This  thesis  is  divided  into  four  parts,  all  centered  around  Constitutional Dynamic  Chemistry  (CDC)  and  Dynamic  Kinetic  Resolution  (DKR)  using biocatalysts for selective transformations, and their applications in screening of bioactive compounds, organic synthesis, and enzyme classification.    In  part  one,  an  introduction  to  CDC  and  DKR  is  presented,  illustrating  the basic  concepts,  practical  considerations  and  potential  applications  of  such dynamic systems, thus providing the background information for the studies in the following chapters.   In part two, Dynamic Systemic Resolution (DSR), a concept based on CDC is exemplified.  With  enzyme-catalyzed  transformations  as  external  selection pressure,  optimal  structures  can  be  selected  and  amplified  from  the  system. This  concept  is  expanded  to  various  types  of  dynamic  systems  containing single, double cascade/parallel, and multiple reversible reactions. In addition, the  substrate  selectivity  and  catalytic  promiscuity  of  target  enzymes  are  also investigated.   In   part   three,   DKR   protocols   using   reversible   reactions   for   substrate racemizations  are  illustrated.  Biocatalysts  are  here  employed  for  asymmetric transformations,  resulting  in  efficient  synthetic  pathways  for  enantioenriched organic compounds.   Part  four  demonstrates  two  unique  applications  of  CDC:  one  resulting  in enzyme  classification  by  use  of  pattern  recognition  methodology;  the  other involving  enzyme  self-inhibition  through  in  situ  transformation  of  stealth inhibitors employing the catalytic activity of the target enzyme. / <p>QC 20130614</p>

The objective of this work was to develop a novel enzyme immobilization scheme for supported lipase sol-gels and to evaluate the potential of the immobilized biocatalyst for the production of biodiesel in a packed bed reactor. Two sources of lipase (EC 3.1.1.3 triacylglycerol hydrolase) were used in this study and the transesterification of methanol and triolein to produce glycerol and methyl oleate was used as a model reaction of biodiesel production. A commercially available form of immobilized lipase, Novozym® 435, was used as a basis for comparison to the literature. Upon establishing a lipase sol-gel formulation technique, the experimental methodology for the transesterification reaction using Novozyme® 435 was developed. Subsequently, a series of inert materials were considered based on their suitability as supports for immobilized lipase sol-gels and the synthesis of methyl oleate. The value of a supported lipase sol-gel is to improve the activity and stability of the enzyme and develop an immobilized biocatalyst that is practical for use under packed bed reactor conditions. Of the six support materials considered (6-12 mesh silica gel, Celite® R633, Celite® R632, Celite® R647, anion exchange resin, and Quartzel® felt), the diatomaceous earth supports (Celite® R633, R632 and R647) exhibited high enzymatic activity, were thermally stable, and possessed high sol-gel adhesion. From the three types of diatomaceous earth considered, Celite® R632 supported lipase sol-gels were identified as the most promising supported lipase sol-gels for methyl oleate production via transesterification. Upon further evaluation, the Celite® R632 lipase sol-gels were found to achieve high methyl oleate percent conversions, glycerol-water absorption was only significant at glycerol levels higher than 75%, and the immobilized lipase had high stability upon storage at 4°C for 1.5 years. To determine the effects of methanol and glycerol inhibition as well as temperature on the reaction kinetics, a ping-pong bi-bi kinetic model was developed and validated over a range of methanol concentrations and temperatures. The optimal methanol concentration for the conditions tested was in the range of 1.3 M to 2.0 M, and increased with increasing temperature. The model developed was consistent with the experimental data and confirmed that glycerol inhibition and the presence of products had significant effects on the reaction kinetics. The methyl oleate production capabilities of the Celite® supported lipase sol-gel were investigated using a packed bed reactor and compared with Novozym® 435 under similar operating conditions. A kinetic and mass transfer based model was developed for the reactor system using a novel efficiency correlation to account for the effect of glycerol on the enzymatic activity. Increasing the flow rate (1.4 mL/min to 20 mL/min) increased the reaction rate, presumably due to the reduction of the glycerol inhibition effect on the immobilized biocatalyst. The Celite® supported lipase sol-gel was found to have superior performance over Novozym® 435 both under batch stirred tank reaction conditions and in a packed bed reactor (83% conversion for Celite® sol-gel vs. 59% conversion for Novozym® 435 at 20 mL/min in the packed bed reactor). Based on the results obtained, Celite® supported lipase sol-gels exhibited good performance for the transesterification of triolein with methanol to produce methyl oleate in both batch and packed bed reactors, and warrant further exploration for the enzymatic production of biodiesel.

