L’objectif de cette thèse est de mieux comprendre les réactions de craquage thermique des naphtènes (hydrocarbures saturés cycliques) se déroulant dans les réservoirs pétroliers. Les naphtènes, représentant une famille importante de composés dans les huiles « Haute Pression/Haute Température » des gisements profonds, ont fait l’objet de très peu d’études dans ces conditions. La pyrolyse du n-butylcyclohexane a été étudiée à haute pression (100 bar) dans des réacteurs fermés en tubes en or, entre 300°C et 425°C. Le n butylcyclohexane produit majoritairement des n-alcanes (C1 à C4), d’autres naphtènes et des composés aromatiques. Un modèle cinétique complexe a été développé (833 réactions essentiellement radicalaires) ; il rend bien compte de nos résultats expérimentaux jusque 60% de conversion. L’extrapolation du modèle dans les conditions géologiques (température initiale de 160°C, gradient thermique de 2°C/MA et temps de réaction en millions d’années), montre que ce composé commence à se décomposer vers 180°C et que son temps de demi-vie correspond à 200-210°C. D’autres systèmes réactionnels impliquant des naphtènes, ont été également étudiés à 400°C et 100 bar. L’étude de la pyrolyse de la n-butyldécaline montre que cette molécule bicylique possède une réactivité similaire à celle du n-butylcyclohexane. L’étude à 400°C du mélange binaire n-octane/n-butylcyclohexane ne met pas en évidence d’effet cinétique significatif du n-butylcyclohexane sur la décomposition thermique du n-octane, mais l’extrapolation du modèle aux conditions géologiques montre que les naphtènes inhibent la décomposition des n-alcanes à basse température (200°C) et à haute pression (100 bar) / This thesis aims at better understanding the thermal cracking reactions of naphthenes (saturated cyclic hydrocarbons), occurring in petroleum reservoirs. Naphthenes represent a significant fraction of “High Pressure/High Temperature” oils in deeply buried reservoirs; however, studies in these conditions are very limited in literature. The pyrolysis of n-butylcyclohexane is studied in a gold sealed tube reactor between 300 and 425°C, at 100 bar. n-Butylcylohexane mainly leads to n-alkanes (C1-C4), other naphthenes and aromatic compounds. A detailed model is developed (833 reactions, mainly free-radical reactions); a good agreement with our experimental results is reached up to a conversion of 60%. According to simulation results obtained by extrapolating to lower temperature, this compound starts to undergo thermal cracking at 180°C and its time of half-life corresponds to a temperature around 200-210°C, while considering the following burial scenario of an oil reservoir: initial temperature of 160°C and a heating rate of 2°C/MY (Million Years). Other chemical systems including naphthenes, are also studied at 400°C and 100 bar. The study of 1-n-butyldecaline shows, that this bicyclic compound and n-butylcyclohexane have a similar reactivity at 400°C. The study of the binary mixture n-butylcyclohexane/n-octane at 400°C does not provide any significant evidence of a kinetic effect of n-butylcyclohexane on the thermal decomposition of n-octane, but the extrapolation of our model at geological conditions shows that naphthenes are inhibitors of the decomposition of n-alkanes at low temperature (200°C) and at high pressure (100 bar)

Os solos brasileiros, assim como aqueles localizados em regiões tropicais, possuem elevada capacidade de sorver fósforo (P) devido ao alto grau de intemperismo e consequente composição mineralógica da fração argila. Os fertilizantes solúveis possuem baixa eficiência em função da rápida adsorção aos minerais presentes nestes solos, como também precipitação com cátions em solução. Um componente do solo que pode diminuir a sorção de P é a matéria orgânica que atua na formação de complexos organominerais, inativando os sítios de adsorção dos minerais. Assim, a adição de biocarvão, um composto orgânico recalcitrante, mas que possui grupos reativos de superfície, pode contribuir na redução da sorção de P no solo. O objetivo do trabalho foi estudar o efeito de diferentes temperaturas de pirólise nas características químicas e adsortivas do biocarvão e disponibilidade e aproveitamento de fósforo do fertilizante aplicado no solo. Os biocarvões foram produzidos por pirólise do bagaço de cana-de-açúcar a 250, 450, 650 ºC e um carvão comercial de eucalipto foi utilizado como controle. Os biocarvões foram caracterizados quimicamente e agitados com soluções contendo diferentes doses de P para verificar o comportamento da adsorção de P (isoterma de adsorção). Após filtragem, os biocarvões retidos no filtro foram submetidos à espectroscopia no infravermelho médio. Foram realizados: (i) Um experimento de incubação, fatorial 4 x 2 x 2 + controle, utilizando um solo contendo 70 g kg-1 de argila, com os tratamentos: 4 tipos