Deep oxidation of aqueous organics over a silicon carbide-activated carbon supported platinum–ruthenium bimetallic catalyst

In previous work, we developed a highly active bimetallic platinum–ruthenium catalyst supported on a very high surface area activated carbon substrate. In fixed bed reactors, this catalyst proved capable of the continuous long-term deep oxidation of a variety of aqueous organic contaminants associated with spacecraft wastewater streams at 121 °C. This work was extended to the mineralization of more typical environmental contaminants, including halocarbons and aromatics. The primary weakness of this catalyst was the tendency toward relatively high rates of chemical decomposition. To overcome this limitation, methods were developed for the production of a silicon carbide coating over the surface of the activated carbon, yielding a reasonable trade-off between increasing resilience and decreasing surface area. Here we report the catalytic decomposition of dissolved organic contaminants at 130 °C using this silicon carbide/activated carbon supported bimetallic catalyst.     

A study of PtRuO2 catalysts thermally formed on titanium mesh for methanol oxidation

Platinum-based catalysts, for the electro-oxidation of methanol, have been made by thermal decomposition of chloride precursors onto titanium mesh. The catalysed electrodes were successfully operated in acidic methanol electrolytes. Electrochemical characterisation has been carried out using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic polarisations. A complete analysis of the electrochemical results showed that the preliminary performance of the catalysed titanium mesh was comparable to that achieved with carbon-supported PtRu catalysts. The catalysts formed on titanium mesh by thermal decomposition also exhibited dimensional stability. Catalysed titanium mesh therefore appears to be a promising alternative to carbon-supported catalysts for certain fuel cell applications.     

Performance of Methanol Oxidation Catalysts with Varying Pt:Ru Ratio as a Function of Temperature

This paper describes the effects of varying the Pt to Ru ratio in carbon-supported catalysts for methanol oxidation as a function of temperature. Previously these effects were studied in isolation, but now it is shown that the composition of a given catalyst as a function of temperature is extremely important for its activity towards methanol oxidation. Platinum rich 3:2 atomic ratio catalysts perform better than a 1:1 catalyst at 25 °C, where only Pt is believed to be active towards methanol dehydrogenation, since this process is a highly thermally activated process on Ru sites. This result is reversed at 65 °C, where the 1:1 catalyst displays much higher currents across the entire range of polarization. This may result from methanol dehydrogenation occurring on both Ru and Pt sites at higher temperatures. At an intermediate temperature, 45 °C, the 3:2 catalyst is seen to perform better at lower current values, while the 1:1 catalyst is superior at higher current densities, with the crossover occurring at 62 A g^–1. As a consequence, when designing fuel cell catalysts, the composition of the catalyst employed should be tailored with respect to the exact operating conditions, in order to promote optimum fuel cell performance.     

A study about the effect of the temperature of hydrogen treatment on the properties of Ru/Al2O3 and Ru/C and their catalytic behavior during 1-heptyne semi-hydrogenation

The 1-heptyne selective hydrogenation carried out at 150 kPa, and at 283 and 303 K using Ru/Al₂O₃ and Ru/C as catalysts, was studied. Catalysts were prepared by the incipient wetness impregnation technique using RuCl₃ as precursor. Ru/Al₂O₃ was treated in hydrogen at 373 or 573 K and Ru/C only at the last temperature. Catalysts were characterized by hydrogen chemisorption, TPR and XPS. Ru dispersion after treatment in hydrogen at the highest temperature is similar for both catalysts. Ru is present as Ru⁰ in Ru/C, while Ru⁰ and Ru electron-deficient species are present on the catalysts surface after hydrogen treatment at the two temperatures using Al₂O₃ as support. The best catalytic behavior was observed for the highest temperature of hydrogen treatment and for 303 K reaction temperature. As a consequence of a shape selectivity effect of the C support, the best conversion is obtained with the alumina supported catalyst.     

