Thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Engineering at the School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand Johannesburg, South Africa October, 2017 / The significant increase in the primary energy demand and the effort to reduce harmful emissions related to the greenhouse gases enhanced the search for alternative energy. Production and modelling processes of biofuel from non-edible oil sources assist in the process development of an environmentally friendly fuel such as biodiesel. This work focused on the kinetic modelling of biodiesel synthesised from non-edible oils. Two types of non-edible oils (Jatropha curcas seed oil and Tobacco seed oil) were used in this study including the development of the kinetic behaviour of the transesterification reaction. A linear polynomial model was generated from experimental data found in literature in order to study the influence of operating parameters during biodiesel production. It was found that the temperature improves the yield of biodiesel; this is attributed to the fact that temperature affects the reaction rate constants; and the higher the reaction rate, the lower the activation energy required for a reaction to occur. The optimum conditions for the transesterification of Jatropha curcas seed oil are a temperature of 55 0C, methanol to oil ratio of 6:1, catalyst concentration of 1.2% KOH (by volume of oil), and agitation speed range of 0-250 rpm. Results from both the homogeneous and heterogeneous reactions of Jatropha curcas oil and tobacco seed oil were used to verify the theoretical kinetic and empirical models. It was found that both models describe the kinetic behaviour of transesterification with minor deviations in the estimated parameters. However, the use of empirical model in determining the reaction order, as opposed to the theoretical assumption, gave a second order with respect to oil triglycerides at a temperature of 60 0C. The theoretical kinetic model gave a first order with respect to oil triglycerides. In this case, the activation energy was found to be 71.83 kJ/mol and pre-exponential factor was found to be 2.48 x1010. More investigation should be done to describe the kinetic behaviour of biodiesel production from non-edible oil in order to confirm the correct reaction order and why there is change in reaction order when the temperature increases above 60°C. / MT2018

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering, October 2017 / The dwindling fossil reserves coupled with environmental pollution necessitate the search for clean and sustainable energy resources. Biohydrogen is emerging as a suitable alternative to fossil fuels and has received considerable attention in recent years due to its economic, social, and environmental benefits. However, the industrial application of biohydrogen has been hindered by low yield. Therefore, development of novel techniques to enhance the yield is of immense importance towards large-scale production of biohydrogen. Thus, this research effort explored various options to enhance the yield of biohydrogen during dark fermentation process. Some options explored included (i) the utilization of feedstocks from the agricultural, industrial and municipal sectors, (ii) parametric optimization of biohydrogen production, (iii) investigation of biohydrogen production using metal ions and nitrogen gas sparging, and (iv) assessing the feasibility of biohydrogen scale-up study to pave the way for pilot-scale development. Solid biowaste feedstocks consisting of apple, bread, brewery residue, cabbage, corn-cob, mango, mealie-pap, pear, potato, and sugarcane were investigated for dark fermentative biohydrogen production using anaerobic mixed sludge. The experimental results showed that substrates which are rich in carbohydrates are suitable for dark fermentative biohydrogen-producing bacteria. Consequently, a maximum biohydrogen fraction of 43.98, 40.32 and 38.12% with a corresponding cumulative biohydrogen yield of 278.36, 238.32 and 215.69 mL H2/g total volatile solids (TVS) was obtained using potato, cabbage, and brewery wastes, respectively. Based on these results, potato waste was chosen as a suitable substrate for subsequent biohydrogen production studies. Parametric optimization was carried out on biohydrogen production via dark fermentation using potato waste as the substrate. Effects of operating variables such as pH, temperature, fermentation time, and substrate concentration were investigated via response surface methodology (RSM) approach using a two-level-four factor (24) central composite design (CCD). The obtained predictive model (statistical model) was used to explain the main and interaction effects of the considered variables on biohydrogen production. In addition, the model was employed in the optimization of the operating conditions. Consequently, a secondorder polynomial regression with a coefficient of determination (R2) of 0.99 was obtained and used in the explanation and optimization of operating variables. The optimum operating conditions for biohydrogen production were 39.56 g/L, 5.56, 37.87 oC and 82.58 h for potato waste concentration, pH, temperature and fermentation time, respectively, with a corresponding biohydrogen yield of 68.54 mL H2/g TVS. These results were then validated experimentally and a high biohydrogen yield of 79.43 mL H2/g