A fermentação anaeróbia da matéria orgânica produz uma mistura de gases chamada biogás. Este biogás contém CH4 e CO2 como componentes majoritários. Estes dois compostos são gases de efeito estufa e sua utilização é muito importante do ponto de vista ambiental e econômico. O presente trabalho teve por objetivo produzir gás de síntese (H2/CO), uma matéria prima de alto valor industrial, a partir da reforma oxidativa do biogás com adição de oxigênio (1,5CH4+1,0CO2+0,25O2) sobre catalisadores de NiO-MgO-ZrO2 e NiO-Y2O3-ZrO2. Os catalisadores foram preparados usando o método de polimerização numa única etapa e foi estudada a variação do teor de MgO e de Y2O3 contido nas amostras. Estes materiais foram caracterizados por DRX, RTP, Adsorção-dessorção de N2, XPS, XAS-XANES, MEV e EDX e foram avaliados na reação de reforma oxidativa de um biogás modelo (composição molar:1,5 CH4/1CO2) em presença de oxigênio, a 750&deg;C e 1atm, visando à obtenção de gás de síntese. Os teores de MgO utilizados no sistema NiO/MgO/ZrO2 foram de 0%, 4%, 20%, 40% e 100% em relação ao ZrO2 (os mesmos teores foram utilizados para Y2O3 no sistema NiO/Y2O3/ZrO2) e o teor mássico de Ni foi 20%. As análises de DRX, TPR, XPS confirmaram a formação das soluções sólidas NiO-MgO e MgO-ZrO2 nos catalisadores NiO-MgO-ZrO2, e das soluções sólidas NiO-Y2O3 e Y2O3-ZrO2 nos catalisadores NiO-Y2O3-ZrO2. Estas soluções sólidas juntas, nos correspondentes catalisadores, melhoraram o desempenho catalítico, levando a altos valores de conversão e baixas taxas de deposição de coque. O teor de MgO ótimo foi de 20%mol no sistema NiO/MgO/ZrO2, e de 20% e 40% mol de Y2O3 no sistema NiO/Y2O3/ZrO2. Nos catalisadores NiO-MgO-ZrO2, a solução sólida NiO-MgO favoreceu principalmente a reação de reforma seca do metano (CH4+CO2), enquanto que nos catalisadores NiO-Y2O3-ZrO2 a solução sólida Y2O3-ZrO2 favoreceu principalmente à oxidação parcial do metano (CH4+1/2O2). Os catalisadores Ni20MZ e Ni20YZ apresentaram resultados promissores para a reforma oxidativa de biogás em presença de oxigênio sendo estes catalisadores melhores do que uma amostra comercial de Ni/Al2O3 (20%Ni) testada nas mesmas condições de reação. A razão H2/CO nos produtos das reações sobre os melhores catalisadores foi muito próxima de 1,0; o que permite seu uso direto em diversas reações, como reação de Fischer-Tropsch, síntese direta de dimetil-éter (processo STD) e síntese de formaldeído. / The anaerobic fermentation of the organic material produces a mixture of gases called biogas. This biogas contains CH4 and CO2 as major components. These two compounds are greenhouse gases and their use are very important from the environmental and economic point of view. The present study aimed to produce synthesis gas (H2/CO), a high-value raw material for the chemical industry, from the oxidative reforming of biogas using oxygen (1.5CH4 +1.0CO2+0.25O2) over NiO-MgO-ZrO2 and NiO-Y2O3-ZrO2 catalysts. These catalysts were prepared by the one-step polymerization method. The variation content of MgO and Y2O3 in each catalyst was studied. These materials were characterized by XRD, TPR, adsorption-desorption of N2, XPS, XAS, SEM and EDX; they were evaluated in the oxidative reforming reaction of a model biogas (molar composition: 1.5 CH4/1CO2) in the presence of oxygen at 750 &deg;C and 1atm, aiming to produce synthesis gas.<br /> The content of MgO in the NiO/MgO/ZrO2 system was varied ranging from 0-100% (0%, 4%, 20%, 40% and 100%mol in relation to ZrO2) , the same contents were used for the Y2O3 in the NiO/Y2O3/ZrO2 system. All catalysts had 20% wt of Ni. The XRD, TPR and XPS confirmed the formation of NiO-MgO and the MgO-ZrO2 solid solutions in the NiO-MgO-ZrO2 catalysts; and NiO-Y2O3 and Y2O3-ZrO2 solid solutions in the NiO-Y2O3-ZrO2 catalysts. These solid solutions together, in the corresponding catalysts, inproved the catalytic performance, leading to high conversion rates and low carbon deposition rates. The optimum MgO content was 20mol% for the NiO/MgO/ZrO2 system and 20% and 40mol% of Y2O3 for the NiO/Y2O3/ZrO2 system. In the NiO-MgO-ZrO2 catalysts, the NiO-MgO solid solution promoted primarily the dry reforming reaction of methane (CH4 + CO2), while in the NiO-Y2O3-ZrO2 catalysts, the Y2O3-ZrO2 solid solution primarily favored the partial oxidation of methane (CH4 + 1/2O2). The Ni20MZ and Ni20YZ catalysts showed promising results for the oxidative reforming of biogas in the presence of oxygen; these catalysts being better than a commercial catalysts (Ni/Al2O3; 20%wt Ni) tested under the same reaction conditions. The H2/CO ratio in the reaction products over the best catalysts was very close to 1.0, which allows its direct use in various processes such as Fischer-Tropsch process, Syngas-to-dimethyl-ether process (STD) and in the synthesis of formaldehyde.

