Probing the electronic structure of an active catalyst surface under high-pressure reaction conditions: the oxidation of methanol over copper

The active phase of a bulk metallic copper catalyst is investigated by surface sensitive X-ray absorption spectroscopy at the oxygen K-edge and the Cu L-edges in the total electron yield mode under practical steady state flow-through conditions. The active catalyst surface contains oxygen atoms revealing significant spectral differences compared to those of known copper oxides. The partial oxidation of methanol to formaldehyde is correlated to the abundance of this copper suboxide. These oxygen atoms probe defects of the copper lattice, which represent catalytically active sites. The suboxide is undetectable under UHV conditions. The total oxidation of methanol is catalysed by a conventional copper(I) oxide species and the abundance of carbon dioxide in the gas phase is increasing with decreasing integrated intensity of the oxide species. This revised version was published online in July 2006 with corrections to the Cover Date.     

CO Oxidation Behavior of Copper and Copper Oxides

Carbon monoxide oxidation activities over Cu, Cu₂O, and CuO were studied to seek insight into the role of the copper species in the oxidation reaction. The activity of copper oxide species can be elucidated in terms of species transformation and change in the number of surface lattice oxygen ions. The propensity of Cu₂O toward valence variations and thus its ability to seize or release surface lattice oxygen more readily enables Cu₂O to exhibit higher activities than the other two copper species. The non-stoichiometric metastable copper oxide species formed during reduction are very active in the course of CO oxidation because of its excellent ability to transport surface lattice oxygen. Consequently, the metastable cluster of CuO is more active than CuO, and the activity will be significantly enhanced when non-stoichiometric copper oxides are formed. In addition, the light-off behaviors were observed over both Cu and Cu₂O powders. CO oxidation over metallic Cu powders was lighted-off because of a synergistic effect of temperature rises due to heat generation from Cu oxidation as well as CO oxidation over the partially oxidized copper species.     

Investigation of Ammonia Oxidation over Copper with In Situ NEXAFS in the Soft X-Ray Range: Influence of Pressure on the Catalyst Performance

The oxidation of ammonia over polycrystalline copper was investigated by means of in situ NEXAFS (near-edge X-ray absorption fine structure) spectroscopy in the soft X-ray range. The reaction, carried out in a 1:12 excess of oxygen, was observed by mass spectrometry. The simultaneous detection of the surface electronic structure and its catalytic performance allows correlation of different reaction products to the current surface structure of the catalyst. It is shown that a change in total pressure from 0.4 to 1.2 mbar severely affects the reaction path. Copper(I) nitride was identified as poison and a copper oxide was found to be the active phase for the selective oxidation of ammonia to nitrogen.     

On the junction effect theory of activity in methanol synthesis catalysts

The junction effect theory which has been propounded to account for the activity in methanol synthesis of oxide supported copper catalysts has been examined in the light of published data on the mechanism of methanol synthesis on copper/zinc oxide/alumina catalysts. The absence of a formate species on the surface of the zinc oxide component of the catalyst after methanol synthesis (the formate species has been shown to be the pivotal intermediate in methanol synthesis on zinc oxide) precludes its involvement in the reaction and negates the applicability of the theory to the copper/zinc oxide/alumina system.     

A SERS spectroelectrochemical investigation of the interaction of 2-mercaptobenzothiazole with copper, silver and gold surfaces

The interaction of the sulfide mineral flotation collector, 2-mercaptobenzothiazole, with silver, copper and gold surfaces has been investigated by surface enhanced Raman scattering (SERS) spectroscopy. 2-mercaptobenzothiazole, the copper, silver and gold compounds of this species, and the dithiolate, 2,2-dithiobis(benzothiazole) were characterised by ¹³C NMR and Raman spectroscopy to provide a basis for identifying surface species. SERS investigations showed that, at pH 4.6 where the solution species is in the protonated form, and at 9.2, where it is present as the ion, adsorption on each metal occurs over a wide potential range. Attachment of the organic compound occurs through bonding between the exocyclic sulfur atom and metal atoms in the surface. X-ray photoelectron spectroscopy confirmed that the adsorbed layer was of monolayer thickness. Adsorption of the protonated 2-mercaptobenzothiazole occurs on copper at pH 4.6 at potentials below that at which charge transfer adsorption commences.     