The use of microalgae culture to convert CO2 from power plant flue gases into biomass that are readily converted into biofuels offers a new frame of opportunities to enhance, compliment or replace fossil-fuel-use. Apart from being renewable, microalgae also have the capacity to utilise materials from a variety of wastewater and the ability to yield both liquid and gaseous biofuels. However, the processes of cultivation, incorporation of a production system for power plant waste flue gas use, algae harvesting, and oil extraction from the biomass have many challenges. Using SimaPro software, Life cycle Assessment (LCA) of the challenges limiting the microalgae (Chlorella vulgaris) biofuel production process was performed to study algae-based pathway for producing biofuels. Attention was paid to material use, energy consumed and the environmental burdens associated with the production processes. The goal was to determine the weak spots within the production system and identify changes in particular data-set that can lead to and lower material use, energy consumption and lower environmental impacts than the baseline microalgae biofuel production system. The analysis considered a hypothetical transesterification and Anaerobic Digestion (AD) transformation of algae-to- biofuel process. Life cycle Inventory (LCI) characterisation results of the baseline biodiesel (BD) transesterification scenario indicates that heating to get the biomass to 90% DWB accounts for 64% of the total input energy, while electrical energy and fertilizer obligations represents 19% and 16% respectively. Also, Life Cycle Impact Assessment (LCIA) results of the baseline BD production scenario show high proportional contribution of electricity and heat energy obligations for most impact categories considered relative to other resources. This is attributed to the concentration/drying requirement of algae biomass in order to ease downstream processes of lipid extraction and subsequent transesterification of extracted lipids into BD. Thus, four prospective alternative production scenarios were successfully characterised to evaluate the extent of their impact scenarios on the production system with regards to lowering material use, lower energy consumption and lower environmental burdens than the standard algae biofuel production system. A 55.3% reduction in mineral use obligation was evaluated as the most significant impact reduction due to the integration of 100% recycling of production harvest water for the AD production system. Recycling also saw water demand reduced from 3726 kg (freshwater).kgBD- 1 to 591kg (freshwater).kgBD- 1 after accounting for evaporative losses/biomass drying for the BD transesterification production process. Also, the use of wastewater/sea water as alternative growth media for the BD production system, indicated potential savings of: 4.2 MJ (11.8%) in electricity/heat obligation, 10.7% reductions for climate change impact, and 87% offset in mineral use requirement relative to the baseline production system. Likewise, LCIA characterisation comparison results comparing the baseline production scenarios with that of a set-up with co-product economic allocation consideration show very interesting outcomes. Indicating -12 MJ surplus (-33%) reductions for fossil fuels resource use impact category, 52.7% impact reductions for mineral use impact and 56.6% reductions for land use impact categories relative to the baseline BD production process model. These results show the importance of allocation consideration to LCA as a decision support tool. Overall, process improvements that are needed to optimise economic viability also improve the life cycle environmental impacts or sustainability of the production systems. Results obtained have been observed to agree reasonably with Monte Carlo sensitivity analysis, with the production scenario proposing the exploitation of wastewater/sea water to culture algae biomass offering the best result outcome. This study may have implications for additional resources such as production facility and its construction process, feedstock processing logistics and transport infrastructure which are excluded. Future LCA study will require extensive consideration of these additional resources such as: facility size and its construction, better engineering data for water transfer, combined heat and power plant efficiency estimates and the fate of long-term emissions such as organic nitrogen in the AD digestate. Conclusions were drawn and suggestions proffered for further study.