Neste trabalho investigou-se a influência do cobre em diferentes catalisadores a base de níquel na decomposição catalítica do metano. Foram avaliados desde aspectos relacionados ao tratamento térmico das amostras até o desempenho catalítico nos testes de atividade. As amostras foram preparadas a partir de dois métodos diferentes. Um grupo foi preparado pelo método de impregnação úmida utilizando sílica como suporte, enquanto o segundo foi preparado pelo método de coprecipitação contínua, utilizando nitratos de cobre, níquel e alumínio em diferentes composições molares. Os ensaios foram realizados em reator tubular de leito fixo acoplado a um forno com controle de temperatura e conectado em linha com cromatógrafo gasoso. Utilizou-se 100 mg de amostra, numa faixa de temperatura de 500 a 750°C, utilizando como alimentação uma mistura reacional de N2:CH4 na proporção de 9:1. A caracterização das amostras foi realizada através das análises de SBET, TGA, TPR, TPO, DRX e Espectroscopia Raman. Os resultados mostraram uma significativa influência do cobre na atividade das amostras em temperaturas superiores a 500°C. A presença de cobre influenciou a área específica e a temperatura de redução das amostras calcinadas. Pequenas quantidades de cobre contribuem ao evitar a desativação do catalisador por sinterização em temperaturas superiores a 500°C. Para os catalisadores coprecipitados, além da influência do cobre, avaliou-se também a influência do gás utilizado no tratamento térmico das amostras. Foram utilizadas amostras não calcinadas, amostras calcinadas em ar por seis horas e calcinadas em N2 pelo mesmo período. Os resultados indicaram que a presença de cobre contribui para uma maior estabilidade e atividade nos ensaios realizados nas temperaturas de 600 e 650°C, principalmente para as amostras calcinadas em ar. As amostras com 11% de cobre na composição apresentaram elevada estabilidade na temperatura de 600°C, mesmo quando não calcinadas, indicando que a etapa de tratamento térmico pode ser evitada para este tipo de amostra. As análises de DRX, TPO e Espectroscopia Raman sugerem que o carbono formado, tanto para os catalisadores suportados quanto para os coprecipitados, depositou-se na forma de nanotubos de paredes múltiplas. / The effect of copper in different nickel-based catalysts in the catalytic decomposition of methane was investigated. Were evaluated aspects from the heat treatment of the samples to the catalytic performance in activity tests. Samples were prepared using two different methods. One group was prepared by the wet impregnation method using silica as the support and the second group was prepared by continuous coprecipitation method using copper nitrate, nickel and aluminum in different molar compositions. Catalytic activity runs were carried out in a tubular fixed-bed reactor coupled to an oven with temperature control and connected in line with a gas chromatograph. Samples of 100 mg were used in a temperature range of 500 to 750°C applying a reaction mixture of N2:CH4 at a ratio 9:1 as feed supply. The characterization of the samples was performed through the analysis of SBET, TGA, TPR, TPO, XRD and Raman spectroscopy. The results showed a significant effect of copper on the activity of the samples at temperatures above 500°C. The presence of copper influenced the specific area and the reduction temperature of the calcined samples. Small amounts of copper contributed to avoid catalyst deactivation by sintering at temperatures above 500°C. For the coprecipitated catalysts in addition to the influence of copper, the effect of the gas used for the thermal treatment of samples was also evaluated. Uncalcined samples and samples calcined in air and in N2 for six hours were used. The results indicated that the presence of copper contributed to a superior stability and activity in runs performed at temperatures of 600 to 650°C, especially for samples calcined in air. Samples with 11% of copper showed high stability at 600°C, even if not calcined, indicating that the thermal treatment step can be avoided for this type of sample. The XRD, TPO and Raman spectroscopy results suggest that the carbon deposited on the spent catalysts was in the form of multi-walled nanotubes, for both the supported and the coprecipitated catalysts.

