The present PhD is focused on the development of new analytical methods based on ICP techniques to carry out the elemental and isotopic analysis of bioethanol samples and other specimens taken along the bioethanol production process. The total sample consumption system, so-called hTISIS, has been used as sample introduction system in ICP-OES for the quantification of major and minor metals, and ICP-MS for the determination of trace metals. The hTISIS has also been successfully set up to carry out the lead isotopic analysis of bioethanol samples. Additionally, metals found in bioethanol have been monitored along the production process of this biofuel to identify the origin of these metals. Finally, volatile organic compounds have been determined in different bioethanol samples to perform the characterization of the matrices and their effect on the accuracy of the methods based on ICP techniques, developed in the present PhD for the elemental and isotopic analysis of these kind of samples. / La presente Tesis Doctoral se centra en el desarrollo de nuevos métodos de análisis basados en técnicas de ICP para llevar a cabo el análisis elemental e isotópico de muestras de bioetanol y muestras tomadas a lo largo del proceso de obtención de dicho biocombustible. Se ha empleado un sistema de consumo total de muestra, conocido como hTISIS, como sistema de introducción de muestras en ICP-OES para la cuantificación de metales mayoritarios y minoritarios, y en ICP-MS para la determinación de metales traza en bioetanol. El sistema hTISIS también se ha empleado con éxito para llevar a cabo el análisis isotópico de plomo en dichas muestras. Además, los metales encontrados en las muestras de bioetanol han sido monitorizados a lo largo del proceso de obtención del mismo para identificar el origen de dichos metales. Finalmente, se han determinado los compuestos volátiles presentes en diferentes muestras de bioetanol, con el objetivo de caracterizar las matrices y como estas pueden afectar a la exactitud de los métodos desarrollados, que emplean técnicas ICP para el análisis elemental e isotópico de este tipo de muestras.

Thesis (Ph. D. (Microbiology)) -- University of Limpopo, 2020 / The use of lignocellulosic biomass for bioethanol production is largely dependent on cost effective production of cellulase enzymes and most importantly, the availability of cellulases with sufficient β-glucosidase activity for complete hydrolysis of cellulose to glucose. Commercial cellulase preparations are often inefficient in the complete hydrolysis of cellulose to glucose. The addition of β-glucosidases to commercial cellulase preparations may enhance cellulolytic activity in the saccharification of cellulose to fermentable sugars. A β-glucosidase producing thermophilic bacterium, Anoxybacillus sp. KTC2 was isolated from a hot geyser in the Zambezi Valley, Zimbabwe. The bacterium identified through biochemical tests and 16S rDNA sequencing, had an optimal growth temperature and pH of 60˚C and pH 8, respectively. The β-glucosidase enzyme had an optimal temperature of 60˚C and a broad pH range for activity, between 4.5 and 7.5 with an optimum at pH 7. The β-glucosidase enzyme retained almost 100% activity after 24 hours’ incubation at 50˚C. The Anoxybacillus sp. KTC2 β-glucosidase was partially purified and a partial amino acid sequence obtained through MALDI-TOF analysis. The whole genome of Anoxybacillus sp KTC2 β-glucosidase was sequenced and a β-glucosidase gene identified. The deduced amino acid sequence corresponded to the peptide sequences obtained through MALDI-TOF, confirming the presence of the a β glucosidase on the genome of Anoxybacillus sp KTC2. Analysis of the deduced amino acid sequence revealed that the β-glucosidase enzyme belongs to the GH family 1. The β-glucosidase gene was isolated by PCR and successfully cloned into an E. coli expression system. The saccharification efficiency of the β-glucosidase enzyme was evaluated through the creation of enzyme cocktails with the commercial cellulase preparation, CelluclastTM. CelluclastTM with the Anoxybacillus sp KTC2 β-glucosidase were used to hydrolyse pure Avicel cellulose, at 50˚C over a 96 hour reaction time. The Anoxybacillus sp KTC2 β-glucosidase enabled a 25% decrease in the total cellulose loading without a decrease in the amount of glucose released. / University of Limpopo staff development programme and VLIR

Im Rahmen dieser Arbeit erfolgte am Beispiel von Weizenstroh die Entwicklung und Optimierung eines Prozesses zur Produktion von Bioethanol. Die Synergie aus effizienter Vorbehandlung mit NaOH, Reaktortyp (Freifallmischer) und einem effizienten Enzymkomplex aus Penicillium verruculosum ermöglichte die Herstellung von bis zu 13 Vol.-% Ethanol. Die Hydrolyse und Fermentation wurden simultan durchgeführt (SSF-Prozess), woraus eine Vermeidung der Produktinhibierung sowie eine Erhöhung der Ethanolproduktivität um 94 % resultierten. Eine in situ-Ethanolentfernung mittels Stripping gewährleistete einen kontinuierlichen SSF-Prozess und ermöglichte die Folgekonversion des Bioethanols mittels katalytischer Dehydratisierung zu Bioethylen. Dadurch wurde eine Wertsteigerung des Ethanols erzielt und eine energie- und kostenintensive Abtrennung, Reinigung und Konzentrierung des Ethanols umgangen. Außerdem gelang eine Übertragung des Prozesses zur Ethanolproduktion vom Labormaßstab (2 L) in den Technikumsmaßstab (200 L). Auch die Anwendung auf andere Biomassen (Miscanthus, Luzerne) sowie Rohstoffe (Weizenkleie) wurde erfolgreich gezeigt.