The objective of this work was to develop a novel enzyme immobilization scheme for supported lipase sol-gels and to evaluate the potential of the immobilized biocatalyst for the production of biodiesel in a packed bed reactor. Two sources of lipase (EC 3.1.1.3 triacylglycerol hydrolase) were used in this study and the transesterification of methanol and triolein to produce glycerol and methyl oleate was used as a model reaction of biodiesel production. A commercially available form of immobilized lipase, Novozym® 435, was used as a basis for comparison to the literature. Upon establishing a lipase sol-gel formulation technique, the experimental methodology for the transesterification reaction using Novozyme® 435 was developed. Subsequently, a series of inert materials were considered based on their suitability as supports for immobilized lipase sol-gels and the synthesis of methyl oleate. The value of a supported lipase sol-gel is to improve the activity and stability of the enzyme and develop an immobilized biocatalyst that is practical for use under packed bed reactor conditions. Of the six support materials considered (6-12 mesh silica gel, Celite® R633, Celite® R632, Celite® R647, anion exchange resin, and Quartzel® felt), the diatomaceous earth supports (Celite® R633, R632 and R647) exhibited high enzymatic activity, were thermally stable, and possessed high sol-gel adhesion. From the three types of diatomaceous earth considered, Celite® R632 supported lipase sol-gels were identified as the most promising supported lipase sol-gels for methyl oleate production via transesterification. Upon further evaluation, the Celite® R632 lipase sol-gels were found to achieve high methyl oleate percent conversions, glycerol-water absorption was only significant at glycerol levels higher than 75%, and the immobilized lipase had high stability upon storage at 4°C for 1.5 years. To determine the effects of methanol and glycerol inhibition as well as temperature on the reaction kinetics, a ping-pong bi-bi kinetic model was developed and validated over a range of methanol concentrations and temperatures. The optimal methanol concentration for the conditions tested was in the range of 1.3 M to 2.0 M, and increased with increasing temperature. The model developed was consistent with the experimental data and confirmed that glycerol inhibition and the presence of products had significant effects on the reaction kinetics. The methyl oleate production capabilities of the Celite® supported lipase sol-gel were investigated using a packed bed reactor and compared with Novozym® 435 under similar operating conditions. A kinetic and mass transfer based model was developed for the reactor system using a novel efficiency correlation to account for the effect of glycerol on the enzymatic activity. Increasing the flow rate (1.4 mL/min to 20 mL/min) increased the reaction rate, presumably due to the reduction of the glycerol inhibition effect on the immobilized biocatalyst. The Celite® supported lipase sol-gel was found to have superior performance over Novozym® 435 both under batch stirred tank reaction conditions and in a packed bed reactor (83% conversion for Celite® sol-gel vs. 59% conversion for Novozym® 435 at 20 mL/min in the packed bed reactor). Based on the results obtained, Celite® supported lipase sol-gels exhibited good performance for the transesterification of triolein with methanol to produce methyl oleate in both batch and packed bed reactors, and warrant further exploration for the enzymatic production of biodiesel.

