二烯酸稳定的Pt金属纳米粒子的制备及催化加氢活性

制备了4-(双(4-(4-丁氧基苯乙烯基)苯基)氨基)苯甲酸(简称二烯酸,Dienoic Acid)保护的铂纳米颗粒,通过UV-Vis,TEM,XRD对其进行了表征.以间苯氧基苯甲醛的催化加氢反应为模型研究了其催化性能及影响催化活性的因素.实验结果表明:金属纳米粒子粒径随金属/稳定剂摩尔比的下降而减小,而催化加氢反应活性随金属/稳定剂摩尔比的上升而增加.在常压、40℃、n(醛)/n(催化剂)=523条件下,反应10 h可以获得纯度大于99%的间苯氧基苯甲醇.     

Gold Trace Separation from some Platinum Group Metals on Cationic Exchanger in the Presence of Amines

Abstract

The sorption behaviour of gold in the presence of amines on different kinds of cationic exchangers with phosphonic groups has bee investigated. The system Cellex P - amine has been found very useful for gold separation from platinum metals. The method was adopted for trace gold determination in PdC1₂ and platinum powder.     

铂、钯负载型活性催化剂的制备及其对一氧化碳的催化氧化活性

用浸渍法分别将铂、钯负载在铝柱撑蒙脱石载体上,制备了铂、钯负载铝柱撑蒙脱石催化剂。运用X射线衍射(XRD)、原子吸收光谱(AAS)、透射电镜(TEM)等分析方法对样品的性能和结构进行了表征,并考察了不同铂、钯负载量的催化剂对一氧化碳的催化氧化性能。结果表明,铂、钯均以高度分散的纳米粒子状态均匀分布在载体表面,并表现出良好的CO催化氧化活性。铂、钯在铝柱撑蒙脱石载体表面的有效负载率在70%~76%之间,在相同的设计负载量条件下,铂的实际负载量和有效负载率均略大于钯。CO催化氧化试验结果表明,相对于负载前,负载后催化剂的催化活性明显增加,且其催化活性随着铂、钯负载量的增加而不断增强。在相同温度和负载量条件下,钯负载型催化剂的催化活性明显高于铂负载型催化剂。     

Colloidal State of the System 4-Octylphenol-NaOH-Water and Its Catalytic Activity in Nucleophilic Substitution in Phosphorus Acid Esters

The kinetics of decomposition of 4-nitrophenyl ethyl ethylphosphonate in the system 4-octylphenol-NaOH-water was studied spectrophotometrically. Electrophoretic, tensimetric, and kinetic studies proved formation of cationic associates in which phenolysis or base hydrolysis occurs, depending on the concentration ratio of 4-octylphenol and NaOH.     

Controlling the Oxidation State of Pt Single Atoms for Maximizing Catalytic Activity

Single-atom catalysts (SACs) have emerged as promising materials in heterogeneous catalysis. Previous studies reported controversial results about the relative level in activity for SACs and nanoparticles (NPs). These works have focused on the effect of metal atom arrangement, without considering the oxidation state of the SACs. Here, we immobilized Pt single atoms on defective ceria and controlled the oxidation state of Pt SACs, from highly oxidized (Pt⁰: 16.6 at %) to highly metallic states (Pt⁰: 83.8 at %). The Pt SACs with controlled oxidation states were then employed for oxidation of CO, CH₄, or NO, and their activities compared with those of Pt NPs. The highly oxidized Pt SACs presented poorer activities than Pt NPs, whereas metallic Pt SACs showed higher activities. The Pt SAC reduced at 300 °C showed the highest activity for all the oxidations. The Pt SACs with controlled oxidation states revealed a crucial missing link between activity and SACs.     

Preparation and Catalytic Properties of Amphiphilic Copolymer-Stabilized Platinum Metals Colloids

Several metal colloids stabilized by an amphiphilic copolymer, poly(1-vinylpyrrolidone-co-acrylic acid) (abbreviated as PVPAA), were prepared by refluxing alcohol-water mixed solutions of the corresponding metal precursors. They had small particle sizes and narrow size distributions. Their catalytic activity was tested by hydrogenation of cyclooctene, 1-dodecene, and ortho-chloronitrobenzene (o-CNB). With the introduction of nickel(II) ions to a PVPAA-stabilized platinum catalytic system, selective hydrogenation of o-CNB to ortho-chloroaniline (o-CAN) with 97.1% selectivity and 100% conversion was obtained. Copyright 2000 Academic Press.     