[ES] La presente tesis doctoral se enmarca en el ámbito de la producción de hidrógeno renovable, y en el estudio metodologías de intensificación de procesos para la producción de hidrógeno mediante reactores de membrana y reactores que operan a alta presión. Para la producción de hidrógeno renovable, se estudió en detalle el proceso de reformado autotérmico (ATR) de bioetanol. Se diseñó y construyó un sistema de reacción de escala de laboratorio, que se operó bajo condiciones reales de operación industrial. En una primera etapa, se realizó la evaluación de distintos catalizadores comerciales para el ATR de etanol. Tras la selección del tipo de catalizador con mejor rendimiento, se probaron distintas variaciones sobre el mismo, añadiendo dopantes a la fase activa y al soporte. Los catalizadores con mejores resultados se probaron durante más de 100 h manteniendo su rendimiento. Una vez seleccionados la composición primara de los catalizadores, se hicieron pruebas para el escalado y optimización de los catalizadores fabricados mediante un proceso industrial. Se estudiaron los efectos de las condiciones de operació, siendo el parámetro de mayor relevancia la relación O/C. El mejor de los catalizadores desarrollados aumentó el rendimiento y disminuyó la producción de hidrocarburos en estas condiciones, alcanzándose un rendimiento de hasta 3.1 mol H2 / mol etanol. Este catalizador se probó durante 200 horas, manteniendo su estabilidad en todo el periodo, validando su aplicación en un reformador de etanol para la producción de hidrógeno. En otro apartado, se estudió la utilización de membranas de transporte de oxígeno como elemento distribuidor de oxígeno para el sistema de reacción de ATR, permitiendo alimentar al reactor oxígeno de alta pureza producido in-situ. Se probaron membranas capilares de BSCF. En el sistema de reacción de ATR, las membranas mostraron una permeación acorde a los valores habituales para este material. Se estudió el comportamiento de las membranas de BSCF en una atmósfera con vapor, en la que la permeación alcanzada disminuyó en presencia de vapor. La utilización de estas membranas en la reacción de ATR requeriría de un escalado correcto, pues el flujo de oxígeno aportado por la membrana sería bajo respecto a las necesidades de oxígeno de la reacción de ATR. Seguidamente, se probaron los efectos de la aplicación de capas protectoras porosas sobre los capilares de BSCF, para mejorar su estabilidad química en ambientes de rección. Mediante la técnica de dip-coating se aplicaron capas porosas de BSCF, CTO-CMO (Ce0.8Tb0.2O2--δ- MnCo2O4) y CTO. La aplicación de estas capas aumentó la permeación por la mejora en el área superficial de intercambio y de las reacciones superficiales, alcanzándose 3 - 3.6 NmL·min-1·cm-2 para las membranas recubiertas, frente a 2.4 NmL·min-1·cm-2 para la membrana sin recubrimiento. Estas mismas membranas se probaron en un reactor de membrana, en reacción con CH4. Las capas aporataron efectos catalíticos y protectores respecto a la membrana sin tratamiento superficial. Las capas de CTO y CTO-CMO aumentaron la permeación de oxígeno y la conversión de CH4, que alcanzó valores del 100%, y además, resultaron estables en las condiciones de reacción, mientras que las membranas con capa de BSCF y sin recubrimiento tuvieron conversiones más bajas y su estructura quedó degradada por la atmósfera de la reacción. Finalmente, se llevó a cabo el diseño y construcción de un sistema de reacción de alta presión para el estudio de procesos de producción de hidrógeno a alta presión a presiones de hasta 300 barg. En esta unidad, se podrán llevar a cabo reacciones de producción de hidrógeno a partir de biomasa en agua supercrítica. Adicionalmente, se diseñó un reactor de membrana que permitirá el trabajo con membranas de permeación de gases en condiciones de alta severidad, con potencial aplicación en la producción de hidrógeno a partir de reacciones de reformado con una alta eficiencia. / [CA] La present tesi doctoral s'emmarca en l'àmbit de la producció d'hidrogen renovable, i en l'estudi metodologies d'intensificació de processos per a la producció d'hidrogen mitjançant reactors de membrana i reactors que operen a alta pressió. Per a la producció d'hidrogen renovable, es va estudiar detalladament el procés de reformat autotérmico (ATR) de bioetanol. Es va dissenyar i va construir un sistema de reacció d'escala de laboratori, que es va operar sota condicions reals d'operació industrial. En una primera etapa, es va realitzar l'avaluació de diferents catalitzadors comercials per al ATR d'etanol. Després de la selecció de la mena de catalitzador amb millor rendiment, es van provar diferents variacions sobre aquest, afegint dopants a la fase activa i al suport. Els catalitzadors amb millors resultats es van provar durant més de 100 h mantenint el seu rendiment. Una vegada seleccionats la composició prevalguera dels catalitzadors, es van fer proves per a l'escalat i optimització dels catalitzadors fabricats mitjançant un procés industrial. Es van estudiar els efectes de les condicions de operació, sent el paràmetre de major rellevància la relació O/C. El millor dels catalitzadors desenvolupats va augmentar el rendiment i va disminuir la producció d'hidrocarburs en aquestes condicions, aconseguint-se un rendiment de fins a 3.1 mol H2 / mol etanol. Aquest catalitzador es va provar durant 200 hores, mantenint la seua estabilitat en tot el període, validant la seua aplicació en un reformador d'etanol per a la producció d'hidrogen. En un altre apartat, es va estudiar la utilització de membranes de transport d'oxigen com a element distribuïdor d'oxigen per al sistema de reacció de ATR, permetent alimentar al reactor oxigen d'alta puresa produït in-situ. Es van provar membranes capil·lars de BSCF. En el sistema de reacció de ATR, les membranes van mostrar una permeación concorde als valors habituals per a aquest material. Es va estudiar el comportament de les membranes de BSCF en una atmosfera amb vapor, en la qual la permeación aconseguida va disminuir en presència de vapor. La utilització d'aquestes membranes en la reacció de ATR requeriria d'un escalat correcte, perquè el