O óxido de zircônio (ZrO2) é um material com características físicas e químicas que pode ser aplicado em vários campos, tanto de interesse industrial como acadêmico. Dentro da catálise, sistemas baseados em ZrO2 estão ganhando um crescente interesse, seja como suportes ou como catalisadores, tendo em vista que é possível alterar suas propriedades pela adição de diversos cátions. Este trabalho teve por objetivo o estudo de catalisadores de níquel suportados em ZrO2 modificados com os cátions, Mg2+, Ca2+, La3+ e Y3+ em diferentes proporções, e a aplicação dos mesmos nas reações de reforma seca de metano, reforma a vapor de metano, oxidação parcial de metano e reforma a vapor de etanol. Os suportes foram sintetizados pelo método de polimerização para a diluição dos cátions dentro da rede cristalina do ZrO2. A adição do níquel foi feita via impregnação úmida em uma proporção de 5% em massa para todos os suportes. Os suportes e catalisadores foram caracterizados por área superficial especifica, pelo método B.E.T., difração de raios-X, redução a temperatura programada, espectroscopia UV-Vis, ressonância paramagnética eletrônica e condutividade elétrica. A partir das caracterizações verificou-se que os suportes formaram soluções sólidas entre o ZrO2 e os cátions adicionados, em todas as proporções utilizadas. Também se observa que houve a estabilização da fase tetragonal do ZrO2, acompanhado de um aumento na área superficial, quando comparado ao ZrO2 puro, que apresentou uma mistura de fases tetragonal e monoclínica e uma baixa área superficial. As medidas de EPR mostraram a presença de radicais oxigênio cuja proporção aumentou em função do teor de aditivo utilizado no ZrO2, este efeito foi atribuído à presença de vacâncias de oxigênio. Nas medidas de RTP, observou-se uma variação no perfil de redução em função destas vacâncias, onde se identificou um efeito promotor na redução do NiO para menores temperaturas com o aumento do teor dos aditivos no ZrO2. Este efeito pode ser atribuído a interações entre as vacâncias de oxigênio nos suportes e espécies de níquel em contato com elas. Medidas de UV-Vis confirmaram a presença destas interações, que são dependentes tanto do cátion adicionado ao ZrO2, quanto do teor utilizado. As medidas de condutividade elétrica confirmaram a presença de vacâncias de oxigênio nos suportes. Nos ensaios de reforma seca de metano observou-se uma relação entre o comportamento catalítico e a condutividade elétrica dos suportes, sugerindo, assim, a participação das vacâncias de oxigênio na ativação das moléculas oxigenadas. Nos ensaios de reforma a vapor de metano e oxidação parcial de metano esta relação direta não foi observada, o que sugere diferentes mecanismos de ativação das moléculas oxigenadas por parte das vacâncias de oxigênio, além da influência de outros fatores. Nos ensaios de reforma a vapor de etanol, observou-se semelhança entre o comportamento catalítico desta reação e das reações de reforma seca, indicando similaridade na influência das modificações catalíticas no comportamento destas reações. / Zirconium dioxide is a material with physics and chemical characteristics that can be applied in many fields, as academic as industrial. In the catalysis, the interest in systems based on zirconia (ZrO2) are growing- up quickly, as a catalyst as a support, considering that ZrO2 properties can be changed by the addition of different cations. The objective of this work was the study of nickel catalyst supported on ZrO2, modified with the cations: Mg2+, Ca2+, La3+ and Y3+ in different proportions and their performance on catalytic tests of dry reforming of methane, steam reforming of methane, partial oxidation of methane and steam reforming of ethanol. The supports were prepared by the polymerization method for the dilution of the cations in the zirconia lattice. The nickel addition was made wet impregnation in a proportion of 5wt% for all the catalysts. Supports and catalysts were characterized by specific surface area (B.E.T method), Xray diffraction, temperature-programmed reduction, UV-Vis spectroscopy, electronic paramagnetic resonance and electrical conductibility. In the characterizations was observed the formation of solid solutions between the ZrO2 and the cations added in all proportions used. Also, it was observed the stabilization of tetragonal phase of ZrO2, accompanied by an increase in the surface area when compared to the pure ZrO2, which is a mixture of tetragonal and monoclinic phases with low surface area. The EPR measurements showed the presence of oxygen radicals whose proportion increased in function of the additive content in ZrO2, this effect was attributed to the presence of oxygen vacancies. In the TPR measurements, a variation on reduction patterns was observed in function of the oxygen vacancy presence, where is possible to identify a promoter effect on NiO reduction to lower temperature with the additive load increase in ZrO2. This effect can be attributed to interactions between the oxygen vacancies of support and nickel species close to them. UV-Vis measurements confirmed these interactions presence that are dependent both of the cation added as well the load used. The electrical conductivity measurements confirm the presence of oxygen vacancies in the supports. In the dry reforming of methane was observed a relation between the catalytic behavior and the electrical conductivity of the supports. This observation suggests the oxygen vacancies participation on oxygenates molecules activation. In the steam reforming of methane and the partial oxidation of methane this relation was not found, suggesting different ways for oxygenates molecules activation by the oxygen vacancies, besides other factors. In the steam reforming of ethanol, it was observed relation between the catalytic behavior of this reaction and the dry reforming of methane, indicating similarity on the influence of the catalyst modifications on the catalytic behavior of these reactions.

