Dissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2011 / Made available in DSpace on 2012-10-25T20:51:20Z (GMT). No. of bitstreams: 1 292665.pdf: 2256970 bytes, checksum: 24cf4078c8291e4895b7de1e4d6471eb (MD5) / A dessulfurização é uma etapa importante no processamento de petróleo e o seu aprimoramento é fundamental para melhorar a qualidade dos derivados de petróleo, reduzir o impacto ambiental causado pelo produto final e diminuir os custos de produção. No presente trabalho, estudou-se a remoção de compostos organossulfurados de óleos lubrificantes de origem naftênica. Esses óleos são provenientes das correntes de destilação à vácuo, chamadas de gasóleo pesado. A sua comercialização, após o processamento nas refinarias, se dá na forma de óleos básicos, tornando-se apenas um óleo lubrificante após a colocação de aditivos pelo distribuidor final. Neste trabalho, avaliou-se tecnicamente a possibilidade de utilizar o processo de adsorção em coluna como alternativa ou complemento aos processos de hidrotratamento utilizados para a dessulfurização de óleos lubrificantes naftênicos. Inicialmente, levantou-se os parâmetros termodinâmicos e cinéticos através da isoterma de equilíbrio e da cinética de adsorção em batelada. A capacidade máxima de adsorção de dibenzotiofeno, presente em óleos lubrificantes, pelo carvão, foi de 249,87mg/g. A análise de dibenzotiofeno, presente em óleos lubrificantes sintéticos, utilizando como elemento de medida a cromatografia gasosa e o método do padrão interno, se mostrou bastante eficaz. O modelo de cinética de pseudo 2.a ordem se ajustou melhor aos dados experimentais, sugerindo uma estrutura microporoso para o carvão que se ratificou com o diâmetro médio dos poros de 8 angstrons, resultante da análise da distribuição dos poros do carvão. As cinéticas de adsorção em processos contínuos foram realizadas em coluna de adsorção em escala laboratorial. Avaliouse nesse experimento a influência da vazão e concentração de alimentação da coluna na eficiência de remoção de enxofre presente em óleos lubrificantes. Para facilitar o escalonamento da coluna desenvolveu-se um simulador utilizando um modelo matemático fenomenológico e o método de volumes finitos para a solução das equações do modelo. Os resultados obtidos pela rotina computacional corroboraram com os dados experimentais. O carvão utilizado foi regenerado à temperatura de 300oC, sendo que 89,68% da sua capacidade de adsorção foi restituída na primeira regeneração. / Desulfurization is an important stage in the processing of petroleum and its improvement is fundamental in order to improve the quality of petroleum derivatives, to reduce the environmental impact of the final product and to decrease the production costs. In this study the removal of organosulfur compounds from lubricating oils derived from naphthene is investigated. These oils are obtained from vacuum distillation streams known as heavy gas oil. They are commercialized, after processing in refineries, in the form of basic oils, becoming lubricating oils only after the addition of additives by the final distributer. In this study the column adsorption process was technically evaluated as a method to replace or complement the hydrotreatment processes used for the desulfurization of naphthenic lubricating oils. Firstly, the thermodynamic and kinetic parameters were determined through equilibrium isotherms and batch adsorption kinetics studies. The maximum capacity for the adsorption of dibenzothiophene (present in lubricating oils) onto carbon was 249,87 mg/g. The determination of dibenzothiophene present in synthetic lubricating oils using gas chromatography and the internal standard method was found to be efficient. A pseudo-second-order kinetic model gave the best fit to the experimental data, suggesting that the carbon has a microporous structure, which was verified by the average pore diameter of 8 angstroms according to the results for the pore size distribution of the carbon. The adsorption kinetics in continuous processes was determined in a laboratory scale adsorption column. In this experiment the influence of the column feed flow and concentration on the efficiency of sulfur removal from lubricating oils was evaluated. To facilitate the scaling of the column, a simulator was developed using a phenomenological mathematical model and the finite volumes method to solve the model equations. The results obtained from the computational routine were consistent with the experimental data. The carbon used was regenerated at a temperature of 300°C, with 89,68% of its adsorption capacity being recovered in the first regeneration.