flux d'oxigen aportat per la membrana seria baix respecte a les necessitats d'oxigen de la reacció de ATR. Seguidament, es van provar els efectes de l'aplicació de capes protectores poroses sobre els capil·lars de BSCF, per a millorar la seua estabilitat química en ambients de recció. Mitjançant la tècnica de dip-coating es van aplicar capes poroses de BSCF, CTO-CMO i CTO. L'aplicació d'aquestes capes va augmentar la permeación per la millora en l'àrea superficial d'intercanvi i de les reaccions superficials, aconseguint-se 3 - 3.6 NmL·min-1·cm-2 per a les membranes recobertes, enfront de 2.4 NmL·min-1·cm-2 per a la membrana sense recobriment. Aquestes mateixes membranes es van provar en un reactor de membrana, en reacció amb CH4. Les capes aporataron efectes catalítics i protectors respecte a la membrana sense tractament superficial. Les capes de CTO i CTO-CMO van augmentar la permeación d'oxigen i la conversió de CH4, que va aconseguir valors del 100%, i a més, van resultar estables en les condicions de reacció, mentre que les membranes amb capa de BSCF i sense recobriment van tindre conversions més baixes i la seua estructura va quedar degradada per l'atmosfera de la reacció. Finalment, es va dur a terme el disseny i construcció d'un sistema de reacció d'alta pressió per a l'estudi de processos de producció d'hidrogen a alta pressió a pressions de fins a 300 barg. En aquesta unitat, es podran dur a terme reaccions de producció d'hidrogen a partir de biomassa en aigua supercrítica. Addicionalment, es va dissenyar un reactor de membrana que permetrà el treball amb membranes de permeación de gasos en condicions d'alta severitat, amb potencial aplicació en la producció d'hidrogen a partir de reaccions de reformat amb una alta eficiència. / [EN] This doctoral thesis is framed in the field of renewable hydrogen production, and in the study of process intensification methodologies for the production of hydrogen through membrane reactors and reactors that operate at high pressure. For the production of renewable hydrogen, the bioethanol autothermal reforming (ATR) process was studied in detail. He designed and built a laboratory scale reaction system, which was operated under real industrial operating conditions. In a first stage, the evaluation of different commercial catalysts for ethanol ATR was carried out. After selecting the type of catalyst with the best performance, different variations were tested on it, adding dopants to the active phase and to the support. The catalysts with the best results were tested for more than 100 h maintaining their performance. Once the primary composition of the catalysts had been selected, tests were carried out for the scaling and optimization of the catalysts manufactured by means of an industrial process. The effects of operating conditions were studied, the most relevant parameter being the O / C ratio. The best of the developed catalysts increased the yield and decreased the production of hydrocarbons under these conditions, reaching a yield of up to 3.1 mol H2 / mol ethanol. This catalyst was tested for 200 hours, maintaining its stability throughout the period, validating its application in an ethanol reformer for the production of hydrogen. In another section, the use of oxygen transport membranes as an oxygen distributor element for the ATR reaction system was studied, allowing the reactor to be fed high-purity oxygen produced in-situ. Capillary membranes from BSCF were tested. In the ATR reaction system, the membranes showed a permeation according to the usual values for this material. The behavior of the BSCF membranes was studied in an atmosphere with steam, in which the permeation achieved decreased in the presence of steam. The use of these membranes in the ATR reaction would require correct scaling, since the flow of oxygen provided by the membrane would be low compared to the oxygen needs of the ATR reaction. Next, the effects of the application of porous protective layers on the BSCF capillaries were tested, to improve their chemical stability in rection environments. By means of the dip-coating technique, porous layers of BSCF, CTO-CMO and CTO were applied. The application of these layers increased the permeation due to the improvement in the surface area of exchange and of the surface reactions, reaching 3 - 3.6 NmL · min-1 · cm-2 for the coated membranes, compared to 2.4 NmL · min-1 · cm-2 for the uncoated membrane. These same membranes were tested in a membrane reactor, in reaction with CH4. The layers supported catalytic and protective effects with respect to the membrane without surface treatment. The CTO and CTO-CMO layers increased oxygen permeation and CH4 conversion, which reached values of 100%, and were also stable under the reaction conditions, while the membranes with BSCF layer and without coating had conversions. lower and its structure was degraded by the atmosphere of the reaction. Finally, the design and construction of a high pressure reaction system was carried out for the study of high pressure hydrogen production processes at pressures up to 300 barg. In this unit, hydrogen production reactions can be carried out from biomass in supercritical water. Additionally, a membrane reactor was designed that will allow work with gas permeation membranes under conditions of high severity, with potential application in the production of hydrogen from reforming reactions with high efficiency. / Represa Bullido, Á. (2022). Desarrollo de sistemas catalíticos e intensificación de procesos para la producción de hidrógeno comprimido y productos de interés [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/183153

