?rea de concentra??o: Qu?mica org?nica. / Data de aprova??o retirada da vers?o impressa do trabalho. / Palavras-chave ausentes no Resumo/Abstract. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-08-04T17:58:56Z No. of bitstreams: 2 myrlene_oliveira_ottone.pdf: 35150534 bytes, checksum: f6a5ce4d99508eed910f62e1d6984580 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-08-14T13:58:08Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) myrlene_oliveira_ottone.pdf: 35150534 bytes, checksum: f6a5ce4d99508eed910f62e1d6984580 (MD5) / Made available in DSpace on 2017-08-14T13:58:08Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) myrlene_oliveira_ottone.pdf: 35150534 bytes, checksum: f6a5ce4d99508eed910f62e1d6984580 (MD5) Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O SiO2-SO3H ? um catalisador heterog?neo, sintetizado a partir de areia de constru??o e carbonato de s?dio, o qual, vem se mostrando eficaz nas s?nteses org?nicas. No presente trabalho, esse catalisador foi usado na s?ntese de ?steres benz?licos e fen?licos, realizada em apenas uma ?nica etapa, com rendimentos entre 80 e 95%. E devido a esse alto rendimento, foi tamb?m realizado rea??es de cetaliza??es, utilizando glicerol, 2,2-dimetil-1,3-propandiol e 1,1,1-hidroximetil-propanol e diversas cetonas. As rea??es com o glicerol apresentaram rendimentos baixos, por ser uma esp?cie muito polar e interagir com os poros da s?lica, evitando a colis?o com as mol?culas de cetonas. Diante desses resultados, foi poss?vel produzir um catalisador heterog?neo que al?m de diminuir o impacto ambiental, carrega caracter?sticas ben?ficas e eficientes para s?ntese org?nica, poss?vel se tonar eficaz para futuras rotas sint?ticas. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / The SiO2 - SO3H is a heterogeneous catalyst synthesized from building sand and sodium carbonate. It has proven to be effective for organic syntheses. In study the catalyst was used in the synthesis of benzyl esters and phenolics and the yields between 80 and 95%. And the high yield was also performed cetaliza??es reactions using glycerol, 2,2- dimethyl- 1,3- propandiol and 1,1,1 -hydroxymethyl- propanol and various ketones. The reactions with glycerol had low yield justified very polar species and interact with the pores of silica, avoiding collision with ketone molecules. These results it was possible to produce a heterogeneous catalyst in addition to reducing environmental impact, carries beneficial and efficient features for organic synthesis. It can be effective tonar for future synthetic routes.

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-06-05T18:19:01Z No. of bitstreams: 2 maisa_costa_santos.pdf: 2334209 bytes, checksum: 9004aeaeb9cd7b271794191d109efa36 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-06-22T12:32:04Z (GMT) No. of bitstreams: 2 maisa_costa_santos.pdf: 2334209 bytes, checksum: 9004aeaeb9cd7b271794191d109efa36 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-06-22T12:32:04Z (GMT). No. of bitstreams: 2 maisa_costa_santos.pdf: 2334209 bytes, checksum: 9004aeaeb9cd7b271794191d109efa36 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016 / Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) / O presente estudo descreve a s?ntese do catalisador heterog?neo SiO2-SO3H, obtido atrav?s da imobiliza??o dos grupos sulf?nicos em SiO2, produzida a partir de uma mistura contendo ?rea de constru??o e carbonato. A imobiliza??o do -SO3H foi confirmada, atrav?s da caracteriza??o inicial da s?lica e do catalisador por IV, MEV, DRX, TGA e isotermas de adsor??o/dessor??o BET, que demonstrou haver modifica??o da estrutura da s?lica ap?s a imobiliza??o dos grupos sulf?nicos, ocasionando diminui??o da ?rea superficial espec?fica (SBET) de 507 para 115 m2 g?1, e uma diminui??o do volume dos poros 0,78 para 0,38 cm3 g-1. Inicialmente, avaliou o desempenho catal?tico da mistura SiO2-SO3H em rea??es de esterifica??o do ?cido ac?tico e do ?cido graxo (octan?ico) com o 2,2-dimetil-1,3-dioxolano-4-metanol, conhecido como ?solketal?, que possui uma cadeia carb?nica grande, al?m de ter outro grupo funcional na sua estrutura. Os resultados obtidos demonstram a efici?ncia do SiO2-SO3H para a s?ntese do acetato 2,2- dimetil-1,3-dioxolan-4-il metil, em que utilizou-se inicialmente, como reagentes, glicerol bruto, acetona e a mistura catal?tica, ap?s 2 hora de