TVS indicating a 15.9% increase was obtained. Furthermore, the optimized fermentation conditions were applied in the scale-up study of biohydrogen production that employed anaerobic mixed bacteria (sludge) which was immobilized in calcium alginate beads. A biohydrogen fraction of 56.38% with a concomitant yield of 298.11 mL H2/g TVS was achieved from the scale-up study. The research also investigated the influence of metal ions (Fe2+, Ca2+, Mg2+ and Ni2+) on biohydrogen production from suspended and immobilized cells of anaerobic mixed sludge using the established optimal operating conditions. A maximum biohydrogen fraction of 45.21% and a corresponding yield of 292.8 mL H2/g TVS was achieved in fermentation using Fe2+ (1000 mg/L) and immobilized cells. The yield was 1.3 times higher than that of suspended cultures. The effect of nitrogen gas sparging on biohydrogen conversion efficiency (via suspended and immobilized cells) was studied as well. Cell immobilization and nitrogen gas sparging were effective for biohydrogen production enhancement. A maximum biohydrogen fraction of 56.98% corresponding to a biohydrogen yield of 294.83 mL H2/g TVS was obtained in a batch process using nitrogen gas sparging with immobilized cultures. The yield was 1.8 and 2.5 times higher than that of nitrogen gas sparged and non-sparged suspended cell system, respectively. Understanding the functional role of microorganisms that actively participate in dark fermentation process could provide in-depth information for the metabolic enhancement of biohydrogen-producing pathways. Therefore, the microbial composition in the fermentation medium of the optimal substrate (potato waste) was examined using PCR-based 16S rRNA approach. Microbial inventory analysis confirmed the presence of Clostridium species which are the dominant biohydrogen-producing bacteria. The results obtained from this research demonstrated the potential of producing biohydrogen using South African solid biowaste effluents. These feedstocks are advantageous in biohydrogen production because they are highly accessible, rich in nutritional content, and cause huge environmental concerns. Furthermore, optimization techniques using these feedstocks will play a pivotal role towards large-scale production of biohydrogen by increasing throughput and reducing the substrate costs which accounts for approximately 60% of the overall costs. The findings from this research also provide a solid basis for further scale-up and techno-economic studies. Such studies are necessary to evaluate the competitiveness of this technology with the traditional processes of hydrogen production. In summary, the findings from this research effort have been communicated to researchers in the area of biohydrogen process development in the form of peer-reviewed international scientific publications and conference proceedings, and could provide a platform for developing an economic biohydrogen scaled-up process. / CK2018

The technical and scientific challenges to provide reliable sources energy for US and global economy are enormous tasks, and especially so when combined with strategic and recent economic concerns of the last five years. It is clear that as part of the mix of energy sources necessary to deal with these challenges, fuel cells technology will play critical or even a central role. The US Department of Energy, as well as a number of the national laboratories and academic institutions have been aware of the importance such technology for some time. Recently, car manufacturers, transportation experts, and even utilities are paying attention to this vital source of energy for the future. In this thesis, a review of the main fuel cell technologies is presented with the focus on the modeling, and control of one particular and promising fuel cell technology, aluminum air fuel cells. The basic principles of this fuel cell technology are presented. A major part of the study consists of a description of the electrochemistry of the process, modeling, and simulations of aluminum air FC using Matlab Simulink™. The controller design of the proposed model is also presented. In sequel, a power management unit is designed and analyzed as an alternative source of power. Thus, the system commutes between the fuel cell output and the alternative power source in order to fulfill a changing power load demand. Finally, a cost analysis and assessment of this technology for portable devices, conclusions and future recommendations are presented. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

No contexto mundial atual, a busca de fontes de energia renováveis e menos poluentes que o petróleo tornou-se inevitável. O uso da biomassa como fonte de energia é extremamente importante, devido principalmente ao seu caráter renovável e a sua abundância. Os resíduos florestais são cada vez mais preconizados como uma importante fonte de biomassa. Isto se deve a sua abundância, facilidade de aprovisionamento e baixo custo. Podemos citar, como exemplo, os resíduos gerados durante a colheita florestal (cascas, folhas, galhos, ponteiros, entre outros) e durante o processamento mecânico da madeira (costaneiras, aparas, pó de serra, entre outros). O uso deste tipo de material para fins energéticos vem crescendo, porém, há um grande espaço para melhorias a serem implementadas nesse campo, envolvendo o melhor