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: Climate change that results from greenhouse gases (GHG’s) released from the burning of fossil fuels, together with the rising price of oil, have sparked interest in renewable biofuels. The production of biofuels also presents potential socio-economic benefits. There are two types of technologies for bioethanol production: · First generation bioethanol is produced from food feedstocks such as juice of sugarcane. · Second generation bioethanol is produced from non-food feedstocks (lignocellulosic materials). This project is concerned with 1st and 2nd generation bioethanol production from sugarcane juice and bagasse and the integration of these technologies. This project comprises a combination of experimental and process modelling work to assess energy efficiencies and the economic viability of integrated and stand-alone processes in the sub-Saharan African context. First generation fermentation experiments were conducted and high ethanol concentrations of up to 113.7 g/L were obtained. It was concluded that a recombinant yeast strain may be able to replace a natural hexose fermenting yeast for 1st generation fermentations to reduce costs. 2nd generation fermentation experiments were performed and ethanol concentrations of close to 40 g/L were obtained. Combinations of 1st and 2nd generation fermentation experiments were performed to improve the 2nd generation fermentation. In one of the experiments it was concluded that the combination of 1st and 2nd generation fermentations significantly improved the 2nd generation fermentation with an overall ethanol concentration of 57.6 g/L in a shorter time than for the pure 2nd generation experiments. It was determined from washing and pressing experiments that pressing the pre-hydrolysate liquor out of the pre-treated bagasse will sufficiently lower the levels of inhibitors in a 2nd generation fermentation when using a hardened yeast. Some of the data from the 1st generation experiments were used along with literature data to model a first generation process in Aspen Plus® which processes 493 tons of cane per hour (tc/hr). Pinch heat integration was used to reduce the utility requirements. The process used the bagasse that was generated to co-produce steam and electricity. The excess electricity was sold for additional revenue. In one scenario the excess bagasse was determined at 57.5%. This bagasse was sold to a stand-alone 2nd generation plant. The first generation process produced 85.5 litres of ethanol per ton of cane (L/tc), the integrated process produced 128 L/tc while the stand-alone 2nd generation process produced 185 litres of ethanol per ton of bagasse (50% moisture) or 25.5 L/tc. The amount of excess electricity that was produced ranged from 14.3 to 70.2 kWh/tc. Economic analyses were performed using South African economic parameters to resemble the sub- Saharan African context. Data from the 1st generation process model and literature data for integrated 1st and 2nd generation and stand-alone 2nd generation processes were used for the analyses. It was found that the integrated plant is the most economically viable (IRR = 11.66%) while the 1st generation process basically broke even (IRR = 1.62%) and the 2nd generation process is unviable. This was as a result of high sugarcane prices and too few incentives for 2nd generation ethanol. / AFRIKAANSE OPSOMMING: Klimaatsverandering wat veroorsaak word deur kweekhuisgasse wat vrygestel word deur die verbranding van fossielbrandstowwe en die stygenede olieprys het belangstelling in hernubare biobrandstowwe laat opvlam. Die produksie van biobrandstowwe hou ook potensiële sosioekonomiese voordele in. Daar is twee tegnologieë vir bioetanol produksie: · Eerste generasie bioetanol word vanaf voedsel bronne soos suikersap geproduseer. · Tweede generasie bioetanol word van nie-voedsel bronne (lignosellulose materiaal) geproduseer. Hierdie projek handel oor 1ste en 2de generasie bioetanol produksie van suikersap en suikerriet bagasse en die integrasie van hierdie tegnologieë. Hierdie projek bestaan uit ‘n kombinasie van eksperimentele- en prosesmodellering werk om die energiedoeltreffendheid en ekonomise vatbaarheid van geïntegreerde en alleenstaande prosesse in die sub-Sahara konteks te ondersoek. Eerste generasie fermentasie eksperimente is uitgevoer en hoë etanol konsentrasies van tot 113.7 g/L is gekry. Dit was bepaal dat ‘n rekombinante gisras ‘n natuurilke heksose fermenterende gisras kan vervang vir 1ste generasie fermentasies om kostes te bespaar. 2de generasie fermentasie eksperimente is gedoen en etanol konsentrasies van amper 40 g/L is behaal. Kombinasies van 1ste en 2de generasie fermentasie-eksperimente was uitgevoer om die 2de generasie fermentasie te verbeter. In een van die eksperimente is dit bepaal dat die kombinasie van 1ste en 2de generasie fermentasie die 2de generasie fermentasie beduidend verbeter het met ‘n etanol konsentrasie van 57.6 g/L en dít in ‘n korter tyd as vir die suiwer 2de generasie eksperimente. Dit was bepaal vanuit pers- en was eksperimente dat om die pre-hidrolisaat vloeistof uit die stoombehandelde bagasse te pers, die vlak van inhibitore in ‘n 2de generasie fermentasie voldoende verlaag vir die gebruik van ‘n verharde gis. Van die data van die 1ste generasie eksperimente was saam met literatuurdata gebruik om ‘n 1ste generasie proses in Aspen Plus® te modelleer wat 493 ton suikerriet per uur prosesseer (tc/hr). Pinch hitte integrasie was gebruik om die dienste vereistes te verminder. In die proses word die bagasse gebruik om stoom en elektrisiteit te genereer. In een geval was die oortillge bagasse bepaal as 57.5%. Hierdie bagasse was verkoop aan ‘n alleenstaande 2de generasie aanleg. Die eerste generasie proses het 85.5 liter etanol per ton suikerriet geproduseer (L/tc), die geïntegreerde proses het 128 L/tc geproduseer terwyl die 2de generasie proses 185 liter etanol etanol per ton bagasse (50% vog) of 25.5 L/tc geproduseer het. Die hoeveelhede oortillige elektrisiteit wat geproduseer is wissel van 14.3 tot 70.2 kWh/tc. Ekonomiese analieses is gedoen met Suid-Afrikaanse ekonomiese parameters om die sub-Sahara Afrika-konteks uit te beeld. Data van die 1ste generasie prosesmodel en literatuurdata van geïntegreerde 1ste en 2de generasie en alleenstaande 2de generasie prosesse was vir die analieses gebruik. Dit is bepaal dat die geïntegreerde model die mees ekonomies vatbare model is (IRR = 11.66%) terwyl die 1ste generasie proses basies gelyk gebreek het (IRR = 1.62%) en die 2de generasie proses is ekonomies onvatbaar. Hierdie bevindinge is as gevolg van hoë suikerrietpryse en te min aansporings vir 2de generasie etanol.