rea??o, foi adicionado no mesmo reator, o ?cido ac?tico em um processo ?one pot?, sem a pr?via extra??o e a purifica??o do solketal (reagente intermedi?rio). Pelo o mesmo procedimento, foi obtido, em excelente rendimento, o octanoato de solketila. Nesses processos reacionais n?o houvera a necessidade do uso de solvente ou aparelhos auxiliares, como clevenger ou dean-stark, para remo??o da ?gua formada durante o processo que envolve 2 rea??es (cetaliza??o e esterifica??o), sendo dessa forma resistente ao processo de lixivia??o. Diante dos excelentes resultados, partiu para rea??es de esterifica??o com outros ?cidos graxos, com at? 18 ?tomos de carbono na cadeia, tais como o ?cido linoleico e oleico. Contudo n?o foi observado a forma??o de produtos nessas rea??es. Acredita-se que esse fato esteja relacionado com a grande afinidade que o solketal apresenta pelo SiO2-SO3H, devido a sua alta polaridade, fazendo com que fique retido dentro dos poros do catalisador. Outro ponto importante foi o tamanho da cadeia carb?nica dos ?cidos graxos utilizados, visto que quanto maior o tamanho da mol?cula, maior a hidrofobicidade, isso faz com que eles sofram repuls?o do catalisador. Acredita-se que esses dois fatores contribu?ram para que n?o ocorresse a intera??o entre os reagentes e o catalisador, levando, em alguns casos, ? forma??o de ?steres de solketila com rendimentos moderados. Essa hip?tese foi comprovada, quando utilizou-se um ?lcool de cadeia carb?nica menor, como o metanol, o qual reagiu com o ?cido linoleico e oleico na presen?a da mistura catal?tica SiO2-SO3H, para produ??o de ?steres met?licos. Os resultados obtidos comprovam a s?ntese do oleato de metila e do linoleato de metila no tempo de 15 min, com rendimento em torno de 96 a 98%. Isso demonstrou que ? de fundamental import?ncia o escoamento dos reagente para os poros do catalisador. O que sugere que para garantir o sucesso das rea??es do solketal com ?cidos de cadeia carb?nica maior o escoamento desse reagentes devem ser facilitado e isso pode ser obtido atrav?s do uso de solvente. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / The synthesis of the heterogeneous SiO2-SO3H, catalyst, obtained by the immobilization of the sulfonic groups in SiO2, produced from a mixture containing building and carbonate. The immobilization of -SO3H was confirmed, through the initial characterization of the silica and the catalyst by IV, SEM, XRD, TGA and adsorption / desorption isotherms, which showed that there was modification of the silica structure after the immobilization of the sulfonic groups, resulting in a decrease of the specific surface area (SBET) from 507 to 115 m2 g-1, and decreasing in volume by 0,78 to 0,38 cm3 g-1. Initially, evaluated the catalytic performance of the SiO2 -SO3H mixture in esterification reactions of acetic acid and fatty acid (octanoic acid) with 2,2-dimethyl-1,3-dioxolane-4-methanol, known as "solketal", it has a large carbon chain, plus another functional group in its structure. The results obtained demonstrate the efficiency of SiO2 -SO3H for the synthesis of 2,2-dimethyl-1,3-dioxolan-4-yl methyl acetate, at where initially used as reagents, crude glycerol, acetone and the catalytic mixture, after 2 hour of reaction, was added in the same reactor, acetic acid in a "one pot", without prior extraction and purification of the solketal (intermediate reagent). By the same procedure, it was obtained, in excellent yield, solketila octanoate. In these reaction processes there was no need for the use of solvents or auxiliary devices, such as clevenger or dean-stark, for the removal of water formed during the process involving 2 reactions (ketalization and esterification), thus being resistant to the leaching process. Given the excellent results, started to esterification reactions with other fatty acids, with up to 18 carbon atoms in the chain, such as linoleic and oleic acid. However, the formation of products in these reactions was not observed. It is believed that this fact is related to the great affinity that the solketal presents by the SiO2-SO3H, due to its high polarity, causing it to be trapped within the catalyst pores. Another important point was the size of the carbonic chain of the fatty acids used, since the larger the size of the molecule, the greater the hydrophobicity, this causes them to undergo catalyst repulsion. It is