Na atualidade, a reforma do metano é de grande interesse industrial para o aproveitamento deste gás na produção de hidrogênio e de gás de síntese. Entre as reações de reforma do metano, destacam-se as reações de reforma a vapor e a reação com dióxido de carbono.O catalisador comumente utilizado nos processos re reforma do metano é Ni/Al2O3. Porém durante este processo, ocorre uma indesejada formação de depósitos de espécies carbonáceas na superfície deste catalisador, os quais levam a sua destruição mecânica e conseqüentemente sua desativação. Por isso, uma das propriedades mais importantes de um bom catalisador para as reações de reforma do metano é a sua resistência à desativação. Entre as propostas para melhorar o desempenho do catalisador encontra-se a incorporação do óxido de céria junto ao suporte alumina.Catalisadores 5%Ni/xCeO2/Al2O3 (x = 0, 1, 5, 10, 20 e 100%) forma preparados, caracterizados e submetidos a ensaios catalíticos nas reações de reforma a vapor e com dióxido de carbono de metano com objetivo de avaliar o efeito da adição de céria ao suporte.Os suportes e os catalisadores forma obtidos pelo método de impregnação e calcinados a 500ºC. Estes compostos foram caracterizados por Fisissorção de Nitrogênio pelo método B. E. T., Espectroscopia dispersiva de raios-X (EDX), espectroscopia de na região do ultra violeta e do visível (UV-vis-NIR) e Redução à Temperatura Programada (RTP). Após todas as reações catalíticas verificou-se que a adição de céria é benéfica ao catalisador Ni/Al2O3 e entre todos os catalisadores avaliados, o melhor desempenho obtido foram dos catalisadores contendo 20% de céria em massa, seguido do catalisador contendo 10%. / Nowadays, the methane reforming is large interest industrial for the take advantage of these gas in production the hydrogen and synthesis gas (syngas). Among in the reactions of methane stand of the reactiosn steam reformig and carbon dioxide reforming of methane. The main catalysts uses in the methane reforming is Ni/Al2O3. However, the supported-nickel catalyst is susceptible to the deactivation or the destruction by coke deposition. The carbon dissolves in the nickel crystallite and its diffuses through the nickel, leading for formation of the carbon whiskers, which results in fragmentation of the catalyst. Modification of such catalysts, like incorporation of suitable promoters, is desirable to achieve reduction of the methane hydrogenolysis and/or promotion of the carbon gasification. Catalysts 5%Ni/xCeO2/Al2O3 (x = 0, 1, 5, 10, 20 e 100%) were prepared, characterized and evalueted in reactions steam and carbon dioxide refoming of methane with objetive the value effect loading oxide ceria in support. The suppots and catalysts were prepared by impregnation method and calcined at 500ºC. The supports and catalysts were characterized by X Nitrogen Adsorption by B.E.T., method -rays diffraction (XRD), , Xrays dispersive spectroscopy (XDS), to spectroscopy in the region of the ultraviolet and the visible (UV-vis NIR) to and temperature programmed reduction (TPR). After all the catalytic reactions check which the addition of cerium is beneficial for Ni/Al2O3 catalysts and the best catlysts is 5%Ni/20%CeO2/Al2O3 following 5%Ni/10%CeO2/Al2O3.

Devido a crescente busca por fontes de energia que utilizem combustíveis renováveis, a utilização do biogás (mistura de gases produzida durante a digestão de matéria orgânica) proveniente do tratamento anaeróbio de águas residuárias e esgotos, surge como um processo promissor para a produção de gás de síntese (mistura de H2 e CO), contribuindo para a geração de produtos de maior valor agregado e para o aproveitamento de rejeitos industriais e domésticos. O biogás normalmente é composto de 60-65% de CH4 e 30-35% de CO2 e, de acordo com a composição do biogás, pode-se combinar processos de reforma do metano com CO2 e reforma a vapor do metano de modo a maximizar o consumo do CH4 excedente presente no biogás, para a geração de gás síntese. Catalisadores baratos e eficientes devem ser desenvolvidos para estas aplicações. Este trabalho tem como objetivo o estudo das melhores combinações destas reações em função da composição de alimentação do reator, aliado ao desenvolvimento de catalisadores de níquel, ítrio e alumínio, buscando minimizar a deposição de carbono, que é o principal problema encontrado nestes processos. Os catalisadores foram preparados pela técnica de coprecipitação de óxido de ítrio e alumínio, no qual se impregnou o óxido de níquel. Os catalisadores foram caracterizados por diversas técnicas: EDX, método B.E.T., DRX, RTP, XAS, além dos ensaios catalíticos para as reações de reforma do metano: com CO2, a vapor e oxidativa. Os resultados mostraram que é possível a preparação de catalisadores de níquel suportado em mistura de Y2O3-Al2O3, e que eles são ativos para as reações de reforma do metano. / Due to the considerable growth in the demand for energy sources that use renewable fuels, the use of biogas (a mixture of gases produced during digestion of organic matter) from the anaerobic treatment of wastewater and sewage, appears as a promising process for the production of synthesis gas (mixture of H2 and CO), contributing to the generation of products with higher value and the use of industrial wastes and domestic. Biogas is typically composed of 60-65% of CH4 and 30-35% of CO2 and, according to the composition of biogas, it can combine the reform processes of methane with CO2 and steam reforming of methane to maximize the consumption of CH4 excess present in the biogas to the production of the synthesis gas. Cheap and efficient catalysts must be developed for these applications. This paper aims to study the best combinations of these reactions depending on the feed composition of the reactor, coupled with the development of catalysts of nickel, yttrium and aluminum in order to minimize the carbon deposition, which is the main problem in these processes. The catalysts were prepared by the technique of co-precipitation of yttrium oxide and aluminum, which is impregnated nickel oxide. The catalysts were characterized by different techniques: EDX, BET method, XRD, TPR, XAS, and catalytic tests for methane reforming reactions: CO2, steam and oxidative. The results showed that it is possible to prepare nickel catalysts supported on mixed Y2O3-Al2O3, and they are active for the methane reactions.