de biocarvão aplicados na dose de 10 g kg-1; dois níveis de pH (4,8 e 5,8) e dois níveis de adubação fosfatada (0 e 50 mg kg-1). As análises realizadas no solo foram pH em solução de CaCl2 e SMP, P disponível e P remanescente. (ii) Um experimento em casa-de-vegetação, fatorial 4 x 3 x 4, com cultivo de plantas de feijão avaliando os 4 tipos de biocarvão produzidos, 3 doses de cada biocarvão (0, 450 e 900 mg kg-1) aplicados na linha de semeadura e 4 doses de P (0, 25, 50 e 100 mg kg-1) aplicadas contato com o biocarvão na linha. Não houve adsorção de P pelos biocarvões avaliados. Os espectros de infravermelho e análise química mostram que o aumento da temperatura causa diminuição da acidez total, porém aumenta aromaticidade e superfície específica dos materiais. No experimento de incubação os solos que receberam biocarvões produzidos com bagaço de cana apresentaram maior P disponível e remanescente, por mecanismos diferentes. Enquanto o biocarvão produzido à 250 ºC promove a redução da adsorção por interações promovidas por grupos ácidos, os biocarvões com estruturas aromáticas formam complexos de ligações não covalentes com os minerais. O biocarvão pode ser um material importante na redução da sorção de fósforo e economia de fertilizantes, porém pesquisas adicionais devem ser realizadas a fim de estudar a influência da matéria-prima e forma de produção nas potencialidades de uso do produto obtido. / The Brazilian soils, as those from tropical environment, have high phosphorus (P) sorption capacity as a result of their weathering degree and consequently the mineralogical composition in the clay fraction. Soluble fertilizers have low efficiency since the fast adsorption occurs in mineral surfaces, as well as precipitation with cations in the soil solution. The organic matter acts decreasing P sorption in the soils after form organomineral complexes with minerals, by inactivation of adsorption sites. In this way, biochar that is a recalcitrant organic compost; however, contains surface reactive functional groups, can contribute decreasing soil P sorption. The aim of this work was to study the effect of different pyrolysis temperatures in biochar adsorption characteristics, P availability in the soil and plant P absorption from phosphate fertilizer. Biochars were produced by pyrolysis of sugarcane bagasse at 250, 450, 650 ºC and eucalyptus biochar was used as control treatment. Biochars were chemically characterized, and after mixed with solutions containing different P concentrations to study the P sorption behaviour (adsorption isotherm). After filtering, the biochars retained in the filters were undergoing to medium infrared spectroscopy. Were performed: (i) Incubation experiment, factorial 4 x 2 x 2 + control in a soil containing 70 g kg- 1 of clay, with the following treatments: the 4 biochar types cited above, applied at 10 g kg-1 rate; 2 pH levels (4,8 and 5,8) and 2 levels of phosphate fertilizer (0 and 50 mg kg-1). The soil pH (CaCl2 salt and SMP), available and remaining P were analysed. (ii) Greenhouse experiment was performed in 4 x 3 x 4 factorial scheme, with cultivation of common bean plants to evaluate the produced biochars; 3 biochar rates (0, 450 and 900 mg kg-1) were applied at the sowing line and 4 P rates (0, 25, 50 and 100 mg kg-1) added in the same line. The evaluated biochars do not adsorb P. Infrared spectroscopy and chemical analysis showed that increasing temperature resulted in a decreasing in the total acidity. However, occurred an increase in the aromaticity and specific surface of materials. Incubation experiment revealed that the soils which received biochar produced by sugarcane bagasse have greater available and remaining P, these influenced by different mechanisms. While biochar produced at 250 ºC promote adsorption reduction by interactions between biochar acid functional groups and mineral adsorption sites, biochars produced at high temperatures contain aromatic structures can complex minerals by noncovalent bonding. Biochar can be an important tool to reduce P sorption and increase the economy of fertilizers. However, further researches must be carried out to study the influence of feedstocks and pyrolysis technology in the potentiality of use of each biochar.