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Efeito do gadolínio nas propriedades catalíticas de óxidos de ferro na reação de WGSSilva, Caio Luis Santos January 2012 (has links)
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Previous issue date: 2012 / CAPES / Devido à necessidade de garantir o suprimento de energia através de
tecnologias de conversão de energia mais limpas e mais eficientes, reduzindo a
emissão de gases causadores do efeito estufa, o interesse pela reação de
deslocamento de monóxido de carbono com vapor d´água (WGSR, water gas shift
reaction) tem aumentado, especialmente devido ao seu papel nas células a
combustível. A fim de obter catalisadores alternativos para essa reação, foi estudado
o efeito da adição e do teor de gadolínio nas propriedades de catalisadores de óxido
de ferro. As amostras foram preparadas pela hidrólise de nitrato de ferro e de
gadolínio, seguida da lavagem do gel com uma solução de acetato de amônio para
obter magnetita e com água para obter hematita. As amostras foram caracterizadas
por termogravimetria, calorimetria diferencial de varredura, espectroscopia no
infravermelho com transformada de Fourier, difração de raios X, medida da área
superficial específica (B.E.T.) e redução à temperatura programada. Os
catalisadores foram avaliados na WGSR a 1 atm, na faixa de 250 a 400 ºC, usando
uma razão molar vapor d´água/gás de processo (3,7% CO, 3,7% CO2, 22,2% H2,
70,4% N2) igual a 0,6. As fases hematita e ferrita de gadolínio foram detectadas em
todos os sólidos lavados com água, enquanto magnetita e ferrita de gadolínio foram
encontradas naqueles lavados com acetato de amônio. No primeiro caso, a área
superficial específica aumentou devido ao gadolínio, independente do seu conteúdo,
um fato que foi relacionado ao seu papel como espaçador e/ou a uma causa de
tensões na rede, produzindo partículas menores. Entretanto, em todos os sólidos
baseados em magnetita, o gadolínio conduziu a uma diminuição da área superficial
específica, devido à predominância da perovskita (ferrita de gadolínio), que
apresenta valores tipicamente baixos. A adição de gadolínio facilita a redução de
espécies Fe3+, em todos os catalisadores, mas aumenta a atividade apenas
naquelas aquecidas sob ar. O sólido com Gd/Fe=0,1, aquecido sob ar, mostrou a
mais alta atividade, provavelmente devido à area superficial específica aumentada
devido ao gadolínio, que também facilitou a redução do ferro, tornando o ciclo redox
mais fácil durante a WGSR. Além disso, os catalisadores baseados em hematita
mostraram as atividades mais elevadas. Isto pode ser atribuído à predominância de
hematita nesses sólidos, quando comparados a outros nos quais a ferrita de
gadolínio foi a fase predominante. Isto significa que as espécies Fe3+, no ambiente
da hematita, são mais ativas na reação de WGS que as espécies Fe4+, no ambiente
da perovskita / Salvador
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Hydrodesulphurization of Light Gas Oil using Hydrogen from the Water Gas Shift ReactionAlghamdi, Abdulaziz January 2009 (has links)
The production of clean fuel faces the challenges of high production cost and complying with stricter environmental regulations. In this research, the ability of using a novel technology of upgrading heavy oil to treat Light Gas Oil (LGO) will be investigated. The target of this project is to produce cleaner transportation fuel with much lower cost of production.
Recently, a novel process for upgrading of heavy oil has been developed at University of Waterloo. It is combining the two essential processes in bitumen upgrading; emulsion breaking and hydroprocessing into one process. The water in the emulsion is used to generate in situ hydrogen from the Water Gas Shift Reaction (WGSR). This hydrogen can be used for the hydrogenation and hydrotreating reaction which includes sulfur removal instead of the expensive molecular hydrogen. This process can be carried out for the upgrading of the bitumen emulsion which would improve its quality.
In this study, the hydrodesulphurization (HDS) of LGO was conducted using in situ hydrogen produced via the Water Gas Shift Reaction (WGSR). The main objective of this experimental study is to evaluate the possibility of producing clean LGO over dispersed molybdenum sulphide catalyst and to evaluate the effect of different promoters and syn-gas on the activity of the dispersed Mo catalyst.
Experiments were carried out in a 300 ml Autoclave batch reactor under 600 psi (initially) at 391oC for 1 to 3 hours and different amounts of water. After the hydrotreating reaction, the gas samples were collected and the conversion of carbon monoxide to hydrogen via WGSR was determined using a refinery gas analyzer. The sulphur content in liquid sample was analyzed via X-Ray Fluorescence.