A reforma do metano é um processo de grande interesse industrial para a produção de hidrogênio e de gás de síntese. Entre as reações de reforma do metano, destacam-se as reações de reforma a vapor e a reação com dióxido de carbono. O catalisador comumente utilizado nos processos e Ni/Al2O3. Porém, durante este processo, ocorre uma indesejada formação de depósitos carbonáceos na superfície do catalisador, os quais levam a sua destruição mecânica e, consequentemente, sua desativação. Por isso, uma das propriedades mais importantes de um bom catalisador para as reações de reforma do metano é a sua resistência a desativação. Entre as propostas para melhorar o desempenho do catalisador encontra-se a incorporação do óxido de cério junto ao suporte alumina. Catalisadores Ni/Al2O3 incorporados em soluções sólidas formadas por CeO2-ZrO2, ZrO2-La2O3 e CeO2-La2O3 foram preparados, caracterizados e submetidos a ensaios catalíticos nas reações de reforma a vapor e com dióxido de carbono e oxidação parcial do metano com objetivo de avaliar o efeito da adição da solução sólida ao suporte. Os suportes foram preparados pelo método da co-precipitação e os catalisadores foram obtidos pelo método de impregnação e calcinados a 500&deg;C. Estes compostos foram caracterizados por Fisissorção de Nitrogênio, Difração de Raios X (DRX), Espectroscopia dispersiva de raios X (EDX), espectroscopia de na região do ultra violeta e do visível (UV-vis-NIR), Redução à Temperatura Programada (RTP), Espectrocopia RAMAN, Espectroscopia fotoeletrônica de Raios X (XPS), Espectroscopia de absorção de Raios X (XAS) e Análise termogravimétrica. Os ensaios catalíticos mostraram que a adição de solução sólida melhorou o desempenho do catalisador Ni/Al2O3 e, dentre todos os catalisadores avaliados, os melhores desempenhos obtidos foram com os catalisadores suportados em Ni/CeO2-La2O3-Al2O3. / Nowadays, the methane reforming is large interest industrial for the take advantage of these gas in production the hydrogen and synthesis gas (syngas). Among in the reactions of methane stand of the reactions steam reforming and carbon dioxide reforming of methane. The main catalysts uses in the methane reforming is Ni/Al2O3. However, the supported-nickel catalyst is susceptible to the deactivation or the destruction by coke deposition. The carbon dissolves in the nickel crystallite and its diffuses through the nickel, leading for formation of the carbon whiskers, which results in fragmentation of the catalyst. Modification of such catalysts, like incorporation of suitable promoters, is desirable to achieve reduction of the methane hydrogenolysis and/or promotion of the carbon gasification. Catalysts 5% Ni/Al2O3 supported on solid solutions formed by ZrO2-CeO2, La2O3 and CeO2-ZrO2-La2O3 were prepared, characterized and evalueted in reactions steam and carbon dioxide refoming and partial oxidation of methane with objetive the value effect loading solution solid in support. The supports were prepared by co-precipitation method and catalysts were prepared by impregnation method and calcined at 500&deg;C. The supports and catalysts were characterized by Nitrogen Adsorption, method -rays diffraction (XRD), X-rays dispersive spectroscopy (XDS), spectroscopy in the region of the ultraviolet and the visible (UV-vis NIR) to and temperature programmed reduction (TPR), RAMAN Spectrocopy, X-ray absorption spectroscopy and Termogravimetric Analysis. After all the catalytic reactions check which the addition of solid solution is beneficial for Ni/Al2O3 catalysts and the best catalysts are Ni/CeO2-La2O3-Al2O3.