Data de aprova??o retirada da vers?o impressa do trabalho. / Incluir a Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) como ag?ncia financiadora. / Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-12-13T16:15:41Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alice_lopes_macedo.pdf: 5251789 bytes, checksum: e988c8abc173c91e128980414db14ef9 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2018-01-03T12:17:24Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alice_lopes_macedo.pdf: 5251789 bytes, checksum: e988c8abc173c91e128980414db14ef9 (MD5) / Made available in DSpace on 2018-01-03T12:17:24Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) alice_lopes_macedo.pdf: 5251789 bytes, checksum: e988c8abc173c91e128980414db14ef9 (MD5) Previous issue date: 2017 / Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) / A crescente demanda global por combust?veis l?quidos para transporte, gera??o de eletricidade, atividade industrial e produ??o agropecu?ria tem imposto planejamento de a??es direcionadas ao uso de fontes ambientalmente limpas de energia. Os derivados da biomassa s?o alternativas econ?mica e tecnicamente vi?veis aos de origem f?ssil, n?o renov?vel, ora dominantes na matriz energ?tica global. O biodiesel, l?quido formado por uma mistura de ?steres de ?cidos graxos, ? adequado ? opera??o em motores de combust?o interna de ciclo Diesel, em substitui??o ou em complemento ao petrodiesel, ou em outras m?quinas t?rmicas. O prop?sito central do presente trabalho foi o desenvolvimento de um catalisador s?lido economicamente vi?vel, quimicamente eficiente e ambientalmente limpo para a produ??o de biodiesel via processos de transesterifica??o de triacilglicer?is dos ?leos de maca?ba ou de soja, com metanol. Foi preparado o catalisador heterog?neo baseado em iodeto de pot?ssio impregnado em s?lica amorfa (SiO2; derivada de areia da constru??o civil) e misturada a um componente magn?tico sint?tico (maghemita, ?Fe2O3). As estruturas qu?mica, cristalogr?fica e hiperfina essenciais e as propriedades magn?ticas dos materiais precursores e do catalisador s?lido foram investigadas. O teor de ?steres e a composi??o dos biodieseis produzidos foram determinados por cromatografia de fase gasosa acoplada a espectr?metro de massa. A composi??o qu?mica do catalisador, verificada por espectroscopias de energia dispersiva sob feixe de el?trons e por fluoresc?ncia de raios X (FRX), confirmou a ocorr?ncia de Si, Fe, K, e I. As ?reas espec?ficas BET encontradas para os componentes individuais, SiO2, ?Fe2O3 e do catalisador SiO2/KI/?Fe2O3, foram 352, 102, e 19 m2 g-1, respectivamente. A significativa redu??o da ?rea espec?fica do catalisador aponta que os componentes foram efetivamente impregnados no suporte. A morfologia das part?culas visualizadas por microscopias eletr?nicas de varredura e de transmiss?o revela a textura esponjosa do catalisador SiO2/KI/?Fe2O3, similarmente ao suporte de s?lica; o ?xido de ferro magn?tico aparece como material altamente organizado, cristalino, disperso no suporte. Os dados M?ssbauer e da magnetometria do ?xido de ferro magn?tico puro e no catalisador confirmam ser a maghemita, resultando em uma magnetiza??o de satura??o do catalisador de 4,6 emu g-1. O catalisador SiO2/KI/?Fe2O3, usado na transesterifica??o de triacilglicer?is, na propor??o em massa em rela??o ao ?leo da am?ndoa de maca?ba de 4,5% e raz?o molar ?leo:metanol de 1:35, levou ? produ??o de 94,3 massa% de ?steres, ap?s 8 h de rea??o. Foi experimentalmente observado que a maghemita tem comportamento qu?mico-catal?tico sin?rgico com os demais componentes do catalisador. O SiO2/KI/?Fe2O3 foi reutilizado em seis rea??es consecutivas com ?leo de soja, na mesma propor??o do catalisador e raz?o molar ?leo:metanol de 1:35, com rendimentos de 94,5% e tempo reacional de 110 min, para o primeiro ciclo, e de 61,2% e 150 min, para o ?ltimo ciclo. O catalisador, antes e ap?s cada ciclo de reuso, e as al?quotas das rea??es foram analisados por FRX, que mostrou que n?o h? perda significativa dos componentes do catalisador. Os resultados demonstram uma perspectiva tecnol?gica que permite redu??o substantiva do volume de efluentes poluentes e utiliza??o de diferentes mat?rias-primas oleaginosas de alto potencial para a produ??o de