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2017-08-18T19:11:56Z No. of bitstreams: 1 Viviane Manozzo 2016.pdf: 3333567 bytes, checksum: ebe7b9726675839238cfd3ee3c4ed3ca (MD5) / Made available in DSpace on 2017-08-18T19:11:56Z (GMT). No. of bitstreams: 1 Viviane Manozzo 2016.pdf: 3333567 bytes, checksum: ebe7b9726675839238cfd3ee3c4ed3ca (MD5) Previous issue date: 2016-08-29 / The whole world is experiencing an energy crisis, though a lot of potential is wasted because it is necessary to develop technologies for the utilization of biomass as a raw material capable of producing energy. Municipal waste, wood waste, agricultural crop residues, plants and algae, breeding animal waste, food processing and organic waste are considered the main sources of production and biomass and boost research in the energy sector in search responses to the crises faced. The objective of this study was to obtain experimental data of thermal decomposition of biomass Pistia stratiotes and Eichhornia crassipes to determine the kinetic parameters through the pyrolysis process. Thus, laboratory studies were conducted in order to determine the chemical and physical properties: particle size, moisture, volatile matter, ash, cellulose, lignin and superior calorific value (PCS), to obtain the thermal decomposition curve by thermogravimetric analysis for biomasses studied ; and determine the kinetic parameters during pyrolysis of biomass decomposition methods using non-isothermal differential. The thermogravimetric analysis was performed under an inert nitrogen atmosphere at temperatures ranging from 60ºC to 990ºC for four heating rates of 5, 10, 15 and 20 °C / min. Results as 10.83 MJ / kg and 12, 96 MJ / kg were found for PCS of biomasses Pistia stratiotes and Eichhornia crassipes respectively. The determination of the kinetic parameters we used the methods: Flyn Wall Osawa, Kissinger and Friedman. The mass loss of biomass Pistia stratiots presented in the temperature range 244-823 ° C. The Eichhornia crassipes in the range 241-991°C. To Pistia stratiotes the activation energy calculated by the FWO method foinde 178.60 kJ / mol - 332.79 kJ / mol. Kissinger 155.89 kJ / mol. Friedman in the range of 153.75 kJ / mol - 369.09 kJ / mol. For Eichhornia crassipes the activation energy calculated by the method presented FWO in the range of 156.59 kJ / mol - 531 80 kJ / mol. Kissinger 130.46 kJ / mol. Friedman in the range of 156.53 kJ / mol - 349.47 kJ / mol. The results obtained were of the same order of magnitude. The kinetic data confirm that the molecular structures are represented by different mechanisms thermal decomposition reaction rate and the decomposition rate with the temperature in the pyrolysis showing that this technique is a powerful tool for transforming biomass into products which contribute to generation of energy. / O mundo todo vive uma crise energética, no entanto um grande potencial é desperdiçado, pois é preciso que se desenvolvam tecnologias para o aproveitamento de biomassas como matéria prima capaz de produzir energia. Os resíduos urbanos, restos de madeira, resíduos de culturas agrícolas, plantas e algas, resíduos de criadouros de animais, de processamento de alimentos e de resíduos orgânicos se apresentam como as principais fontes de produção e biomassa e impulsionam as pesquisas no setor energético em busca de respostas para as crises enfrentadas. Assim, o objetivo deste estudo foi obter dados experimentais de decomposição térmica das biomassas Pistia stratiotes e Eichhornia crassipes visando determinar os parâmetros cinéticos por meio do processo de pirólise. Desta forma, estudo laboratoriais foram desenvolvidos visando determinar as propriedades químicas e físicas: granulometria, umidade, material volátil, cinzas, celulose, lignina e poder calorífico superior (PCS), obter as curvas de decomposição térmica através de análises termogravimétricas para as biomassas em estudo; e determinar os parâmetros cinéticos durante a pirólise de decomposição das biomassas utilizando métodos não isotérmicos diferenciais. A termogravimetria foi realizada em atmosfera inerte de nitrogênio, com temperaturas variando de 60ºC a 990ºC, para quatro taxas de aquecimento: 5, 10, 15 e 20ºC / min. Resultados como 10,83 MJ/kg e 12, 96 MJ/kg foram encontradas para o PCS das biomassas Pistia stratiotes e Eichhornia crassipes respectivamente. A determinação dos parâmetros cinéticos utilizou–se dos métodos: Flyn Wall Osawa, Kissinger e o Friedman. A perda de massa da biomassa Pistia stratiotes apresentou na faixa de temperatura de 244 – 823 °C. A Eichhornia crassipes na faixa de 241 – 991 °C. Para Pistia stratiotes a energia de ativação calculada pelo método FWO foi de 178,60 kJ / mol – 332,79 kJ / mol. Por Kissinger 155,89 kJ / mol. Por Friedman na faixa de 153,75 KJ / mol – 369,09 kJ / mol. Para Eichhornia crassipes a energia de ativação calculada pelo método FWO apresentou na faixa de 156,59 kJ / mol – 531, 80 kJ / mol. Por Kissinger 130,46 kJ / mol. Por Friedman na faixa de 156,53 kJ / mol – 349,47 kJ / mol. Os resultados obtidos foram da mesma ordem de grandeza. Os dados cinéticos obtidos confirmam que as estruturas moleculares são representadas por diferentes mecanismos de decomposição térmica, taxas de reação e taxa de decomposição com a temperatura no processo de pirólise comprovando que a técnica é uma poderosa ferramenta para transformar biomassas em produtos que contribuem para geração de energia.