believed that these two factors contributed to the lack of interaction between the reactants and the catalyst, leading in some cases to the formation of solketila esters with moderate yields. This hypothesis has been proven, used a lower carbon alcohol, such as methanol, which reacted with linoleic and oleic acid in the presence of the catalytic mixture SiO2 -SO3H, for the production of methyl esters. The results obtained demonstrate the synthesis of methyl oleate and methyl linoleate in the 15 min time, with yield around 96 to 98%. This has demonstrated that it is of fundamental importance the flow of the reactants into the pores of the catalyst. This suggests that to ensure the success of solketal reactions with higher carbonic acids the flow of these reagents should be facilitated and this can be obtained through the use of solvente.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T22:35:16Z No. of bitstreams: 1 JoaoPauloDaCostaEvangelista_TESE.pdf: 3170006 bytes, checksum: b1459f824b08153ad43dfbda6bced227 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T20:54:29Z (GMT) No. of bitstreams: 1 JoaoPauloDaCostaEvangelista_TESE.pdf: 3170006 bytes, checksum: b1459f824b08153ad43dfbda6bced227 (MD5) / Made available in DSpace on 2016-06-01T20:54:29Z (GMT). No. of bitstreams: 1 JoaoPauloDaCostaEvangelista_TESE.pdf: 3170006 bytes, checksum: b1459f824b08153ad43dfbda6bced227 (MD5) Previous issue date: 2015-07-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Esse estudo prop?s-se a obter biodiesel a partir da esterifica??o do ?cido oleico com os catalisadores Zr-SBA-15, Nb-SBA-15, SO42-/Zr-SBA-15 e SO42-/Nb-SBA-15 obtidos pela inser??o de Zr e Nb no suporte SBA-15 e sulfata??o do suporte impregnado. O suporte SBA-15 foi sintetizado pelo m?todo hidrot?rmico. O catalisador foi incialmente sintetizado pelo m?todo de impregna??o via ?mida, adicionando 4,2 mL de uma solu??o ? 30 % do percursor do metal (Zr e Nb) em cada grama da SBA-15. Ap?s a impregna??o foi realizado o processo de sulfata??o. As condi??es reacionais da s?ntese do biodiesel utilizadas nesse estudo foram: quantidade de catalisador (5% em massa), raz?o molar de metanol:?cido oleico (20:1), tempo reacional (8 h) e temperatura de refluxo (65?C). Os catalisadores foram analisados por: difra??o de raios-X (DRX), an?lise termogravim?trica (TG/DTG), espectroscopia de infravermelho por transformada de Fourier (FTIR), adsor??o/dessor??o de nitrog?nio, microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva (EDS) e teste de acidez para identifica??o da estrutura, composi??o e verifica??o da presen?a de s?tios ?cidos. Os resultados de caracteriza??o indicaram que o suporte SBA-15 preservou a estrutura hexagonal ordenada, ap?s a incorpora??o de Zr e Nb. Observou-se a presen?a de nanopart?culas desses metais dispersas na superf?cie e no interior dos canais microporosos e mesoporosos dos catalisadores Zr-SBA-15 e Nb-SBA-15. Ap?s a sulfata??o, aumentou a quantidade de s?tios ?cidos e a estrutura ordenada foi mantida. Para os catalisadores Zr-SBA-15 e SO42-/Zr-SBA-15 houve a forma??o das estruturas tetragonal e monocl?nica do ZrO2, j? para os demais catalisadores Nb-SBA-15 e SO42-/Nb-SBA-15 formaram-se estruturas amorfas. A atividade catal?tica foi avaliada pela rea??o de esterifica??o do ?cido oleico via rota et?lica, utilizando todos os catalisadores sintetizados. O biodiesel obtido com SO42-/Zr-SBA-15 apresentou propriedades f?sico-qu?micas dentro das normas especificadas pela resolu??o N?7/2008 da ANP e melhor rendimento com 80,7%. Foi verificado que os catalisadores sulfatados, produziram maior rendimento com rela??o aos n?o sulfatados. O suporte SBA-15 n?o apresentou atividade catal?tica. / Fatty acids such as oleic acid, have received particular attention as raw material, due to its abundance, availability and relatively high purity, being considered as potential materials for production of biodiesel. The esterification reaction of oleic acid using heterogeneous catalysts can be a promising alternative for biodiesel production. This study proposes to find a biodiesel through esterification of oleic acid with Zr-SBA-15, Nb-SBA-15, SO42?/Zr-SBA-15 and SO4 2?