甲醇选择氧化金属氧化物催化剂的结构与其催化性能的关系

甲醇是一个重要的平台分子, 实现其高效转化为能源和化学品的关键是揭示相关反应过程中催化剂的结构与催化性能之间的关系和反应机理. 围绕这个关键问题, 以甲醇选择氧化为探针反应, 本文总结了负载氧化钼、负载氧化钒和杂多酸等典型催化剂体系以及近年来发展的氧化铼、氧化钌等新催化剂体系在认识催化活性中心结构和反应机理, 进而调控它们的氧化中心和酸中心等方面所取得的进展. 这些认识将有助于设计制备性能优异的新催化剂和实现甲醇到目标氧化产物的定向转化.     

Li3V2(PO4)3/C的P123辅助流变相法制备及电化学性能

以V₂O₅、NH₄H₂PO₄、LiOH、柠檬酸、三嵌段聚合物表面活性剂P123为原料, 用流变相(RPR)法制备了Li₃V₂(PO₄)₃/C正极材料. 用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等方法表征, 结果表明: 材料为单一纯相的单斜晶体结构, 颗粒均匀并呈现珊瑚结构; 恒流充放电, 循环伏安(CV)及电化学交流阻抗(EIS)等电化学性能测试表明, 采用P123 辅助合成材料电化学性能明显优于未采用P123 辅助合成材料. 3.0-4.3 V放电区间, 0.1C充放电下P123 辅助合成Li₃V₂(PO₄)₃/C材料首次放电比容量为129.8 mAh·g^-1, 经过50 次循环后容量只衰减0.9%; 倍率性能及循环性能优异, 1C、10C、25C的首次放电比容量分别为128.2、121.3、109.1 mAh·g^-1, 50次循环后容量保持率分别为99.1%, 96.9%, 90.7%. 这归因于三嵌段聚合物P123 作为分散剂的同时也作为有机碳源在颗粒表面及间隙形成碳网络, 有利于材料导电率的改善, 降低了其电荷转移阻抗, 减小了电极充放电过程的极化现象.     

Preparation of optical active polydiacetylene through gelating and the control of supramolecular chirality

Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the corresponding xerogel under UV-irradiation. Optically active polydiacetylene (PDA) were subsequently obtained. Supramolecular chirality of PDA could be controlled by the chirality of gelators. Left-handed and right-handed helical fibers were obtained by using Land D-gelators in xerogels respectively, and...     

Basic Functionalization of Hexagonal Mesoporous Silica

Recently, a novel method of modification, i.e., functionalizing the internal surface of mesoporous materials has been reported1-5, owing to the large pore size, the silanol groups, which are in a big population in mesoporous materials, can chemically couple with the active groups of some bulky organic functional molecules. Based on this approach, one can obtain novel solid basic catalysts. Here we functionalized the hexagonal and hexagonal-like mesoporous silica materials SBA-3 and HMS wi…     

Polybinaphthyls of (R)-3,3′-Diiodo-2,2′-binaphtho-20-crown-6 with p-Divinylbenzene via Heck Cross-coupling Reaction

IntroductionFunctional polymers bearing chiral moietiesand the extended conjugatedπ system have attract-ed considerable attention during the pastdecade[1,2 ] .The enantiodifferation properties ofsuch macromolecules give rise to multiple applica-tions in the fields of asymmetric catalysis,chiralsensors,polarized light emission and nonlinear op-tical materials[3 ,4] .Especially the incorporation ofoptically active binaphthyls in the main chain ofconjugated polymers can lead to an efficient ands…     

D_∞-APPROXIMATION OF QUADRATIC VARIATIONS OF SMOOTH IT PROCESSES

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＩｎ［５］，ＭａｌｉａｖｉｎａｎｄＮｕａｌａｒｔｄｅｆｉｎｅｄｔｈｅｎｏｔｉｏｎｏｆ（ｒｅａｌ）ｓｍｏｏｔｈｍａｒｔｉｎｇａｌｅｓａｎｄｗｅｔｈｅｎｐｒｏｖｅｄｉｎ［６］ｔｈａｔｔｈｅｐｒｏｃｅｓｏｆｑｕａｓｉｓｕｒｅｑ...     

Synthesis of Quinolone Analogues: 7-[(2S,4R)-2-Aminomethyl-4- hydroxypyrrolidin-1-yl] Quinolones

Quinolone antibacterial agents have emerged as one of the dominant classes chemotherapeutic drugs for the treatment of various bacterial infections1. We have focused our attention on the modification of the C-7 basic group of the quinolone which has been most varied. In 1987, Uno et al.2 reported that 3-hydroxypyrrolidine quinolones showed more active antibacterial activities than Norfloxacin in vivo. In 1998, Fujita et al.3 reported that 2-aminomethylpyrrolidine quinolones have the same …     

ESR Approach to the Nature of Solvation by Using s-Butyl n-Heptafluorobutyryl Nitroxide Probe

Because the solvent dependency of aN, g factors and line widths of some bulky and stable di-t-alkyl nitroxides1, ESR has been proved to be a useful tool in searching for the nature of medium effects ( solvation ) to chemical reactivity. A large number of fluorinated nitroxides with a wide variety of structures have been generated and subjected to extensive studies in our laboratory2. Amongst, t-butyl perfluoroalkyl nitroxides, much less hindered, with noβ-H atoms, have been employed as sp…     

Impedance Characterization of Adsorption Process of Calmodulin on Au Substrate and its Combination with Ca~(2+)

Recently, the adsorption behavior of protein on solid substrate has attracted much attention for the reason that adsorption on a substrate is the first key step for other further electrochemical investigation1. Meanwhile the free adsorption could provide a relative well-ordered structure, with which some fundamental study could be carried out conveniently2. As we know, the electrochemical impedance spectroscopy (EIS) method has become one of the powerful techniques to detect the change of i…