conhecimento de suas características e o potencial de aplicação de processos para sua conversão em produtos mais otimizados em relação aos seus valores energéticos. Diante desse quadro, e em se considerando a madeira, surge a oportunidade para adoção de processos de tratamento térmico, para os quais já existem referências que indicam a ocorrência de mudanças nas características desse material, o que conduz à previsão de se poder obter resultados positivos em relação ao que se exige para usos energéticos. Além do tradicional e amplamente usado processo de secagem, constatase, no campo do tratamento térmico, o crescimento do interesse pela aplicação da chamada torrefação e da termorretificação, compreendendo faixas de temperatura entre 150 e 300 °C. Neste contexto, resíduos da colheita florestal de eucalipto e pinus foram submetidos a tratamento térmico conduzido em estufa elétrica laboratorial, numa faixa de temperatura entre 140 e 300 °C. O objetivo foi estudar as alterações que o tratamento pudesse proporcionar às características do material, no sentido de se potencializar ainda mais o seu uso para fins energéticos, mediante a avaliação da densidade a granel do material, tamanho das partículas dos resíduos, poder calorífico superior, índice de combustão, análise imediata, resistência à moagem (redução granulométrica) e avaliação de imagens microscópicas. Os resultados indicaram, para ambas as espécies, que o aquecimento exerceu influência significativa nos rendimentos mássicos e nas características dos ensaios acima citados, com alteração dos valores com a elevação da temperatura, exceto para o teor de cinzas do eucalipto. A influência exercida pelo tratamento térmico foi mais evidente a partir de 220 °C, sendo isto mais fortemente observado à temperatura de 300 °C, com a constatação da maior fragmentação dos materiais tratados em comparação ao material testemunha. Além do aumento da friabilidade dos materiais estudados, constatado pelo ensaio de resistência à moagem, onde houve um relevante aumento da quantidade de material de baixa granulometria (menor que 4 mm), os mesmos apresentaram um maior ganho energético (maior poder calorífico) levando-se em conta a testemunha, principalmente a 300 °C, com índices de combustão elevados para os resíduos de eucalipto e pinus. / In the current worldwide context, the search for renewable energy sources and less polluting fuels than petroleum has become unavoidable. The use of biomass energy as source of energy is extremely important, especially due to its renewable character and abundance. The forest residues have been increasingly recommended as an important source of biomass. This is due to its abundance, facility of provision and low cost. We can cite examples such as the residues generated during the forest harvest (bark, leaves, branches, stem tips, among others) and during the mechanical processing of wood (slabs, chips, sawdust, among others). The use of this kind of material for energetic purposes has been increasing, however, there is room for benefits to be implemented in this field, involving a deeper knowledge on its characteristics and the potential for the application of processes to its conversion into more optimized products in relation to its energy values. In this scenario, and considering the wood, there comes the opportunity to the adoption of thermal treatment processes, to which there are already references that indicate the occurrence of changes in the characteristics of this material, which leads to the prediction of the possibility to obtain positive results in relation to what is demanded for energetic uses. Besides the traditional and widely used process of drying, it is observed, in the field of thermal treatment, the increase in the interest for the application of the so-called torrefaction and thermal rectification, comprising zones of temperature between 150 and 300 °C. In this context, residues of eucalyptus and pine forest harvest were submitted to a thermal treatment conducted in an electric laboratory oven, at temperatures between 140 and 300 °C. The goal was to study the alterations that the treatment might provide to the characteristics of the material, aiming at empowering its use to energetic purposes, through the density evaluation of a sample of the material, the size of residue particles, gross calorific value, combustion index, immediate analysis, resistance to grinding (particle size reduction) and the evaluation of microscopic images. The results indicated, for both species, that the heating caused a significant influence on the gravimetric yields and on the characteristics of the experiments cited above with changes in the values with the increase of the temperature, except for the ash content of eucalyptus. The effect of the thermal treatment was more evident from 220 °C, which is more strongly observed at the temperature of 300 °C, with a larger fragmentation of the treated materials in comparison to the control material. Besides the increase in the friability of the studied materials, found in the experiment of resistance to grinding, in which there was a relevant increase in the amount of low granulometry material (smaller than 4 mm), they presented a higher energetic gain (more calorific value) considering the witness, mainly at 300 °C, with high combustion indexes for the eucalyptus and pine residues.