二氧化硅负载支链有机膦的合成及其在二氧化碳催化氢化反应中的催化性能

以改性二氧化硅为核,利用发散法合成出二氧化硅负载的1～6代端胺基树枝状高分子(SiO2-PAMAM),样品经FT-IR,TG和端胺基分析表征.利用功能化载体表面的氨基与[Ph2P(CH2OH)2]+Cl-发生反应,合成出SiO2-PAMAM负载的有机膦(SiO2-PAMAM-PPh2),与三氯化钌复配成催化体系,考察了其对吗啉存在下的二氧化碳催化氢化反应的催化性能,该催化体系的催化活性(TOF)可达4 195.     

神府煤萃取物组成结构的特征分析

采用苯、甲醇、丙酮、等体积的CS2与丙酮的混合溶剂和四氢呋喃依次萃取神府煤,得到其萃取物E1E5,并采用钌离子催化氧化法氧化各级萃取物,所得氧化产物经重氮甲烷酯化后再进行GC/MS分析,以产物组成结构的差异来推测各级萃取物组成结构的差异。结果表明,神府煤萃取物所得酯化产物的主要成分是烷酸甲酯和烷二酸二甲酯,推测其萃取物中含有大量的烷基芳烃和α,ω-二芳基烷烃;且随着溶剂极性的增强,其萃取物氧化后的酯化产物中,烷酸甲酯和烷二酸二甲酯的碳链长度呈一定的递增趋势,推测神府煤中长链烷基芳烃和α,ω-二芳基烷烃易溶于极性较强的溶剂;在氧化产物中还检测出19种甾烷酸甲酯、萜烷酸甲酯和霍烷酸甲酯,表明神府煤萃取物中含有与芳环相连的甾烷基、萜烷基和霍烷基结构。     

Organo-zincate molten salts as immobilising agents for organometallic catalysis

The combination of 1-n-butyl-3-methylimidazolium chloride with ZnCl₂ affords ionic mixtures with different melting point temperatures depending on the zinc molar fraction. RuCl₂(PPh₃)₃ immobilised in the low melting mixture (60°C) promotes the 1-hexene hydrogenation (turnover frequencies up to 44 min^–1) and the recovered solid catalyst phase can be reused several times.     

中国科学院成功研制出氧化钛“光开关”材料

采用循环伏安电沉积技术在钛基上获得水合氧化钌(RuOx·nH2O),其比容量为105F/g。通过电化学测试(循环伏安、恒电流充放电)、X射线衍射(XRD)、扫描电镜(SEM)以及X射线光电子能谱(XPS)等方法研究了沉积物的电化学性质、物相及组成。结果表明:电沉积法获得的水合氧化钌呈非晶态结构,它由多氧化态钌混合羟基氧化物组成。在1.0mol·L-1H2SO4溶液中,该氧化物呈准电容特征,有较高电化学可逆性,可用作电化学电容器电极材料。     

混合电容器多孔氧化钌阴极涂层的制备与表征

采用电沉积方法制备了混合电容器钽基多孔氧化钌阴极涂层材料,探讨了电沉积过程中电沉积液的pH值随电沉积时间的变化关系,研究了电沉积时间对氧化钌沉积质量的影响.用X射线衍射和扫描电镜分别表征了热处理前后的涂层结构及涂层的多孔形貌,用循环伏安法测量了涂层的电容,并研究了热处理温度对电容量大小及其稳定性的影响.结果表明:电沉积的氧化钌为非晶态,涂层为纳米多孔结构;热处理有利于涂层孔隙结构及大小的均匀性,不同温度的热处理使涂层具有不同的电容,经热处理后涂层的电容稳定;经100℃热处理1 h后的多孔氧化钌涂层具有最大的比电容.     

IrO2对Ti基阳极电化学性能的影响

根据阳极在各行业中应用的要求，从贵金属（铂、铑、铱、钌等）中筛选了铱和钌，在钛基体上进行涂覆，然后，在不同温度下烧结制备成RuO2-IrO2-TiO2/Ti阳极，并对涂层阳极的强化寿命和析氯开路电位进行了测试，采用扫描电镜（SEM）对涂层结构进行了观测分析，结果表明，RuO2-IrO2-TiO2/Ti钛基涂层阳极的最佳烧结温度为450℃，IrO2含量的最佳值为30％（摩尔百分比）。