No presente trabalho foi proposta a construção de eletrodos de níquel e algumas ligas (Sn, Ru), assim como de materiais nanoestruturados, para a determinação de etanol em amostras de bebidas e medicamentos. Para isto, foram utilizadas técnicas como a voltametria cíclica, a cronoamperometria, a espectroscopia de impedância eletroquímica, a microscopia de força atômica e a microscopia de transmissão. O eletrodo da liga Ni-Sn foi preparado por eletrodeposição, utilizando um banho de Watts contendo 6,25 g de NiCl2.6H2O e 0,5 g de SnCl2.2H2O em 25 mL de solução aquosa. Os depósitos foram modificados com RuO2, utilizando uma solução RuCl3 0,1 M. O eletrodo da liga foi deixado na solução em banho de ultrasson e posteriormente aquecido a 400ºC em forno em presença de oxigênio, para a decomposição térmica. O Ni nanoestruturado foi preparado a partir de uma solução contendo 1,8 g NiCl2.6H2O dissolvido em 30 mL etanol, adicionando uma mistura de 3,5 g de Zn em pó e 10 mL de aminoetanol, em agitação. A separação do pó preto foi feita com uma placa magnética. Para a confecção do eletrodo foi adicionada uma alíquota 10 mL da solução contendo o pó, náfion e etanol, na superfície do eletrodo de grafite pirolítico. Os perfis voltamétricos foram analisados em meio de hidróxido de sódio 0,5 M, podendo-se assim observar as reações de oxi-redução característica do Ni, da liga Ni-Sn, da liga modificada com RuO2 e da nanoestrutura. Foi utilizado intervalo de potencial de 100 a 700 mV com velocidade de 50 mVs-1. As medidas de impedância eletroquímica foram realizadas em sistemas com etanol com o intuito único de demonstrar a presença de um loop indutivo, que pode ser associado à transformação óxido superior/óxido inferior na superfície do eletrodo. Este loop foi observado para os eletrodos de Ni e liga, não sendo muito evidente para o eletrodo modificado com RuO2. Foram realizadas medidas de AFM para a caracterização topográfica dos eletrodos, mostrando a diferença entre as superfícies, indicando que o Ni liso foi modificado com o eletrodepósito da liga Ni-Sn e que esta também foi modificada pela deposição do RuO2. A morfologia da nanoestrutura foi observada por microscopia eletrônica de transmissão, podendo observar que se obtiveram estruturas de níquel em escala nanométrica. Os eletrodos foram utilizados na determinação de etanol em meio de NaOH 0,5 mol L-2, com a construção de curvas analíticas pelo método da adição consecutiva de alíquotas de etanol, a partir de uma solução estoque. Após a curva analítica ser levantada, foram feitos os tratamentos estatísticos obtendo-se os valores para os limites de detecção e quantificação. Com o eletrodo Ni nanoestruturado obteve-se o melhor resultado sendo este empregado na determinação de etanol nas amostras de conhaque, cachaça e enxaguante bucal, utilizando a técnica de cronoamperometria. A excelente porcentagem de recuperação obtida mostrou que o efeito da matriz, nestas determinações, é praticamente desprezível, o que está de acordo com o mecanismo da reação de oxidação do etanol sobre Ni, fortemente catalisado pela superfície dos eletrodos em estudo. / This objective of this work is related to the development of nickel and some nickel-alloys electrodes, as well as some nanostructured nickel surfaces, for ethanol determinations in drinks and in pharmacological formulations. For this, some experimental techniques were employed, as cyclic voltammetry, cronoamperometry, electrochemical impedance spectroscopy, atomic force microscopy and transmission microscopy. The Ni-Sn alloy electrode was prepared by electrodeposition from a Watts bath containing 6,25 g NiCl2.6H2O and 0,5 g SnCl2.2H2O and water in order to produce 25 mL of aqueous solution. The electrodeposits were further modified with RuO2 obtained from a 0.1 mol L-1 RuCl3 solution. The Ni-Sn alloy electrode were allowed in the ruthenium solution in ultrasonic bath and further heated to 400 oC in the presence of oxygen, in order to promote the thermal decomposition of ruthenium chloride. The nanostructured Ni surface was obtained from a chemical deposition in a solution composed by 1.8 g NiCl2.6H2O dissolved in 30 mL ethanol and adding 3.5 g of powdered Zn and 10 mL of aminoethanolic solution, under mechanical stirring. The black powder precipitated was separated by a magnetic rod. In order to prepare the electrode, with such powder, a 10 mL aliquot of solution containing the Ni powder, Nafion® and ethanol were dipped in a pirolitic graphite surface and allowed to dry. The voltammetric profiles were analyzed in order to evaluate the oxireduction characteristics of Ni surfaces, as well as the Ni-Sn alloy and the RuO2 modified surfaces and the nanostructured one. A potential window between 100 and 700 mV was scanned at 50 mV s-1, in 0.5 mol L-1 NaOH electrolyte. The electrochemical impedance spectroscopy measurements were performed in electrolytes containing ethanol, in order to observe the presence of an inductive loop, which has been associated to the low/high valences Ni oxides formed during ethanol oxidation on such surfaces. This loop was quite evident in Ni surfaces but not on the surfaces modified with RuO2. AFM measurements were performed in order to obtain the topological characteristics of the surfaces, indicating the eventual alterations associated with the RuO2 modifications. The nanostructures morphology was investigated by transmission microscopy were the nanometric dimensions of Ni phases were evident. The developed electrodes were applied in ethanol determinations in 0.5 mol L-1 NaOH solutions, prepared with Milli-Q water. The successive standard additions were used to obtain an analytical plot. After the analytical plot has been obtained, statistical analyses were performed, in order to determine the detection and quantification limits, as well as the errors involved in such determinations. As the Ni nanostructured electrodes yielded the best results, it was used in the determination of ethanol in samples of cognac, \"aguardente\" (sugar cane distilled drink) and mouthwash liquids, using chronoamperometry. The excellent recoveries percentages obtained showed that the matrix effect, in such determinations, was almost depreciable. This is related with the high catalytic power of Ni surfaces towards the ethanol oxidation reaction.