Catalymetric Determination of Rhodium Based on the Reaction of the Oxidation of Triphenylamine-4-Sulfonic Acid by Sodium Periodate

The catalytic activity of rhodium(III) was studied in the reaction of the oxidation of triphenylamine-4-sulfonic acid by sodium periodate at pH 3. The dependence of the reaction rate on the technique of catalyst preparation, the presence of activators, the concentrations of the components, and the acidity and temperature of solutions was revealed. A sensitive and selective method for the catalymetric determination of rhodium(III) is proposed and tested with synthetic mixtures.     

氟代苯基异羟肟酸钴的合成及其对乙苯氧化的催化性能

以全氟碘丁烷为原料,分别与4-碘硝基苯和4-碘苯甲酸反应合成了4-全氟丁基硝基苯（1）和4-全氟丁基苯甲酸（3）; 1经还原反应,3经酰氯化反应,后再缩合反应制得氟代苯基异羟肟酸（5）; 5经络合反应合成了氟代苯基异羟肟酸钴（6）, 其结构经 UV-Vis, ¹H NMR, FT-IR和HR-MS（EI）表征。在氟两相中考察了其对乙苯氧化的催化性能。结果表明：在全氟己烷中,6 0.04 mmol,于60 ℃反应6 h,乙苯的转化率为49.2%,苯乙酮的选择性为88.3%。6循环使用5次,选择性保持良好。     

Understanding the Role of Gold Nanoparticles in Enhancing the Catalytic Activity of Manganese Oxides in Water Oxidation Reactions

The Earth‐abundant and inexpensive manganese oxides (MnO_x) have emerged as an intriguing type of catalysts for the water oxidation reaction. However, the overall turnover frequencies of MnO_x catalysts are still much lower than that of nanostructured IrO₂ and RuO₂ catalysts. Herein, we demonstrate that doping MnO_x polymorphs with gold nanoparticles (AuNPs) can result in a strong enhancement of catalytic activity for the water oxidation reaction. It is observed that, for the first time, the catalytic activity of MnO_x/AuNPs catalysts correlates strongly with the initial valence of the Mn centers. By promoting the formation of Mn³⁺ species, a small amount of AuNPs (<5 %) in α‐MnO₂/AuNP catalysts significantly improved the catalytic activity up to 8.2 times in the photochemical and 6 times in the electrochemical system, compared with the activity of pure α‐MnO₂.     

层状粘土负载的金催化剂制备及其常温催化氧化活性

为了研究粘土的性质对其负载的金催化剂在CO常温氧化反应中的催化活性的影响,将金溶胶分别负载到类水滑石(LDHs)和经过壳聚糖改性的蒙脱石(CS-MMT)表面,得到纳米金颗粒呈高度分散状态的金催化剂样品.通过XRD、XRF、TEM、XPS等手段表征了金催化剂样品的物相、金的含量、金颗粒的粒径分布及金的存在价态,测试了催化剂样品对CO的常温转化率.结果表明:Au0是粘土负载的金催化剂对CO常温氧化反应的主要活性物种,碱性载体LDHs负载的金催化剂样品1.83%Au/Mg Al-CO32--LDHs表面只检测到Au0,金颗粒的平均粒径为2.6 nm,对CO的常温转化率能够达到100%,而酸性载体CS-MMT负载的金催化剂样品1.71%Au/CS-MMT表面同时存在氧化态和金属态的金,且Auδ+/Au0=1.1,金颗粒的平均粒径为2.1 nm,对CO的常温转化率仅为25%.     

铁酸镍纳米微粒的固相合成及其催化性能

微波辐射;乙苯脱氢;铁酸镍纳米微粒的固相合成及其催化性能     

The Progress in Understanding the Mechanisms of Methanol and Formic Acid Electrooxidation on Platinum Group Metals (a Review)

Russian Journal of Electrochemistry - The reactions of electrooxidation of methanol and formic acid pertain to the most important model electrocatalytic processes and are used in direct...     

