Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-14Bitstream added on 2014-06-13T20:35:17Z : No. of bitstreams: 1 leite_mp_me_guara.pdf: 5697159 bytes, checksum: 3d01e115bf6ba84fde15df65623ceef4 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foi realizado o estudo da fragilização pelo hidrogênio em um tubo de aço API 5L X65 de alto grau de limpidez para uso em dutos de condução para aplicação em ambientes que contém gás sulfídrico. Ensaios normalizados foram realizados com o objetivo de caracterizar as propriedades do material em estudo, através de análise química, análise microestrutural, ensaios mecânicos - dureza, tração, impacto e drop weight (DWTT), ensaios de corrosão - ensaios de HIC e SSC - e ensaios eletroquímicos - curvas de polarização potenciodinâmica, voltametria cíclica e medições de corrente de permeação de hidrogênio. Os resultados apresentaram: a) microestrutura refinada predominante de ferrita acicular, b) caracterização mecânica com resultados dentro do especificado pela norma de fabricação, c) análise química e ensaios de corrosão com resultados superando os requisitos da norma de fabricação e d) nos ensaios eletroquímicos foi evidenciado que o aço em estudo apresentou uma baixa corrente de permeação e uma maior resistência à corrosão em meio de NaCl 3,5% em relação a um aço padrão. Os resultados indicam que o material em estudo atende os critérios da norma de fabricação do tubo (API 5L), sendo evidenciado que o mesmo é adequado para utilização ao ambiente que lhe é proposto / In this paper, it was carried out a study of a hydrogen embrittlement in a pipe API 5L X65 with high level of cleanness for linepipe used in sour service environment.. It was performed standardized testing in order to perform an assessment of the material properties, through the chemical analysis and microstructural analysis, mechanical tests – hardness, tensile, impact and drop weight tear test (DWTT), corrosion tests - HIC and SSC tests - and electrochemical tests - potentiodynamic polarization curves, cyclic voltammetry and hydrogen permeation current measurements. The results presented: a) refined microstructure predominant of acicular ferrite, b) mechanical characterization with results that fulfilled with the pipe fabrication standard, c) chemical analysis and corrosion tests with results exceeding the requirements of the standard and d) electrochemical tests showing the studied steel presenting a low permeation current and a higher corrosion resistance in a environment of NaCl 3,5% in relation of standard steel. The results indicate that the studied material complies with the acceptance criteria of the pipe fabrication standard (API 5L), and it was evidenced that the material is suitable for use in sour service environment

This thesis describes an electrochemical investigation of the processes occurring at the hydrogen evolving cathode during the industrial production of fluorine in molten KF–2HF. A 1A laboratory cell, designed for the purposes of the project, is described. Observations of the operation of this cell are reported. A comparison of a range of electrode materials is given, both with regard to electrochemical overvoltage and the bubbling releasing characteristics, for which photographic evidence is presented. In addition, measurements of the ohmic potential drop, caused by the presence of bubbles, were made for different bubble types. Included in the above is a description of any effects of metallic impurities present in the melt both on overvoltage and bubble release. A mechanistic study of hydrogen evolution on platinum is described and compared with the reaction at a mild steel electrode. A preliminary investigation into the use of parallel strand expanded metal electrodes was made and further photographic evidence presented.

This thesis is concerned with the preparation of regiospecifically labelled compounds by homogeneous metal catalysed hydrogen isotope exchange reactions. The features of homogeneous hydrogen isotope exchange reactions are discussed in Chapter 1, along with other exchange methods; acid, base, heterogenous metal, radiation, enzymic and zeolite catalysis. In Chapter 2, homogeneous rhodium trichloride is investigated for regiospecificity of tritium labeling in a wide range of aromatic compounds. High regiospecificity of labelling ortho to carboxyl, carboxamide and methanamide groups is found, with the regiospecificity determined by 3H nmr spectroscopy. Also discussed is a study to determine whether any other Group VIII metal complexes will catalyse the ortho tritiation of benzoic acid, in addition to rhodium trichloride. The results of detritiation studies performed on benzoic acids using ruthenium acetylacetonate as catalyst as a model for rhodium trichloride are presented in Chapter 3, A possible reaction mechanism is also presented. Finally, an application of the rhodium trichloride system to the labelling of biologically useful molecules is discussed in Chapter 4. The deuteration and tritiation of a number of drugs and metabolites containing known ortho directing groups is described. In a large number of cases, the regiospecificity for ortho labelling is very high.