硫酸盐酸性镀液中碳纤维电镀铜

针对在硫酸铜酸性镀铜液中碳纤维电镀出现的镀层粗糙、"黑心"等问题,研究了纤维预处理、镀液成分和电解规范对镀层的影响,确定了合适的碳纤维电镀铜工艺. 预处理采用空气高温氧化和硝酸粗化氧化,SEM和XPS分析显示,预处理后碳纤维表面粗糙度增加,并且存在大量亲水性含氧官能团. 讨论了镀液中游离硫酸浓度、有机添加剂及Cl-等对镀铜层质量的影响,并采用SEM, XRD等方法考察了镀层质量. 结果表明,在CuSO4 60 g/L, H2SO4 180 g/L镀液中加入适量2-巯基苯并咪唑、乙撑硫脲和聚二硫二丙烷磺酸钠等添加剂,控制Cl-含量20~60 mg/L,以及选择合适的工艺参数,可以在碳纤维表面得到均匀、平整、与纤维结合紧密的镀铜层.     

碳纳米管的化学镀铜

A simple chemical method was employed to coat carbon nanotubes with a layer of copper. Due to the hydrophobic nature, large surface curvature, small diameter and large aspect ratio, it is difficult to gain continuous electroless plating layer on the surface of carbon nanotubes. In this paper, a series methods (oxidization, sensitization and activation) are used to add active sites before electroless plating, and the adjustment of the traditional composition of copper electroless plating bath and operating condition can decelerate electroless plating rate. The samples before and after coating were analyzed using transmission electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that the surface of carbon nanotubes was successfully coated with continuous layer of copper, which lays a good foundation for applying carbon nanotubes in composites.     

Methanol Decomposition Over Copper/Silica: Effect of Temperature and Co-reactant on Carbon Deposition

The interaction of methanol with a copper/silica catalyst at 373 and 523K under reducing, oxidising and inert carrier gas flows has been studied. Under all conditions there is retained material associated solely with the copper. In general the retained species is adsorbed methanol/methoxy; only over an oxidised catalyst after treatment at 523K is there no evidence for adsorbed methanol/methoxy. Desorption of carbon dioxide is associated with an up-take in dioxygen indicating oxidation of a surface species, probably formate. After laydown under reducing or inert gas flow, the copper does not re-oxidise under the TPO gas flow, even at temperatures >673K indicating that material is still retained by the copper. Bulk re-oxidation of the reduced catalyst in the absence of retained species is rapid at 293K. Under oxidising conditions at 523K there is no evidence for adsorbed methanol/methoxy on the surface of the copper; in this case the retained species may be more akin to a carbonate.     

Electroless Plating of Carbon Nanotubes with Copper

A simple chemical method was employed to coat carbon nanotubes with a layer of copper. Due to the hydrophobic nature, large surface curvature, small diameter and large aspect ratio, it is difficult to gain continuous electroless plating layer on the surface of carbon nanotubes. In this paper, a series methods (oxidization, sensiti-zation and activation) are used to add active sites before electroless plating, and the adjustment of the traditional composition of copper electroless plating bath and operating condition can decelerate electroless plating rate. The samples before and after coating were analyzed using transmission electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that the surface of carbon nanotubes was successfully coated with continuous layer of copper, which lays a good foundation for applying carbon nanotubes in composites.     