Orientadores: Gustavo Paim Valença, Ricardo Vieira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T00:05:40Z (GMT). No. of bitstreams: 1 Oliveira_NataliaMairaBraga_M.pdf: 2188373 bytes, checksum: 7d467de1163b278869ab8a52ee898f4f (MD5) Previous issue date: 2012 / Resumo: A reação de deslocamento de gás d'água, também conhecida como water gas shift reaction (WGSR), é muito utilizada na produção de hidrogênio, por meio da conversão do monóxido de carbono em CO2 e da água em H2. No presente trabalho, catalisadores de cobre e níquel suportados em alumina ou nanofibras de carbono (NFC) foram utilizados para estudo da WGSR. Os catalisadores foram preparados através da impregnação de nitrato do metal nos suportes, sendo 5% em massa o valor nominal de teor metálico empregado. Os materiais foram secados, calcinados e caracterizados através de Microscopia Eletrônica de Varredura (MEV), Difração de Raios X (DRX), Adsorção Física de Nitrogênio e Espectrometria de Emissão Óptica por Plasma Indutivamente Acoplado (ICP OES). Depois de calcinados, os catalisadores foram carregados no reator, reduzidos e então testados na WGSR a baixas temperaturas (125 - 300 °C). Os gases que saíram do reator foram analisados online por Cromatografia Gasosa (CG). Houve produção de CO2, H2 e, provavelmente, de coque em pequenas quantidades. A pressão parcial de CO variou entre 4,64 e 11,35 kPa, e a pressão parcial de água variou entre 20,01 e 47,44 kPa. As condições de reação mais favoráveis para 5% Cu/Al2O3 foram pH2O = 38,64 kPa e pCO = 11,35 kPa, em todas as temperaturas reacionais empregadas. Já para 5% Cu/NFC as condições mais favoráveis foram pH2O = 20,01 kPa e pCO = 6,56 kPa, correspondendo a uma razão molar H2O:CO de 3,05. Outra variável testada foi corrente elétrica aplicada em 5% Ni/NFC, com o objetivo de verificar sua influência na atividade do catalisador. Entretanto, diferentes intensidades de corrente elétrica (entre -1,4 e 1,4 A) não alteraram a taxa ou a seletividade da WGSR. Dentre os catalisadores testados, 5% Cu/Al2O3 foi o mais ativo em todas as condições reacionais, devido à alta dispersão das partículas metálicas no suporte. Níquel suportado em Al2O3 se mostrou pouco ativo, porque as partículas metálicas estavam muito dispersas e, provavelmente, não foram reduzidas pelo H2. Ni/NFC e Cu/NFC apresentaram baixas conversões de CO, devido à hidrofobicidade do suporte. A energia de ativação aparente calculada para a WGSR foi de 86,05 kJ/mol para 5% Cu/Al2O3 e de 69,80 kJ/mol para 5% Cu/NFC. O mecanismo de reação proposto para Cu/NFC foi redox de cooperação e as ordens aparentes de reação obtidas foram 0,64 em relação ao CO e aproximadamente zero em relação à água / Abstract: The water gas shift reaction (WGSR) is widely used in the production of hydrogen, by the conversion of carbon monoxide into CO2 and of water into H2. In the present work, copper and nickel catalysts supported on alumina or carbon nanofibers (CNF) were used to study the WGSR. The catalysts were prepared by impregnating metal nitrate in the supports, with a nominal mass metallic content of 5%. The solids were dried, calcined and characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Nitrogen Adsorption and Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES). After calcination, the catalysts were loaded into the reactor, reduced and then tested in the WGSR at low temperatures (125 - 300 °C). The gases from reactor were analyzed online by Gas Chromatography (GC). The products were CO2, H2 and, probably, small amounts of coke. The CO partial pressure varied between 4.64 and 11.35kPa, and the water partial pressure varied between 20.01 and 47.44 kPa. The most favorable reaction conditions for 5% Cu/Al2O3 were pH2O = 38.64 kPa and pCO = 11.35 kPa, for all reaction temperatures used in this work. For 5% Cu/CNF the most favorable conditions were pH2O = 20.01kPa and pCO = 6.56 kPa, corresponding to a molar ratio H2O:CO of 3.05. In a different experiment, electrical current was used in the 5% Ni/CNF bed, in order to verify its influence on the catalyst activity. The electrical current was varied between -1.4 and 1.4 A and no change was observed in the rate or selectivity of the WGSR. Among the catalysts tested, 5%Cu/Al2O3 was the most active under all conditions used in this work, due to the high dispersion of the metal particles on the support. Nickel supported on Al2O3, under reaction conditions studied, was less active, because the metal particles were widely dispersed and, probably, were not reduced by H2. Ni/CNF and Cu/CNF had low CO conversions, due to the support hydrophobicity. The apparent activation energy calculated for the WGSR was 86.05kJ/mol for 5% Cu/Al2O3 and 69.80 kJ/mol for 5% Cu/CNF. For Cu/CNF a co-operative redox reaction mechanism was proposed, and apparent reaction orders were 0.64 in relation to CO and approximately zero in relation to water / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