Hydrogen is considered a possible alternative to fossil fuels. Hydrogen can be produced through dark fermentation with 1 mol hexose yielding a maximum of 4 mol hydrogen in association with acetate production, and 2 mol hydrogen in association with butyrate production. However, an economically and technically feasible process is yet to be established. So far research into fermentative hydrogen production has focused on pure and soluble carbohydrates, particularly glucose. To reduce substrate costs, use of more complex low-cost co- and waste products of the food industry or biomass crops which have undergone minimum pre-treatment would be desirable. Also, whilst much research to date has focused on use of pure bacterial strains, an easily obtainable mixed microflora would be preferable to avoid costs of substrate sterilisation. Therefore this research project focused on fermentative hydrogen production from three abundant (in the UK) low cost substrates, namely a wheat starch co-product, sugarbeet and perennial ryegrass. Anaerobic digester sludge obtained from the local sewage works was used as inoculum in a continuously stirred tank reactor. Production of hydrogen and other fermentation products was measured to gain information about the main metabolic pathways used. To lower hydrogen partial pressure the reactor was sparged with nitrogen and the effect on hydrogen production observed. It was demonstrated that stable fermentative hydrogen production from the wheat starch co-product and sugarbeet water extract was possible in continuous operation. Hydrogen production from grass extract was demonstrated in batch mode. Sparging with nitrogen significantly increased hydrogen yields, by 46% for the wheat starch co-product, by 67% for sugarbeet water extract, and by 184% for ryegrass extract. Maximum yields achieved were 1.9 mol hydrogen per mol hexose converted for 16 days on starch, 1.7 mol per mol hexose converted for 5 days on sugarbeet water extract and 0.8 mol hydrogen per mol hexose converted in batch from grass extract. Therefore up to 48% of the maximum theoretical hydrogen yield was produced. Various factors were identified as preventing higher hydrogen yields. Hydrogen production was more closely related to butyrate than acetate concentration. Also, lactate, ethanol and propionate, which are products of carbohydrate fermenting metabolic pathways that do not produce hydrogen, were detected, as were signs of hydrogen consuming homoacetogenesis in continuous operation.

The conformational equilibria in disubstituted cyclohexanes containing polar groups lead to a diversity of conformational forms. In solution, the conformational preference is shown to be highly dependent upon the nature of the solvent. In the cyclohexandiol series, the formation of intramolecular and intermolecular hydrogen bonds determines the conformational preference with regard to the molecule as a whole and with respect to the rotamer conformation of the hydroxyl groups. Polar solvents capable of hydrogen bonding to the hydroxyl group have been shown to influence the position of equilibrium between the alternative chair conformations. In cyclohexanol, the equilibrium is always shifted towards the equatorial conformation. 13C nmr, 1H nmr, solution i.r. and matrix isolation i.r. techniques have been used to determine the conformational structures in the cyclohexandiol series and the nature of the solvent interactions. Two types of solvent interaction have been identified, a hydrogen bonded interaction and a non-bonded dipole interaction. A Computer Graphic Simulation has been used to' quantify the conformational energy differences and to rationalize the experimental results in terms of the Van der Waals repulsion energy. The experimental results give strong evidence that in cis cyclohexan-1,3-diol, two types of internal hydrogen bond exist in the diaxial conformation. The Computer Graphic simulation supports this reasoning on thermodynamic grounds.