This dissertation sets its goal in application of the water footprint indicator, which is a practical and multi-layered indicator of water sources consumption. Of human activities, agriculture presents the most significant demands on water sources consumption. Therefore I have turned my focus to the widely-discussed issue of biofuels production, because the input materials for production of this kind of energy are agricultural crops (in the Czech republic those are: oilseed rape, sugar beet, Indian corn and winter wheat). The calculated results of water footprints of the selected industrial crops (m3 /t) and of water footprints of the heating value units of that crops (m3 /GJ) offer us a concrete notion of energy requirements of water of that chosen industrial crops in the conditions of the Czech republic. Keywords: water footprint indicator, biofuels, oilseed rape, water consumption, biodiesel, bioethanol, evapotranspiration.

A possível escassez dos recursos fósseis, juntamente com o aumento imprevisível dos respectivos preços, levou, nas últimas décadas, a um aumento considerável de iniciativas dedicadas não só à procura de fontes alternativas de produtos químicos e polímeros a partir de fontes renováveis, mas também de fontes alternativas de energia - em particular a biomassa vegetal. O estudo desenvolvido no presente trabalho está inserido neste contexto. A despolimerização de celulose de sisal pode ocorrer via hidrólise, ácida ou enzimática, podendo resultar nos açúcares fermentescíveis necessários para a produção do chamado etanol celulósico e, em etapas intermediárias do processo, em micro e nanopartículas, que podem atuar como reforço de matriz polimérica baseada, por exemplo, em quitosana. O estudo aqui relatado está relacionado à análise do material celulósico não reagido durante a hidrólise, e do licor que contém principalmente glicose. As reações de hidrólise ácida e enzimática de polpa de sisal (constituída de celulose e hemicelulose) foram exploradas. Uma importante característica que envolve a hidrólise ácida de biomassa é a possibilidade de utilização de diversos ácidos, pois a princípio, necessita-se apenas de uma fonte de prótons no meio aquoso para que a reação ocorra. Neste contexto, em uma primeira etapa, uma série de reações de hidrólise ácida de polpa de sisal, previamente tratada com solução alcalina (mercerizada) ou não, foi feita com ácido sulfúrico (0,9 - 4,6 molL-1, 100°C, 6h de reação). Em uma segunda etapa, o ácido sulfúrico foi substituído por ácido oxálico, e os tempos de reação foram maiores (18h) que aqueles considerados para o ácido sulfúrico, tendo em vista o menor valor do pKa do ácido oxálico. Reações de hidrólise enzimática foram realizadas com o uso de um complexo enzimático comercial (Accellerase 1500 - Genencor), e dois diferentes pré-tratamentos, ambos visando à eliminação de hemiceluloses, foram avaliados, sendo: mercerização e tratamento com solução de ácido oxálico 0,9 molL-1. Para acompanhar os processos, em determinados intervalos de tempo, foram retiradas alíquotas do meio reacional, sendo que os licores foram analisados por cromatografia líquida de alta eficiência (CLAE), a fim de avaliar a natureza e o teor dos produtos da hidrólise. As polpas residuais (não hidrolisadas), suspensas no licor, foram avaliadas por microscopia eletrônica de varredura, massa molar média por viscosimetria capilar, índice de cristalinidade por difração de raios X e tamanhos médios das fibras a partir de um analisador de fibras (MorFi - analisador de tamanho médio de fibras por imagem), e espalhamento de luz (FOQELS). Para todas as reações de hidrólise ácida estudadas, as massas molares médias das polpas residuais diminuíram até dez vezes logo nos primeiros minutos de reação e os valores de índice de cristalinidade mostraram que as regiões não cristalinas da celulose são primeiramente hidrolisadas, sendo as regiões cristalinas uma grande barreira frente à hidrólise. Os resultados mostraram que o aumento da concentração do catalisador ácido elevou consideravelmente a porcentagem de hidrólise, principalmente no caso do ácido oxálico que, quando usado na concentração de 0,9 molL-1, não foi capaz de hidrolisar com eficiência as cadeias de celulose, mas apenas eliminou as hemiceluloses presentes na polpa, motivo que levou à sua aplicação como agente de pré-tratamento para a polpa frente à hidrólise enzimática. Os rendimentos das reações mostraram que o ácido sulfúrico chega a ser aproximadamente 25% mais eficiente que o ácido oxálico em termos de produção de glicose. Entretanto, o ácido oxálico possui a grande vantagem de ser proveniente de fontes renováveis e, se usado nas concentrações adequadas, pode ser uma excelente opção como pré-tratamento da polpa de celulose para as reações de hidrólise. Os resultados de hidrólise enzimática mostraram que a polpa que passou pelo pré-tratamento da mercerização foi mais eficiente como material de partida do que aquela tratada com ácido oxálico, já que a primeira levou a concentrações de glicose até 2,5 vezes maiores, nas mesmas condições de concentração de enzima, temperatura e tempo de reação. As reações de hidrólise ácida e enzimática de material lignocelulósico são de grande importância no que diz respeito à produção de etanol de segunda geração e micro/nanofibras que podem ser incorporadas em materiais. Filmes de matriz de quitosana foram