铂催化硅氢加成反应研究进展

硅氢加成反应是合成有机硅材料最重要的途径之一,铂催化剂作为其应用最广的催化剂,具有重要的意义。本文首先介绍了硅氢加成反应机理的研究现状;分析了聚合物长链段铂配合物、含多个铂原子铂簇化合物及N-杂环卡宾铂配合物均相铂催化剂的研究进展,致力于改善均相催化剂催化选择性差、催化活性难以控制等缺点;分别阐述了不同铂催化剂载体如无机二氧化硅、炭载体、金属氧化物、有机高分子、固载液等作为铂催化剂载体的优点,负载铂催化剂具有可回收、产物选择性好的优点,有效解决了工业上铂损失的问题;最后对铂催化硅氢加成反应的发展趋势进行了展望分析,铂负载能力的提高、铂负载催化剂的分离、硅氢加成反应的原理、催化范围的扩大等均是今后研究的重要方向。     

Two-State Reactivity: Personal Recounting of its Conception and Future Prospects

This essay tells the story of the conception of the Two-State Reactivity (TSR) notion. Since scientific career is part of life's flow, the story blends sub-stories of scientific colleagues and events. This is also a story of a beguiling paradigm, which has started from a puzzling reactivity of the diatomic oxidant FeO⁺, has continued to larger oxidants, like the active species of Cytochrome P450 and of nonheme enzymes, and its extension to reductive processes. Finally, the essay discusses prospects of experimental probing of the reactive spin-state, and of the transition state constitution for these reactions by means of tunneling-augmented kinetic isotope effects.     

烯唑醇的合成研究

选用氯甲特丁酮与1H－1，2，4－三唑反应，生成物再与2，4－二氯苯甲醛反应，生成Z－酮衍生物，经异构化，还原反应，即得烯唑醇（E体）。     

丙烯腈/醋酸乙烯酯/甲基丙烯磺酸钠三元水相共聚体系竞聚率的研究

根据该AN/VAC/SMAS三元共聚体系特征,根据竞聚率计算的原理,融合二元共聚和三元共聚的基础理论,利用核磁共振技术测定共聚物组成,用Mayo-lewis共聚物组成方程拟合实验数据计算竞聚率.同时研究了AN/VAC/SMAS三元水相共聚反应体系的特征,测定了该三元共聚体系表现竞聚率.     

Wetting and interfacial reactions in liquid Au-Ti alloys / ZrO2 system

This study investigates wetting of zirconia by Au-Ti alloys containing 0.6–4 wt% Ti in view of brazing zirconia to titanium with pure gold for biomedical applications. Experiments were carried out using sessile and dispensed drop methods under high vacuum at 1040–1250 °C. Bulk drops and Au-Ti / ZrO₂ interfaces were characterized by SEM and FEG-SEM with EDXS analysis. While Au does not wet zirconia, the contact angle θ being ∼ 120°, the addition of Ti in Au leads to a significant improvement of wetting due to the formation of a wettable oxide layer at Au-Ti / ZrO₂ interface. The nature of this oxide was determined by X-ray diffraction of the reaction layer after the detachment of the droplet from the substrate or after the dissolution of the droplet. The mechanism of formation and growth of the oxide layer and its growth kinetics were determined based on fine analysis of the Au-Ti / oxide layer / ZrO₂ interfacial system.     