1. The preparation, purification and properties of a water-soluble membrane component from S. flava using the synthetic detergent Lubrol L has been described. This fraction contained carotenoid, glucose and peptide, was highly stable to heat and pH extremes, and release of free carotenoid from it proved extremely difficult. The possible effect of the binding of the membrane components within detergent micelles is discussed and the dangers inherent, in the determination of molecular weights, by osmometry or ultracentrifugation, in the presence of detergent have been indicated. 2. The polar carotenoid subfractions from S. flava have been characterised and found to consist of carotenoid, glucose and peptide. The linkage between carotonoid and glucose is presumed to be glycosidic, and a model for the in vivo orientation of the carotenoid complex in the bacterial membrane has been proposed. A possible correlation between membrane stability and carotenoid content has been found, and this is discussed in relation to the model. 3. After complete removal of the free pigments from S. morrhuae by solvent extraction, a water soluble carotenoid fraction was isolated and characterised. The material, whose molecular weight is approximately 9,000 contains carotenoid, glucose and peptide. The bond between glucose and carotenoid is again presumed to be glycosidlc, and the peptide moiety contains high proportions of the acidic amino acids, the significance of which is discussed. This bound pigment is also thought to represent one form in which: carotenoid is bound in the bacterial membrane. 4. The effect of the age of the culture on the chemical composition of the total membrane fraction from S. flava has been investigated. Both protein and lipid contents decrease with age although there is little variation in carbohydrate content. It is suggested that the decreased lipid content is a reflection of the increased binding of lipid to protein with age. Considerable variation in the fatty acid composition with age was observed, which makes the use of the fatty acid profile as a taxonomic criterion for this species of doubtful value. The presence of a sterol in S. flava membrane lipids is indicated although from GLC data, it seems unlikely that this is cholesterol. Mono-saccharides detected in membrane hydrolysates were ribose, rhamnose, glucose, and mannose. The presence of glucosamine and galactosamine was also indicated. 5, The general ultrastructural features of whole cells of both S. flava and S. morrhuae have been described. S. flava exhibits many of the fine structural features common to Gram-positive organisms and was seen to form the packets of cells typical of the Sarcinae. Cell division in S. flava was shown to be of the cell membrane septation type, and a mechanism for this mode of division has been proposed. Preparation of protoplasts from S. flava using the method of Baird-Parker and Woodroffe (1967) was unsuccessful, but the treatment with lysozyme, revealed a layered appearance of the cell wall. Several intracytoplasmic membranous inclusions were seen in these cells and their relationship to mesosomes is discussed. Mesosomes as such were also present, but never in association with developing septa. The effect of varying conditions of fixation on the fine structure of S. flava was also studied. Evidence has been presented that, under certain conditions, sporulation may occur in S. flava. Good fixation of S. morrhuae cells proved difficult to achieve, and this may be due to insufficient concentration of salts in the fixation medium. Cells of S. morrhuae are approximately twice the size of S. flava cells, and division was seen to occur in a much more random fashion, producing irregular clumps of cells with common cell walls. Spherical or ovoid bodies of unknown composition were seen in association with the cytoplasmic membrane.

The infrared spectra of mixtures of HC1 and the following have been recorded in the gas phase and low temperature matrices: argon, ethene, ethyne, de-benzene, fluorobenzene, CO, CO 2 , SOz, CC1*, CHCls, de-acetone, ethanal, HCN and acrylonitrile. The features which have been measured are: firstly the changes in the integrated intensity of lines in the rotation-vibration spectrum of the fundamental HC1 band as a function of interactions with other components of the mixture, and secondly bands associated with specific interactions forming hydrogen-bonded complexes. The enhancement of HC1 is generally found to vary linearly with the pressure of added gas over a limited pressure range. Assuming that line enhancement is caused by collisionally-induced rotation-translation energy exchange to or from the HC1 molecule, a combination of expressions derived from Ehrenfest's Adiabatic Principle and the "rigid rotor" approximation leads to a model which qualitatively predicts the enhancements observed. The model also rationalises the enhancement of HCN and SOa absorptions by HC1. Examination of the experimentally determined data leads to the conclusion that the total intermolecular force between the monomer base and HC1 controls the degree of enhancement but it is concluded that there is no general connection between the degree of HC1 enhancement and hydrogen-bond strength. Hydrogen-bonded complexes were examined in the gas and argon matrix phases and the shifts in the modified hydrogen chloride stretch compared for various bases. The spectra of pi-complexes formed between HC1 and ethene, ethyne and benzene were found to be detectable by low-resolution infrared spectroscopy at room temperature. Complexation of HCN, he-acetone and de-acetone with HC1 caused CN and C=O band shifts. The Chem-X molecular modelling program was evaluated by using it to predict the geometry of simple complexes for which experimental data is already available. It is concluded that the program requires more development before it can be confidently used as a theoretical aid with which to study hydrogen-bonded dimers.