Experimental results showed that using more water will enhance WGSR but at the same time inhibits the HDS reaction. It was also shown that the amount of sulfur removed depends on the reaction time. The plan is to investigate the effect of synthesis gas (syngas) molar ratio by varying CO to H2 ratio. It is also planned to use different catalysts promoters and compare them with the un-promoted Mo based catalysts to achieve the optimum reaction conditions for treating LGO.
The results of this study showed that Ni and Co have a promoting effect over un-promoted Mo catalysts for both HDS and WGSR. Ni was found to be the best promoter for both reactions. Fe showed no significant effect for both WGSR and HDS. V and K have a good promoting effect in WGSR but they inhibited the HDS reaction. Potassium was found to be the strongest inhibitor for the HDS reaction since no sulfur was removed during the reaction
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Hydrodesulphurization of Light Gas Oil using Hydrogen from the Water Gas Shift ReactionAlghamdi, Abdulaziz January 2009 (has links)
The production of clean fuel faces the challenges of high production cost and complying with stricter environmental regulations. In this research, the ability of using a novel technology of upgrading heavy oil to treat Light Gas Oil (LGO) will be investigated. The target of this project is to produce cleaner transportation fuel with much lower cost of production.
Recently, a novel process for upgrading of heavy oil has been developed at University of Waterloo. It is combining the two essential processes in bitumen upgrading; emulsion breaking and hydroprocessing into one process. The water in the emulsion is used to generate in situ hydrogen from the Water Gas Shift Reaction (WGSR). This hydrogen can be used for the hydrogenation and hydrotreating reaction which includes sulfur removal instead of the expensive molecular hydrogen. This process can be carried out for the upgrading of the bitumen emulsion which would improve its quality.
In this study, the hydrodesulphurization (HDS) of LGO was conducted using in situ hydrogen produced via the Water Gas Shift Reaction (WGSR). The main objective of this experimental study is to evaluate the possibility of producing clean LGO over dispersed molybdenum sulphide catalyst and to evaluate the effect of different promoters and syn-gas on the activity of the dispersed Mo catalyst.
Experiments were carried out in a 300 ml Autoclave batch reactor under 600 psi (initially) at 391oC for 1 to 3 hours and different amounts of water. After the hydrotreating reaction, the gas samples were collected and the conversion of carbon monoxide to hydrogen via WGSR was determined using a refinery gas analyzer. The sulphur content in liquid sample was analyzed via X-Ray Fluorescence.
Experimental results showed that using more water will enhance WGSR but at the same time inhibits the HDS reaction. It was also shown that the amount of sulfur removed depends on the reaction time. The plan is to investigate the effect of synthesis gas (syngas) molar ratio by varying CO to H2 ratio. It is also planned to use different catalysts promoters and compare them with the un-promoted Mo based catalysts to achieve the optimum reaction conditions for treating LGO.
The results of this study showed that Ni and Co have a promoting effect over un-promoted Mo catalysts for both HDS and WGSR. Ni was found to be the best promoter for both reactions. Fe showed no significant effect for both WGSR and HDS. V and K have a good promoting effect in WGSR but they inhibited the HDS reaction. Potassium was found to be the strongest inhibitor for the HDS reaction since no sulfur was removed during the reaction
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[en] INTERNATIONAL STANDARDIZATION AND ORGANIZATIONAL LEARNING IN COMPLEX ADAPTIVE SYSTEMS: THE CASE OF ISO 26000 SOCIAL RESPONSIBILITY STANDARD / [pt] NORMALIZAÇÃO INTERNACIONAL E APRENDIZAGEM ORGANIZACIONAL EM SISTEMAS ADAPTATIVOS COMPLEXOS: O CASO DA NORMA DE RESPONSABILIDADE SOCIAL ISO 26000EDUARDO CAMPOS DE SAO THIAGO 11 July 2013 (has links)
[pt] O objetivo da dissertação é analisar a dinâmica de aprendizagem
organizacional (AO) relativa ao processo de elaboração da Norma Internacional
de Responsabilidade Social (ISO 26000), segundo a perspectiva da complexidade
social. No contexto da normalização internacional e à luz dos desafios estratégicos
enfrentados pela ISO referentes à governança global, parte-se do pressuposto de
que a abordagem da complexidade social de AO pode contribuir para uma melhor
compreensão do papel da aprendizagem na formação de consenso em dois níveis:
entre as diversas categorias de stakeholders e entre países. A metodologia de
