Orientadores: Antonio Jose Gomez Cobo, Inmaculada Rodriguez Ramos / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-09T18:45:47Z (GMT). No. of bitstreams: 1 Zonetti_PrisciladaCosta_D.pdf: 1969256 bytes, checksum: 26749d2eefdd647b4142060303484744 (MD5) Previous issue date: 2007 / Resumo: Os compostos organoclorados são substâncias químicas que têm como característica uma elevada toxicidade e persistência, tanto no meio ambiente quanto nos organismos vivos. Tal é o caso do pentaclorofenol, usado como herbicida e pesticida na proteção de lavouras e como biocida no tratamento de madeiras e couros. Um método de tratamento bastante promissor é a hidrodescloração catalítica desses compostos empregando catalisadores à base de paládio. Dentro desse contexto, o presente trabalho tem como objetivo principal estudar as condições de preparação de catalisadores Pd/TiO2 e o comportamento dos sistemas bimetálicos Pd-Ni/TiO2, Pd-Ru/TiO2 e Pd-Ti/TiO2. Dentre as variáveis de preparação dos catalisadores Pd/TiO2, foram estudadas as influências do tratamento de ativação, bem como do teor de Pd no sólido sobre o desempenho catalítico. Para tanto, os catalisadores de Pd/TiO2 foram preparados pelo método de impregnação a seco e os catalisadores bimetálicos foram preparados pelo método de co-impregnação. Os sólidos obtidos foram caracterizados por meio das técnicas de adsorção de N2 (BET), análise espectrométrica de raios X (EDX), espectroscopia fotoeletrônica de raios X (XPS), redução à temperatura programada (RTP), espectroscopia no infravermelho da adsorção do CO (FTIR) e microcalorimetria da adsorção do CO. O desempenho dos catalisadores foi avaliado na reação de hidrodescloração do pentaclorofenol, empregandose um reator Parr do tipo "slurry". A reação foi conduzida à pressão de 5 bar e temperatura de 383 K. Os resultados dos testes catalíticos mostram que o catalisador 3%Pd/TiO2 não calcinado e não reduzido permite obter maiores valores para o rendimento e a seletividade de fenol, com uma atividade catalítica relativamente elevada. Os catalisadores bimetálicos com Ni e Ti são seletivos à formação de fenol, enquanto que o catalisador contendo Ru se mostra muito seletivo para a obtenção do cicloexanol, através da hidrogenação do anel benzênico / Abstract: Organic-chlorine compounds are chemicals which main characteristic is high toxicity and persistence, both in live organisms and in the environment. Such is the case of pentachlorophenol, used as herbicide and pesticide for harvest protection and as biocide for treating woods and leathers. A very promising treatment method is the catalytic hydrodechlorination of these products using palladium based catalysts. In this context, the following work is aimed at studying the Pd/TiO2 preparation conditions and the behavior of bimetallic Pd-Ni/TiO2, Pd-Ru/TiO2 and Pd-Ti/TiO2 systems. Within the preparation variables of Pd/TiO2 catalysts, the effects of the activation treatment as well as the influence of Pd content in the solid on the catalysts performance were studied. Therefore, Pd/TiO2 catalysts were prepared by means of the dry impregnation method, and the bimetallic catalysts were prepared by co-impregnation method. The so obtained solids were characterized by the N2 adsorption technique (BET), Xray spectrometry analysis (EDX), X-ray photoelectron spectroscopy (XPS), temperatureprogrammed reduction (TPR), Fourier transformed-infrared spectroscopy of the chemisorbed CO (FTIR) and CO adsorption microcalorimetry. Catalysts performance was evaluated in the entachlorophenol hydrodechlorination reaction using a slurry Parr reactor. The reaction was conducted at 5 bar pressure and at 383 K temperature. Catalytic test results show that the non calcinated and non reduced 3% Pd/TiO2 catalyst allows to attain higher values for yield and for phenol selectivity, with a relatively high catalytic activity. Bimetallic catalysts with Ni and Ti are selective in the phenol formation, while the catalyst with Ru is likely more selective to attain the cyclohexanol by means of the benzene ring hydrogenation / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química

Global energy demands are constantly increasing and fossil fuels are a finite resource. The shift towards alternative, more renewable and sustainable fuels is inevitable. Furthermore, the increased emissions of greenhouse gases have forced a pressing need to find cleaner, more environmentally friendly sources of fuel. Biomass energy is a promising alternative fuel because it offers several important advantages. It is a renewable energy form, it comes from many sources and produces biogas (CH4 and CO2). Furthermore, it can have a zero carbon footprint; this is due to the fact that the carbon produced is from the same carbon used to make the biomass. In addition, by replacing fossil fuels, the emissions of CH4 and CO2 (both greenhouse gases) is reduced. Biomass-derived syngas (H2 and CO) can be utilized as a feedstock for many important industrial processes such as methanol synthesis, ammonia synthesis and Fischer-Tropsch synthesis (FTS) to produce long chain hydrocarbon fuels. Municipal solid waste (MSW) biomass is considered as the source of the biomass for this dissertation work. MSW accounts for 20% of man-made methane emissions making it an attractive source for utilization. However, methane reforming to synthesis gas (H2 and CO) typically occurs at temperatures higher than 600°C making it economically challenging at the smaller scale of MSW conversion processes. This dissertation effort focused on formulating low precious metal loaded heterogeneous catalysts that can reform methane at low temperature (T<500°C) making the process more industrially viable. The effect of select contaminants (siloxanes) in the biogas on the reforming