/Nb-SBA-15 catalysts, obtained by insertion of Zr and Nb in support SBA-15 and sulfation of the impregnated support. SBA-15 support was synthesized by hydrothermal method. Support SBA-15 was synthesized by hydrothermal method. The catalyst was initially synthesized by the wet impregnation method, followed by sulfation process. The catalysts were analyzed: X-ray diffraction (XRD), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption/desorption, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and acidity test to identify the structure, composition and verification the presence acid sites. The characterization results indicated that the SBA-15 support preserved the ordered hexagonal structure after the incorporation of Zr and Nb. It was observed the presence of nanoparticles these metal dispersed on the surface and within the microporous and mesoporous channels of Zr-SBA-15 and Nb-SBA-15 catalysts. After sulfation, increased amount of acid sites and the ordered structure was maintained. For Zr-SBA-15 and SO4 2?/Zr-SBA-15 catalyst was the formation of tetragonal and monoclinic structures of ZrO2, as for the other, Nb-SBA-15 and SO42?/Nb-SBA-15 catalyst were formed amorphous structures. The catalytic activity was evaluated by the esterification reaction of oleic acid via ethyl route, using all the synthesized catalysts. Biodiesel obtained with SO42?/Zr-SBA-15 presented physicochemical properties within the standards specified by the Resolution N? 45/2014 ANP and obtained the best yield with 80.7%. It was found that sulfated catalysts, produced higher yields with respect to nonsulfated. The SBA-15 support showed no catalytic activity.

Made available in DSpace on 2014-12-17T15:01:15Z (GMT). No. of bitstreams: 1 GiselleSA.pdf: 952912 bytes, checksum: 583e1e7c4f17927714ce3fb3a4b8916d (MD5) Previous issue date: 2008-09-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The production of biodiesel has become an important and attractive process for the production of alternative fuels. This work presents a study of the biodiesel production from coconut oil (Cocos nucifera L.), by two routes: direct transesterification using NaOH as catalyst and esterification (with H2SO4) followed by basic transesterification. The reactor was built in pirex with 1L of capacity and was equipped with a jacket coupled with a thermostatic bath to temperature control, a mecanical stirring is also present in the reactor. The analysis of oil composition was carried out by gas chromatography and esters compounds were identified. The parameters of molar ratio oil/alcohol, reaction time and temperature were studied and their influence on the conversion products was evaluated using experimental planning (23). The molar ratio was the most significant variable by the statistical planning analysis. Conversions up to 85.3% where achived in the esterification/transesterification, with molar ratio 1:6 at 60?C and 90 minutes of reaction. For the direct transesterification, route conversions up 87.4% eas obtained using 1:6.5 molar ratio at 80?C and 60 minutes of reaction. The Coconut oil was characterized by their physic chemical properties and key constituents of the oil. The lauric acid was the main constituint and the oil showed high acidity. The biodiesel produced was characterized by its main physicochemical properties, indicating satisfactory results when compared to standard values of National Petroleum Agency. The work was supplemented with a preliminary assessment of the reaction kinetic / A produ??o de biodiesel tem se tornado um processo atrativo visando o est?mulo na produ??o de combust?veis alternativos. Este trabalho apresenta resultados do estudo da produ??o de biodiesel a partir de ?leo de coco (Cocos nucifera L.), atrav?s de duas rotas: transesterifica??o direta utilizando o NaOH como catalisador e cat?lise ?cida (com H2SO4) seguida de transesterifica??o b?sica. O reator utilizado foi constru?do de vidro pirex de aproximadaente 1L, enjaquetado, com tr?s sa?das, onde foi introduzido um agitador mec?nico e acoplado um banho termostatizado para controle da temperatura. A determina??o da composi??o do ?leo e identifica??o dos ?steres foi feita atrav?s de cromatografia gasosa. Foi avaliado o efeito das vari?veis: raz?o molar ?leo/?lcool, tempo de rea??o e temperatura sobre a convers?o atrav?s de um planejamento experimental 23 com ponto central em triplicata para cada rota analisada. A vari?vel raz?o molar foi a que exerceu maior efeito como resultado da an?lise do planejamento estat?stico. Na rota 1 (cat?lise ?cida seguida de