by Zhi-Jie Ni. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 143-153.

by Ka-Man Mak. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / Text in English; abstract also in Chinese. / by Ka-Man Mak. / Acknowledgement --- p.i / Abstract --- p.ii / List of tables --- p.v / List of figures --- p.vi / Table of contents --- p.xi / Chapter Chapter One --- Introduction --- p.1-1 / Chapter 1.1 --- History of intermetallics --- p.1-1 / Chapter 1.2 --- Properties of intermetallic compounds --- p.1-5 / Chapter 1.2.1 --- Magnetic properties --- p.1-5 / Chapter 1.2.2 --- Chemical properties --- p.1-6 / Chapter 1.2.3 --- Semiconducting properties --- p.1-7 / Chapter 1.2.4 --- Superconducting properties --- p.1-7 / Chapter 1.2.5 --- Hydrogen storage --- p.1-8 / References --- p.1-9 / Chapter Chapter Two --- Background --- p.2-1 / Chapter 2.1 --- Some Behaviours of Intermetallics / Chapter 2.1.1 --- Intergranular and cleavage fracture --- p.2-1 / Chapter 2.1.2 --- Corrosion --- p.2-3 / Chapter 2.1.3 --- Oxidation in high-temperature intermetallics --- p.2-5 / Chapter 2.1.4 --- Hot corrosion --- p.2-8 / Chapter 2.2 --- Nickel aluminides --- p.2-9 / Chapter 2.2.1 --- Ni3Al --- p.2-10 / Chapter 2.2.2 --- NiAl --- p.2-12 / References --- p.2-14 / Chapter Chapter Three --- Oxidation --- p.3-1 / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.2 --- Specimens preparation --- p.3-1 / Chapter 3.3 --- Experiment process --- p.3-5 / Chapter 3.3.1 --- Instrumentation --- p.3-5 / Chapter 3.3.2 --- Choosing of experimental temperature --- p.3-9 / Chapter 3.3.3 --- Methodology --- p.3-9 / Chapter 3.4 --- Results and Discussions --- p.3-10 / Chapter 3.4.1 --- Dependence of time --- p.3-10 / Chapter 3.4.2 --- Dependence of temperature --- p.3-14 / Chapter 3.4.3 --- Dependence of composition --- p.3-15 / Chapter 3.4.4 --- Activation energy of oxidation --- p.3-15 / Chapter 3.4.5 --- Oxidation morphology and mechanism --- p.3-16 / Chapter 3.5 --- Conclusions --- p.3-20 / References --- p.3-21 / Chapter Chapter Four --- Hot corrosion --- p.4-1 / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Specimens preparation --- p.4-1 / Chapter 4.3 --- Experiment process --- p.4-3 / Chapter 4.3.1 --- Instrumentation --- p.4-3 / Chapter 4.3.2 --- Choosing of experimental environment and temperature --- p.4-5 / Chapter 4.3.3 --- Methodology --- p.4-6 / Chapter 4.3.3.1 --- Experiment --- p.4-6 / Chapter 4.3.3.2 --- Experimental setup --- p.4-8 / Chapter 4.4 --- Results and discussions --- p.4-9 / Chapter 4.4.1 --- Dependence of time --- p.4-9 / Chapter 4.4.2 --- Dependence of temperature --- p.4-10 / Chapter 4.4.3 --- Comparison between hot corrosion with oxidation --- p.4-11 / Chapter 4.4.4 --- Dependence of composition --- p.4-12 / Chapter 4.4.4.1 --- Comparison between S1 and S2 --- p.4-12 / Chapter 4.4.4.2 --- Comparison between S3- S7 --- p.4-12 / Chapter 4.4.5 --- Results from XRPDS --- p.4-13 / Chapter 4.4.6 --- Study of microstructure --- p.4-13 / Chapter 4.4.6.1 --- Dependence on time --- p.4-14 / Chapter 4.4.6.2 --- Dependence on temperature --- p.4-14 / Chapter 4.4.6.3 --- Dependence on composition --- p.4-14 / Chapter 4.5 --- Corrosion mechanism --- p.4-15 / Chapter 4.5.1 --- Chemical reactions --- p.4-15 / Chapter 4.5.2 --- Corrosion process --- p.4-16 / Chapter 4.5.2.1 --- Temperature effect --- p.4-16 / Chapter 4.5.2.2 --- Composition dependence --- p.4-17 / Chapter 4.6 --- Conclusions --- p.4-18 / References --- p.4-19 / Chapter Chapter Five --- Conclusionsand suggestions for further studies --- p.5-1 / Chapter 5.1 --- Oxidation --- p.5-1 / Chapter 5.2 --- Hot corrosion --- p.5-2 / Chapter 5.3 --- Further development --- p.5-3