This research work presents the thermodynamic analysis of hydrogen production using steam methane reforming process at different conditions. The model is developed using HSC 4.1 software and spreadsheet. Methane is chosen to represent the carbonaceous fuel and steam methane reforming process (once through and cyclic) for hydrogen production is analyzed based on 1st law and 2nd law of thermodynamics i.e., energetic and exergetic efficiencies. The mass, energy and exergy analysis of each step is done. The optimal condition for production of maximum hydrogen is found using CO2 removal agent and O2 transfer compound. The efficiency is calculated as a function of steam content, temperature and amount of CO2 removal agent and O2 transfer compound. The pressure is kept constant at one atmosphere. Operating temperature, CaO loading, Fe2O3 loading and H2O content is determined from the once through process. It is found that the maximum H2 production is with the cyclic process. Maximum H2 produced in cyclic process with CaO & Fe2O3 loadings is 99.2%. Also CO2 content is comparatively lower in cyclic process. Theoretical efficiencies can be used to compare with the available data which will help to minimize the losses in the process. The results can be used as a baseline for the design of H2 production technology. The main aim of this research is to develop a thermodynamic protocol for evaluating hydrogen production processes.

Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-10Bitstream added on 2014-06-13T20:46:44Z : No. of bitstreams: 1 silva_me_dr_guara.pdf: 1609658 bytes, checksum: 0cb4727c6a54e7b5a7d9332744cc30e2 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Neste trabalho se estuda o processo de reforma a vapor de etanol para a produção de hidrogênio avaliando aspectos técnicos, econômicos e ecológicos. Inicialmente são apresentados conceitos e tecnologias referentes à produção de hidrogênio num âmbito geral, realçando o etanol, processos de produção de hidrogênio, aplicações do hidrogênio, reformas a vapor, suportes catalíticos e catalisadores promissores para a reforma a vapor do etanol. Logo após, desenvolve-se uma metodologia para a investigação dos aspectos técnicos relacionados à reforma a vapor do etanol, visando a preparação de catalisadores mono e bimetálicos à base de platina, níquel e cobre (Pt, Ni e Cu) suportado em óxidos de alumina (γ-Al2O3), zircônia (ZrO2), céria (CeO2) e em óxidos mistos (γ-Al2O3-25%ZrO2; γ-Al2O3-25%CeO2; CeO2-25%ZrO2). Em seguida, são apresentados protótipos de reformadores de etanol, assim como, seus componentes, características de funcionamento e resultados de testes experimentais, os quais revelaram uma produção de gás de síntese rico em hidrogênio com 75,24% antes do sistema de purificação e 99,84% de H2 após processo de purificação por adsorção molecular PSA (Pressure Swing Adsorption). Em outra etapa, é estudada a viabilidade econômica, a qual permite avaliar a atratividade de um projeto analisando os custos de investimento, operação e manutenção do reformador de etanol. Além disso, também, é apresentado um estudo de projeção dos custos do hidrogênio, em US$/kWh, para sistemas de reforma a vapor de etanol com capacidades de produção de hidrogênio entre 1 e 1500 Nm3/h. Em ultima etapa, são investigados os aspectos ecológicos, na qual é apresentada uma análise de emissões do processo de reforma e o cálculo da eficiência ecológica, cujo resultado mostra que o processo de produção de hidrogênio via reformador de etanol é uma rota... / This work examines the process of steam reforming of ethanol for hydrogen production by evaluating the technical, economic and ecological aspects. Initially we present concepts and technologies related to hydrogen production in a general context, enhancing the ethanol, hydrogen production processes, applications of hydrogen, steam reforming, catalyst supports and catalysts promising for the ethanol steam reforming. Soon after, it develops a methodology to investigate the technical aspects related to the ethanol steam reforming in order to prepare mono and bimetallic catalysts based on platinum, nickel and copper (Pt, Ni and Cu) supported on γ-alumina (γ-Al2O3), zirconia (ZrO2), ceria (CeO2) and mixed oxides (γ-Al2O3; ZrO2; CeO2; γ-Al2O3-25%ZrO2; γ-Al2O3- 25%CeO2; CeO2-25%ZrO2). Next, ethanol reformers prototypes are presented, as well as their components, operating characteristics and results of experimental tests, which revealed a production of synthesis gas rich in hydrogen with 75,24% and 99,84% of H2, respectively, before the purification system and after purification process by adsorption process of molecular PSA (Pressure Swing Adsorption). In another step, we study the economic feasibility, which allows us to evaluate the attractiveness of a project analyzing the investment and operation and maintenance of ethanol reformer. Furthermore, it is presented a study projecting the costs of hydrogen, in US$kWh for systems of ethanol steam reforming with production capacity of hydrogen between 1 and 1500 Nm3/h. In the last step, we investigated the ecological aspects of the system of ethanol steam reforming, which presents emissions analysis of the reform process and the ecological efficiency calculation, whose result shows that the process of producing hydrogen by ethanol reformer technological route is an environmentally attractive because it has a high ecological efficiency... (Complete abstract click electronic access below)