pesquisa compreende: (i) revisão bibliográfica e documental sobre normalização
internacional; sistemas adaptativos complexos; e aprendizagem organizacional,
com especial atenção para abordagens integradoras; (ii) descrição do processo de
desenvolvimento da norma internacional ISO 26000; (iii) proposição de modelo
conceitual que integra normalização internacional e aprendizagem organizacional,
segundo a perspectiva da complexidade social; (iv) pesquisa survey junto a
especialistas do Grupo de Trabalho ISO-TMB-WG SR e de seu comitê espelho
brasileiro; e (v) estudo de caso de AO no processo de elaboração da Norma
Internacional ISO 26000, com resultados da pesquisa survey. Esses resultados
incluem: (i) a análise da dinâmica de AO relativa ao processo de elaboração da
norma ISO 26000; (ii) relação dos principais fatores facilitadores de AO neste
caso, considerando os dois níveis de análise; e (iii) recomendações endereçadas à
ISO e à ABNT para futuros desenvolvimentos de normas internacionais em
ambientes sociais complexos. / [en] The main objective of this dissertation is to analyze the learning dynamics
and the specific learning mechanisms experimented by the different groups during
the development process of ISO 26000 standard, through the lens of the social
complexity perspective of organizational learning (OL). In the context of ISO
26000’s learning process, it was assumed that the social complexity perspective of
organizational learning (OL) could be especially useful as it can improve the
understanding of the role of learning in a double level of consensus – amongst
stakeholders and across countries – in the light of the strategic challenges faced by
ISO within the global governance arena. The research methodology comprises: (i)
bibliographical and documental review on international standardization; social
complex adaptive systems; organizational learning, with special attention to
integrative approaches; (ii) review of the development process of ISO 26000
standard; (iii) design of a conceptual model that integrates the international
standardization and organizational learning, through the lens of the social
complexity perspective; (iv) development and application of a survey
questionnaire to representatives of ISO-TMB-WG SR, including its Brazilian
Mirror Committee; and (v) description of ISO 26000 study case. The main
results can be summarized as follows: (i) learning dynamics analysis of the
development process of ISO 26000 standard; (ii) list of main facilitating and
constraining factors for OL in this case; and (iii) recommendations addressed to
ISO regarding future international standardization processes in social complex
environments.
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Efeito do agente precipitante nas propriedades de catalisadores de hematita contendo alumínio e cobreBraga, Cláudio Taranto Lima 10 February 2014 (has links)
Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2014-09-09T17:09:12Z
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DISSERTAÇÃO - CLÁUDIO TARANTO.pdf: 18450159 bytes, checksum: 76f9d1c02e4cdba72b38d11a61fcc786 (MD5) / Considerando a busca por tecnologias mais limpas e sustentáveis, o hidrogênio surge como
uma das fontes de energia mais práticas e sustentáveis do futuro. Esse combustível é obtido
comercialmente pela reforma de gás natural, seguido de uma etapa de purificação, conhecida
como conversão de monóxido a dióxido de carbono com vapor d’água (reação de HTS, High
Temperature Shift). Os catalisadores comerciais empregados nessa reação são constituídos
por hematita (-Fe2O3) contendo cromo hexavalente, um íon tóxico aos seres humanos e ao
meio ambiente. Por essa razão, diversas pesquisas têm sido desenvolvidas visando a
substituir o cromo nesses sólidos. Com o objetivo de otimizar as propriedades de catalisadores
baseados em hematita contendo alumínio (Fe/Al=10) e cobre (Fe/Cu=10) para a reação de
HTS, neste trabalho, estudou-se o efeito do agente precipitante sobre as propriedades desses
sólidos. As amostras foram preparadas através do processo sol-gel, misturando-se soluções
de nitrato férrico e nitrato de alumínio e usando diferentes agentes precipitantes (hidróxido de
sódio e hidróxido de amônio), seguida de impregnação com solução alcoólica de cobre. Os
sólidos foram caracterizados por termogravimetria, espectroscopia no infravermelho com
transformada de Fourier, difração de raios X, medida de área superficial específica e de
porosidade, redução à temperatura programada e espectroscopia Mössbauer. Os
catalisadores foram avaliados na reação de HTS a 1 atm e 400 °C. Observou-se a formação
da hematita e magnetita nos catalisadores antes e após a reação, respectivamente, não se