十四酸铜超疏水表面的溶剂热法制备及其润湿性

超疏水表面是防止低温条件下风机叶片表面结冰、保证机组安全运行的重要材料之一。本文以十四酸乙醇溶液和铜片为前体,基于溶剂热法将十四酸铜原位生长于铜片表面,通过调控前体浓度和反应时间获得了不同润湿性的疏水表面,实现了疏水表面润湿性的有效调控。此外,采用扫描电子显微镜（SEM）观察了十四酸铜团簇的微结构及分布状态;借助X射线衍射仪（XRD）验证团簇粉末的晶格成分;通过接触角测量仪量化不同条件下样品的表面润湿性。结果表明,随着铜片表面十四酸铜团簇密集程度的增加,液滴与铜片的接触角增大,铜片润湿性降低;十四酸乙醇溶液浓度及反应时间可以显著改变十四酸铜分布状态,进而改变表面润湿性。疏水表面润湿性的变化是由于Ostwald熟化促进晶体生长,使表面的“禾苗”状聚合物逐渐生长成十四酸铜微米花。     

Comparison of Oxidized Polycrystalline Copper Foil with Small Deposited Copper Clusters in Their Behavior in Ammonia Oxidation: An Investigation by Means of In Situ NEXAFS Spectroscopy in the Soft X-Ray Range

The oxidation of ammonia to nitrogen or nitric oxide was investigated using on the one hand a polycrystalline copper foil and on the other hand deposited copper clusters prepared with the inert gas aggregation technique. The behavior in the oxidation of ammonia of both model catalysts was studied using in situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in the soft X-ray range and mass spectrometry. It is shown that the copper foil reacts in a similar way to the copper clusters. Differences appear only with respect to the reaction temperature required, which is lower for the cluster sample. It can be concluded that the results obtained in experiments with polycrystalline copper foil are exemplary for and can be transferred to a supported copper catalyst consisting of small copper particles.     

Cu-Zn-Ti催化剂上顺酐气相催化加氢制备γ-丁内酯

通过共沉淀法制备了Cu-Zn-Ti系列催化剂,并对还原前后的样品进行了XRD、XPS、TPR以及BET等表征分析。结果表明,Cu-Zn-Ti催化剂催化顺酐加氢制备γ-丁内酯的活性与选择性和催化剂的原子配比有关。铜含量较低时,CuO与ZnO及TiO₂之间存在强的相互作用。铜含量较高时,存在游离的CuO。催化剂还原后,铜以Cu0形式存在。当CuO以表面结合形态存在时,还原得到的Cu0有利于顺酐深加氢反应的进行。     

Amperometric determination of thiourea in alkaline media on a copper oxide–copper electrode

A copper oxide–copper electrode was tested in alkaline media for the anodic electrochemical detection of thiourea (TU). The correlation between the history of the electrode and potential range for optimum sensing of the particular susceptible species was analysed by electrochemical and surface layer techniques. The chemical composition and morphology of surface layers were examined using the SEM/EDX technique. Electrochemical data were obtained by cyclic voltammetry (CV) and chronoamperometry (CA). The linear calibration plots for an amperometric detection of TU in a delimited potential range, using CV and CA, were obtained for the 1–8 mM concentration range. Some considerations on the correlation between TU, electrode formation and polarization conditions are proposed. A copper oxide–copper electrode can be used as an inexpensive alternative for amperometric determination of TU in alkaline media without fouling the electrode surface.     

模拟化工大气环境中不同类型铜管的腐蚀研究

在自制的实验箱中模拟化工大气环境,考察了裸铜管、化学镀標铜管和化学镀操-染黑铜管的腐蚀情况,并利用扫描电镜和三维形貌仪观察了不同类型铜管腐蚀前后的微观组织及腐蚀后的局部三维形貌。结果表明:在模拟化工大气环境中腐蚀后裸铜管表面存在连成片且很深的蚀坑,化学镀襟铜管表面的胞状物消失,化学镀鎳-染黑铜管表面存在沿着缝隙分布的大面积细小蚀坑;化学镀铢铜管的耐蚀性最好,其次是化学镀操-染黑铜管,裸铜管的耐蚀性最差。     

普通钢铁铜盐电解着彩色研究

为提高钢铁件的耐蚀、耐热及装饰等性能,用电沉积法研究了钢铁表面在硫酸铜溶液中的着色工艺,研究了pH值、电流密度、时间等工艺条件对着色效果的,利用光电子能谱仪分析了着色膜的成分。结果表明：钢铁表面在铜盐着色液中能获得多种颜色,着色膜主要成分为铜元素,其发色机理为光干扰效应。     