biodiesel. / Tese (Doutorado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The global demand for liquid fuels destined to propel automobile motors and for all other types of transport has been growing significantly over the last decades in response to the needs of the population for mobility. These fuels are also necessary for the generation of electricity to support industrial and agricultural activities. However, the principal concern involved in the generation of mechanical work involves the threat that the effluents from burning fuels, particularly those from fossil origin, impart to the environment. Biomass-derived fuels are energetically, economically and environmentally interesting alternatives to the non-renewable fossil fuels, which still dominate the global energy matrix. Biodiesel, a liquid that is composed of a mixture of esters of fatty acids, is mainly suitable for use in Diesel-cycle internal combustion engines, totally replacing or partially complementing petrodiesel. The main purpose of the present work was the development of an economically viable, environmentally clean and chemically efficient solid catalyst for the production of biodiesel via the transesterification reaction of triacylglycerols from maca?ba or soybean oil with methanol. The proposed heterogeneous catalyst was based on potassium iodide-impregnated particles of amorphous silica (SiO2; derived from construction sand) mixed with a synthetic magnetic iron oxide (maghemite, ?Fe2O3). The essential chemical, crystallographic and hyperfine structures and magnetic properties of the starting materials and of the solid catalyst mixture were assessed by physical laboratory techniques. The ester content and the chemical composition of the biodiesel produced were determined by gas chromatography coupled with mass spectrometry. The chemical composition of the catalyst, as determined by electron energy dispersive and X-ray fluorescence (FRX) spectroscopies, confirmed the occurrence of Si, Fe, K, and I. Specific BET surface areas for the SiO2 and ?Fe2O3 components and for the SiO2/KI/?Fe2O3 catalyst were found to be 352; 102 and 19 m2 g-1, respectively. The significant reduction in the specific area of the catalyst indicates that the solid components were intimately mixed and that KI was indeed impregnated on the support. The morphology of the particles, as visualized from the scanning and transmission electron microscopy images, reveals the spongy texture of the SiO2/KI/?Fe2O3 catalyst, which was quite similar to that of the initial silica support. The atomic framework of the magnetic iron oxide appeared to be a highly organized, crystalline nano-material, relatively well dispersed on the silica support. The M?ssbauer and magnetometric data for the pure magnetic iron oxide and for the catalyst confirm that the component is essentially maghemite. The resulting saturation magnetization of the catalyst mixture was 4.6 emu g-1. From the chemical point of view, this maghemite was found to act synergically with the other components of the catalyst and to significantly improve its catalytic activity. The transesterification reaction of triacylglycerols using the SiO2/KI/?Fe2O3 catalyst at a mass ratio corresponding to 4.5 mass% relative to the maca?ba kernel oil and a methanol:oil molar ratio 30:1 yielded 94.3 mass% of esters after 8 h of reaction. The SiO2/KI/?Fe2O3 catalyst was reused for six consecutive transesterification reactions of triacylglicerols in soybean oil employing the same mass proportion of the catalyst and a methanol:oil molar ratio 35:1. A 94.5% yield of esters was obtained after 110 min of reaction in the first cycle, and a 61.2% yield was obtained in the last reaction cycle after 150 min. The compositions of the catalyst before and after each reaction cycle, along with detection of residual chemical elements in the liquid mixture of esters formed, were duly monitored by FRX. There was no significant leaching of the catalyst components during the reactions. These results open a perspective for (i) a substantial reduction in the volume of polluting effluents and (ii) the use bio-oils from native Brazilian flora (maca?ba) as raw materials for the industrial production of biodiesel.

?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.

