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Ku, Sin Yee = 添加鎳對網絡結構Fe₈₀C₂₀合金機械性能的影響 / 古倩儀. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Ku, Sin Yee = Tian jia nie dui wang luo jie gou Fe₈₀C₂₀ he jin ji xie xing neng de ying xiang / Gu Qianyi. / Abstract --- p.i / Acknowledgements --- p.v / List of Tables --- p.viii / List of Figures --- p.ix / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Composite Materials --- p.1 / Chapter 1.1.1 --- Parti culate-reinforced Composites --- p.2 / Chapter 1.1.2 --- Fibre-reinforced Composites --- p.2 / Chapter 1.1.3 --- Structural Composites --- p.3 / Chapter 1.1.4 --- Metal Matrix Composites --- p.3 / Chapter 1.2 --- Phase Transformations --- p.4 / Chapter 1.2.1 --- Introduction --- p.4 / Chapter 1.2.2 --- Stability and Equilibrium --- p.4 / Chapter 1.2.3 --- Undercooling --- p.6 / Chapter 1.2.4 --- Solidification of Undercooled Melts --- p.7 / Chapter 1.2.4.1 --- Nucleation --- p.8 / Chapter 1.2.4.1.1 --- Homogeneous Nucleation --- p.8 / Chapter 1.2.4.1.2 --- Heterogeneous Nucleation --- p.9 / Chapter 1.2.4.2 --- Growth --- p.11 / Chapter 1.2.5 --- Binary Systems with a Solid Miscibility Gap --- p.12 / Chapter 1.2.6 --- Phase Separation Mechanisms in a Solid Miscibility Gap --- p.14 / Chapter 1.2.6.1 --- Nucleation and Growth --- p.14 / Chapter 1.2.6.2 --- Spinodal Decomposition --- p.15 / Chapter 1.2.6.2.1 --- Uphill Diffusion --- p.16 / Chapter 1.2.6.2.2 --- Diffusion Equation of Spinodal Decomposition --- p.17 / Chapter 1.2.6.2.3 --- Solution to the Diffusion Equation --- p.19 / Chapter 1.2.7 --- Metastable Liquid Miscibility Gap --- p.21 / Chapter 1.3 --- Mechanical Properties --- p.22 / Chapter 1.3.1 --- Hardness --- p.22 / Chapter 1.3.2 --- Strength --- p.23 / Chapter 1.3.3 --- Ductility --- p.23 / Chapter 1.3.4 --- Strengthening Mechanisms --- p.25 / Chapter 1.3.4.1 --- Grain Boundary Strengthening --- p.25 / Chapter 1.3.4.2 --- Solid Solution Strengthening --- p.26 / Chapter 1.4 --- Objectives of This Project --- p.27 / Figures --- p.29 / References --- p.42 / Chapter Chapter 2: --- Experimental --- p.43 / Chapter 2.1 --- Formation of Bulk Network Nanostructured Alloys --- p.43 / Chapter 2.1.1 --- Preparation of Fused Silica Tubes --- p.43 / Chapter 2.1.2 --- Weighing and Alloying --- p.44 / Chapter 2.1.3 --- Fluxing and Quenching --- p.45 / Chapter 2.2 --- Sample Preparation --- p.46 / Chapter 2.2.1 --- "Cutting, Grinding and Polishing" --- p.46 / Chapter 2.2.2 --- Etching --- p.47 / Chapter 2.2.3 --- Sample Preparation for Transmission Electron Microscopy Analysis --- p.48 / Chapter 2.3 --- Mechanical Tests --- p.49 / Chapter 2.3.1 --- Microhardness Test --- p.49 / Chapter 2.3.2 --- Compression Test --- p.50 / Chapter 2.4 --- Microstructural Analysis --- p.51 / Chapter 2.4.1 --- Scanning Electron Microscopy Analysis --- p.51 / Chapter 2.4.2 --- Transmission Electron Microscopy Analysis --- p.52 / Chapter 2.4.2.1 --- Indexing Diffraction Patterns --- p.52 / Chapter 2.4.2.2 --- Energy Dispersive X-Ray Analysis --- p.53 / Chapter 2.4.2.3 --- Electron