Ph.D. / This thesis deals with the synthesis of nitrogen-donor compounds and their reaction with metal ions. The first type of nitrogen-donor compounds are the unconjugated diimines (N,N´-bis(diphenylmethylene)ethylenediamine (L1) and (N,N´-bis(diphenylmethylene)propylenediamine (L2). Compounds L1 and L2 were reacted with [NiBr2(DME)] or [NiCl2·6H2O] to form complexes (2.1a), (2.2a), (2.3a) and (2.4a). These nickel complexes were characterized by IR spectroscopy, elemental analysis and mass spectrometry. When the complexes were left in chloroform for prolonged periods, hydrolysis of the diimine ligand took place, leading to the formation of nickel complexes 2.1b, 2.2b, 2.3b and 2.4b. The identity of the hydrolysed nickel complexes 2.1b and 2.2b was confirmed by single crystal X-ray crystallography. Complex 2.1b crystallised in the P21/n space group, whilst 2.2b crystallised in the P-1 space group. Compounds L1 and L2 were also reacted with [PdClMe(MeCN)2] to form the palladium complexes (3.1) and (3.2). The palladium complexes were characterized by NMR spectroscopy, elemental analysis and single crystal X-ray crystallography. Attempts to recrystallize 3.1 from a dichloromethane solution led to the formation of 3.1a. Both complexes 3.1a and 3.2 crystallised in the P21/n space group. Complexes 3.1 and 3.2 were tested as catalysts for the Heck coupling reaction of iodobenzene with methyl acrylate or butyl acrylate at 80 C. The products from the coupling reactions were characterized by GC and NMR spectroscopy. These complexes were found to be highly active with 100% conversions observed in some instances. The second type of ligands that were prepared are the benzoylpyrazolyl compounds, (3,5-dimethylpyrazol-1-yl)phenylmethanone (C1), (3,5-ditertiarybutylpyrazol-1-yl)phenylmethanone (C2), (3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone (C3), (3,5-ditertiarybutylpyrazol-1-yl)-o-toluoylmethanone (C4), (2-chlorophenyl)-(3,5-dimethylpyrazol-1-yl)methanone (C5), (2-chlorophenyl)-(3,5-ditertiarybutylpyrazol-1-yl)methanone (C6), (2-flourophenyl)-(3,5-dimethylpyrazol-1-yl)methanone (C7), (2-flourophenyl)-(3,5-ditertiarybutylpyrazol-1-yl)methanone (C8). These compounds were fully characterized using NMR spectroscopy, IR spectroscopy and elemental analysis. Compounds C1, C3, C5 and C7 were reacted with [NiBr2(DME)] to form nickel complexes (4.31-4.34). These nickel complexes were found to be insoluble in all common organic solvents and hence were characterized only by IR spectroscopy and elemental analysis. Compounds C1-C8 were also reacted with [PdCl2(MeCN)2] to form palladium complexes (4.35-4.42). Complexes 4.35-4.42 were characterized using NMR spectroscopy, IR spectroscopy, elemental analysis and in selected cases single crystal X-ray crystallography. Complex 4.39 crystallised in the C2/n space group and complex 4.42 crystallised in the P21/n space group. Attempts to recrystallize 4.37a led to the formation of 4.37b, which contains both 3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone and 3,5-dimethylpyrazole as ligands. Complex 4.37b was confirmed by NMR spectroscopy and single crystal X-ray crystallography. Complex 4.37b crystallised in the Pbca space group. The formation of 4.37b is attributed to hydrolysis of 3,5-dimethylpyrazol-1-yl)-o-toluoylmethanone ligand in 4.37a due to the presence of adventitious water in the solvent. The palladium complexes (4.35-4.42) were tested as catalysts for the Heck coupling reaction of iodobenzene with butyl acrylate and also for the Suzuki coupling reaction of iodobenzene with phenylboronic acid or 4-chlorophenylboronic acid. In these reactions, complexes 4.35-4.42 were found to be highly active at 120 C. The pyrazolyl nickel and palladium complexes were further tested as catalysts in ethylene oligomerization reactions using EtAlCl2 as the co-catalyst. The nickel complexes were found to be the most active reaching TONs of 10.8105 g mol-1 h-1. The palladium analogues only gave TONs of up to 3.9105 g mol-1 h-1. The oligomers were characterized by GC and NMR spectroscopy and were found to be in the C10-C16 range, with C16 the most abundant olefin.