catalysts was studied through accelerated poisoning. Finally, the syngas ratio was improved by combining low temperature dry reforming with steam reforming (termed bi-reforming). The catalyst system used for this dissertation study was comprised of 1.34wt%Ni- 1.00wt%Mg on a Ceria-Zirconia oxide support (0.6:0.4 ratio respectively). The catalysts were doped with platinum (0-0.64% by mass) and compared to palladium doped catalysts (0-0.51% by mass). The ratio chosen for the support, Ce0.6Zr0.4, was determined to be the best ratio in terms of activity and surface area by previous studies done in this group [1]. Nickel has been widely studied as methane reforming catalyst [2-6]. Alone, nickel atoms are prone to carbon deposition especially during methane decomposition, however, coupling NiO with MgO helps to reduce carbon deposition by reducing agglomeration of Ni crystallites, thereby improving catalyst lifetime [2, 7]. Furthermore, addition of small amounts of noble metals such as Pt or Pd help to drive the reduction of the catalyst to lower temperatures and enhance catalytic activity. Different metal loadings of Pt and Pd were tested to determine the optimum catalyst that will reform methane at low temperatures, is resistant to deactivation and produces a high syngas ratio (~2:1) which is necessary for processes such as FTS. Preliminary results have shown that in general Pt is superior in this catalyst system for low temperature reforming of methane. It consistently had syngas ratios near the desired ratio compared to Pd, it did not deactivate with extended time on stream and overall had higher turnover frequencies. This catalyst system has potential to make industrial reforming of methane from biomass feedstock more economically viable.

Les travaux de recherche présentés ici avaient pour objectif principal la synthèse de copolymères statistiques à base d’éthylène et d’acide acrylique (AA). Pour cela, la déprotection des groupements esters d’un copolymère statistique précurseur, le poly(éthylène-co-(tert-butyl)acrylate), a été effectuée par hydrolyse à l’aide d’iodure de triméthylsilyle. La synthèse de ce précurseur est réalisée par polymérisation catalytique en présence d’un système à base de Palladium (Pd). Le deuxième objectif a été d’étudier et de caractériser des polymères synthétisés à l’état solide et en suspension colloïdale. Plusieurs copolymères précurseurs comprenant différents pourcentages molaires en tert-butyl acrylate (4 à 12% molaires) ont été synthétisés avec succès, puis déprotégés par hydrolyse pour obtenir des poly(éthylène-coacide acrylique) (pE-co-AA) avec différentes compositions. Seuls les copolymères comprenant 10% molaire ou plus de AA sont solubles dans le Tétrahydrofurane (THF) et uniquement dans ce solvant. De telles solutions peuvent être dialysées dans l’eau, ce qui conduit à un échange lent entre cette dernière et le THF, et l’autoassemblage du copolymère dans l’eau peut ensuite être étudié. C’est ainsi qu’ont pu être observées des nanoparticules stables dans le temps dont le comportement est sensible au pH et à la température. Les polymères synthétisés ont été caractérisés par Résonance Magnétique Nucléaire (RMN) ainsi que par spectroscopie Infra-Rouge (IR), avant et après déprotection. Les pourcentages molaires d’AA ont été déterminés par combinaison des résultats de RMN et ii de titrages conductimètriques. A l’état solide, les échantillons ont été analysés par Calorimétrie différentielle à balayage (DSC) et par Diffraction des rayons X. Les solutions colloïdales des polymères pE-co-AA ont été caractérisées par Diffusion dynamique de la lumière et par la DSC-haute sensibilité. De la microscopie électronique à transmission (TEM) a permis de visualiser la forme et la taille des nanoparticules. / The first objective of this research is to synthesize random linear copolymers of ethylene and acrylic acid (AA). The synthesis relies on the deprotection of the functional groups in the copolymer’s precursor, which is represented by poly(ethylene-co-tertbutyl acrylate). The synthesis of the precursor was realized by the catalytic approach, where Pd-based catalytic systems are frequently utilized nowadays. The deprotection was carried out by hydrolysis of the ester functionality using trimethylsilyl iodide agent. The second objective is to investigate and characterize the synthesized polymers in the bulk and in colloidal solution. A set of different precursor polymers with various degrees of molar incorporation of tertbutyl acrylate (from 4 to 12 mol %) was successfully synthesized and deprotected. The resulting poly(ethylene-co-acrylic acid) copolymers were found to be soluble in tetrahydrofuran THF, when the molar incorporation of AA reaches the value of 12 and more. This aspect gave the possibility to study the self-assembly of this copolymer in aqueous medium by slow THF to water exchange (dialysis). It was found that the copolymers self-assemble into nano-sized structures and these nanoparticles remain stable in colloidal solution for extended periods of time. Moreover, it was shown that the nanoparticles formed by the discussed copolymer possess thermo- and pH-responsive behaviour. The polymers synthesized were characterized by nuclear magnetic resonance (NMR) and infrared spectroscopies (IR) before and after deprotection. The bulk samples were analyzed by conventional differential scanning calorimetry and by X-ray diffraction iv technique. The molar percentages of AA were determined using a combination of NMR and conductimetric titration. Colloidal solutions of pE-co-AA copolymers were analyzed by dynamic light scattering and high-sensitivity differential scanning calorimetry techniques. The nanoparticles formed were visualized and characterized by transmission electron microscopy.