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Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by R. Sheldon Carpenter. / B.S.

This Dissertation investigates the kinetics of CO2 methanation over nickel and cobalt catalysts. Methanation was studied for both Ni/γ-Al2O3 and Co/ZrO2 catalysts, which were synthesised using an incipient wetness impregnation technique and subsequently characterised using analyses based on gas adsorption, XRD, TPR and thermogravimetry. Separately a CO hydrogenation reaction, the Fischer-Tropsch process, was modelled numerically to examine the influence of mass transfer in practical, commercial pellets of catalyst. The kinetics of methanation was investigated for Ni/γ-Al2O3 over a wide range of reactant partial pressures using a gradientless, spinning-basket reactor operated in batch mode and in a laboratory-scale, continuous fixed-bed reactor. Langmuir-Hinshelwood kinetic models were developed to represent the observed kinetics in each reactor: these models were then compared. For the batch reactor, a rate expression based the dissociation of a chemisorbed CO intermediate being the rate-limiting step was found to be consistent with the experimental results. However, results from the fixed-bed suggested that the hydrogenation of an adsorbed C atom determined the rate of reaction. These differences in the kinetics on Ni/γ-Al2O3 between the fixed-bed and batch reactors suggest that a Langmuir approach using a single, rate-determining step may not be representative across all conversions. The rate over the Co/ZrO2 catalyst was characterised in the fixed-bed reactor over a range of reactant partial pressures at temperatures between 433 K and 503 K. The rate was observed to be dependent on hydrogen partial pressure and temperature, with the rate increasing with both. Previous research has reported a wide range of values of the apparent activation energy, with a study suggesting it was sensitive to pressure. Accordingly, the apparent activation energy was investigated for pressure sensitivity over a range of pressures between 5 and 15 barg: it was found to be constant. The values determined (~88-91±8 kJ/mol) were notably consistent with those reported for CO hydrogenation on cobalt. Kinetic schemes based on Langmuir-Hinshelwood and power law equations were evaluated, with the results best described by a reaction scheme based on the carbide pathway, with a rate-determining step of CH hydrogenation. A reaction-diffusion model of the Fischer-Tropsch process in a 2-D hollow cylinder was developed and analysed across a range of Thiele moduli and the extents of error in both effectiveness factor and selectivity were quantified relative to one-dimensional sphere and slab analogues. The errors between 2-D and 1-D analogues were found to be most significant between Thiele moduli of ~0.25 and ~3. Hollow cylinder effectiveness factors were bounded by those of sphere and slab above and below Thiele moduli of ~0.75 and ~1.15 respectively for the conditions examined, with the effectiveness factors exceeding those of both sphere and slab models between these moduli. A comparison of the hollow cylindrical pellets against spheres of equivalent volume demonstrated that hollow cylinders provided improved fixed-bed performance, with improved effectiveness factors and selectivities due to the lowered diffusion lengths of the hollow cylindrical geometry.

He, Lisi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 69-73). / Abstracts in English and Chinese. / Acknowledgement --- p.I / Table of Contents --- p.II / Abstract --- p.III / Abstract (Chinese Version) --- p.IV / Abbreviation --- p.V / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- "Synthesis of Terminal 1,1 -Disubstituted Olefins" --- p.1 / Chapter 1.2 --- Nickel Hydride Reactions with Olefins --- p.5 / Chapter 1.3 --- Objective and Approach --- p.16 / Chapter CHAPTER 2 --- RESULTS AND DISCUSSION --- p.20 / Chapter 2.1 --- Reaction Condition Optimization --- p.20 / Chapter 2.2 --- Substrates Scope Expansion --- p.27 / Chapter 2.3 --- Examples of Post-coupling Modifications --- p.35 / Chapter 2.4 --- Application in a sp2-sp3 Heck-like Reaction --- p.38 / Chapter CHAPTER 3 --- CONCLUSION --- p.43 / APPENDIX EXPERIMENTAL --- p.46 / REFERENCE --- p.69 / GC CHROMATOGRAMS & NMR SPECTRA FOR NEW COMPOUNDS