M.Sc. (Chemistry) / This study deals with the synthesis of nitrogen-donor pyrazole- and pyrazolylethylamine compounds, their reactions with palladium(II) and nickel(II) precursors to form complexes and the applications of theses palladium(II) and nickel(II) complexes as catalysts for ethylene oligomerization reactions and reactions of higher α-olefins in Friedel-Crafts alkylation of aromatic solvents. A series of ligands, 3,5-di-tert-butyl-1H-pyrazole (L3), 3,5-diphenyl-1H-pyrazole (L4), 5-phenyl-3-(trifluoromethyl)-1H-pyrazole (L5) were synthesized using appropriate amounts of diketones and hydrazine hydrate; while ligands, 2-(1H-pyrazol-1-yl)ethylamine (L6), 2-(3,5-dimethyl-1H-pyrazol-1-yl)-ethylamine (L7), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)-ethylamine (L8), 2-(3,5-diphenyl-1H-pyrazol-1-yl)-ethylamine (L9) and 2-(5-phenyl-3-(trifluoromethyl)-1H-pyrazol-1-yl)ethylamine (L10) were prepared via the N sp3 alkylation of the corresponding pyrazoles with bromoethylamine Reactions of L1-L5 with [PdCl2(CNMe)2] formed five complexes of general formula [PdCl2 (L)2] {L = L1 (2.1), L2 (2.2), L3 (2.3), L4 (2.4) and L5 (2.5)}. Similarly [NiBr2(DME)] formed five complexes of general formula [NiBr2(L)2] {L = L1(2.6), L2 (2.7), L3 (2.8), L4 (2.9) and L5 (2.10)}. Complexes 2.1-2.10 were synthesized in a 2:1 mole ratio of ligand and metal precursor. Reactions of L6-L10 with [PdCl2(MeCN)2] yielded complexes 3.1-3.5 respectively. Ligands L6-L10 were also complexed with NiCl2.6H2O to give complex 3.6 while [NiCl2(DME)] and [NiBr2(DME)] gave complexes 3.7-3.8 and 3.9-3.13 respectively...

M.Sc. / In search of developing new pyrazolyl complexes that can be used for ethylene transformation reactions, bis(pyrazolyl)alky carbonyl and amine complexes were prepared. The reaction between 3,5-dimethylpyrazole with alkyl-carbonyl chloride linkers in the presence of triethylamine as a base produced the ligands, 1,3-bis(3,5- dimethylpyrazol-1-yl)-propan-1-one (L1), 1,2-bis(3,5-dimethylpyrazol-1-yl)-ethane- 1,2-dione (L2), 1,4-bis(3,5-dimethylpyrazol-1-yl)-butane-1,4-dione (L3) and 1,6- bis(3,5-dimethylpyrazol-1-yl)-hexane-1,6-dione (L4) as white to brown crystalline solids in good yields. Ligand L5 was prepared by using bis(2-chloroethyl)-amine hydrochloride and 3,5- dimethylpyrazolevia via a phase-transfer reaction, while L6 was obtained using the bis(2-chloroethyl)-amine hydrochloride and 3,5-diphenypyrazole in the presence of triethylamine as a base. They were isolated in moderate yields, while their ditertiarypyrazole derivative was not obtained at all. All the ligands were characterized by a combination of 1H and 13C{1H}-NMR spectroscopy, infrared spectroscopy, elemental analysis and mass spectrometry. Ligands L1 and L4 were further confirmed by X-ray crystallography. Ligands L1 and L6 were subsequently used to prepare their corresponding Pd, Ni and Cr complexes. L1 was reacted with [PdCl2(NCMe)2] to form a bidentate complex 1,3- bis-(3,5-dimethylpyrazol-1-yl)-propan-1-one palladium dichloride (1a) when the reaction was heated at 80 oC, while a tridentate complex 1,3-bis(3,5-dimethylpyrazol- 1-yl)-propan-1-one palladium chloride (1b) was obtained when the reaction was refluxed. 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one nickel(II) bromide (2) was obtained when NiBr2 was reacted with L1 at room temperature while the reaction between L1 and [CrCl3(THF)3] gave 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one chromium(III) chloride (3). Ligand L6 was reacted with the same metal salts to give bis[2-(3,5-dimethylpyrazol- 1-yl)-ethyl] amine palladium(II) chloride (4), bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine nickel(II) chloride (5) and bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine chromium(III) chloride (6). All the complexes were characterized by the already mentioned characterization techniques and X-ray analysis was performed for 1b and 4. Ethylene transformation reactions were performed with complexes 1a, 2, 3, 5 and 6, and complexes 1a and 4 were not used because of their geometrical structures, which prevented them to be active for such reactions. Using MMAO and EtAlCl2 as cocatalysts complexes 1a and 3 showed no activity, however complexes 2 and 6 were active. Complex 2 was used with MMAO and showed no activity, while with EtAlCl2 oligomers were produced. Gas-chromatography analysis of the products showed that C6-C14+ oligomers were obtained. Temperature variation reactions performed under standard conditions of 20 bar ethylene pressure and 200 equivalents of EtAlCl2 in one hour showed that certain oligomers were not favoured under certain temperatures. Ethylene reactions with complex 6 and EtAlCl2 did not form any product but with MMAO polymer material was obtained. Analysis of the polymer by differential scanning calometry proved that the product was high density polyethylene. Studies of temperature, co-catalyst and pressure variations were performed. As expected for temperature studies the catalyst decomposed at high temperatures (above 40 oC), while for co-catalyst studies 3000 equivalents of MMAO gave the lowest TON. Pressure variations studies showed that an increase in ethylene pressure also increased the TON, but above 30 bar the activity became stable.