The Interaction of CuS and Halothiobacillus HT1 Biofilm in Microscale Using Synchrotron Radiation-Based Techniques

In order to investigate the microbe-mineral interaction in the micro scale, spatial distribution and speciation of Cu and S in Halothiobacillus HT1 biofilm formed on a CuS surface was examined using synchrotron-based X-ray techniques. Confocal laser scanning microscope (CLSM) results indicated that Halothiobacillus HT1 biofilm formation gave rise to distinct chemical and redox gradients, leading to diverse niches in the biofilm. Live cells were distributed at the air-biofilm and membrane-biofilm interface. CuS was oxidized by Halothiobacillus HT1 biofilm, and copper penetrated into the biofilm. Sulfide was oxidized to cysteine (77.3%), sulfite (3.8%) and sulfonate (18.9%). Cu-cysteine-like species were involved in the copper homeostasis. These results significantly improve our understanding of the interfacial properties of the biofilm-mineral interface.     

The Effect of ZnAl2O4 on the Performance of Cu/ZnxAlyOx+1.5y Supported Catalysts in Steam Reforming of Methanol

This paper demonstrates the benefit of using spinel (ZnAl₂O₄) as a support for copper catalysts in hydrogen generation. We have investigated the influence of catalyst pre-treatment, support composition and copper content on the physicochemical and catalytic properties of copper catalysts supported on Zn_xAl_yO_x+1.5y in the methanol steam reforming. The physicochemical properties of the catalysts were examined by X-ray diffraction, temperature-programmed reduction, specific surface area and porosity, X-ray photoelectron spectroscopy, FTIR and chemisorption methods. The reduced copper catalysts showed higher conversion of methanol and higher hydrogen production. We also found that the presence of Cu⁺ and Cu⁰ species on the catalyst surface strongly influences the reaction yield and hydrogen production. FTIR measurements performed for copper catalysts confirmed that increasing of aluminium content in the case of catalytic systems caused the growth of adsorbed species on the catalyst surface.     

Study on brown oxidation process with imidazole group,mercapto group and heterocyclic compounds in printed circuit board industry

The adhesion strength of the interface between copper foil and resin is an important technological parameter for applications in microelectronics. In this study, a new brown oxidation solution of copper foil, including the recipe composition and reliability tests, was fully discussed. We provided an overview of brown oxidation process used in the semi-flexible printed circuit boards production industry by investigating the brown oxide film. The morphology of the copper oxide film was changed from lamellar structure to honeycomb structure with the increasing of oxidation time. The peel adhesion strength of the Cu/polyimide laminates was increased from about 2–16 N/cm by altering the immersion time and the concentration of inhibitors in brown oxidation solution. Scanning electron microscopy, peel tests and X-ray diffraction indicated that the higher adhesion strength was resulted from the rougher surface and the proper etching depth of copper foil, which was caused by chemical reactions on the interface surface of copper foil.     

2A12铝合金冷喷铜涂层的组织与性能

铝合金是常用的导电类零部件基材,工程上一般采用电镀铜或热喷涂铜技术在铝合金零部件表面制备单质铜涂层提高其导电性,但电镀铜层与基体结合不稳定,热喷涂铜涂层存在粗糙度大、易氧化的问题。以冷喷涂技术为手段在2A12铝合金基体上制备单质铜涂层,采用显微镜、扫描电镜、X-射线衍射、表面粗糙度测量仪、显微硬度计和划痕试验机进行涂层组织与性能研究。结果表明,涂层氧化率较低,粗糙度与电弧喷铜涂层相比明显减小,涂层组织过渡良好,未发现明显的疏松与空洞,结合力高于电弧喷涂涂层,电阻率约小于电弧喷涂。     

阿司匹林铜的一步法合成及表征

以醋酸铜与阿司匹林为原料,以甲醇为溶剂一步法合成标题化合物。产物经高效液相色谱仪、原子吸收光谱仪、红外光谱仪、X-射线衍射仪确定纯度和结构。