线性低价铂系金属簇合物的研究

长链线性配合物具有特有的结构、成键和性质,在分子器件和特殊性能低维材料等方面展示出潜在的应用前景。在低价状态下,铂系金属可自聚合形成一类含有多个金属原子的线性金属链式簇合物。本文就有关线性低价铂系金属簇合物的研究进展作一简述。     

酸性介质中1,2-丙二醇在铂电极上吸附和氧化过程的原位FTIR反射光谱研究

应用电化学循环伏安和原位FTIR反射光谱研究1,2-丙二醇在Pt电极上吸附和氧化过程。结果指出1,2-丙二醇的电氧化可按双途径进行。其一经1,2-丙二醇在Pt上解离吸附产物氧化至CO_2。但在较低电位下这些解离吸附产物(红外检测为CO_(ad)、[﹥C=CH_2]_(ad)等)累积吸附于电极上, 毒化Pt表面抑制其它反应。当电位大于0.3 V后它们一经生成即氧化脱附, 从而使1,2-丙二醇得以在未毒化Pt表面经反应中间体氧化至CO_2。在实验条件下,原位FTIR反射光谱检测到的反应中间体可能有HOC-CHOHCH_3(或CH_2OHCOCH_3)和HOOC-COCH_3(或HOOC-CHOHCH_3)等物种。     

环境和生物样品中铂族金属的分析研究进展

评述了近年来环境和生物样品中痕量铂族金属的分析研究进展，重点介绍了样品的预处理和分离富集技术以及检测手段等。     

反相高效液相色谱法分离铂族金属及其伴生元素

本文报道以２－（６－甲基－２－苯并噻唑偶氮）－５－二乙氨基酚作柱前衍生试剂，以甲醇／水＝８２／１８（Ｖ／Ｖ），含１０ｍｍｏｌ／ＬｐＨ５．０醋酸盐缓冲溶液，１０ｍｍｏｌ／Ｌ水杨酸钠，５ｍｍｏｌ／ＬＴＢＡ．Ｂｒ作流动相，反相高效液相色谱法定量分离测定Ｒｕ（Ⅲ），Ｒｈ（Ⅲ）、Ｐｄ（Ⅱ）、Ｏｓ（Ⅳ）、Ｉｒ（Ⅳ）、Ｐｔ（Ⅱ）、Ｃｏ（Ⅱ）、Ｎｉ（Ⅱ）和Ｃｕ（Ⅱ）。当Ｓ／Ｎ＝３时，各金属离子的检出限分别为（ｎｍ     

Influence of Metal Oxides on Platinum Activity towards Methanol Oxidation in H2SO4 solution

Pt–CeO₂/C, Pt–TiO₂/C, and Pt–ZrO₂/C electrocatalysts were prepared by using a modified microwave‐assisted polyol process. Physical characterization was performed by using XRD, TEM, and EDX analyses. The incorporation of different metal oxides increased the dispersion degree of Pt nanoparticles and reduced their diameter to 2.50 and 2.33 nm when TiO₂ and ZrO₂ were introduced to Pt/C, respectively. The electrocatalytic activity of various electrocatalysts was examined towards methanol oxidation in H₂SO₄ solution by using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Among the studied composites, Pt–ZrO₂/C was selected to be a candidate electrocatalyst for better electrochemical performance in direct methanol fuel cells.     

Fundamental Differences between Group 8 Metals: Unexpected Oxidation State Preferences and Mechanisms in Ruthenium Borylene Complex Formation

The reaction of the salts K[Ru(CO)₃(PMe₃)(SiR₃)] (R=Me, Et) with Br₂BDur or Cl₂BDur (Dur=2,3,5,6‐Me₄C₆H) leads to both boryl and borylene complexes of divalent ruthenium, the former through simple salt elimination and the latter through subsequent CO loss and 1,2‐halide shift. The balance of products can be altered by varying the reaction conditions; boryl complexes can be favored by the addition of CO, and borylene complexes by removal of CO under vacuum. All of these products are in competition with the corresponding (aryl)(halo)(trialkylsilyl)borane, a reductive elimination product. The Ru^II borylene products and the mechanisms that form them are distinctly different from the analogous reactions with iron, which lead to low‐valent borylene complexes, highlighting fundamental differences in oxidation state preferences between iron and ruthenium.