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Química, Florianópolis, 2010 / Made available in DSpace on 2012-10-24T22:26:10Z (GMT). No. of bitstreams: 0 / Um dos constituintes do petróleo, o enxofre, é um dos mais prejudiciais poluentes ao meio-ambiente que atualmente existe. Desta forma, políticas ambientais são cada dia mais severas, com o intuito de diminuir a concentração deste componente nos derivados de petróleo, incorrendo assim em custos adicionais para a indústria do petróleo, objetivando a diminuição de compostos sulfurados em seus produtos. Estes compostos são geralmente retirados das correntes de destilados por processo catalítico de hidrogenação, sob condições de elevadas temperaturas e pressões, chamado de hidrotratamento (HDT), sendo assim, um processo de elevado custo operacional. A adsorção se mostra como um excelente processo de pré ou póstratamento das correntes de HDT, por operar em baixas pressões e temperaturas, diminuindo assim as condições severas de processamento e da mesma forma os custos de capital e operacional. A literatura já traz trabalhos relacionados à dessulfurização por adsorção de destilados leves que originam combustíveis tais como gasolina, óleo diesel e combustível de aviação. Porém, os destilados de petróleo mais pesados que originam óleos lubrificantes, ainda não foram abordados na literatura com relação à aplicação do método adsortivo para dessulfurização. Os lubrificantes possuem um valor agregado cerca de três vezes maior que os combustíveis convencionais, possuindo assim um grande atrativo econômico. Desta forma, no presente de trabalho foi estudada a adsorção de compostos orgânicos sulfurados em destilados pesados naftênicos industriais e sintéticos, utilizando carvão ativado como adsorvente. O carvão ativado foi escolhido devido à sua grande capacidade de adsorção a uma grande gama de compostos organo-sulfurados, reportadas em trabalhos científicos para combustíveis convencionais. O estudo adsortivo consistiu no levantamento de isotermas de equilíbrio, tanto para frações naftênicas de petróleo, como para compostos sintéticos, objetivando a determinação da capacidade e seletividade adsortiva do carvão; da mesma forma, houve o estudo de curvas cinéticas de adsorção, visando à determinação do comportamento difusivo do sistema em estudo. As influências da temperatura, da massa molecular, da presença de inibidores (água, fenol, naftaleno e carbazol) e da concentração inicial de compostos sulfurados usualmente presentes em destilados pesados foram determinadas em processo de batelada. Foram desenvolvidos modelos para representar o processo adsortivo em estudo e um algoritmo para a predição do comportamento cinético do sistema via simulação numérica. Os resultados encontrados mostraram que, de uma forma geral, o aumento da massa molecular das moléculas sulfuradas presentes nos destilados naftênicos, assim como, a presença de moléculas de outras classes orgânicas, atuando como inibidores, desfavoreceram o fenômeno adsortivo dos compostos sulfurados sobre o carvão ativado. Já o aumento da temperatura favoreceu a adsorção dos compostos sulfurados dos destilados de petróleo, devido a uma possível resistência difusional de acesso aos sítios ativos do carvão, a qual diminuiu com o aumento da temperatura, ou seja, o aumento da energia interna das moléculas. / Sulfur is a component of the oil, which is one of the most dangerous pollutants that exist at the environmental. Therefore politics are harder to decrease the sulfur concentration in refined oils that increase the oil industry costs. This component is normally extracted by hydrogen catalytic processes of distilled streams, at high pressures and temperatures, called hydrotreatment (HDT). The adsorption is presented as an excellent treatment of the inner and outers HDT streams, decreasing their severity, capital and operation costs. The literature shows works which are related with distilled oils desulfurization by adsorption, that origin fuels like gasoline, óleo diesel and aviation fuel. However, the heavier distilled oils which originate lubrificating base oil were not studied yet about the use of adsorption methods to desulfurization. These lubrificating base oils have monetary values about two or three times higher than the conventional fossil fuels, having a great economic attractive. Therefore, the sulfur species adsorption in commercial and synthetic naphthenic heavy distilled oils, using activated carbon as adsorbent was studied in this work. The activated carbon was chosen due to its high capacities adsorption to great variety of sulfur compounds, reported in scientific works to conventional fossil fuels. The adsorption study was based on thermodynamic adsorption on synthetic and real distillates, getting adsorbent capacities and selectivities, and on kinetics adsorption determining diffusivity behavior of the systems. The temperature, molecular size, inhibitors presence (water, phenol, naphtalene and carbazole) and initial concentration influences of the common sulfur species encountered in heavy distillates were determine in batch experiments. Models were developed to represent de experimental data and a numeric algorithm was made to predict the kinetic behavior of the system. In