produzidos com a inserção de fibras de celulose sem tratamento, mercerizada, e residuais das reações de hidrólise ácida e enzimática, em diferentes concentrações (2,5, 7,5 e 15% em massa). Os filmes foram submetidos à solicitação de tração, e a morfologia foi acessada por microscopia eletrônica de varredura de emissão de campo (FEG-MEV). Os resultados mostraram que, no geral, o filme de quitosana (69 MPa), assim como os baseados em quitosana/celulose (75 MPa), apresentam resistência à tração superior ou no mesmo patamar de filmes similares descritos na literatura. Este trabalho forneceu resultados promissores e está largamente inserido no interesse atual de utilização de materiais provenientes de fontes renováveis preferencialmente àqueles de fontes fósseis. / The possible shortage of crude oil and the unpredictable increase in its prices have led to an impressive expansion of initiatives in the last decades dedicated not only to the search of alternative sources of chemicals and polymers, but also to suppliers of energy, both from vegetal biomass. The depolymerization of sisal cellulose may occur via acid or enzymatic hydrolysis, resulting in the fermentable sugars used in the production of the so-called cellulosic ethanol and also at the intermediate steps of the process, in micro and nanoparticles that may act as reinforcement in polymeric matrices, including those derived from cellulose. The study here reported is related to the analysis of the unreacted cellulosic material and to the liquor containing mainly glucose, from acid and enzymatic hydrolysis of sisal pulp formed by cellulose and hemicellulose. An important characteristic that involves the acid hydrolysis of biomass is the possibility of utilization of different acids, since only a source of protons in the media is required for the reaction to occur, in principle. In this context, a series of reactions of acid hydrolysis of sisal pulp was carried out under varying concentrations of sulfuric acid, from 0,9 to 4,6 molL-1, at 100°C as a first step. In a second step, the acid catalyst was replaced by oxalic acid, and the reaction lengths were bigger than those considered for sulfuric acid due to the lower value of pKa of oxalic acid. The reactions of enzymatic hydrolysis were carried out with a commercial enzymatic complex (Accellerase 1500 - Genencor), and two different pretreatments, both aiming at the elimination of hemicelluloses, were essayed as follows: mercerization and treatment with oxalic acid 0,9 molL-1. To follow the processes of acid and enzymatic hydrolysis in determined time intervals, aliquots were withdrawn from the reaction media so as to be analyzed by High Performance Liquid Chromatography (HPLC) aiming at the evaluation of the nature and content of the hydrolysis products. The unreacted cellulose suspended in the liquor was characterized by Scanning Electron Microscopy, capillary viscometry, X ray diffraction, and average size of fibers by using a fiber analyzer and light scattering. For all acid hydrolysis reactions studied, the average molar mass of the unreacted cellulose decreased up to ten times in the first minutes of reaction, and the values of crystallinity index showed that the non-crystalline regions of cellulose are firstly hydrolyzed, and the crystalline regions act as barriers to the hydrolysis. The results of HPLC showed that an increase in concentration considerably increases the yield of hydrolysis, mainly in the case of oxalic acid as a catalyst, which was not able to hydrolyze the chains of cellulose when in low concentrations (0,9 molL-1). It only eliminated the hemicellulose present in the pulp, reason why this acid was used as a pretreatment agent in enzymatic hydrolysis at this concentration. The reaction yields showed that the sulfuric acid can be up to 25% more efficient than the oxalic acid in terms of glucose production. However, the oxalic acid has the great advantage of possibly being produced from natural resources as well as being an excellent choice as a pretreatment agent for the lignocellulosic biomass to be used in hydrolysis reactions if used in the adequate concentrations. The results of enzymatic hydrolysis showed that the mercerized pulp was more efficient as raw material than the one treated with oxalic acid, as the first led to higher glucose content at the same conditions of concentration, temperature and time of reaction. The reactions of acid and enzymatic hydrolysis of lignocellulosic materials are of great importance to the production of second generation ethanol and micro and nanofibers, which may be incorporated into biocomposites. Films of chitosan matrix were prepared with the addition of cellulose fibers (untreated, mercerized and residual from the acid and enzymatic hydrolysis reactions) under various concentrations (2,5, 7,5 e 15% wt%). The films were subjected to traction analysis and its morphology was accessed by field emission scanning electron microscopy (SEM-FEG). The results showed that, in general, chitosan films (69 MPa), just like films based on chitosan-cellulose (75 MPa) presented tensile strength values that are superior or the same as similar films described in literature. Therefore, the study here reported produced promising results and is widely inserted in the current interest of utilization of materials from renewable resources instead of those from fossil resources.