Pretende-se estudar um caminho alternativo para a obtenção de biocombustíveis sintéticos, para uso veicular, utilizando-se para tal a rota tecnológica conhecida como Biomass-to-Liquids (BTL) que consiste na utilização da síntese Fischer-Tropsch para a construção de cadeias de hidrocarbonetos a partir de unidades monoméricas obtidas de uma mistura gasosa majoritariamente formada por monóxido de carbono (CO) e hidrogênio (H), conhecida como syngas quando proveniente de fontes energéticas fósseis como o carvão mineral ou o gás natural ou também biosyngas quando proveniente de matéria-prima carbonada renovável, como é o caso da biomassa. O presente trabalho visa abordar o começo dessa cadeia produtiva ao introduzir um conceito para biomassa e os meios para obtenção do biosyngas através do processo conhecido como gaseificação; é feita uma menção à obtenção bem sucedida de biosyngas nas dependências do Instituto de Pesquisas Tecnológicas (IPT) de São Paulo. Segue-se com a utilização desse insumo na síntese Fischer-Tropsch largamente utilizada ao longo do século XX em países específicos para abastecimento da frota veicular local onde seu princípio fundamental é introduzido, assim como os principais mecanismos de formação de cadeias de hidrocarbonetos de diferentes pesos moleculares permitindo assim a obtenção de gasolina e óleo diesel. Essa dissertação apresenta conceitos para a palavra combustível, da mesma forma que introduz os combustíveis fósseis, seus importantes derivados e suas propriedades gerais para que seja possível, adiante, utilizá-los como comparativo com os biocombustíveis sintéticos; é apresentada a evolução histórica dessa tecnologia e são também abordadas a primeira e segunda gerações de biocombustíveis, para se trazer dados que indiquem as vantagens do óleo diesel Fischer-Tropsch quando comparado com seu equivalente oriundo da petroquímica convencional e por fim demonstrar sua superior qualidade sócio-ambiental como biocombustível sintético para o futuro da matriz energética mundial. / What is supposed to be on board of this study consists in an alternative way focused on vehicular use synthetic fuels obtaining, using as main process the technological route known as Biomass-to-Liquids (BTL), which one consists on Fischer-Tropsch synthesis use for hydrocarbons chain building starting from monomer units obtained from a gas mixture made up mostly by carbon monoxide (CO) and hydrogen (H), known as syngas from fossil energy sources such as coal or natural gas or also biosyngas from carbonaceous renewable raw materials, such as biomass. This paper aims to address the beginning of the production chain in order to introduce a concept for biomass and the biosyngas obtaining means through the process known as gasification, a reference is made to a successful biosyngas obtaining the dependencies at the Institute for Technological Research (IPT) from Sao Paulo. Then there is the use of that input in the Fischer-Tropsch synthesis widely used throughout the twentieth century, in specific countries, to supply the local vehicle fleet where its basic principle is introduced, as well as the main hydrocarbons chain formation mechanisms thus different molecular weights providing gasoline and diesel oil. This essay presents concepts for the word fuel, the same way that makes it for fossil fuels, their major products and their properties in order to use them as a comparison standard for synthetic biofuels, it was also presented the historical development of this technology and first and second generation of biofuels, in order to bring evidence to suggest the benefits of the Fischer-Tropsch diesel fuel once compared to its conventional equivalent come from the petrochemical and finally to demonstrate it as a socio-environmentally superior quality synthetic biofuel for the future of global energy matrix.