cat?lise b?sica) a m?xima convers?o alcan?ada foi de 85,3% para uma raz?o molar de 1:6, temperatura de 60?C e tempo de rea??o de 90 minutos. Na transesterifica??o b?sica direta, a m?xima convers?o alcan?ada foi de 87,4% para uma raz?o molar de 1:6,5, temperatura de 80?C e tempo de rea??o de 60 minutos. O ?leo de Coco foi caracterizado em rela??o as suas propriedades fisico-qu?micas e principais constituintes presentes no ?leo. O ?cido l?urico foi seu principal componente e o mesmo apresentou elevada acidez. O biodiesel produzido foi caracterizado em rela??o as suas principais propriedades f?sico-qu?micas que apresentaram resultados bastante satisfat?rios quando comparados com os valores estabelecidos pelas normas da Ag?ncia Nacional do Petr?leo. O trabalho foi complementado com uma avalia??o preliminar da cin?tica da rea??o

Made available in DSpace on 2014-12-17T15:01:35Z (GMT). No. of bitstreams: 1 SamuelAO_DISSERT.pdf: 6693517 bytes, checksum: 0be8bd399faaff3fe4e2da515c357889 (MD5) Previous issue date: 2014-01-30 / Among the heterogeneous catalysts materials made from niobium show up as an alternative to meet the demand of catalysts for biodiesel production. This study aims to evaluate the potential of a heterogeneous catalyst derived from a complex of niobium in the reaction of methyl esterification of oleic acid. The catalyst was synthesized after calcination at different temperatures of a niobium complex ((NH4)3[NbO(C2O4)3].H2O) generating a niobium oxide nanostructure with a different commercial niobium oxide used to synthesize the complex. The commercial niobium oxide, the complex niobium and niobium catalyst were characterized by thermogravimetry (TG and DTA), surface area analysis (BET), scanning electron microscopy (SEM) and X-ray diffraction (XRD), showing the catalyst has researched morphological and crystallographic indicating a catalytic potential higher than that of commercial niobium oxide characteristics. Factorial with central composite design point, with three factors (calcination temperature, molar ratio of alcohol/oleic acid and mass percentage of catalyst) was performed. Noting that the optimal experimental point was given by the complex calcination temperature of 600?C, a molar ratio alcohol/oleic acid of 3.007/1 and the catalyst mass percentage of 7.998%, with a conversion of 22.44% oleic acid in methyl oleate to 60 min of reaction. We performed a composite linear and quadratic regression to determine an optimal statistical point of the reaction, the temperature of calcination of the complex at 450?C, the molar ratio of alcohol/oleic acid 3.3408/1 and mass percentage of catalyst of 7.6833% . Kinetic modeling to estimate parameters for heterogeneous catalysis it set well the experimental results with a final conversion of 85.01% with 42.38% of catalyst and without catalyst at 240 min reaction was performed. Allowing to evaluate the catalyst catalytic studied has the potential to be used in biodiesel production / Dentre os catalisadores heterog?neos os materiais a base de ni?bio mostram-se como uma alternativa para suprir a demanda de catalisadores para a produ??o de biodiesel. O presente trabalho visa avaliar o potencial de um catalisador heterog?neo derivado de um complexo de ni?bio na rea??o de esterifica??o met?lica do ?cido oleico. O catalisador foi sintetizado ap?s a calcina??o em diferentes temperaturas de um complexo de ni?bio ((NH4)3[NbO(C2O4)3].H2O) gerando um ?xido de ni?bio com uma nanoestrutura diferente do ?xido de ni?bio comercial, usado para sintetizar o complexo. O ?xido de ni?bio comercial, o complexo de ni?bio e o catalisador de ni?bio foram caracterizados por termogravimetria (TG e DTA), an?lise de ?rea superficial (BET), microscopia eletr?nica de varredura (MEV) e difra??o de raios-X (DRX), demostrando que o catalisador pesquisado possui caracter?sticas morfol?gicas e cristalogr?ficas que indicam um potencial catal?tico superior ao ?xido de ni?bio comercial. Foi realizado um planejamento fatorial composto com ponto central, com tr?s fatores (temperatura de calcina??o, raz?o molar de ?lcool/?cido oleico e percentual m?ssico de catalisador). Verificando que o ponto ?timo experimental se deu mediante a temperatura de calcina??o do complexo em 600?C, uma raz?o molar de ?lcool/?cido oleico de 3,007/1 e percentual m?ssico de catalisador de 7,998%, apresentando uma convers?o