A crescente necessidade de se obter fontes de energia e materiais mais sustentáveis tem aumentado o interesse em processos baseados na conversão de biomassa. Microalgas são particularmente interessantes por não competirem com alimentos e serem facilmente adaptáveis ao meio de crescimento. Além disso, microalgas podem ser processadas termicamente para geração tanto de biocombustíveis quanto de produtos químicos úteis. Estudos de conversão térmica de microalgas tem aparecido apenas em anos recentes, endereçando principalmente temperaturas entre 350 e 500 ºC. Neste estudo, a pirólise em temperaturas entre 500 e 900 ºC foi avaliada pelo interesse em se obter biocombustíveis e produtos químicos úteis. As classes de compostos obtidos a partir da pirólise isotérmica da microalga da espécie Chlorella vulgaris foram investigadas através de um sistema composto por um pirolisador conectado a um CG/MS. Dentre as classes identificadas, houve uma predominância de compostos aromáticos e nitrogenados, principalmente derivados de proteínas. Além disso, a maioria dos compostos identificados na corrente de produtos voláteis está presente em todas as temperaturas de reação estudadas. Os parâmetros cinéticos de energia de ativação aparente, constante de reação e ordem de reação foram determinados através de três modelos cinéticos conhecidos como K-A-S, Osawa e Freeman-Carroll, a partir de dados termogravimétricos. A energia de ativação determinada para Chlorella apresentou valores entre 60 e 206 kJ/mol, enquanto a ordem de reação teve como resultado valores entre segunda e décima ordem, de acordo com o modelo cinético. / The increasing need to obtain more sustainable sources of energy and raw materials has attracted attention to processes based on biomass conversion. Microalgae are particularly interesting because they do not compete with human food and they are easily adaptable to the growth medium. Besides, microalgae can be thermally processed to produce both biofuels and useful chemicals. Studies on thermal conversion of microalgae have appeared only in recent years, addressing mainly reaction temperatures between 350 and 500 °C. In this study, pyrolysis in temperatures ranging from 500 to 900 ºC have been investigated considering the interest in producing biofuels and useful chemical compounds. The classes of products obtained by isothermal pyrolysis of the Chlorella vulgaris microalgae have been investigated using a pyrolyzer directly connected to a GC/MS system. Among the classes identified, there was a predominance of aromatic and nitrogenous compounds, mainly protein derived compounds. In addition, most products identified in the volatile products stream are present in all reaction temperatures investigated. The kinetic parameters of apparent activation energy, reaction constant and order of reaction were determined through three kinetic models known as K-A-S, Osawa and Freeman-Carroll, calculated from thermogravimetric data. The activation energy for Chlorella presented values within the range of 60 and 206 kJ/mole, while the order of reaction resulted in values between second and tenth order, from the different methods.

No description available.