Na atualidade, a geração de eletricidade e a produção de etanol de segunda geração a partir de materiais lignocelulósicos se apresentam como uma alternativa de desenvolvimento tecnológico no setor sucroenergético. Não obstante, a introdução de novos processos produtivos representa um verdadeiro desafio devido à complexidade e diversidade das rotas tecnológicas alternativas que podem ser avaliadas. Além disso, existem fatores econômicos e ambientais, que devem ser considerados durante o desenvolvimento e consolidação destas novas configurações. Nesse sentido, o presente trabalho tem como objetivo desenvolver uma metodologia para realizar a hierarquização exergética e exergo-ambiental de processos para obtenção de etanol e eletricidade a partir da cana-de-açúcar em distintas configurações de biorrefinarias. Para este fim, dados técnicos de operação foram adotados nas rotas tecnológicas envolvidas, bem como os aspectos ambientais da utilização destes sistemas. Os modelos propostos avaliaram as rotas Convencional (Caso 1), Bioquímica (Caso 2) e Termoquímica (Caso 3), utilizando programas de simulação e ferramentas matemáticas para simular estes processos. Ainda, a integração dos processos e diferentes usos para o bagaço excedente foram estudados, junto com diversos métodos de pré-tratamento visando à otimização e hierarquização destas rotas. O resultado final indicou configurações ótimas que permitiram a hierarquização em termos do índice exergético de renovabilidade dos processos de produção das rotas analisadas. Desse modo a rota convencional otimizada apresentou a máxima eficiência exergética dos processos e, por tanto, o menor custo exergético unitário médio das plataformas avaliadas. Ao passo que a rota bioquímica foi o sistema que promoveu um incremento de 28,58 % e 82,87 % na produção de etanol, quando comparado com o Caso 1 e o Caso 3, respectivamente. Além disso, a rota termoquímica apresentou a configuração com a maior taxa de geração de eletricidade excedente (214,98 kWh/TC). Em relação aos resultados do impacto ambiental das rotas tecnológicas, encontrou-se que a configuração mais sustentável foi a plataforma bioquímica, apresentando as menores taxas de emissões globais de CO2 (131,45 gCO2/MJ produtos). / Currently, electricity generation and second-generation bioethanol production from lignocellulosic materials represent technological alternatives in the sugar-energy sector. Nevertheless, the introduction of new production processes represents a real challenge due to the complexity and diversity of the technological routes that can be evaluated. In addition, there are economic and environmental factors that must be considered during the development and consolidation of these new configurations. Accordingly, this project aims to develop a methodology to perform the exergy and exergo-environmental analysis, evaluation and ranking of processes in order to obtain ethanol and electricity from sugarcane in different biorefinery configurations. Hence, operating technical data of each technological route were adopted as well as the environmental aspects of using these systems. The proposed models assessed the Conventional (Case 1), Biochemical (Case 2) and Thermochemical (Case 3) routes using simulation programs and mathematical tools to simulate the ethanol production and electricity generation. Furthermore, the process integration and different uses for the excess bagasse were studied with various pretreatment methods aiming the optimizing and ranking of routes. The results indicated optimal settings that allowed the ranking in terms of the environmental exergy indicator \"renewability\" of the production processes for analyzed routes. In this way, the optimized conventional route presented the maximum exergy efficiency of the processes, therefore the lowest exergetic cost average of the evaluated platforms. While the biochemical route was the system that promoted an increase of 28.58 % and 82.87% in the ethanol production, when compared to Case 1 and Case 3, respectively. In addition, the thermochemical route presented the configuration with the highest power generation rate exceeding (214.98 kWh/TC). Concerning, the environmental impact results, it was found that the most sustainable configuration was the biochemical platform, which presented the lowest overall CO2 emissions rates (131.45 gCO2/MJ products).

