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Previous issue date: 2014-03-12 / The diesel combustion form sulfur oxides that can be discharged into the atmosphere as particulates and primary pollutants, SO2and SO3, causing great damage to the environment and to human health. These products can be transformed into acids in the combustion chamber, causing damage to the engines. The worldwide concern with a clean and healthy environment has led to more restrictive laws and regulations regulating the emission levels of pollutants in the air, establishing sulfur levels increasingly low on fuels. The conventional methods for sulfur removal from diesel are expensive and do not produce a zero-level sulfur fuel. This work aims to develop new methods of removing sulfur from commercial diesel using surfactants and microemulsion systems. Its main purpose is to create new technologies and add economic viability to the process. First, a preliminary study using as extracting agent a Winsor I microemulsion system with dodecyl ammonium chloride (DDACl) and nonyl phenol ethoxylated (RNX95) as surfactant was performed to choose the surfactant. The RNX95 was chosen to be used as surfactant in microemulsioned systems for adsorbent surface modification and as an extracting agent in liquid-liquid extraction. Vermiculite was evaluated as adsorbent. The microemulsion systems applied for vermiculite surface modification were composed by RNX95 (surfactant), n-butanol (cosurfactant), n-hexane (oil phase), and different aqueous phases, including: distilled water (aqueous phase),20ppm CaCl2solution, and 1500ppm CaCl2solution. Batch and column adsorption tests were carried out to estimate the ability of vermiculite to adsorb sulfur from diesel. It was used in the experiments a commercial diesel fuel with 1,233ppm initial sulfur concentration. The batch experiments were performed according to a factorial design (23). Two experimental sets were accomplished: the first one applying 1:2 vermiculite to diesel ratio and the second one using 1:5 vermiculite to diesel ratio. It was evaluated the effects of temperature (25?C and 60?C), concentration of CaCl2in the aqueous phase (20ppm and 1500ppm), and vermiculite granule size (65 and 100 mesh). The experimental response was the ability of vermiculite to adsorb sulfur. The best results for both 1:5 and 1:2 ratios were obtained using 60?C, 1500ppm CaCl2solution, and 65 mesh. The best adsorption capacities for 1:5 ratio and for 1:2 ratio were 4.24 mg sulfur/g adsorbent and 2.87 mg sulfur/g adsorbent, respectively. It was verified that the most significant factor was the concentration of the CaCl2 solution. Liquid-liquid extraction experiments were performed in two and six steps using the same surfactant to diesel ratio. It was obtained 46.8% sulfur removal in two-step experiment and 73.15% in six-step one. An alternative study, for comparison purposes, was made using bentonite and diatomite asadsorbents. The batch experiments were done using microemulsion systems with the same aqueous phases evaluated in vermiculite study
and also 20ppm and 1500 ppm BaCl2 solutions. For bentonite, the best adsorption capacity was 7.53mg sulfur/g adsorbent with distilled water as aqueous phase of the microemulsion system and for diatomite the best result was 17.04 mg sulfur/g adsorbent using a 20ppm CaCl2solution. The accomplishment of this study allowed us to conclude that, among the alternatives tested, the adsorption process using adsorbents modified by microemulsion systems was considered the
best process for sulfur removal from diesel fuel. The optimization and scale upof the process constitutes a viable alternative to achieve the needs of the market / Os ?xidos de enxofre formados pela combust?o do ?leo diesel podem ser
descarregados para a atmosfera sob a forma de particulados e poluentes prim?rios como SO2 e SO 3, acarretando grandes preju?zos ao meio ambiente e ? sa?de humana e, ainda, podem se transformar em ?cidos na c?mara de combust?o, causando danos aos motores. A preocupa??o
mundial com o meio ambiente saud?vel e despolu?do tem levado ? institui??o de normas e leis no sentido de reduzir os n?veis de emiss?o de poluentes no ar, estabelecendo teores de enxofre cada vez mais baixos nos combust?veis, de modo a seter produtos menos agressivos ao meio ambiente e ? sa?de p?blica. Os m?todos convencionais de remo??o de enxofre do diesel t?m custo elevado, al?m de n?o serem capazes de produzir combust?veis com n?vel zero de enxofre.
