Made available in DSpace on 2014-12-17T15:42:13Z (GMT). No. of bitstreams: 1
PauloRP_TESE.pdf: 5067014 bytes, checksum: b7746014c5447355f701f5568c4dabae (MD5)
Previous issue date: 2011-06-28 / Biodiesel production has increased over the last decade because of the benefits
associated with this fuel, including renewability, domestic feedstock, lower toxicity,
and biodegradability. From 2008, the use of beef tallow as a feedstock for biodiesel
production in Brazil has increased in significance, representing the second largest
source of biodiesel, after soybeans. However, the performance of biodiesel in cold
weather conditions is worse than diesel because of deposition of insoluble at low
temperatures, accelerating the plugging of fuel filters and injectors of the vehicle
engine. Studies have been conducted on beef tallow biodiesel, mostly related to the
properties of thermal and oxidative stability. However, few studies have described the
nature of the precipitate formed and its influence on product quality. Research
suggests that the cause of deposition is related to the nature of saturated esters and
monoacylglycerols as inducing agents. This study monitored the levels of mono-, diand
triacylglycerols, the oxidation stability and the cold filter plugging point (CFPP) in
beef tallow biodiesel samples from two commercial producers in Brazil for a period of
twelve months. Filtered precipitates were analyzed by comparative techniques of GCFID,
HPLC-UV/VIS, HPLC-MS-IT-TOF and TG to verify the nature, using
monopalmitin and monostearin as reference standards. The formation of precipitate
reduced the levels of monoacylglycerols in the beef tallow biodiesel. GC-FID and LCMS-
IT-TOF results confirmed the nature of the deposit as saturated
monoacylglycerols, predominantly monostearin and monopalmitin as the second
major component. Moreover the TG analysis of the residue indicated similar thermal
decomposition of the reference standards. The precipitate did not affect the oxidation
stability of beef tallow biodiesel and the CFPP characteristic of blends up B60.
However, the presence of iron reduced significantly the oxidation stability of
biodiesel / A produ??o de biodiesel aumentou na ?ltima d?cada em fun??o dos benef?cios
associados a este combust?vel, incluindo renovabilidade, mat?rias-primas nacionais,
menor toxicidade e biodegradabilidade. Desde 2008, o uso do sebo bovino como
mat?ria-prima na produ??o de biodiesel no Brasil tem aumentado em import?ncia,
representando a segunda fonte de produ??o, depois da soja No entanto, o
desempenho do biodiesel em condi??es de clima frio ? pior que do ?leo diesel
devido ? ocorr?ncia de materiais insol?veis a baixas temperaturas, acelerando o
entupimento de filtros e injetores de motores de ve?culos. Estudos t?m sido
realizados acerca do biodiesel de sebo bovino, em sua maioria relacionados ?s
propriedades de estabilidade t?rmica e oxidativa; no entanto, poucos abordam a
natureza do precipitado formado e sua influ?ncia na qualidade do biodiesel.
Pesquisas sugerem que a causa da deposi??o esteja relacionada ? natureza de
?steres saturados, sendo os monoacilglicer?is prov?veis agentes indutores. Este
trabalho apresenta os n?veis de mono-, di- e triacilglicer?is, a estabilidade ? oxida??o
e o ponto de entupimento de filtro a frio (PEFF) de amostras de biodiesel de sebo
bovino de dois produtores comerciais, avaliados por um per?odo de 12 meses.
Amostras de precipitados filtrados foram analisadas pelas t?cnicas comparativas de
CG-DIC, CLAE-UV/VIS, CLAE-MS-IT-TOF e TG para verificar a composi??o,
utilizando monopalmitina e monoestearina como padr?es de refer?ncia. Verificou-se
que a forma??o de precipitado reduziu os n?veis de monoacilglicer?is no biodiesel de
sebo bovino. Os resultados cromatogr?ficos confirmaram a natureza do precipitado
como monoacilglicer?is saturados, com predomin?ncia de monoestearina e
monopalmitina como segundo componente majorit?rio. Al?m disso, a an?lise de TG
do precipitado resultou perfil de decomposi??o t?rmica semelhante ao dos padr?es
de refer?ncia. O dep?sito formado n?o afetou a estabilidade ? oxida??o do biodiesel
de sebo bovino e a caracter?stica de PEFF em misturas at? B60. No entanto, a
presen?a de ferro reduziu significativamente a estabilidade ? oxida??o do biodiesel
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17735 |
| Date | 28 June 2011 |
| Creators | Pivesso, Paulo Roberto |
| Contributors | CPF:42314070453, http://lattes.cnpq.br/1595902438130772, Ara?jo, Ant?nio Souza de, CPF:35530502415, http://lattes.cnpq.br/9770622597949866, Fernandes, Glauber Jos? Turolla, CPF:72074442491, http://lattes.cnpq.br/6067867622712912, Moura, Jos? Ant?nio de, CPF:83791680463, http://lattes.cnpq.br/9124578454468834, Stragevitch, Luiz, CPF:48809071034, http://lattes.cnpq.br/2730416923915211, 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/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 |
Page generated in 0.0023 seconds