general, the results showed that the sulfur molecular size increasing and the presence of molecules with other molecular composition, acting as inhibitors, decrease the adsorption of sulfur compounds on activated carbon. However, the temperature increasing gives a better sulfur compounds adsorption to petroleum distillates, due to a possible diffusional resistance of activated sites access, which is decreased to higher temperatures, due to molecular internal energy increasing.Sulfur is a component of the oil, which is one of the most dangerous pollutants that exist at the environmental. Therefore politics are harder to decrease the sulfur concentration in refined oils that increase the oil industry costs. This component is normally extracted by hydrogen catalytic processes of distilled streams, at high pressures and temperatures, called hydrotreatment (HDT). The adsorption is presented as an excellent treatment of the inner and outers HDT streams, decreasing their severity, capital and operation costs. The literature shows works which are related with distilled oils desulfurization by adsorption, that origin fuels like gasoline, óleo diesel and aviation fuel. However, the heavier distilled oils which originate lubrificating base oil were not studied yet about the use of adsorption methods to desulfurization. These lubrificating base oils have monetary values about two or three times higher than the conventional fossil fuels, having a great economic attractive. Therefore, the sulfur species adsorption in commercial and synthetic naphthenic heavy distilled oils, using activated carbon as adsorbent was studied in this work. The activated carbon was chosen due to its high capacities adsorption to great variety of sulfur compounds, reported in scientific works to conventional fossil fuels. The adsorption study was based on thermodynamic adsorption on synthetic and real distillates, getting adsorbent capacities and selectivities, and on kinetics adsorption determining diffusivity behavior of the systems. The temperature, molecular size, inhibitors presence (water, phenol, naphtalene and carbazole) and initial concentration influences of the common sulfur species encountered in heavy distillates were determine in batch experiments. Models were developed to represent de experimental data and a numeric algorithm was made to predict the kinetic behavior of the system. In general, the results showed that the sulfur molecular size increasing and the presence of molecules with other molecular composition, acting as inhibitors, decrease the adsorption of sulfur compounds on activated carbon. However, the temperature increasing gives a better sulfur compounds adsorption to petroleum distillates, due to a possible diffusional resistance of activated sites access, which is decreased to higher temperatures, due to molecular internal energy increasing.Sulfur is a component of the oil, which is one of the most dangerous pollutants that exist at the environmental. Therefore politics are harder to decrease the sulfur concentration in refined oils that increase the oil industry costs. This component is normally extracted by hydrogen catalytic processes of distilled streams, at high pressures and temperatures, called hydrotreatment (HDT). The adsorption is presented as an excellent treatment of the inner and outers HDT streams, decreasing their severity, capital and operation costs. The literature shows works which are related with distilled oils desulfurization by adsorption, that origin fuels like gasoline, óleo diesel and aviation fuel. However, the heavier distilled oils which originate lubrificating base oil were not studied yet about the use of adsorption methods to desulfurization. These lubrificating base oils have monetary values about two or three times higher than the conventional fossil fuels, having a great economic attractive. Therefore, the sulfur species adsorption in commercial and synthetic naphthenic heavy distilled oils, using activated carbon as adsorbent was studied in this work. The activated carbon was chosen due to its high capacities adsorption to great variety of sulfur compounds, reported in scientific works to conventional fossil fuels. The adsorption study was based on thermodynamic adsorption on synthetic and real distillates, getting adsorbent capacities and selectivities, and on kinetics adsorption determining diffusivity behavior of the systems. The temperature, molecular size, inhibitors presence (water, phenol, naphtalene and carbazole) and initial concentration influences of the common sulfur species encountered in heavy distillates were determine in batch experiments. Models were developed to represent de experimental data and a numeric algorithm was made to predict the kinetic behavior of the system. In general, the results showed that the sulfur molecular size increasing and the presence of molecules with other molecular composition, acting as inhibitors, decrease the adsorption of sulfur compounds on activated carbon. However, the temperature increasing gives a better sulfur compounds adsorption to petroleum distillates, due to a possible diffusional resistance of activated sites access, which is decreased to higher temperatures, due to molecular internal energy increasing.

