?rea de concentra??o: Produtos e coprodutos. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-06-22T19:43:47Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) barbara_goncalves_rocha.pdf: 2671242 bytes, checksum: 17dfa18bc6c5622c294695227a582c58 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-07-18T12:29:56Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) barbara_goncalves_rocha.pdf: 2671242 bytes, checksum: 17dfa18bc6c5622c294695227a582c58 (MD5) / Made available in DSpace on 2018-07-18T12:29:56Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) barbara_goncalves_rocha.pdf: 2671242 bytes, checksum: 17dfa18bc6c5622c294695227a582c58 (MD5) Previous issue date: 2018 / A diversifica??o da matriz energ?tica, por raz?es econ?micas, ambientais e da pr?pria pol?tica energ?tica das na??es, tem suscitado foco especial nos biocombust?veis, particularmente no bioetanol e no biodiesel. Na ind?stria, o biodiesel (?steres de ?cidos graxos com um ?lcool de cadeia molecular curta) ?, mais comumente, produzido pela transesterifica??o de triacilglicer?is de ?leos vegetais ou gordura animal, com metanol ou etanol, sob cat?lise homog?nea com uma base (KOH ou NaOH). Por representarem alternativas potencialmente mais sustent?veis, dos pontos de vistas econ?micos e ambientais, o presente trabalho foi dedicado a avaliar a efici?ncia qu?mica de catalisadores heterog?neos baseados em materiais de min?rios: (i) de ni?bio, enriquecido em Nb2O5 (Geo.Nb2O5); (ii) de areia monaz?tica (Geo.Mona), uma fonte mineral de terras raras, e (iii) de rejeitos de minera??o de fosfato, ricos em magnetita (Geo.Mag.CMT e Geo.Mag.CMA). Os materiais minerais foram preparados em mistura com componentes ?cidos (H2SO4; HCl ou HF) ou b?sicos (KOH; , KBr, NaOH; CaO; KI; KF ou KCl). As rea??es de transesterifica??o foram conduzidas sob refluxo, com ?leo de soja comercial e metanol, sob a??o dos catalisadores s?lidos. A raz?o molar padr?o ?leo:metanol foi de 1:100, com 10% de catalisador em rela??o ao ?leo, a 60 ?C. Dos testes realizados com os materiais preparados com CaO sint?tico comercial, nas mesmas condi??es, a mistura calcinada a 800 ?C por 4 h rendeu ?steres met?licos sempre acima de 99%; o menor tempo de rea??o (2 h, para completar a transesterifica??o) foi conseguido com o catalisador baseado na Geo.Mona, em rela??o ao Geo.Nb2O5 (5 h), ao Geo.Mag.CMT (3 h) e o Geo.Mag.CMA tamb?m (2 h). Analisou-se o reuso consecutivo do catalisador. Ap?s cada rea??o, o catalisador s?lido era lavado com metanol e seco a 100 oC. O melhor resultado foi obtido com o rejeito magn?tico com CaO calcinados a 200 ?C por 4 h, para o que se conseguiu at? 8 rea??es consecutivas. Nas impregna??es com ?cidos e bases, os melhores resultados foram com a mistura Geo.Nb2O5 e KOH calcinada a 600 ?C, para a qual conseguiu 8 rea??es consecutivas, com rendimento qu?mico em ?steres met?licos de praticamente 100% e tempo reacional de 10 min, no primeiro uso. O efeito catal?tico sin?rgico mais significativo foi conseguido com o catalisador baseado em cada um dos tr?s materiais avaliados em mistura com CaO: nenhum efeito catal?tico significativo na rea??o de transesterifica??o de triacilglcier?is do ?leo foi observado apenas com o material mineral puro calcinado. O CaO puro como catalisador, tamb?m calcinado e usado em rea??o, levou a rendimentos qu?micos pouco acima de 80%. A mistura individual do material mineral com CaO, nas mesmas condi??es de prepara??o anteriores, levaram a rendimentos qu?micos de efetivamente 100%. Os presentes resultados revelam a excepcional potencialidade, dos pontos de vista qu?mico, econ?mico e ambiental, dos catalisadores mistos, dos materiais minerais com CaO, ora avaliados, nos processos de produ??o industrial de biodiesel. / Tese (Doutorado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The diversification of the energy matrix has been drawing special attention to biofuels, especially bioethanol and biodiesel, mainly for economic and environmental reasons and national energy policies. In industry, biodiesel (esters of fatty acids with a short-chain alcohols) is most commonly produced by the transesterification of triacylglycerols in vegetable oils or animal fats with methanol or ethanol using homogeneous catalysis with a base (KOH or NaOH). The present work was devoted to the evaluation of the chemical efficiency of heterogeneous catalysts based on mineral materials: (i) niobium, enriched in Nb2O5 (Geo.Nb2O5); (ii) monazite sand (Geo.Mona), a mineral source of rare earths, and (iii) phosphate mining tailings, rich in magnetite (Geo.Mag.CMT e Geo.Mag.CMA). The mineral materials were prepared in admixture with acidic (H2SO4, HCl or HF) or basic (KOH, KBr, NaOH, CaO, KI, KF or KCl) components. The transesterification reactions were conducted under reflux with commercial soybean oil and methanol in the presence of the solid catalysts. The standard molar ratio of oil:methanol was 1:100, using 10% catalyst relatively to the quantity of oil, at 60 ?C. According to the tests performed with the materials prepared with commercial synthetic CaO under the same conditions, the yield of methyl esters with the mixture calcined at 800 ?C for 4 h was always greater than 99%. The shortest reaction time (2 h to complete the transesterification) was achieved with the Geo.Mona catalyst; the reaction times with Geo.Nb2O5 (5 h), the Geo.Mag.CMT (3 h) and the Geo.Mag.CMA also (2 h) were longer. The consecutive reuse of the catalyst was also verified. After each reaction, the solid catalyst was washed with methanol and dried at 100 ?C. The best result was obtained with the magnetic waste with CaO calcined at 200 ?C for 4 h, with which up to eight consecutive reactions were achieved. On impregnating with acids or bases, the best results are obtained with the Geo.Nb2O5 and KOH mixture calcined at 600 ?C, with which eight consecutive reactions were completed. Virtually 100% yields of methyl esters were obtained in a reaction time of 10 min in the first use. The most significant synergistic catalytic effect was achieved with each of the three minerals mixed with CaO. No significant catalytic effect on the transesterification reaction of triacylglycerols in the oil was observed with the pure calcined minerals. When the calcined CaO is used alone as catalyst, the reaction yielded just over 80%. For the mixture of the individual minerals with CaO under the same preparation conditions described above, the transesterification reaction led to virtually 100% yields. The present results reveal an outstanding potential regarding the chemical, economic and environmental aspects of the mixed catalysts (the mineral material with CaO) for chemical processes leading to the industrial production of biodiesel.