TPD技术在煤／半焦气化研究中的应用

本文综述了近年来国外用程序升温脱附(TPD)技术在煤／半焦气化研究中的应用，着重讨论了担载金属半焦在含氧气化剂作用下碳-氧-金属之间的相互作用，H2O和CO2脉冲气化后的TPD可以分析担载不同金属盐类后脉冲气化所生成的H2，CO和CO2．一般来说。随担载金属量的增加．其反应掉的H2O和CO2量增加，生成的CO和H2增加。从碳和CO2及H2O的气化反应的氧平衡可以求出在反应过程中吸附在试样表面的氧量，由表面含氧络合物的形态和含量可以分析碳和金属与氧的相互作用，氧迁移机理及催化活性的大小等重要问题。     

煤焦反应活性影响因素的探讨

总结了前人在热处理对煤焦反应活性的影响方面的研究结果 ,并得到如下的结论 :热处理过程使得煤焦中碳结构排列有序化及具有催化能力的矿物质组分烧结或熔融 ,从而导致了煤焦反应活化能增加 ,反应活性下降 .煤焦反应活性可以用低温下其对氧的化学吸附量来表征 ,使用分布活化能模型能较好地考察煤焦本征反应活性在反应过程中的变化     

粉煤灰火山灰反应性及其反应动力学

通过酸溶法测定了粉煤灰-Ca(OH)2-H2O系统中粉煤灰的反应率,以此来评估不同品质低钙粉煤灰的火山灰反应性,并据此建立了低钙粉煤灰火山灰反应的动力学模型。探讨了不同品质粉煤灰火山灰活性上的差异对水泥基材料强度的影响。结果表明：相比于Ⅱ级粉煤灰,Ⅰ级粉煤灰的火山灰活性未必更高。粉煤灰的火山灰反应符合一级反应动力学模型。不同品质粉煤灰火山灰活性上的差异宏观上对水泥砂浆强度影响甚微。     

From clay- to organoclay-film modified electrodes: tuning charge selectivity in ion exchange voltammetry

The surface of two natural smectite-type clay samples was chemically modified by covalent grafting of amine groups, by reaction with γ-aminopropyltriethoxysilane, which were easily protonated in HCl medium. Multisweep cyclic voltammograms of clay-film modified glassy carbon electrodes made of either the raw clays or the propylammonium-functionalized samples exposed to Ru(NH₃)₆³⁺ or Fe(CN)₆³⁻ electroactive probes were obtained. The results indicated a permselective behavior of these clay and organoclay-films based on either favorable or unfavorable electrostatic interactions. The cation-exchanging raw clay film modified electrodes exhibited accumulation properties for Ru(NH₃)₆³⁺ species while rejecting Fe(CN)₆³⁻, whereas the anion-exchanging organoclay coatings acted as a barrier against Ru(NH₃)₆³⁺ while increasing dramatically the concentration of Fe(CN)₆³⁻ species at the electrode surface. Strong binding of the probe to the organoclays resulted in a potential shift of ca. 0.1 V of the voltammetric signals characteristic of the Fe(CN)₆^3−/4− couple in the anodic direction. Their good preconcentration efficiency at low analyte concentration highlighted their interest for electroanalytical applications.     

还原温度对Mo基催化剂物相及其加氢脱氧性能的影响

以碳纳米管(CNTs)为载体,通过控制催化剂合成的还原温度制备了一系列负载型Mo基催化剂。采用XRD、TEM、N₂物理吸附、XPS以及NH₃/H₂-TPD等技术对催化剂进行了表征,并研究了Mo基催化剂对硬脂酸催化加氢脱氧性能的影响。结果表明:随着还原温度的升高,催化剂表面的Mo物种逐渐被还原,还原过程为:MoO₃→MoO₂→Mo→Mo₂C。还原温度为450℃和550℃时,催化剂的活性相为MoO₂;还原温度为600℃时,催化剂的活性相为MoO₂/Mo/β-Mo₂C的混合相;还原温度为650℃和700℃时,催化剂的活性相全部转化为β-Mo₂C。与活性相MoO₂催化剂相比,β-Mo₂C催化剂具有更高的加氢脱氧活性。此外,还原温度为600℃的MoO₂/Mo/β-Mo₂C混合相催化剂因具有较大的比表面积、较多的酸中心数量和较强的H₂吸附能力,使得该催化剂在硬脂酸加氢脱氧反应中表现出最优越的催化活性。