Submitted by Gustavo Caixeta (gucaixeta@gmail.com) on 2017-02-21T13:14:53Z No. of bitstreams: 1 texto completo.pdf: 339223 bytes, checksum: 05053be3fb027d334a0a4fdb00eea1a1 (MD5) / Made available in DSpace on 2017-02-21T13:14:53Z (GMT). No. of bitstreams: 1 texto completo.pdf: 339223 bytes, checksum: 05053be3fb027d334a0a4fdb00eea1a1 (MD5) Previous issue date: 1996-02-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES, Brasil / Estudaram-se a absorção e o metabolismo do S influenciados pelo Al em dois cultivares de sorgo, um sensível (BR007A) e outro tolerante (BR006R) ao Al, com o objetivo de esclarecer alguns aspectos da tolerância a este elemento. As plantas, cultivadas em solução nutritiva, pH 4,0, foram submetidas a duas concentrações de Al (0 e 0,185 mM) e a duas concentrações de sulfato (0 e 0,6 mM) durante 10 dias. Determinaram-se, então, os pesos de matéria seca; os teores de Al, S-total, S-orgânico, S-sulfato e tióis totais; as constantes cinéticas de absorção de S; e a atividade da sulfurilase do ATP. A produção de matéria seca foi bastante reduzida tanto na ausência de S quanto na presença de Al. O Al acumulou-se principalmente no sistema radicular dos dois cultivares, independentemente da presença de S e reduziu o valor das constantes cinéticas V max e K m nos dois cultivares ou apenas no sensível, respectivamente. O C min foi idêntico nos dois cultivares, não tendo sido influenciado pelo Al. Os efeitos do Al sobre estas constantes foram sempre mais intensos quando as plantas foram cultivadas na sua presença. Os teores das frações sulfuradas decresceram na ausência de S ou na presença de Al nos dois cultivares, especialmente no sistema radicular. As reduções nas frações sulfuradas causadas pelo Al foram sempre maiores na presença de S. O cultivar tolerante, apesar do menor teor de S-total, apresentou índice de utilização deste elemento na presença de Al maior do que o cultivar sensível, principalmente no sistema radicular. O teor de tióis, independentemente da presença de S, aumentou nos tratamentos com Al, principalmente no sistema radicular. Este aumento, contudo, parece ser uma reação geral da planta ao estresse e não um mecanismo específico de tolerância das plantas de sorgo ao Al. A redução do sulfato pela sulfurilase do ATP deu-se, preferencialmente, na parte aérea. A atividade desta enzima, maior no cultivar tolerante, decresceu fortemente na presença de Al, independentemente da presença de S. / Sulfur uptake and metabolism influenced by Al were studied in two sorghum cultivars, one Al-sensitive (BR007A) and other Al-tolerant (BR006R), with the main objective to better understand some aspects of Al tolerance. Plants grown in nutrient solution, pH 4.0, were exposed to two Al concentrations (0 and 0.185 mM) and to two S concentrations (0 and 0.6 mM) during 10 days. Dry weight, Al, total-S, organic-S, sulfate-S, soluble thiol concentrations, kinetic constant of S uptake and ATP sulfurylase activity were determined. Dry weight yield was strongly reduced in the absence of S and, or presence of Al. Aluminum acumulated mainly in the root system of both cultivars, independent of the presence of S. The kinetic constants: V max and K m were reduced in the presence of Al in both cultivars or only in the Al-sensitive cultivar, respectively. The C min was identical in the two cultivars and did not change with Al treatment. Aluminum effects on those kinetic constants were always stronger when Al was added to the growth medium than in the absorption medium. The concentration of the various S fractions decreased in the S absence or Al presence, especially in the root system of both cultivars. The Al-induced reductions in these S fractions were always stronger when S was present. Although showing lower S- total concentration the Al-tolerant cultivar had in the presence of Al a higher S utilization index than the Al-sensitive one. The thiol concentration increase with Al treatment independent of S presence, especially in the root system. This increase however seems to be a general plant reaction to the stress rather than a specific Al tolerance mechanism in sorghum. The sulfate reduction, based on ATP sulfurylase activity occurred mainly in the leaves. The activity of this enzyme, higher in the Al-tolerant cultivar, was strongly reduced by Al in both cultivars, whether S was present or not in the growth medium.