Orientador: Afonso Lopes / Banca: Newton La Scala Júnior / Banca: Gilberto Hirotsugu Azevedo Koike / Banca: José Marques Júnior / Banca: Carlos Alberto Alves de Oliveira / Resumo: A introdução do biodiesel na matriz energética do Brasil é motivada principalmente pela possibilidade de desenvolvimento econômico e social para o País, gerando emprego e renda, além dos benefícios ambientais decorrentes da substituição de recursos fósseis por renováveis. O presente trabalho teve por objetivo avaliar comparativamente desempenho operacional do trator agrícola em operação de preparo de solo e opacidade da fumaça em função da utilização de diferentes tipos de biodiesel. Também foi objeto deste trabalho medir opacidade da fumaça em função do período de amaciamento do motor e das condições do óleo lubrificante do cárter, cujos fatores estudados foram tipo de biodiesel e proporções de mistura biodiesel/diesel. O experimento foi conduzido no Departamento de Engenharia Rural, da UNESP de Jaboticabal-SP, em parceria com o LADETEL da USP de Ribeirão Preto-SP. O tipo de biodiesel foi de dendê, mamona e tucumã, e as proporções de mistura de biodiesel com diesel foram B0, B5, B25, B50, B75 e B100 (em que o número indica a percentagem de biodiesel no diesel), o tempo de amaciamento do motor foi novo, 50 e 100 horas de trabalho, e as condições do óleo lubrificante do cárter foram 250 horas de trabalho e novo, utilizando proporções de biodiesel de dendê. Para comparar os tratamentos, foram avaliados consumo de combustível, força de tração na barra, velocidade real de deslocamento, patinagem das rodas, potência na barra de tração e opacidade da fumaça de combustão. Os resultados evidenciaram aumento no consumo específico a partir da mistura com 50% de biodiesel; entretanto, o tipo de biodiesel não influenciou no consumo. Com relação à opacidade da fumaça, houve redução com aumento das proporções de biodiesel, com o tipo de biodiesel influenciando, aumento no período de amaciamento do motor e quando se utilizou óleo lubrificante novo no cárter do motor do trator / Abstract: The introduction of biodiesel in Brazil's energy matrix is motivated mainly by the possibility of economic and social development for the country, generating jobs and income, in addition to the environmental benefits of replacing fossil fuels for renewable ones. The present study aimed to comparatively evaluate the operating performance of the agricultural tractor in operation of soil preparing and smoke opacity due to the use of different types of biodiesel. It was also object of this work to measure the smoke opacity according to the engine softening period and carter lubricating oil conditions, in which the factors studied were type of biodiesel and mixing portions of biodiesel/diesel. The experiment was conducted in the Department of Agricultural Engineering, UNESP of Jaboticabal-SP, in partnership with the LADETEL the USP of Ribeirão Preto-SP. The type of biodiesel was palm, castor and tucumã, and the proportions of biodiesel blend with diesel were B0, B5, B25, B50, B75 and B100 (in which the number indicates the percentage of biodiesel in diesel), the time of engine softening was new, 50 and 100 hours of work, and the carter lubricating oil conditions were 250 hours of work and new, using proportions of biodiesel from palm oil. In order to compare the treatments were evaluated fuel consumption, bar traction power, real displacement speed, wheel slip, potential in traction bar and opacity of combustion smoke. The results showed an increase in specific consumption from the mixture of 50% biodiesel, however the type of biodiesel did not influence consumption. Regarding the smoke opacity, there was a decrease with increasing proportions of biodiesel, with the type of biodiesel influencing increase in engine softening period and when used lubricating oil in the new carter of tractor engine / Doutor

La biomasse des microalgues tropicales a des vertus naturelles qui peuvent être utilisées dans une large gamme de bioproduits. Leur valorisation peut permettre une production durable et commercialement viable. En effet, les microalgues tropicales représentent une grande biodiversité et bénéficient de conditions environnementales favorables à une production à grande échelle. Dans ce contexte, cette thèse vise à étudier de nouvelles souches tropicales afin de connaître leur potentiel de valorisation dans le domaine des biotechnologies, et plus particulièrement sur trois aspects : énergie, nutraceutique et antifouling. Ce dernier domaine a été étudié dans le cadre du projet ANR-CD2I « BIOPAINTROP » dont l’objectif est la lutte écoresponsable contre le biofouling. Ces travaux s’orientent vers des applications biotechnologiques, mais aussi vers le développement des nouvelles méthodes de caractérisation de l’activité antifouling. Sur les 50 souches étudiées, certaines ont montré la production de métabolites d'intérêt tels que le glycosylglycerol, des lipides de qualité pour la nutraceutique et la production de biodiesel. La souche Amphidinium sp. (P-43) a conduit à un extrait méthanolique possédant une activité biologique significative. Son efficacité dans la lutte contre le biofilm a été démontrée. De plus, l'étude d'écotoxicologie réalisée laisse présager d'un faible impact environnemental. / Biomass of tropical microalgae have natural virtues that can be used in a wide range of bioproducts. Their valuation can enable sustainable and commercially viable production. Indeed, tropical microalgae represent a large biodiversity and benefit from favourable environmental conditions for large scale production. In this context, this thesis aims to explore new tropical strains to determine their potential development in the field of biotechnology, particularly in three areas: energy, nutraceutical and antifouling. This field is studied in the project ANR-CD2I "BIOPAINTROP" whose objective is the eco-responsible fight against biofouling. These works target biotechnological applications, but also development of new methods to characterize antifouling activity.Of the 50 strains studied, some have shown interest in the production of metabolites such as glycosyl glycerol, quality nutraceutical and lipids for biodiesel production. The Amphidinium sp. (P-43) stain led to a methanol extract having biological activity of interest. Its efficiency against biofilm was demonstrated. Moreover, the ecotoxicology study has suggested a low environmental impact.