Energy Loss Spectroscopy --- p.53 / Figures --- p.55 / References --- p.62 / Chapter Chapter 3: --- Dependence of the Mechanical Properties of FesoC2o Network Alloys on the Addition of Ni --- p.63 / Chapter 3.1 --- Abstract --- p.63 / Chapter 3.2 --- Introduction --- p.64 / Chapter 3.3 --- Experimental --- p.64 / Chapter 3.4 --- Results --- p.66 / Chapter 3.5 --- Discussions --- p.74 / Chapter 3.6 --- Conclusions --- p.79 / Tables --- p.80 / Figures --- p.82 / References --- p.100 / Bibliography --- p.101

by Yu, Chak Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 129-133). / by Yu, Chak Chung. / PREFACE --- p.i / ACKNOWLEDGMENT --- p.iv / ABSTRACT --- p.v / Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Barkhausen effect --- p.2 / Chapter 1.2 --- Magnetoacoustic emission --- p.4 / Chapter 1.3 --- Methods of measurements --- p.5 / Chapter 1.3.1 --- Magnetization of a sample --- p.6 / Chapter 1.3.2 --- Signal detection --- p.8 / Chapter 1.3.3 --- Signal processing --- p.9 / Figures for chapter1 --- p.11 / References --- p.14 / Chapter 2 --- MAGNETIC PHENOMENA AND THEORIES --- p.17 / Chapter 2.1 --- Magnetostriction --- p.17 / Chapter 2.1.1 --- Spontaneous magnetostriction --- p.18 / Chapter 2.1.2 --- Saturation magnetostriction --- p.19 / Chapter 2.1.3 --- Field induced magnetostriction --- p.20 / Chapter 2.1.4 --- Magnetostriction at an angle θ to the magnetic field --- p.21 / Figures for section 21 --- p.24 / Chapter 2.2 --- Domain theory --- p.26 / Chapter 2.2.1 --- Magnetic domains --- p.26 / Chapter 2.2.2 --- Magnetostatic energy --- p.27 / Chapter 2.2.3 --- Magnetization process --- p.29 / Figures for section 22 --- p.30 / Chapter 2.3 --- Domain walls and domain processes --- p.33 / Chapter 2.3.1 --- Properties of domain walls --- p.33 / Chapter 2.3.2 --- "180° and non-180° domain walls, and closure domains" --- p.34 / Chapter 2.3.3 --- Domain wall motion --- p.35 / Chapter 2.3.4 --- Reversible and irreversible domain processes --- p.36 / Chapter 2.3.5 --- Barkhausen emission and magnetoacoustic emission --- p.38 / Figures for section 23 --- p.39 / Chapter 2.4 --- Hindrances to wall motion --- p.43 / Chapter 2.4.1 --- Residual stress --- p.43 / Chapter 2.4.1.1 --- Dislocation --- p.44 / Chapter 2.4.1.2 --- Magnetostriction --- p.45 / Chapter 2.4.1.3 --- Plastic deformation --- p.46 / Chapter 2.4.2 --- Inclusions --- p.47 / Chapter 2.4.3 --- "Domain nucleation, annihilation, and wall motion" --- p.48 / Figures for section 24 --- p.50 / References --- p.55 / Chapter 3 --- MEASUREMENT OF BARKHAUSEN EMISSION AND MAGNETOACOUSTIC EMISSION FROM A FRACTURED STEEL BAR --- p.57 / Chapter 3.1 --- Introduction --- p.57 / Chapter 3.2 --- Experiments --- p.58 / Chapter 3.3 --- Results and discussions --- p.60 / Chapter 3.3.1 --- BE and MAE profiles --- p.60 / Chapter 3.3.2 --- Defects --- p.61 / Chapter 3.3.3 --- Elongated grains --- p.62 / Chapter 3.3.4 --- Effect of annealing --- p.63 / Chapter 3.4 --- Conclusions --- p.64 / Figures and table for chapter3 --- p.66 / References --- p.70 / Chapter 4 --- NONDESTRUCTIVE