitroalkanes, respectively. Mesoporous silica SBA-15 showed higher activity than silica gel for the synthesis of aromatic nitroalkenes by the reactions of the corresponding aldehydes with CH3NO2 catalyzed by n-C6H13NH2. 相似文献
52.
Ordered, mesoporous SBA-15 functionalized with organic and inorganic moieties exhibits efficient catalytic activity in a variety
of organic transformations. In this account, reviewing our own work, three-sets of surface-modified SBA-15 materials have
been investigated. The first-set of materials consists of SBA-15 modified with organo-acidic (propyl thiol and propyl sulfonic
acid) and basic (propyl amine and propyl adenine) moieties. The second-set of materials was prepared by grafting Mn complexes
to the organo-functionalized SBA-15. The third-set composes of nanocrystalline metal oxides supported on SBA-15. All these
catalysts have been characterized by structural and spectroscopic techniques. Catalytic activities of the first-set of solid
materials have been investigated in acid/base-catalyzed reactions viz., ring-opening of epoxides with amines (producing β-amino
alcohols), esterification, three-component-Mannich reactions and cycloaddition of CO2 to epoxides. The Mn complexes grafted on organofunctionalized SBA-15 are efficient catalysts for the chemo-, regio- and stereoselective
aerial oxidation of monoterpenes at ambient conditions. TiOx, VOx, MoOx and WOx supported on SBA-15 catalyzed biomimetic oxyhalogenation of aromatic compounds. In all these reactions, the functionalized
SBA-15 showed high selectivity. 相似文献
53.
SBA-15负载CeO2纳米晶的溶胶-凝胶一步合成 总被引:2,自引:0,他引:2
以P123为模板剂, 正硅酸乙酯和硝酸铈为前驱体, 通过溶胶-凝胶路线在酸性条件下合成了SBA-15负载氧化铈(CeO2与SiO2质量比为28.7%)有序介孔材料. 采用热重/差热分析(TGA/DTA)、X射线衍射(XRD)、透射电镜(TEM)和氮气吸附等手段对所合成材料进行了表征. 结果表明, 合成的材料具有类似于SBA-15的结构, 孔径、孔容和比表面积分别为38.7 Å, 0.46 cm3/g和570 m2/g. X射线衍射(XRD)、透射电镜(TEM)、X射线能谱(EDS)和选区电子衍射花样联合表征证实了铈物种以高分散的CeO2纳米晶的形式分布在介孔基体中. 相似文献
54.
55.
The direct electron transfer between hemoglobin (Hb) and an electrode was realized by first immobilizing the protein onto
SBA-15.The results of the immobilization showed that the adsorption was pH-dependent with a maximum adsorption near the isoelectric
point of the protein, and SBA-15 with a larger pore diameter showed greater adsorption capacity for Hb. UV–vis spectroscopy
and nitrogen adsorption analysis indicated that Hb was adsorbed within the channel of SBA-15 and no significant denaturation
occurred to the protein. The Hb/SBA-15 composite obtained was used for the fabrication of a Hb biosensor to detect hydrogen
peroxide. A pair of well-defined redox peaks at −0.337 and −0.370 V on the Hb/SBA-15 composite modified glassy carbon electrode
was observed, and the electrode reactions showed a surface-controlled process with a single proton transfer at a scan rate
range from 20 to 1,000 mV/s. The sensor showed a fast amperometric response, a low detection limit (2.3 × 10−9 M) and good stability for the detection of H2O2. The electrochemical results indicated that the immobilized Hb still retained its biological activity. 相似文献
56.
Li-Wen Xu Ming-Song Yang Jian-Xiong Jiang Hua-Yu Qiu Guo-Qiao Lai 《Central European Journal of Chemistry》2007,5(4):1073-1083
Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as
cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst
in these reactions could be carried out and the catalyst used at least five times without significant loss in activity.
相似文献
57.
Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas 总被引:1,自引:0,他引:1
Vladimir M. Gun’ko Vladimir V. Turov Alexander V. Turov Vladimir I. Zarko Vasiliy I. Gerda Victor V. Yanishpolskii Inna S. Berezovska Valentin A. Tertykh 《Central European Journal of Chemistry》2007,5(2):420-454
Structural characteristics of synthesized ordered mesoporous silicas MCM-41, MCM-48 and SBA-15 were studied using XRD, nitrogen
adsorption and FTIR methods. Pure water and mixtures with water/benzene and water/chloroform-d adsorbed onto silicas were studied by 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial liquids. Concentrated aqueous suspensions of MCM-48
and SBA-15 were studied by thermally stimulated depolarization current (TSDC) method. Benzene and chloroform-d can displace a portion of water to broad pores from the pore walls and from narrower pores, especially in the case of a large
excess of an organic solvent. This process is accompanied by diminution of both interaction energy of water with an adsorbent
surface and freezing temperature depression of adsorbed water. The effect of nonpolar benzene on pore water is much stronger
than that of weakly polar chloroform-d. Modifications of the Gibbs-Thomson relation to describe the freezing point depression of mixtures of immiscible liquids
confined in pores allow us to determine distribution functions of sizes of structures with unfrozen pore water and benzene.
Former address: Pisarzhevskii Institute of Physical Chemistry, 31 Prospect Nauki, Kiev, Ukraine 相似文献
58.
59.
SBA-15负载钒氧化物催化剂上甲烷选择氧化反应 总被引:5,自引:0,他引:5
对SBA-15负载的钒、钼、钨氧化物催化的甲烷选择氧化反应性能进行了比较,发现VOx/SBA-15催化剂优于MoOx/SBA-15和WOx/SBA-15催化剂.针对钒氧化物催化剂,考察了不同钒源、不同载体以及少量P元素的添加对催化性能的影响,结果表明以SBA-15为载体的催化剂的性能好于MCM-41和Cab-O-Sil为载体的催化剂;与V2O5,VO(C2O4)相比,NH4VO3是制备性能良好的VOx/SBA-15的钒源;在VOx/SBA-15中,添加少量P元素后,HCHO的选择性有一定程度的提高.XRD,N2物理吸附、UN-Raman和H2-TPR表征结果表明,负载量低于3 wt%时,钒组分可能主要以高分散的单核的VOx物种存在,我们推测该物种对甲烷选择氧化制甲醛起关键作用. 相似文献
60.
以有序介孔材料SBA-15为基质, β-环糊精和氨基β-环糊精为配体, 通过环糊精端口的羟基和氨基与3-异氰酸丙基三乙氧基硅烷偶联剂上活泼的异氰酸酯基之间的加成反应, 制备了2种不同单键合臂的β-环糊精修饰SBA-15手性固定相(CDSP和NCDSP), 它们分别含有稳定的氨基甲酸酯基和脲基键合臂. 在反相高效液相色谱模式下, 以灭菌唑、 烯唑醇、 己唑醇和戊唑醇等10种常见的三唑类手性农药为探针, 考察了CDSP和NCDSP的基本手性色谱性能. 研究结果表明, 2种新固定相对三唑类农药对映体均有较好的快速拆分能力, 所需分离时间较短(< 30 min), 其中灭菌唑和烯唑醇的选择性因子(α)分别为1.29和1.28, 分离度分别达到3.84和3.23. 采用甲醇、 乙腈和水组成的简单流动相, 室温下在CDSP和NCDSP上分别拆分了9种和8种三唑类手性农药对映体. 研究发现拥有适当大小和手性碳连接羟基的三唑类农药在上述2种新固定相上有较好的拆分效果, 说明固定相上的环糊精配体对溶质的包结、 氢键和空间位阻等协同作用对空间手性识别有重要贡献. 不同批次CDSP和NCDSP的键合量分别为0.139~0.156和0.120~0.137 μmol/m2, 表明2种固定相的制备方法有较好的重现性. 与涂覆型纤维素商品柱相比, 新的脲基环糊精固定相性能更稳定, 反相色谱实用性更强, 且制备方法简便, 成本较低, 在三唑类手性农药对映体残留量检测中具有良好的应用前景. 相似文献