Nesse trabalho foram produzidas lipases da levedura Pseudozyma hubeiensis (HB85A) em reator de 14 L. Após produção da enzima, a lipase foi imobilizada por adsorção em suporte hidrofóbico por processo contínuo em reator de leito fixo. As melhores condições de imobilização foram: tempo de imobilização de 2 h e 29 min., pH de 4,76 e quantidade de enzima livre adicionada por grama de suporte de 1282 U/ g de suporte, sendo que, a máxima atividade da lipase imobilizada obtida foi de 143 U/g de suporte. O sobrenadante contendo lipase e o biocatalisador heterogênio foram caracterizados por planejamento fatorial. A máxima atividade da enzima imobilizada (71 U/g de suporte) foi obtida em pH 6,0 à temperatura de 52 °C. A imobilização da lipase resultou em um aumento na estabilidade dessa enzima em temperaturas altas, pH ácidos e neutros, presença de detergentes não-iônicos e altas concentrações de solventes orgânicos como iso-propanol, metanol e acetona. Foi possível a reutilização da lipase imobilizada por apenas uma vez na reação de hidrólise, havendo uma perda de 72 % da atividade após o primeiro reuso. Analisou-se ainda a estabilidade da lipase livre e imobilizada durante 40 dias de armazenamento a 4 °C. Durante o período de armazenamento, a lipase imobilizada manteve 50 % de sua atividade original e a lipase livre apresentou 80 %. O catalisador heterogêneo foi testado quanto a sua eficácia na produção de biodiesel. A reação de transesterificação foi realizada na ausência de co-solvente utilizando-se como matérias-primas metanol, etanol e iso-propanol e quatro fontes diferentes de triglicerídeo (óleo de soja, óleo de mamona, óleo residual de restaurante e a gordura bovina). A partir dos testes realizados, obteve-se um rendimento máximo quanto à produção de biodiesel de 3,15 % utilizando-se óleo de mamona e iso-propanol como matéria-prima pelo período de 24 h. A produção de biodiesel utilizando diferentes quantidades de lipase imobilizada e também a lipase livre como catalisador foi testada na presença de hexano, iso-propanol e óleo de mamona pelo período de 24 h nas temperaturas de 40, 50 e 60 °C. No entanto, não houve produção de biodiesel nas condições analisadas. / In this work, lipases from yeast Pseudozyma hubeiensis (strain HB85A) were produced in a 14 L reactor. After lipase from yeast P. hubeiensis (strain HB85A) production, the enzyme was immobilized by adsorption in polyestyrene divinylbenzene hydrophobic support in a packet bed column. The best conditions for lipase immobilization were: 2 h and 29 min. immobilizing time, pH 4.76 and rate of free enzyme added per gram of support equal to 1282 U/g. The maximum activity of immobilized lipase was reached of 143 U/g. The lipases of P. hubeiensis (HB85A) supernatant culture and the heterogeneous catalyst were characterized through response surface methodology by factorial design. The maximum activity of immobilized lipase was reached for a support rate of 71 U/g, with pH 6.0 and temperature of 52 °C. It was detected that lipase immobilization increased enzyme stability under high temperatures, neutral and acid pH levels, non-ionic detergent and high concentration of organic solvent like iso-propanol, methanol and acetone. The reuse of immobilized lipase was possible only once for hydrolysis reaction, with activity losses of 72 % after first re-use. Also, it was tested lipase stability in a period of 40 days, under 4 °C storage conditions. During storage period, immobilized lipase kept 50 % of its original activity. Free lipase kept 80 %. After the development of heterogeneous catalyst, its efficiency as catalyst for biodiesel production was analyzed in this study. The transesterification reaction was tested in co-solvent absence using as raw material three differents sources of alcohols (methanol, ethanol and iso-propanol) and four differents triglicerides source (soybean oil, castor oil, waste cooking oil and bovine fat) and as catalystis the immobilized lipase. Based in test results, the maximum biodiesel production yield was 3.15 % using castor oil and methanol as raw material for 24 h. The biodiesel production was also tested with different amount of immobilized lipase and with free lipase as catalystis at the presence of methanol, castor oil and the co-solvent hexane for 24 h at 40, 50 e 60 °C. However there was no biodiesel production at the tested conditions.