INSPECTION OF A FRACTURED NICKEL BAR BY BARKHAUSEN AND MAGNETOACOUSTIC EMISSIONS --- p.71 / Chapter 4.1 --- Introduction --- p.71 / Chapter 4.2 --- Experiments --- p.72 / Chapter 4.3 --- Results --- p.73 / Chapter 4.4 --- Discussions --- p.74 / Chapter 4.4.1 --- Barkhausen emission --- p.74 / Chapter 4.4.2 --- Magnetoacoustic emission --- p.75 / Chapter 4.4.3 --- Comparison of nickel and mild steel --- p.77 / Chapter 4.5 --- Conclusions --- p.78 / Figures and table for chapter4 --- p.81 / References --- p.83 / Chapter 5 --- DETERMINATION OF THE ROLLING DIRECTION OF ELECTROLYTIC ZINC-COATED STEEL PLATE BY BARKHAUSEN EMISSION --- p.84 / Chapter 5.1 --- Introduction --- p.84 / Chapter 5.2 --- Experiments --- p.85 / Chapter 5.3 --- Results --- p.86 / Chapter 5.4 --- Discussions --- p.87 / Chapter 5.4.1 --- BE profiles 、 --- p.87 / Chapter 5.4.2 --- Effects of hardness and defects --- p.89 / Chapter 5.5 --- Conclusions --- p.90 / Figures for chapter5 --- p.91 / References --- p.97 / Chapter 6 --- MAGNETIC MEASUREMENTS MADE ON A NICKEL PLATE WITH HIDDEN HOLE --- p.98 / Chapter 6.1 --- Introduction --- p.98 / Chapter 6.2 --- Experiments --- p.99 / Chapter 6.3 --- Results and discussions --- p.100 / Chapter 6.3.1 --- Barkhausen emission --- p.100 / Chapter 6.3.2 --- Magnetoacoustic emission --- p.102 / Chapter 6.4 --- Conclusions --- p.103 / Figures for chapter6 --- p.105 / Chapter 7 --- CONCLUSIONS AND SUGGESTIONS FOR FURTHER STUDIES --- p.114 / APPENDIX --- p.118 / Chapter A1 --- Experimental setup for BE measurement --- p.118 / Chapter A2 --- Experimental setup for MAE measurement --- p.119 / Chapter A3 --- Specifications and models of the equipment used in the experiments --- p.120 / Chapter A4 --- List of figures --- p.121 / BIBLIOGRAPHY --- p.129

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 268-376. / by Rakesh Agrawal. / Sc.D.

Este trabalho consiste no estudo de complexos de Ni(II) com dialquilsulfóxidos. Os compostos foram sintetizados e caracterizados através de espectroscopia vibracional e eletrônica, medidas magnéticas e de condutância e determinação de ponto de fusão. Obtiveram-se os seguintes complexos: [Ni(R2SO)6](ClO4)2 (R = Me, n-Pr, n-Bu e i-Bu); [Ni (Me2SO)6] (NO3)2; [Ni (Me2SO)4 (NO3)](NO3); [Ni(R2SO)3 (NO3)2] (R = Me2SO, Me2SO-d6, n-Bu e i-Bu) e [Ni(R2SO)2 (N03)2] (R = n-Pr, i-Bu e t-Bu). O método de síntese é crítico para a obtenção de compostos bem definidos, principalmente no caso dos nitratos onde existe a possibilidade de formação de compostos de diferentes estequiometrias para o mesmo sulfóxido. Os complexos [Ni(Me2SO)6] (Cl04)2 e [Ni(Me2SO)4 NO3] NO3 não fundem até 245° C. Os demais fundem em temperaturas relativamente baixas. Alguns complexos de nitrato apresentam grandes intervalos de fusão, que podem ser devidos a perdas de ligante. Os complexos são octaédricos com os sulfôxidos coordenados ao Ni(II) através do átomo de oxigênio, conforme evidenciado por medidas magnéticas e espectroscopia vibracional e eletrônica. A influência doânion é marcante. O grupo perclorato não se