Degradation processes change the chemical composition of oil and can be affected by the mixing of oil into the environment. Here, a ramped pyrolysis (RP) isotope technique is implemented to investigate thermochemical and isotopic changes in coastal environments impacted by the 2010 BP Deepwater Horizon oil spill (DwH). Marsh sediment determined to contain oil by PAH analysis display relatively low thermochemical stability and depleted stable carbon (13C) and radiocarbon (14C) isotopic signatures. The ability of RP to separate oil from background organic material (OM) is established by high oil composition for pyrolysates evolved at low temperatures, as determined by radiocarbon measurement. Applying the RP isotopic technique to beach sediment, tar, and marsh samples collected over a span of 881 days reveals a predominance of oil in the organic material for up to 881 days and varying rates of degradation. Pyrolysis profiles show that the oil degraded faster where rates of mixing were higher. Observing how oil changes thermochemically over time provides a new perspective on oil degradation and its relationship with mixing. / acase@tulane.edu

The importance of two sources of NO formation, nitrogen in combustion air and nitrogen in the fuel, during black liquor combustion was studied using a laminar entrained flow reactor. Pyrolysis and combustion experiments were conducted in nitrogen atmosphere and in a mixture of argon and helium in the composition 99% argon, 1% helium. The experiments were performed at three different temperatures: 700, 900, and 1100��C and at two residence times: 0.6 and 1.6 seconds. The results indicated that there was NO formation from the combustion air which was found to be prompt NO. There was NO formation from combustion air at all temperatures, and it decreased as temperature increased. Depending on conditions, prompt NO formation accounted for 6-80% of the total NO formation. NO reduction experiments were conducted to investigate the effect of molten sodium carbonate on NO reduction. The experiments were performed at two different temperatures, 800��C which is lower than the melting point of sodium carbonate and 900��C which is higher than the melting point of sodium carbonate. The rate constant for NO reduction was calculated and was found to agree well with that obtained in a previous study. The effect of the molten sodium carbonate on NO reduction was found to be negligible during black liquor pyrolysis. The rate in absence of any reducing gas components could explain NO reduction during black liquor combustion only to a limited extent. Models for nitrogen evolution during pyrolysis and combustion were developed by using data from previous studies. A model for nitrogen release during pyrolysis was developed as a function of residence time and temperature. Nitrogen release during pyrolysis was also found to be directly proportional to carbon release and the rate of nitrogen evolution with respect to the rate of carbon evolution decreased as temperature increased. / Graduation date: 1997

No description available.

In this thesis work, it was aimed to optimize the conditions to produce silicon carbide (SiC), from rice husks from Turkish Thrace Region, via pyrolysis. Rice husks, coked at 500oC, were high energy ball-milled prior to pyrolysis, in order to investigate the effects of ball-milling on pyrolysis temperature, pyrolysis time and morphology of the SiC produced. Samples of rice husks subjected to different ball milling conditions, were pyrolyzed at temperatures varying from 1500oC to 1600oC and for times varying from &frac12 / hour to 2 hours. Results of experiments showed that, ball-milling reduced the pyrolysis temperature and pyrolysis time to some extent. It was also experimentally shown that ball-milling favored the formation of SiC particles rather than formation of SiC whisker.

Cashew nut and coconut shells are two potential renewable and environmentally friendly energy sources that are commonly found as agro-industrial wastes in tropical countries. Despite this fact, they are not yet widely studied as such. Given this lack of specific technical and reliable data, technologies for their conversion into energy cannot be designed with confidence as it happens with other commonly studied biomass feedstock. Thus, the need to generate these data guided this research in order to provide technical information for the designing of appropriate thermochemical conversion technologies for energy generation, particularly, in remote areas, where electricity grid is neither a feasible nor an affordable solution.Among thermochemical processes, pyrolysis plays a key role as it is found in both combustion and gasification at their earlier stages. In both technologies, pyrolysis products are generated and later submitted to further transformations according to the process in use.Hence, pyrolysis was selected for thermal characterisation of cashew nut and coconut shells. The main characteristics envisaged are i) pyrolysis profiles; ii) global, semi-global and individual kinetics; iii) pyrolysis global and individual yields; iv) modelled pyrolysis yields at high heating rates; and, v)char combustion kinetics and reactivity. The main technique used for experimental data generation is thermogravimetry and FTIR spectroscopy. Data experimentally generated from TG and TG-FTIR experiments were processed through different methods and codes, such as the Coats and Redfern model-fitting method, the modelfree methods of Ozawa-Flynn-Wall, Friedman and ASTM E698, for semi-global and global kinetics; DAEM and FG-Biomass were used for pyrolysis individual kinetics and yields determination. Proximate and ultimate analyses were performed as well.The study revealed peculiar characteristics compared to the commonly known lignocellulosic biomass. The volatiles content was above 66%w/w; hemicelluloses DTG peak did not overlap with the cellulose peak; the global pyrolysis activation energies were around 200 and 120 kJ/mol for coconut and cashew nut shells, respectively. Hemicelluloses and cellulose showed varying activation energies as 130-216 and 155-208 kJ/mol, respectively. Char combustion showed two steps with activation energies of 135 and 121 kJ/mol (cashew nut shells); 105 and 190kJ/mol (coconut shells). Individual yields and kinetics were determined for 17 compounds, including tars. These data are of key importance for modelling and the consequent data generation for the designing of appropriate thermochemical energy for these biomasses. / QC 20100914