Due to the increasingly detrimental impacts of the global fossil fuel-driven energy economy, technological solutions that can mitigate the deleterious emissions from fossil fuel conversion or that can lessen societal dependence on fossil fuels are urgently required. The conversion of biomass, a renewable energy feedstock, into energy and fuels that are fungible with those derived from fossil fuels would help supplant some of the global fossil fuel consumption with sustainable energy generation. However, one of the main disadvantages of biomass as an energy feedstock when compared to fossil fuels is its low energy density. The majority of thermochemical biomass conversion technologies therefore focus on converting a low energy density feedstock in biomass to a higher energy density end product. Due to the operating parameters involved in these processes, they are typically accomplished on larger and more centralized scales by skilled operators. Few technologies exist that utilize biomass in a sustainable manner under a distributed energy framework, which would allow energy consumers to use locally available resources and waste material to generate energy. The alkaline thermal treatment of biomass has recently been proposed as a novel method for producing high purity H₂ with suppressed COₓ formation under moderate reaction conditions (i.e., 573 K and ambient pressure). Essentially, biomass, which in this study were the model compounds of glucose and cellulose, is reacted with an alkali metal hydroxide, such as NaOH, in such a molar proportion that all of the carbon and oxygen embodied in the reactants is fixed as an alkali metal carbonate, while all of the elemental hydrogen is released as pure H₂ gas. Thus, fuel cell ready H₂ can be produced from biomass in a single reactor. This technology has great potential for sustainable bioenergy production since it can handle a wide range of feedstocks including biomass and biogenic wastes with high water content. In addition to having the potential to be a distributed energy generation technology, the alkaline thermal treatment of biomass could help meet increasing industrial demand for H₂ in a more sustainable manner, as 96% of current H₂ generation is derived from fossil fuels. The alkaline thermal treatment technology is also relatively unexplored; thus, the effects of parameters such as feedstock type, reaction temperature, heating rate, NaOH:Biomass ratio, method of reactant mixing, flow of steam, and concentration of steam flow, on the gaseous and solid products formed are not fully understood. This study was undertaken to quantify the effects of these non-catalytic variables on the alkaline thermal treatment reaction and to elucidate potential reaction pathways in order to better evaluate the potential of the alkaline thermal treatment technology as a viable biomass conversion technology. In the study of the alkaline thermal treatment of glucose, NaOH did play an important role in suppressing COₓ formation while facilitating H₂ production and promoting CH₄ formation. The non-catalytic alkaline thermal treatment of glucose in the absence of steam flow resulted in a maximum H₂ conversion of about 27% at 523 K with a stoichiometric mixture of NaOH and glucose. The solids analysis confirmed the presence of Na₂CO₃ in the solid product, indicating the inherent carbon management potential of the alkaline thermal treatment process. The addition of steam flow increased conversion to H₂ from 25% to 33%, while decreasing total CH₄ formation 5 fold. After the investigation of the alkaline thermal treatment applied to glucose, cellulose was studied as a feedstock because it is the predominant component of lignocellulosic biomass, the target feedstock source for second generation biofuels. Like in the glucose study, it was found that H₂ and hydrocarbon formation occurred with the addition of NaOH to cellulose under thermal treatment, while the further addition of steam enhanced H₂ production and suppressed hydrocarbon formation. Both the enhancement of H₂ conversion and the suppression of hydrocarbon formation with the addition of steam flow was found to be more significant for cellulose than it was for glucose, with in the cellulose case H₂ conversion doubling from 25% to 48%, and CH₄ formation falling 35 times from the no steam flow case. Also like the glucose study, much of the carbon and oxygen present in the reactants were converted to Na₂CO₃. With the knowledge gained about the effects various reaction parameters had on the alkaline thermal treatment reaction, a study of the reaction pathways of the alkaline thermal treatment of cellulose reaction was undertaken. Compounds formed at intermediate temperatures were identified, tested for gaseous production when reacted with NaOH, and the gas product formation rate trends of these reactions were compared