coordena ao íon metálico, enquanto que o grupo nitrato pode não se coordenar ou, então, atuar como ligante monodentado ou bidentado, competindo com o sulfóxido na primeira esfera de coordenação do Ni(II). Os complexos contendo perclorato comportam-se como eletrólitos do tipo 1:2 em nitrometano. Os compostos contendo nitrato, ao contrário, comportam-se todos como nao condutores no mesmo solvente, embora os sólidos de Me2SO com proporção molar níquel-sulfóxido 1:6 e 1:4 apresentem nitrato iônico. Isto é uma evidência de que as espécies em solução não são as mesmas presentes nos sólidos. Os espectros eletrônicos confirmam este fato. As diferenças de basicidade e estereoquímica dos sulfóxidos afetam pouco os valores de Dq e B dos complexos contendo perclorato. Portanto, os sulfóxidos di-propílico e di-butílicos estudados ocupam a mesma posição do Me2SO na série espectroquímica e, também, na série nefelauxética. / This work consists on the study of Ni(II) complexes with dialquilsulfoxides. The compounds were synthesized and characterized by vibrational and electronic spectroscopies, magnetic and conductance measurements and melting point determination. The following complexes were obtained: [Ni(R2SO)6](ClO4)2 (R = Me, n-Pr, n-Bu and i-Bu); [Ni (Me2SO)6] (NO3)2; [Ni (Me2SO)4 (NO3)] NO3; [Ni(R2SO)3 (NO3)2] (R = Me2, Me2SO-d6, n-Bu and i-Bu) and [Ni(R2SO)2 (NO3)2] (R = n-Pr, i-Bu and t-Bu). The synthetic procedure is critical for the preparation of well defined compounds, mainly for the nitrates where the possibility of formation of compounds with different stoichiometry for the same sulfoxide exists. The complexes [Ni (Me2SO 6] (ClO4)2 and [Ni (Me2SO)4 NO3] NO3 do not melt up to 245°C, and the others melt at relatively low temperatures. Some nitrate complexes show broad melting point ranges, which may be due to ligand loss during the heating. The complexes are octahedral, and have the sulfoxides coordinated to the Ni(II) through the oxygen atom, as shown by magnetic measurements and the vibrational and electronic spectra. The anion influence is very important. The perchlorate group does not coordinate to the metal ion, while the nitrate group may either be non coordinating or behave as a monodentate or bidentate ligand, competing with the sulfoxide for the first coordination sphere of Ni(II). The perchlorate complexes are l:2 type electrolytes in nitromethane solution. The nitrate complexes, on the other hand, are non conducting in the same solvent, although the solid compounds of Me2SO which have molar Ni: sulfoxide ratios of l:6 and l:4 possess ionic nitrate in their molecules. This is an evidence of the existence of different species in the solid state and in solution in these cases. The electronic spectra confirm this fact. The differences in the basicity and in the stereochemistry of the sulfoxides affect little the Dq and B values in the perchlorate complexes. This implies the di-propyl and di-butylsulfoxide studied fall in the same position as the dimethylsulfoxide in the spectrochemical and nephelauxetic series.