Acidez, sulfato e cloreto são constantemente relacionados ao potencial corrosivo do etanol hidratado combustível (EHC), pois mesmo em baixas concentrações podem induzir processos que danificam dutos de transporte e peças dos veículos. Em vista dessa problemática, as agências reguladoras estabeleceram limites máximos para estes constituintes a serem determinados por titulação, no caso da acidez, e por cromatografia de íons para cloreto e sulfato. Os procedimentos propostos no presente trabalho tiveram como objetivo apresentar alternativas de baixo custo, instrumentação simples, pouca influência do analista (automação das etapas) e baixa geração de efluentes. Para a avaliação da acidez, foi construído um titulador automático, explorando um algoritmo de procura binária em um sistema de análises químicas em fluxo baseado em multicomutação. Sob condições otimizadas, o sistema foi capaz de titular amostras de etanol diluídas a 50% (v/v), gerando cerca de 11,5 mL de efluente por determinação, com coeficiente de variação < 1,0% e frequência de análises > 10 h-1. Além disso, o sistema não necessitou de calibração, fazendo com que todas as etapas fossem realizadas automaticamente. Para as determinações de sulfato e de cloreto, foram montados módulos de análises baseados em fluxo-batelada com detecção espectrofotométrica. Os analitos foram determinados sem etapas de preparo de amostra. Para realizar a determinação indireta do sulfato, foi empregada a reação de deslocamento dos íons bário do complexo dimetilsulfonazo III de bário (DMS-Ba+), promovido pelos íons sulfato; para a determinação de cloreto, foi explorado o efeito dos íons cloreto na fotogeração (UV) de nanopartículas de prata (Ag-NPs). Para sulfato e cloreto, as faixas lineares de resposta, limites de detecção (95%) e coeficientes de variação foram: 0,1 - 1,5 mg L-1 e 0,05 - 0,8 mg L-1; 48 e 12 µg L-1 e 1,0% e 2,2%, respectivamente. Na determinação de sulfato e cloreto, as frequências de análises foram de 35 e 30 h-1, respectivamente; com geração de efluentes < 5 mL por determinação em ambos os procedimentos. Todos os procedimentos desenvolvidos atendem aos limites estabelecidos pela agência reguladora brasileira, e os resultados obtidos foram comparados com os procedimentos oficiais, não havendo diferença significativa entre métodos, ao nível de 95% de probabilidade / Acidity, sulfate and chloride are often related to the hydrous ethanol fuel (HEF) corrosive potential, as even at low concentrations they may induce processes deleterious to transportation ducts and vehycle components. Thus, the regulatory agencies established maximum limits for these constituents to be determined by titration in the case of acidity and by chromatography of ions for chloride and sulfate. The procedures herein proposed aimed at to present alternatives of low cost, simple instrumentation, little influence of the analyst (automation of the stages) and low generation of effluents. For acidity evaluation, an automatic titrator exploiting a binary search algorithm in a analytical flow system based on multicommutation was built up. Under optimized conditions, the system was able of titrating ethanol samples diluted to 50% (v/v), generating about 11.5 mL of effluent per determination, with coefficient of variation <1.0% and sample throughput > 10 h-1. Moreover, the flow system did not require calibration, and all steps were automatically performed. For sulfate and chloride determinations, flow-batch analytical systems with spectrophotometric detection were set up, allowing the analytes to be determined without sample preparation steps. For the indirect determination of sulfate, the reaction of displacement of the barium ions from its dimethylsulfonazo III complex (DMS-Ba+) promoted by the sulfate ions was used; for the determination of chloride, the effect of this analyte on the photo-generation (UV) of silver nanoparticles (Ag-NPs) was exploited. For sulfate and chloride, linear response ranges, detection limits (95% confidence level) and coefficients of variation were: 0.1 - 1.5 and 0.05 - 0.8 mg L-1; 48 and 12 ?g L-1, and 1.0 and 2.2%, respectively. In the sulfate and chloride determinations, the analytical frequency were 35 and 30 h-1, respectively, with effluents generation of < 5 mL per determination for both procedures. The developed procedures meet the limits established by the Brazilian regulatory agency, and results obtained were compared with the official procedures, and no significant differences between methods at the 95% probability level were found

La conversion de la biomasse en énergie génère des flux de gaz carbonique qui peuvent être captés,transportés puis stockés dans des strates géologiques. Ce procédé, nommé BCCS (Biomass Carbon Captureand Storage), réduit drastiquement les émissions carbonées et dans certaines conditions le puits artificiel peutstocker plus de carbone que le système de conversion n’en aura produit (émissions négatives). Ainsi, le BCCSrend plus envisageable l’obtention de certains plafonds de concentrations de CO2 atmosphériques inférieurs ouégaux à 450ppm. Des incitations économiques sont nécessaires pour déclencher l’investissement dans leBCCS de la part d’acteurs du secteur privé. Ceux-ci sont confrontés à une incertitude de grande ampleurconcernant le prix du carbone. Nous étudions dans cette thèse le comportement d’un décideur ayant le choixd’investir dans une variante du BCCS, à savoir la production de bioéthanol à partir de betteraves sucrières.Après une analyse déterministe sur un cas réel, nous étudions l’influence de différentes incertitudes sur le profild’investissement via une approche par options réelles. Nous analysons notamment l’influence de l’incertitudedu progrès technique via une loi de Poisson et montrons que l’investisseur tend à attendre l’innovation. Nousdistinguons ensuite progrès de court terme et de long terme. Puis, nous nous intéressons à l’incertitude derégulation climatique. Le marché du carbone est alors modélisé par un mouvement de retour à la moyenneavec des sauts de prix à dates fixes / Using biomass to produce energy emits carbon dioxide. These emissions can be captured, transported andstored into geological formations. This process is named BCCS (Biomass Carbon Capture and Storage). Itleads to massive reductions and the whole system carbon balance system could be negative given specificassumptions, which is called ‘negative emissions’. BCCS may help to achieve low CO2 concentration target,even below the 450ppm threshold. Providing suitable incentives is necessary to trigger private investment.Private investors are facing considerable uncertainty, about the carbon market. We study in this dissertation thebehavior of decision makers who can invest in a specific variant of BCCS, which is the production ofbioethanol coming from sugar beets. After a deterministic analysis based on a real case study, we consider theinfluence of different kinds of uncertainties on the investment profile through a real option approach. Thetechnical progress uncertainty has been modeled with Poisson jumps. We show that investors tend to wait forinnovations. We distinguish two cases depending on the progress rate: early or delayed technical progressrate. First allowance price is driven by geometric Brownian motion. Second, the price follows a mean revertingprocess with jumps at specific fixed dates, to take into account the international round of negotiations aboutclimatic change, as a kind of climate regulation uncertainty.