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Previous issue date: 2011-03-11 / Biodiesel is a fuel made up by mono-alkyl-esters of long chain fatty acids, derived from
vegetable oils or animal fat. This fuel can be used in compression ignition engines for
automotive propulsion or energy generation, as a partial or total substitute of fossil
diesel fuel. Biodiesel can be processed from different mechanisms. Transesterification is
the most common process for obtaining biodiesel, in which an ester compound reacts
with an alcohol to form a new ester and a new alcohol. These reactions are normally
catalyzed by the addition of an acid or a base. Initially sunflower, castor and soybean oil
physicochemical properties are determined according to standard test methods, to
evaluate if they had favorable conditions for use as raw material in the
transesterification reaction. Sunflower, castor and soybean biodiesel were obtained by
the methylic transesterification route in the presence of KOH and presented a yield
above 93% m/m. The sunflower/castor and soybean/castor blends were studied with the
aim of evaluating the thermal and oxidative stability of the biofuels. The biodiesel and
blends were characterized by acid value, iodine value, density, flash point, sulfur
content, and content of methanol and esters by gas chromatography (GC). Also studies
of thermal and oxidative stability by Thermogravimetry (TG), Differential Scanning
Calorimetry High Pressure (P-DSC) and dynamic method exothermic and Rancimat
were carried out. Biodiesel sunflower and soybean are presented according to the
specifications established by the Resolution ANP no 7/2008. Biodiesel from castor oil,
as expected, showed a high density and kinematic viscosity. For the blends studied, the
concentration of castor biodiesel to increased the density, kinematic viscosity and flash
point. The addition of castor biodiesel as antioxidant in sunflower and soybean
biodiesels is promising, for a significant improvement in resistance to autoxidation and
therefore on its oxidative stability. The blends showed that compliance with the
requirements of the ANP have been included in the range of 20-40%. This form may be
used as a partial substitute of fossil diesel / Biodiesel ? um combust?vel constitu?do por mono-alquil-?steres de ?cidos graxos de
cadeias longas, derivado de ?leos vegetais ou gordura animal. Este combust?vel pode
ser utilizado em motores de igni??o por compress?o para a propuls?o de ve?culos
autom?veis ou gera??o de energia, como um substituto parcial ou total de diesel f?ssil
combust?vel. O biodiesel pode ser processado a partir de diferentes mecanismos. A
transesterifica??o ? o processo mais comum para obten??o do biodiesel, em que um
?ster reage com um ?lcool para formar outro ?ster e um novo ?lcool. Essas rea??es s?o
normalmente catalisadas pela adi??o de um ?cido ou uma base. Inicialmente, foram
determinadas as propriedades f?sico-qu?micas dos ?leos de girassol, mamona e soja de
acordo com as especifica??es de metodologias de teste padronizadas, com o intuito de
avaliar se os mesmos possu?am condi??es favor?veis para serem utilizados como
mat?ria-prima na rea??o de transesterifica??o. O biodiesel desses ?leos foi obtido
atrav?s da rea??o de transesterifica??o pela rota met?lica, fazendo uso de KOH no
preparo do catalisador (met?xido de pot?ssio). O rendimento das rea??es de
transesterifica??o foi acima de 93% m/m. Os biocombust?veis e as blends foram
caracterizados pelos ?ndices de acidez e iodo, ponto de fulgor, pela massa espec?fica,
pelos teores de enxofre, metanol e ?steres. As estabilidades t?rmica e oxidativa foram
avaliadas atrav?s da Termogravimetria (TG), da Calorimetria Explorat?ria Diferencial
sob Press?o (P-DSC) pelos m?todos din?mico e isot?rmico, e do Rancimat. As amostras
de biodiesel de girassol e soja apresentaram conformidade com as especifica??es
estabelecidas pela Resolu??o ANP no 7/2008. O biodiesel de mamona, como esperado,
apresentou elevadas massa espec?fica e viscosidade cinem?tica. A adi??o do biodiesel
de mamona como antioxidante ao biodiesel de girassol e de soja ? promissora, pois
promoveu uma melhora significativa na resist?ncia ? auto-oxida??o e, por conseguinte,
na estabilidade oxidativa de ambos. Para as blends estudadas, o aumento da
concentra??o de biodiesel de mamona contribuiu para um aumento da massa espec?fica,
viscosidade cinem?tica e ponto de fulgor. As blends que apresentaram conformidade ?s
exig?ncias da ANP foram ?quelas compreendidas na faixa de 20-40% de biodiesel de
mamona adicionado, o que as tornam candidatas ? substituta do diesel f?ssil
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17763 |
| Date | 11 March 2011 |
| Creators | Silva, Hellyda Katharine Tomaz de Andrade |
| Contributors | CPF:42314070453, http://lattes.cnpq.br/1595902438130772, Gondim, Amanda Duarte, CPF:03014598437, http://lattes.cnpq.br/6738828245487480, Souza, Antonio Gouveia de, CPF:15760715453, http://lattes.cnpq.br/7481128465396350, Ara?jo, Ant?nio Souza de, CPF:35530502415, http://lattes.cnpq.br/9770622597949866, Fernandes J?nior, Valter Jos? |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| 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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