O processo de fosfatização é amplamente utilizado na indústria de tratamento de superfície de metais, especialmente de placas de baixa espessura, melhorando a aderência entre a superfície do metal e o revestimento de tinta, e aumentando a durabilidade dos sistemas de pintura contra ataques corrosivos. Os fosfatos tricatiônicos contendo zinco, níquel e manganês são comumente aplicados em aço, e muito se discute sobre a substituição do níquel por outro elemento com o objetivo de obter um fosfato mais amigável ao meio ambiente, tanto em seus processos como para as pessoas envolvidas. O nióbio tem sido avaliado nesse sentido. Os impactos ambientais mais significativos dos fosfatos estão relacionados com a presença do níquel e do cromo hexavalente utilizado no processo, devido a exposição ao contato humano e a contaminação residual da água e do solo. Seguindo a linha de pesquisa que estudou a substituição do níquel por nióbio em camadas formadas sobre o aço carbono, o presente estudo avaliou e caracterizou camadas de fosfato contendo zinco, manganês e nióbio, formadas em aço galvanizado, comparando os resultados com o fosfato de zinco, manganês e níquel, bem como com o fosfato de zinco e manganês, sem a adição de nióbio. Embora o uso de cromo não seja recomendado mundialmente, ainda hoje é utilizado no processo de selagem da porosidade da camada de fosfato, em banhos contendo cromo hexavalente, que é reconhecido por ser carcinogênico, estando associado a várias doenças. Devido às características passivantes do nióbio, este estudo também avaliou o banho tricatiônico contendo oxalato amoniacal de nióbio, como etapa de passivação das camadas, tanto em banhos bicatiônicos, quanto nos tricatiônicos, com resultados muito interessantes como opção de substituição do cromo hexavalente. Os resultados obtidos neste trabalho são promissores, pois algumas das formulações contendo nióbio se apresentaram equivalentes ao fosfato contendo níquel, tanto em morfologia, verificadas em microscopia eletrônica de varredura, ensaios gravimétricos, de porosidade e de aderência, quanto nas características de proteção anticorrosivas, verificadas nos ensaios eletroquímicos e em câmara de névoa salina. Embora apresentando eficácia compatível com fosfato contendo níquel, ajustes na estabilidade dos banhos ainda são necessários e mais estudos utilizando técnicas voltadas para o entendimento dos fenômenos que ocorrem na base dos poros, devem orientar as próximas etapas da linha de pesquisa. / The phosphating processes are widely used in industry as surface treatments for metals, especially for low thickness plates, improving the adhesion between the metallic surface and the paint coating, and increasing the durability of paint systems against corrosion attacks. The tricationic phosphates containing zinc, nickel and manganese are commonly applied on steel. There is much discussion about the replacement of nickel by another element in order to have an environmentally friendly phosphating process. Niobium as a replacement for nickel has been evaluated. The most significant environmental impacts of phosphating processes are related to the presence of nickel and hexavalent chromium used in the process, this last as a passivation treatment. Nickel and hexavalent chromium are harmful to human and environment leading to contamination of water and soil. In the present study phosphate layers containing zinc, manganese and niobium have been evaluated and characterized on galvanized steel, and the results were compared with phosphates containing zinc, manganese and nickel, or a bicationic phosphate layer with zinc and manganese. Although the use of hexavalent chromium is not recommended worldwide, it is still used in processes for sealing the porosity of phosphate layers. This element is carcinogenic and has been associated with various diseases. Due to the passivation characteristics of niobium, this study also evaluated the tricationic bath containing niobium ammonium oxalate as a passivation treatment. The results showed that it could act as a replacement for the hexavalent chromium. The results of the present study showed that formulations containing niobium are potential replacements for hexavalent chromium and similar corrosion protection was obtained for the phosphate containing nickel or that with niobium. The morphology observed by scanning electron microscopy, gravimetric tests, porosity and adhesion evaluation results indicated that the phosphate obtained with passivation treatment in niobium containing solution could be considered as a promising alternative to replace passivation with hexavalent chromium ions. Despite of the promising results, adjustments in the baths to obtain stability are still needed and should guide the next steps of the subject of this research.