with those trends observed from the alkaline thermal treatment of cellulose reaction. The intermediates identified included sodium carboxylate salts, namely sodium formate, sodium glycolate, and sodium acetate, among others. The reactions of these compounds with NaOH were found to yield H₂ and CH₄, with the gaseous formation rate trends being similar to trends observed for the alkaline thermal treatment reaction for cellulose in certain temperature regions. Particular focus was placed on sodium glycolate, which was an intermediate found in high concentration and that reacted with NaOH to produce both H₂ and CH₄. The formation of Na₂CO₃ at intermediate temperatures was also studied, and the comparison of Na₂CO₃ conversion to H₂ conversion at intermediate temperatures revealed that H₂ and Na₂CO₃ formation do not always occur at the 2:1 H₂:Na₂CO₃ molar ratio implied by the proposed stoichiometry of the alkaline thermal treatment reaction for cellulose. The aforementioned studies were conducted both in the presence and absence of steam flow to study its influence on the reaction. Finally H₂ formation kinetic studies were performed on the alkaline thermal treatment of cellulose system as well as the H₂-producing sodium carboxylate salt reaction systems. Sodium formate and sodium oxalate were found to have better selectivity toward H₂ formation and their reactions were more kinetically favored than sodium glycolate with NaOH. A comparison of the isothermal H₂ kinetics between the cellulose and sodium glycolate systems at higher temperatures, however, revealed that H₂ conversion in the alkaline thermal treatment of cellulose appeared to be limited by the rate of conversion of sodium glycolate. From the results of these studies, recommendations are made for future research directions aimed at improving the alkaline thermal treatment of cellulose reaction.

The demand for energy continues to grow but concerns over climate change means that conventional fossil fuels will eventually need to be replaced. The solution to the energy crisis will require a combination of both conventional energy sources with CO2 capture and renewable technologies. While many renewable technologies exist, it is not common that CO2 capture is incorporated into the process. Biomass is an ideal feed-stock for bio-energy production as it is CO2 neutral. Many thermochemical conversion technologies exist, but the Alkaline Thermal Treatment (ATT) reaction is particularly interesting because it combines conventional thermochemical conversion with CO2 capture in order to create a process that is potentially CO2 negative. By reacting biomass with a metal hydroxide, high purity H2 can be produced while simultaneously locking the carbon as a stable carbonate, which is a form of Bio-energy with Carbon Capture & Storage (BECCS). The H2 can then be used for applications ranging from Fischer-Tropsch synthesis to PEM fuel cells. Group I & II hydroxides were investigated for their ability to react with cellulose (a biomass model compound) in the ATT reaction scheme. Comparison between both groups indicated that NaOH and Ca(OH)2 were the best hydroxides from groups I & II respectively. However, the amount of H2 produced during the ATT of cellulose with Ca(OH)2 is considerably lower than with NaOH. A 10% Ni/ZrO2 catalyst was then added to increase the yield of H2 from the reaction between cellulose and Ca(OH)2. It was found that at 20% catalyst loading, the amount of H2 produced and the suppressed level of CO2 was similar to the ATT with NaOH. Several other catalytic metals were also investigated and found to have the following H2 production activity: Ni > Pt≈Pd > Co > Fe, Cu. Since Ni was the most active and has a considerably lower cost than noble metals it was chosen for additional studies. The ATT reaction in the presence of Ni has two distinct steps in the formation of H2 from cellulose. The presence of Ca(OH)2 enhances the formation of linear oxygenates from cellulose. These oxygenates are then reformed over the Ni-based catalyst to H2 and CO2, the latter of which is captured by Ca(OH)2 to form CaCO3. If either Ca(OH)2 or Ni was removed from the reaction, the yield H2 fell significantly. Although the reactants and the catalyst are all solid materials, they do not need to be physically mixed. The Ni-based catalyst produced H2 primarily through the reforming of gaseous species and therefore could be placed ex-situ of the cellulose and Ca(OH)2 mixture. However, placing the catalyst away from Ca(OH)2 prevented CO2 capture. In order to remedy this Ca(OH)2 was mixed with the Ni-based catalyst and mixture was placed ex-situ of pure cellulose. This created a process whereby cellulose could be decomposed thermally followed by a single gas-phase Alkaline Thermal Treatment (GATT) reforming step of the pyrolysis vapors to H2 with suppressed CO2.