Assim, este trabalho tem como objetivo desenvolver novos m?todos de remo??o de enxofre do diesel utilizando tensoativos e sistemas microemulsionados, procurando associar novas
tecnologias e viabilidade econ?mica aos processos. Para escolha do tensoativo, foi feito um
estudo de extra??o na regi?o de Winsor I, com cloreto de dodecilam?nio (DDACl) e nonil fenol
etoxilado (RNX 95). A partir dos resultados foi escolhido o RNX 95, como constituinte dos
sistemas microemulsionados utilizados na modifica??o dos adsorventes, para os processos de adsor??o e, como extratante, para extra??o l?quido-l?quido. Utilizou-se como adsorvente a vermiculita tratada com uma microemuls?o constitu?da por RNX 95 (tensoativo), n-butanol (cotensoativo), hexano (fase oleosa) e ?gua destilada, solu??o salina de CaCl220 ppm, solu??o salina de CaCl2 1500 ppm (fase aquosa), nos processos de adsor??o, em banho finito e em coluna, cuja fase fluida foi o ?leo diesel comercial (1233 ppm de enxofre). Na etapa de adsor??o
em banho finito aplicaram-se duas abordagens estat?sticas pelo m?todo do planejamento fatorial completo (23), com tr?s vari?veis (temperatura, concentra??o da solu??o salina de CaCl2 e granulometria da vermiculita) em dois n?veis experimentais (superior e inferior), variando a raz?o vermiculita:diesel, sendo um planejamento fatorial para a raz?o igual a 1:2 e outro para raz?o igual a 1:5. A resposta experimental foi a capacidade da vermiculita em adsorver o enxofre. Os melhores resultados, tanto para a raz?overmiculita/diesel de 1:5 como para a raz?o
1:2, foram obtidos a uma temperatura de 60?C, concentra??o de CaCl
2 1500 ppm e granulometria da vermiculita 65 mesh, obtendo-se capacidades de adsor??o de 4,24 mg/g para a
raz?o 1:5 e 2,87 mg/g, para a raz?o 1:2, indicando que a vari?vel mais significativa, em ambas as raz?es, foi a concentra??o da solu??o salina de CaCl2. Na extra??o l?quido-l?quido, realizada em duas e em seis etapas, utilizou-se a mesma propor??o de tensoativoe diesel e obtiveram-se
percentuais de extra??o de 46,8% e 73,15%, respectivamente. Foi realizado tamb?m um estudo
alternativo de modifica??o de outros adsorventes para fins de compara??o. Os ensaios foram
feitos em banho finito com bentonita e diatomita, modificadas com microemuls?o. Os agentes
modificadores foram os j? estudados neste trabalho acrescidos de solu??es salinas de BaCl220 ppm e 1500 ppm, como fases aquosas dos sistemas microemulsionados. Para a bentonita a melhor capacidade de adsor??o foi de 7,53 mg/g utilizando o sistema microemulsionado com ?gua destilada na fase aquosa e para a diatomita o melhor resultado ocorreu com a microemuls?o contendo solu??o salina de CaCl2 20ppm, obtendo-se uma capacidade de
adsor??o de 17,04 mg/g. A realiza??o deste estudo permite concluir que, dentre as alternativas testadas, a adsor??o utilizando adsorventes impregnados por microemuls?es foi considerado o melhor processo de remo??o do enxofre do diesel e que a sua otimiza??o e scale upconstitui-se
em uma alternativa vi?vel e de custo compat?vel comas necessidades do mercado
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/15933 |
| Date | 12 March 2014 |
| Creators | Duarte, Kahildete Rodrigues Forte |
| Contributors | CPF:05641284491, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4783215D9, Peres, Ant?nio Eduardo Clark, CPF:04457641634, http://lattes.cnpq.br/8666548473150908, Leite, Ricardo Henrique de Lima, CPF:52264343400, http://lattes.cnpq.br/3801476460958779, Medeiros, Gilson Gomes de, CPF:19989849404, http://lattes.cnpq.br/9423866978987831, Moura, Maria Carlenise Paiva de Alencar, CPF:21414130368, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4702157Y9, Barros Neto, Eduardo Lins de, CPF:59545844434, http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4798645D3, Dantas, Tereza Neuma de Castro, Dantas Neto, Afonso Avelino |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Engenharia Qu?mica, UFRN, BR, Pesquisa e Desenvolvimento de Tecnologias Regionais |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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