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / A gelatina comestÃvel usada como precursor orgÃnico no mÃtodo sol-gel protÃico gerou nanopartÃculas de Aluminato de NÃquel (NiAL2O4 ). Foram elaborados seis sÃries de soluÃÃes preparadas com gelatina comestÃvel, Ãgua e sais de Ni (NiCL2.6H2O) e de AL (ALCL3.6H2O) ou (AL(NO3)3 9H2O), sendo a razÃo de Ni:AL de 1:4. Cinco sÃries foram submetidas a secagem e sinterizaÃÃo em temperatura variando de 500ÂC a 1000ÂC com intervalos de 100ÂC sob uma taxa de aquecimento de 10 C/min. A sÃrie restante seguiu o mesmo processo, entretanto foi mantida em temperatura constante de 800ÂC e variando o tempo, sendo doze(12h), nove(9h),seis(6h) e trÃs(3h) horas. Nas temperaturas acima de 700ÂC foram obtidos cristais bastante uniformes de NiAL2O4, mas em geral, na temperatura de 800ÂC foram encontrados os menores tamanhos de partÃcula, atà cerca de 5nm. Com base na difraÃÃo de raios-X (DRX) do material sintetizado foi feitaa caracterizaÃÃo estrutural pelo MÃtodo Rietveld de refinamento, com essa anÃlise foram obtidos parÃmetros estruturais como concentraÃÃo de fases cristalinas, tamanho das partÃculas e a morfologia da estrutura. O tamanho das partÃculas obtido usando a fÃrmula de Scherrer foi comparado com o valor obtido pelo grÃfico de Williamsom-Hall, bem como a microdeformaÃÃo das amostras foi calculada com base nesse grÃfico. Algumas amostras foram submetidas à analise de DSC para determinar as variaÃÃes de energia . Algumas amostras foram submetidas à analise de B.E.T como forma de determinar Ãrea superficial do material, importante parÃmetro para aplicaÃÃo em catÃlise. Observou-se que foi bastante viÃvel a obtenÃÃo do NiAL2O4 via mÃtodo sol-gel protÃico e que o material obtido apresentou boas propriedades para aplicaÃÃo em catÃlise e para indÃstria da pigmentaÃÃo.

This thesis focuses on development of new regents which are suitable for recovering nickel, cobalt and copper from laterite leach solutions, specifically focusing on reagent requirements for novel base metal flowsheets developed by Anglo American. The work aims to design reagents which can extract nickel(II), cobalt(II) and copper(II) from a highly acidic aqueous sulfate solutions whilst showing selectivity over iron(II) and iron(III). Chapter 1 reviews current extractive metallurgy processes for separating and concentrating metals in laterite ores and describes new flowsheets proposed by Anglo American. Chapter 2 considers whether single reagent molecules with sets of tridentate donor atoms can generate sufficiently stable nickel(II) complexes to allow selective extraction of nickel from an aqueous sulfate solution. The salicylaldimines, 3-X-4-alkyl-6-(quinolin-8-imino)phenol, 3-X-4-alkyl-6-(2- methoxyphenylimino)phenol and 3-X-4-alkyl-6-(2-thiomethoxyphenylimino)phenol (alkyl = tert-butyl or tert-octyl; X = H, Br or NO2), were selected for study. The synthesis and characterisation of these proligands and their nickel(II) complexes are reported. XRD structures of Br-substituted salicylaldimines and their nickel(II) complexes are compared and discussed. The 4-tert-octylsalicylaldimines were used to extract nickel(II) from an aqueous sulfate solution with a pH > 2.8 and 3- nitro-4-tert-octyl-6-(quinolin-8-imino)phenol was found to be the strongest extractant in the series with a pH0.5 of 3.5. Computational studies of an analogous series of salicylaldimine proligands in the gas phase calculated the formation energies of their nickel(II) complexes and the predicted trend follows the experimentally determined solvent extraction results. Chapter 3 investigates modifications to phenolic pyrazoles, which are known copper(II) extractants. A series of 6-X-4-methyl-2-(5-alkyl-1H-pyrazol-3-yl)-phenols (X = H, OMe, Br and NO2) was synthesised and characterised. Varying the 6-X-substituent of the phenolic pyrazole altered the strength of copper extraction and 6-nitro-4-methyl-2-(5-(1,3,5-tri-methyl-pentyl)-1H-pyrazol-3-yl)-phenol was found to be the strongest extractant in the series. Analysis of XRD structures of related phenolic pyrazoles and their copper(II) complexes showed evidence of inter- and intra-molecular hydrogen bonding. Computational DFT studies in the gas phase were carried out to calculate the formation energies of analogous phenolic pyrazole copper complexes. The predicted order of these energies followed the same trend shown by experimental solvent extraction studies. The double deprotonation of 4-tert-butyl-(pyrazol-3-yl)-phenol at high pH forms a polynuclear complex in the organic phase with a copper(II) to ligand ratio of 1:1, thereby increasing the mass transport efficiency of copper by the reagent. The