The aim of this study was to investigate the catalytic activity of three complexes exhibiting Lewis acid character: butylstannoic acid, di-n-butyl-oxo-stannane and ibutyltin dilaurate. These catalysts were tested in ethanolysis of soybean oil in order to obtain a mixture of alkyl esters, known as biodiesel. The interest of this study is to verify the efficiency of catalysts in reactions of ethanolysis and determine the yield of biodiesel. Ethanol was employed as alcoholysis agent due their renewable nature and be less toxic than methanol. In all conditions tested the following order of activity can be established: DBTO> DBTDL> BTA. All experiments performed in the closed reactor shown higher yields compared to those obtained employing one reactor operating under reflux conditions. In the reactions carried out in the presence of ethanol, lower yields were obtained compared to methanol. / O objetivo deste trabalho foi investigar a atividade catalítica de três complexos metálicos exibindo caráter ácido de Lewis: ácido butilestanóico, óxido de dibutil estanho e dibutildilaurato de estanho. Esses catalisadores foram testados na etanólise do óleo de soja visando a obtenção de uma mistura de ésteres alquílicos, denominada biodiesel. O interesse desse estudo é verificar a eficiência dos catalisadores em reações de etanólise e determinar o rendimento em biodiesel. O etanol foi empregado como agente de alcóolise por ser proveniente de fontes renováveis e ser menos tóxico que o metanol. Em todas as condições testadas a seguinte ordem de atividade pode ser estabelecida: DBTO > DBTDL > BTA. Todos os experimentos realizados no reator fechado apresentaram rendimentos superiores comparados ao reator operando em condições de refluxo. Nas reações conduzidas na presença do etanol, foram obtidos rendimentos inferiores, comparativamente ao metanol.

Due to the requirement for economic sustainability, studies on the use of biomass or biofuels to energy obtention has increased in recent years. Biomass energy is obtained by burning wood, bagasse, forest and agricultural residues, among others. Nowadays, renewable resources represent about 20% of total energy supply in the world and biomass is about 14%. The production of electricity from biomass is currently advocated as very important alternative for developing countries. The present work aims to study species adaptable to northeastern of Brazil for energy generation. In this context, Cnidoscolus quercifolius (faveleira) and Annona muricata L. (graviola), are characterized as raw materials with potential use for alternative energy source. Besides the possibility of evaluating the various parts of the plant for power generation, it is possible to employ the seeds, due their high content of oil which can be used as a source of triacylglycerols for the biodiesel production. / Devido à busca pela sustentabilidade econômica, estudos sobre obtenção de energia através do uso direto biomassa ou de biocombustíveis, tem aumentando nos últimos anos. A energia da biomassa é obtida através da combustão de lenha, bagaço de cana, resíduos florestais, resíduos agrícola, entre outros. Já a energia proveniente do biodiesel é obtida através de sua síntese a partir de fontes vegetais ou seu uso como combustível líquido. Dessa forma a energia gerada é renovável. Hoje os recursos renováveis apresentam cerca de 20% de suprimento total de energia no mundo, sendo que só de biomassa seria da ordem de 14%. A produção de energia elétrica a partir da biomassa, atualmente, é muito defendida como importante alternativa para países em desenvolvimento. O presente trabalho tem como objetivo estudar espécies adaptáveis ao nordeste brasileiro para geração de energia. Nesse contexto, cnidoscolus quercifolius Pax et K. Hoffm (faveleira) e annona muricata L. (graviola), se caracterizam como matérias-primas com potencial uso para fonte alternativa de energia. Além da possibilidade de avaliação das várias partes da planta na geração de energia, existe a possibilidade de empregar as sementes. As mesmas contêm alto teor de óleo que pode ser empregado como fonte de triacilgliceróis para a produção de biodiesel e a torta, resultante da extração, pode ser igualmente avaliada como resíduo de biomassa.