Les travaux de recherche présentés ici avaient pour objectif principal la synthèse de copolymères statistiques à base d’éthylène et d’acide acrylique (AA). Pour cela, la déprotection des groupements esters d’un copolymère statistique précurseur, le poly(éthylène-co-(tert-butyl)acrylate), a été effectuée par hydrolyse à l’aide d’iodure de triméthylsilyle. La synthèse de ce précurseur est réalisée par polymérisation catalytique en présence d’un système à base de Palladium (Pd). Le deuxième objectif a été d’étudier et de caractériser des polymères synthétisés à l’état solide et en suspension colloïdale. Plusieurs copolymères précurseurs comprenant différents pourcentages molaires en tert-butyl acrylate (4 à 12% molaires) ont été synthétisés avec succès, puis déprotégés par hydrolyse pour obtenir des poly(éthylène-coacide acrylique) (pE-co-AA) avec différentes compositions. Seuls les copolymères comprenant 10% molaire ou plus de AA sont solubles dans le Tétrahydrofurane (THF) et uniquement dans ce solvant. De telles solutions peuvent être dialysées dans l’eau, ce qui conduit à un échange lent entre cette dernière et le THF, et l’autoassemblage du copolymère dans l’eau peut ensuite être étudié. C’est ainsi qu’ont pu être observées des nanoparticules stables dans le temps dont le comportement est sensible au pH et à la température. Les polymères synthétisés ont été caractérisés par Résonance Magnétique Nucléaire (RMN) ainsi que par spectroscopie Infra-Rouge (IR), avant et après déprotection. Les pourcentages molaires d’AA ont été déterminés par combinaison des résultats de RMN et ii de titrages conductimètriques. A l’état solide, les échantillons ont été analysés par Calorimétrie différentielle à balayage (DSC) et par Diffraction des rayons X. Les solutions colloïdales des polymères pE-co-AA ont été caractérisées par Diffusion dynamique de la lumière et par la DSC-haute sensibilité. De la microscopie électronique à transmission (TEM) a permis de visualiser la forme et la taille des nanoparticules. / The first objective of this research is to synthesize random linear copolymers of ethylene and acrylic acid (AA). The synthesis relies on the deprotection of the functional groups in the copolymer’s precursor, which is represented by poly(ethylene-co-tertbutyl acrylate). The synthesis of the precursor was realized by the catalytic approach, where Pd-based catalytic systems are frequently utilized nowadays. The deprotection was carried out by hydrolysis of the ester functionality using trimethylsilyl iodide agent. The second objective is to investigate and characterize the synthesized polymers in the bulk and in colloidal solution. A set of different precursor polymers with various degrees of molar incorporation of tertbutyl acrylate (from 4 to 12 mol %) was successfully synthesized and deprotected. The resulting poly(ethylene-co-acrylic acid) copolymers were found to be soluble in tetrahydrofuran THF, when the molar incorporation of AA reaches the value of 12 and more. This aspect gave the possibility to study the self-assembly of this copolymer in aqueous medium by slow THF to water exchange (dialysis). It was found that the copolymers self-assemble into nano-sized structures and these nanoparticles remain stable in colloidal solution for extended periods of time. Moreover, it was shown that the nanoparticles formed by the discussed copolymer possess thermo- and pH-responsive behaviour. The polymers synthesized were characterized by nuclear magnetic resonance (NMR) and infrared spectroscopies (IR) before and after deprotection. The bulk samples were analyzed by conventional differential scanning calorimetry and by X-ray diffraction iv technique. The molar percentages of AA were determined using a combination of NMR and conductimetric titration. Colloidal solutions of pE-co-AA copolymers were analyzed by dynamic light scattering and high-sensitivity differential scanning calorimetry techniques. The nanoparticles formed were visualized and characterized by transmission electron microscopy.