synthesis and characterisation of the [Cu16(4-tert-butyl-(pyrazol-3-yl)- phenolate)16(EtOH)4(H2O)2] wheel complex was carried out to demonstrate how such polynuclear copper(II) complexes could be formed under solvent extraction conditions. Chapter 4 explores the solvent extraction of nickel(II) and cobalt(II) by novel combinations of neutral nitrogen-donor heterocyclic ligands with organic acids, such as dinonylnaphthelenesulfonic acid (DNNSAH). The synthesis and characterisation of 2,6-bis(5-alkyl-1H-pyrazol-3-yl)-pyridine, 2-(5- alkyl-1H-pyrazol-3-yl)-pyridine and 5,5'-alkyl-3,3'-bi-1H-pyrazole (alkyl = tert-butyl or nonyl) and their nickel(II) complexes were reported. Also reported are synthesis and 6-N-alkyl-2-(2-pyridinyl)- benzothiazole (alkyl = n-butyl or n-decyl) and 2-(1-Isopropyl-benzimidazol-2-yl)-pyridine. The extraction of nickel(II) from highly acidic mixed metal aqueous sulfate solutions by some of these ligands was studied. These synergistic mixtures demonstrated remarkable strength and selectivity for nickel(II), and cobalt(II) over iron(II). XRD structures of nickel(II) complexes of 2,6-bis(5-tert-butyl- 1H-pyrazol-3-yl)-pyridine, 2-(5-tert-butyl-1H-pyrazol-3-yl)-pyridine and 5,5'-tert-butyl-3,3'-bi-1Hpyrazole with sulfonates or perchlorates as ion-pairs have intermolecular hydrogen bonding interactions between the inner-sphere ligands and the counterions.

Direct methanol fuel cells (DMFCs) are considered a clean source of electrical power for future energy demand, creating a potential to reduce our dependency on fossil fuels. Despite their advantages, including high energy density, efficiency and easy handling and distribution of fuel, the commercialization of DMFCs has suffered from some drawbacks, including methanol crossover and contamination of the system. Metal cation contaminants (such as Ni, Co, etc) introduced through the degradation of fuel cell components (bipolar plate and electro-catalyst layer) can significantly affect the Nafion-membrane properties and overall fuel cell performance. In the current study, a systematic approach is taken to characterize and identify the mechanism of the effect of metal solution contaminants on the activities of electro-catalysts of DMFCs. Cyclic voltammetry and rotating disk electrode (RDE) techniques were utilized in order to characterize the effect of various concentrations (i.e., 2x10-x M (x=1-7)) of six metal solution contaminants (i.e., Co, Ni and Zn with sulfate and nitrate as counter-anions) on the voltammetric properties and electro-catalytic activity of polycrystalline Pt during methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). The results showed a decrease in the MOR and ORR activities of Pt as the concentration of metal solution increased. The effect of counter-anion on the Pt activity was further investigated. The results showed that a combined effect of counter-anions and metal cations may be responsible for the decrease in the electro-catalytic activity of Pt. The effect of metal solution contaminants on the Nafion-ionomer of anode electro-catalysts was investigated using Nafion-coated Pt electrode. Voltammetric properties and MOR activities of Nafion-coated and bare Pt electrodes in the presence of Ni solution contaminants were characterized using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The overall results showed a significant negative effect of Ni solution contaminants on the electro-catalytic activity of bare Pt electrode as compared to the Nafion-coated Pt electrode. Based on the results, it appears that Nafion-ionomer film may interact with metal cations (through its sulfonate groups) and repel them away from the Pt active sites, partially inhibiting the negative effect of metal cations on the Pt activity of Nafion-coated Pt electrode. The effect of metal solution contaminants on the carbon-supported platinum nanoparticle (Pt/C) with various Nafion-ionomer distributions and contents (i.e., Nafion-incorporated Pt/C and Nafion-coated Pt/C electrodes) was further investigated. Cyclic voltammetry and EIS techniques were employed to characterize the effect of Ni solution contaminants on the voltammetric properties and MOR activities of Nafion-incorporated and Nafion-coated Pt/C electrodes. The overall results showed a stronger negative effect of Ni solution contaminants on the electro-catalytic activity of Nafion-incorporated Pt/C electrodes as compared to the Nafion-coated Pt/C electrodes. This further confirms previous observations showing the sulfonate groups of Nafion-ionomer film may attract the Ni metal cations, localize them away from the Pt active sites, and subsequently suppress the negative effect of cations on the activity of Nafion-coated Pt/C electrodes.