Made available in DSpace on 2014-06-11T19:31:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-31Bitstream added on 2014-06-13T19:19:55Z : No. of bitstreams: 1 lima_lp_dr_jabo.pdf: 1123333 bytes, checksum: 7c7bb5fb0ba4ead0d9e0761065d97d1d (MD5) / A introdução do biodiesel na matriz energética do Brasil é motivada principalmente pela possibilidade de desenvolvimento econômico e social para o País, gerando emprego e renda, além dos benefícios ambientais decorrentes da substituição de recursos fósseis por renováveis. O presente trabalho teve por objetivo avaliar comparativamente desempenho operacional do trator agrícola em operação de preparo de solo e opacidade da fumaça em função da utilização de diferentes tipos de biodiesel. Também foi objeto deste trabalho medir opacidade da fumaça em função do período de amaciamento do motor e das condições do óleo lubrificante do cárter, cujos fatores estudados foram tipo de biodiesel e proporções de mistura biodiesel/diesel. O experimento foi conduzido no Departamento de Engenharia Rural, da UNESP de Jaboticabal-SP, em parceria com o LADETEL da USP de Ribeirão Preto-SP. O tipo de biodiesel foi de dendê, mamona e tucumã, e as proporções de mistura de biodiesel com diesel foram B0, B5, B25, B50, B75 e B100 (em que o número indica a percentagem de biodiesel no diesel), o tempo de amaciamento do motor foi novo, 50 e 100 horas de trabalho, e as condições do óleo lubrificante do cárter foram 250 horas de trabalho e novo, utilizando proporções de biodiesel de dendê. Para comparar os tratamentos, foram avaliados consumo de combustível, força de tração na barra, velocidade real de deslocamento, patinagem das rodas, potência na barra de tração e opacidade da fumaça de combustão. Os resultados evidenciaram aumento no consumo específico a partir da mistura com 50% de biodiesel; entretanto, o tipo de biodiesel não influenciou no consumo. Com relação à opacidade da fumaça, houve redução com aumento das proporções de biodiesel, com o tipo de biodiesel influenciando, aumento no período de amaciamento do motor e quando se utilizou óleo lubrificante novo no cárter do motor do trator / The introduction of biodiesel in Brazil's energy matrix is motivated mainly by the possibility of economic and social development for the country, generating jobs and income, in addition to the environmental benefits of replacing fossil fuels for renewable ones. The present study aimed to comparatively evaluate the operating performance of the agricultural tractor in operation of soil preparing and smoke opacity due to the use of different types of biodiesel. It was also object of this work to measure the smoke opacity according to the engine softening period and carter lubricating oil conditions, in which the factors studied were type of biodiesel and mixing portions of biodiesel/diesel. The experiment was conducted in the Department of Agricultural Engineering, UNESP of Jaboticabal-SP, in partnership with the LADETEL the USP of Ribeirão Preto-SP. The type of biodiesel was palm, castor and tucumã, and the proportions of biodiesel blend with diesel were B0, B5, B25, B50, B75 and B100 (in which the number indicates the percentage of biodiesel in diesel), the time of engine softening was new, 50 and 100 hours of work, and the carter lubricating oil conditions were 250 hours of work and new, using proportions of biodiesel from palm oil. In order to compare the treatments were evaluated fuel consumption, bar traction power, real displacement speed, wheel slip, potential in traction bar and opacity of combustion smoke. The results showed an increase in specific consumption from the mixture of 50% biodiesel, however the type of biodiesel did not influence consumption. Regarding the smoke opacity, there was a decrease with increasing proportions of biodiesel, with the type of biodiesel influencing increase in engine softening period and when used lubricating oil in the new carter of tractor engine