Resumo: Neste trabalho se estuda o processo de reforma a vapor de etanol para a produção de hidrogênio avaliando aspectos técnicos, econômicos e ecológicos. Inicialmente são apresentados conceitos e tecnologias referentes à produção de hidrogênio num âmbito geral, realçando o etanol, processos de produção de hidrogênio, aplicações do hidrogênio, reformas a vapor, suportes catalíticos e catalisadores promissores para a reforma a vapor do etanol. Logo após, desenvolve-se uma metodologia para a investigação dos aspectos técnicos relacionados à reforma a vapor do etanol, visando a preparação de catalisadores mono e bimetálicos à base de platina, níquel e cobre (Pt, Ni e Cu) suportado em óxidos de alumina (γ-Al2O3), zircônia (ZrO2), céria (CeO2) e em óxidos mistos (γ-Al2O3-25%ZrO2; γ-Al2O3-25%CeO2; CeO2-25%ZrO2). Em seguida, são apresentados protótipos de reformadores de etanol, assim como, seus componentes, características de funcionamento e resultados de testes experimentais, os quais revelaram uma produção de gás de síntese rico em hidrogênio com 75,24% antes do sistema de purificação e 99,84% de H2 após processo de purificação por adsorção molecular PSA (Pressure Swing Adsorption). Em outra etapa, é estudada a viabilidade econômica, a qual permite avaliar a atratividade de um projeto analisando os custos de investimento, operação e manutenção do reformador de etanol. Além disso, também, é apresentado um estudo de projeção dos custos do hidrogênio, em US$/kWh, para sistemas de reforma a vapor de etanol com capacidades de produção de hidrogênio entre 1 e 1500 Nm3/h. Em ultima etapa, são investigados os aspectos ecológicos, na qual é apresentada uma análise de emissões do processo de reforma e o cálculo da eficiência ecológica, cujo resultado mostra que o processo de produção de hidrogênio via reformador de etanol é uma rota... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work examines the process of steam reforming of ethanol for hydrogen production by evaluating the technical, economic and ecological aspects. Initially we present concepts and technologies related to hydrogen production in a general context, enhancing the ethanol, hydrogen production processes, applications of hydrogen, steam reforming, catalyst supports and catalysts promising for the ethanol steam reforming. Soon after, it develops a methodology to investigate the technical aspects related to the ethanol steam reforming in order to prepare mono and bimetallic catalysts based on platinum, nickel and copper (Pt, Ni and Cu) supported on γ-alumina (γ-Al2O3), zirconia (ZrO2), ceria (CeO2) and mixed oxides (γ-Al2O3; ZrO2; CeO2; γ-Al2O3-25%ZrO2; γ-Al2O3- 25%CeO2; CeO2-25%ZrO2). Next, ethanol reformers prototypes are presented, as well as their components, operating characteristics and results of experimental tests, which revealed a production of synthesis gas rich in hydrogen with 75,24% and 99,84% of H2, respectively, before the purification system and after purification process by adsorption process of molecular PSA (Pressure Swing Adsorption). In another step, we study the economic feasibility, which allows us to evaluate the attractiveness of a project analyzing the investment and operation and maintenance of ethanol reformer. Furthermore, it is presented a study projecting the costs of hydrogen, in US$kWh for systems of ethanol steam reforming with production capacity of hydrogen between 1 and 1500 Nm3/h. In the last step, we investigated the ecological aspects of the system of ethanol steam reforming, which presents emissions analysis of the reform process and the ecological efficiency calculation, whose result shows that the process of producing hydrogen by ethanol reformer technological route is an environmentally attractive because it has a high ecological efficiency... (Complete abstract click electronic access below) / Orientador: José Luz Silveira / Coorientadora: Marivone Nunho Sousa / Banca: Celso Eduardo Tuna / Banca: Roberto Zenhei Nakazato / Banca: Adonis Marcelo Saliba Silva / Banca: Gilmar Clemente Silva / Doutor