de 22,44% do ?cido oleico em oleato de metila em 60 min de rea??o. Realizou-se uma regress?o linear e quadr?tica composta para se determinar de um ponto ?timo estat?stico da rea??o, sendo a temperatura de calcina??o do complexo em 450?C, raz?o molar de ?lcool/?cido oleico de 3,3408/1 e percentual m?ssico de catalisador de 7,6833%. Foi realizada uma modelagem cin?tica para estima??o de par?metros para a cat?lise heterog?nea que se ajustou satisfatoriamente aos resultados experimentais com uma convers?o final de 85,01% com catalisador e de 42,38% sem o catalisador em 240 min de rea??o. Permitindo avaliar que o catalisador estudado possui potencial catal?tico para ser utilizado na produ??o de biodiesel

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-06-02T20:34:08Z No. of bitstreams: 2 camila_diana_lima.pdf: 4383425 bytes, checksum: a00aa24c475acb8858df11e235a0c29c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-06-14T19:40:25Z (GMT) No. of bitstreams: 2 camila_diana_lima.pdf: 4383425 bytes, checksum: a00aa24c475acb8858df11e235a0c29c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-06-14T19:40:25Z (GMT). No. of bitstreams: 2 camila_diana_lima.pdf: 4383425 bytes, checksum: a00aa24c475acb8858df11e235a0c29c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017 / O presente trabalho descreve o estudo de novas metodologias para obten??o de ?steres benz?licos e ?steres met?licos de ?cidos graxos (biodiesel) utilizando o NbCl5 s?lido e catalisadores heterog?neos ?cidos. No estudo, o NbCl5 s?lido foi utilizado como reagente, e nos outros m?todos foi empregado um catalisador de ni?bio enxertado em s?lica e um catalisador de grupos sulf?nicos imobilizado em s?lica. Nos processos heterog?neos a SiO2 (507 m2g-1, ?rea espec?fica) utilizada como suporte dos catalisadores, foi produzida a partir de areia constru??o e carbonato. O NbCl5 e os grupos ?SO3H foram imobilizados diretamente ? temperatura ambiente na SiO2, formando respectivamente o SiO2-Nb, com 412 m2g-1 de ?rea espec?fica e o SiO2-SO3H, com 115 m2g-1 de ?rea espec?fica. Nas esterifica??es utilizando NbCl5 s?lido foi determinado que para a obten??o de rendimentos razo?veis de ?steres de benz?licos (>85%) e ?steres met?licos (>70%) em rea??es a temperatura ambiente, a propor??o m?nima em moles de NbCl5:?lcool benz?lico deve ser 1,5:1,0 e para obten??o dos ?steres met?licos a propor??o de 1,5:6,0. Nas metodologias aplicando os catalisadores heterog?neos foi utilizada uma quantidade de 7% (m/m) do catalisador SiO2-SO3H para catalisar a esterifica??o de diferentes ?cidos carbox?licos com ?lcool benz?lico. E para as mesmas rea??es com o catalisador SiO2-Nb foi utilizada uma raz?o de 10% (m/m) do catalisador. Ambos os processos foram realizados sob refluxo na aus?ncia de um solvente; rendimentos muito semelhantes foram obtidos apesar do catalisador SiO2-SO3H possuir uma ?rea superficial muito menor que o catalisador SiO2-Nb. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The current work describes the study of new methodologies for obtaining benzyl esters and methyl esters of fatty acids (biodiesel) using solid NbCl5 and heterogeneous acid catalysts. In this study, solid NbCl5 was used as a reagent, and in the other methods a silica grafted niobium catalyst and a sulphonic group catalyst immobilized on silica were used. In the heterogeneous processes the SiO2 (507 m2g-1, specific area) used as support of the catalysts, was produced from sand building and carbonate. The NbCl5 and the -SO3H groups were directly immobilized at room temperature in SiO2, forming respectively SiO2-Nb, with 412 m2g-1 of specific area and SiO2 -SO3H, with 115 m2g-1 of specific area. In the esterifications using solid NbCl5 it was determined that in order to obtain reasonable yields of benzyl esters (>85%) and methyl esters (>70%) in reactions at room temperature, the minimum mole ratio of NbCl5/benzyl alcohol should be 1,5:1,0 and in the obtainment of the methyl esters at a ratio of 1,5:6,0. In the methodologies applying the heterogeneous catalysts to an amount of 7% (w/w) of the catalyst SiO2 -SO3H to catalyze an esterification of different carboxylic acids with benzyl alcohol. Both processes were performed under reflux in the absence of a solvent; very similar yields were obtained although the SiO2-SO3H catalyst had a much lower surface area than the SiO2-Nb catalyst.