The concern about fossil fuel reserves depletion, pollution due to extensive use of conventional fuels and stricter standards for emission are the forces that drive research on alternative fuels. Amongst these are the biodiesel in which the use of vegetable oils has become an attractive to replace diesel from petroleum because of its physico-chemical characteristics and no toxic emissions. This work aimed to study the effect of diferente variables on conversion of peanut oil to biodiesel; determine the influence of temperature and pH in the purification process in order to optimize the amount of water used and study the thermodynamic equilibrium of the system biodiesel-glycerine-alcohol (decreasing the production of effluents). The process of production and purification of peanut biodiesel obtained by transesterification was studied. In this reaction was used sodium hydroxide (NaOH) as a basic catalyst, anhydrous ethanol and peanut crude oil (non-degummed) in a pilot production unit. In the purification process was used sulphuric acid diluted in distilled water and drying agent (magnesium sulphate). A 22 factorial design was performed to determine the influence of chemical variables on the amount of water required for thepurification. The variables for the production process were: temperature (30o, 70oC), stirring speed (150 rpm, 350 rpm), molar ratio oil/alcohol (1:4 and 1:10), amount of catalyst (0,5% and 1,5%) and reaction time (0,5 h, 2 h). For the purification process the variables analysed were: temperature (30o and 70oC) and pH (2 and 5). For the study of the system´s thermodynamic equilibrium was used purified biodiesel, jacketed glass reactor with circulating water, titration with biodiesel and glycerine. The evaluation parameter for the production process is the conversion to biodiesel determined by gaseous chromatography and for the purification process were the amount of water utilized and the determination of the influence of the temperature on the system´s thermodynamic equilibrium. The conversion to biodiesel varied between total saponification to a conversion of 87%. In the purification was observed that the effect of the pH variable could be ignored and the effect of the temperature and the interaction of the temperature and pH can be considered. The thermodynamic equilibrium of the system biodiesel/glycerine/alcohol and the tie lines did not have its behaviour influenced by the different temperatures, not influencing the miscibility of the mixture. / A preocupação com o esgotamento das reservas de combustíveis fósseis, a poluição devido ao grande uso de combustíveis convencionais e as normas rigorosas em relação às emissões são as forças que impulsionam as pesquisas com combustíveis alternativos. Dentre estes, temos o biodiesel no qual o uso de óleos vegetais tem se tornado uma alternativa atrativa em substituição ao diesel do petróleo devido às suas características físico-químicas e emissões não tóxicas. Esse trabalho teve como objetivos estudar o efeito de diferentes variáveis na conversão do óleo de amendoim a biodiesel; determinar a influência da temperatura e do pH no processo de purificação, a fim de otimizar a quantidade de água utilizada e, estudar o equilíbrio termodinâmico do sistema biodiesel-glicerina-álcool (diminuindo a produção de efluentes). Foi estudado o processo de produção e purificação do biodiesel de amendoim, obtido através da reação de transesterificação. Nessa reação foi utilizado hidróxido de sódio (NaOH) como catalisador básico, etanol anidro e óleo de amendoim bruto (não-degomado) em uma unidade piloto de produção. No processo de purificação foi utilizado ácido sulfúrico diluído em água destilada e agente dessecante (sulfato de magnésio). Um planejamento fatorial 2² foi realizado a fim de se determinar a influência das variáveis químicas na quantidade de água requerida para a purificação. As variáveis para o processo de produção foram: temperatura (30° e 70°C), velocidade de agitação (150 rpm e 350 rpm), razão molar óleo/álcool (1:4 e 1:10), quantidade de catalisador em massa (0,5% e 1,5%) e tempo de reação (0,5 h e 2 h). Para o processo de purificação foram analisadas as variáveis: temperatura (30° e 70°C) e pH (2 e 5). Para o estudo do equilíbrio termodinâmico foi utilizado o biodiesel purificado, reator de vidro com camisa de circulação de água, titulação com glicerina e biodiesel. O parâmetro de avaliação para a produção é o rendimento em biodiesel determinado por cromatografia gasosa e para o processo de purificação, a quantidade de água utilizada e a determinação da influência da temperatura no equilíbrio termodinâmico do sistema. A conversão a biodiesel variou de total saponificação até uma conversão de 87%. Na purificação, foi observado que o efeito da variável pH pode ser desprezado e o efeito da temperatura e da interação dessas duas variáveis pode ser considerado. O equilíbrio termodinâmico do sistema biodiesel/glicerina/álcool e suas tie lines não sofreram influência de comportamento nas diferentes temperaturas estudadas, não influenciando na miscibilidade da mistura.