Neste trabalho foram avaliadas as atividades de catalisadores do tipo perovskita LaNi1-xCoxO3 frente à reação de reforma a vapor de etanol. Devido à baixa área superficial, característica de óxidos do tipo perovskita, esses foram suportados em SiO2, Al2O3 e ZrO2, a fim de verificar o efeito do suporte na atividade catalítica.<br /> Os catalisadores foram preparados pelo método da co-precipitação e caracterizados por espectrometria de emissão atômica por plasma induzido, difração de raios X pelo método do pó, adsorção de nitrogênio pelo método B.E.T, redução a temperatura programada e espectroscopia de absorção de raios X.<br /> Para estudar o processo de redução e a possibilidade de oxidação durante a reação catalítica, foram realizados estudos in situ da reação de reforma a vapor, através da espectroscopia de absorção de raios X. Estes dados foram comparados com os resultados de aplicação das técnicas de RTP e DRX às amostras parcial e totalmente reduzidas e foi proposto um mecanismo de redução do óxido do tipo perovskita durante o processo de ativação do catalisador.<br /> Todos os catalisadores mostraram-se ativos nas reações de reforma a vapor de etanol e a seletividade dos produtos foi dependente do tipo do catalisador avaliado. De acordo com os resultados obtidos, destaca-se o catalisador não suportado LaNiO3, com conversão de etanol de 99% e seletividade para H2, CO e CO2 de 4,8; 1,1 e 1,3, respectivamente. Além disso, o ensaio com dois catalisadores simultâneos (LaNiO3 + LaCoO3) foi o que apresentou melhor estabilidade na reação, com 100% de conversão de etanol e seletividade semelhante à obtida pelo catalisador LaNiO3. / In this work, the catalytic activity of perovskite oxides, LaNi1-xCoxO3, was evaluated in the ethanol steam reforming. Due to the low surface area, characteristic of perovskite oxides, these catalysts were supported on SiO2, AI2O3 and ZrO2 and the effect of the support was evaluated. The catalysts were prepared by the co-precipitation method and characterized by Atomic Induced Plasma Spectroscopy, X-Ray Powder Diffraction (XRD), Nitrogen adsorption by B.E.T. method, Temperature Programmed Reduction (TPR) and X-ray Absorption Near Edge Structure (XANES).<br /> The catalytic process was accompanied by XANES in situ to verify changes in the oxidation state of the active phase during the activation process with H2 and also during the process of steam reforming of ethanol. By relation of these results with TPR and XRD, for samples partially and fully reduced, it was proposed a mechanism for the reduction of the perovskite oxides during the conditions of activation.<br /> All catalysts showed activity for the ethanol steam reforming with the selectivity dependent of the catalyst evaluated. Summarizing, the results showed that the unsupported catalyst LaNiO3 presented the better performance, with the ethanol conversion of 99% and selectivity for H2, CO and CO2 of 4.8; 1.1 and 1.3, respectively. Moreover, the test using two simultaneous catalysts (LaNiO3 + LaCoO3), showed better stability in the reaction, presenting ethanol conversion of 100% and selectivity to H2, CO and CO2 similar to the LaNiO3 catalyst.