detectando nenhuma outra fase. Os dopantes foram inseridos na rede do óxido de ferro, o
que pode ser explicado pela similaridade dos raios iônicos das espécies Cu+2, Al+3 e Fe+3;
esse processo foi facilitado pelo hidróxido de amônio. Quando presentes isoladamente, o
alumínio e o cobre aumentaram a área superficial específica dos sólidos obtidos com hidróxido
de amônio mas o hidróxido de sódio inibiu a ação textural do cobre e alumínio, juntos ou
isoladamente. O hidróxido de amônio favoreceu o desenvolvimento de mesoporos
interparticulares nos sólidos macroporosos obtidos. A redutibilidade da hematita foi alterada
pela presença dos dopantes e pela natureza do agente precipitante; o alumínio dificultou a
formação da magnetita (Fe3O4) e do ferro metálico enquanto o cobre e o hidróxido de amônio
facilitaram esses processos. Dessa forma, a presença simultânea dos dopantes favoreceu a
formação da fase ativa (magnetita) e a estabilidade do catalisador, retardando sua
desativação pela formação de ferro metálico. Todos os catalisadores foram ativos na reação
de HTS, mas aqueles contendo cobre, e obtidos com hidróxido de sódio, foram os mais ativos,
devido a um aumento na atividade dos sítios ativos e à maior facilidade de formação da fase
ativa (magnetita). O papel do alumínio foi relacionado ao aumento da resistência dos
catalisadores à redução da fase ativa. O catalisador mais promissor foi aquele preparado com
hidróxido de sódio, que apresentou elevada atividade (10,68 x 10-7 mol.s-1.g-1) e alta
resistência à redução da fase ativa (magnetita), com a vantagem de não ser tóxico, podendo
ser manuseado e descartado sem risco à saúde humana e ao meio ambiente. / Considering the search for cleaner and more sustainable technologies, hydrogen emerges as
one of the most practical and sustainable energy source in the future. This fuel is commercially
obtained by natural gas reforming, followed by a purification step known as the water gas shift
reaction at high temperatures (HTS, High Temperature Shift). The commercial catalysts for
this reaction are composed of hematite (-Fe2O3) containing hexavalent chromium, a toxic ion
to humans and the environment. For this reason, many studies have been carried out aiming
to replace chromium in these solids. In order to optimize the properties of catalysts based on
hematite containing aluminum (Fe/Al= 10) and copper (Fe/Cu= 10) for the HTS reaction, the
effect of precipitating agent on the properties of these solids was studied in this work. Samples
were prepared by sol-gel process by mixing solutions of iron nitrate and aluminum nitrate and
using different precipitating agents (sodium hydroxide and ammonium hydroxide) and
impregnated with an alcoholic solution of copper. The solids were characterized by
thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffraction, specific surface
area and porosity measurement, temperature programmed reduction and Mössbauer
spectroscopy. The catalysts were evaluated in the HTS reaction at 1 atm and 400 °C. It was
found hematite and magnetite in the catalysts before and after reaction, respectively and no
other phase was detected. The dopants were found to be into the iron oxide lattice, a fact that
was explained by the similarity of the ionic radii of Cu+2, Al+3 and Fe+3 species, this process
being facilitated by ammonium hydroxide. Aluminum and copper alone increased the specific
surface area of the solids obtained with ammonium hydroxide but sodium hydroxide inhibited
the textural action of copper and aluminum, together or separately. Ammonium hydroxide
favored the development of nterparticlemesopores in the macroporous solids obtained. The
reducibility of hematite was changed by the dopants and by the kind of the precipitating agent,
aluminum hindering the formation of magnetite (Fe3O4) and metallic iron while copper and
ammonium hydroxide facilitated this process. Therefore, the dopants favored the formation of
active phase (magnetite) and the catalyst stability, delaying its deactivation through the
formation of metallic iron. All catalysts were active in HTS reaction, those containing copper
and obtained with sodium hydroxide being the most active ones, due to increase in the activity
of the active sites and the ease of formation of active phase (magnetite). The role of aluminum
was related to increased resistance to reduction of the active phase. The most promising
catalyst was the one prepared with sodium hydroxide, which showed high activity (10.68 x 10-
7 mol.s-1.g-1) and high resistance against the reduction of the active phase (magnetite), with
the advantage of being non-toxic and can be handled and disposed without risk to human
health and the environment.
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