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Formic and Levulinic Acid from Cellulose via Heterogeneous Catalysis / Myr- och levulinsyra ur cellulosa via heterogen catalysAhlkvist, Johan January 2014 (has links)
The chemical industry of today is under increased pressure to develop novel green materials, bio-fuels as well as sustainable chemicals for the chemical industry. Indeed, the endeavour is to move towards more eco-friendly cost efficient production processes and technologies and chemical transformation of renewables has a central role considering the future sustainable supply of chemicals and energy needed for societies. In the Nordic countries, the importance of pulping and paper industry has been particularly pronounced and the declining European demand on these products as a result of our digitalizing world has forced the industry to look at alternative sources of revenue and profitability. In this thesis, the production of levulinic and formic acid from biomass and macromolecules has been studied. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type were also discussed. Nordic sulphite and sulphate (Kraft) cellulose originating from two Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin, Amberlyst 70, for which the optimal reaction conditions leading to best yields were determined. Cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of ‘green’ levulinic and formic acid. The kinetic experiments were performed in a temperature range of 150–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. It was concluded that the most important parameters in the one-pot hydrolysis of biomass were the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The reaction route includes dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids. The theoretical maximum yield can hardly be obtained due to formation of humins. For this system, maximum yields of 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. The maximum yields were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt % and belong to the upper range for solid catalysts so far presented in the literature. The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here and a one-pot procedure providing a route to green platform chemicals was developed. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed.
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Part I. The syntheses and reactions of methyl 2-methyl-3-oxo-1-cyclopentene-1-carboxylate and ethyl 2-methyl-3-oxocyclopentanecarboxylate ; Part II. A study of the reactions of Grignard readgents with esters of Levulinic acid /McPherson, James Louis January 1953 (has links)
No description available.
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Využití metod termické analýzy při studiu účinku mikrobiálních inhibitorů / Utilization of thermal analysis in the study on effects of microbial inhibitorsBošeľová, Miriam January 2019 (has links)
This diploma thesis deals with the use of thermal analysis in the study on effects of microbial inhibitors. The main aim of this work was to determine the utilization of the method, which is mainly used in different fields of science and research. Three bacterial strains: Cupriavidus necator H16, its mutant strain Cupriavidus necator PHB-4 and Halomonas halophila, were used as model microorganisms. The inhibitory effect of levulinic acid on growth and metabolic activity was monitored by microcalorimetry. It was found that bacteria were able to adapt to levulinic acid to a certain concentration - Cupriavidus necator to 5 g/l and Halomonas halophila to 2 g/l. The thermal analysis results were compared to a conventional method, which is commonly used to study the growth of microorganisms.
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Exploring hydrothermal reactions : from prebiotic synthesis to green chemistryKopetzki, Daniel January 2011 (has links)
In this thesis chemical reactions under hydrothermal conditions were explored, whereby emphasis was put on green chemistry. Water at high temperature and pressure acts as a benign solvent. Motivation to work under hydrothermal conditions was well-founded in the tunability of physicochemical properties with temperature, e.g. of dielectric constant, density or ion product, which often resulted in surprising reactivity. Another cornerstone was the implementation of the principles of green chemistry. Besides the use of water as solvent, this included the employment of a sustainable feedstock and the sensible use of resources by minimizing waste and harmful intermediates and additives.
To evaluate the feasibility of hydrothermal conditions for chemical synthesis, exemplary reactions were performed. These were carried out in a continuous flow reactor, allowing for precise control of reaction conditions and kinetics measurements. In most experiments a temperature of 200 °C in combination with a pressure of 100 bar was chosen. In some cases the temperature was even raised to 300 °C.
Water in this subcritical range can also be found in nature at hydrothermal vents on the ocean floor. On the primitive earth, environments with such conditions were however present in larger numbers. Therefore we tested whether biologically important carbohydrates could be formed at high temperature from the simple, probably prebiotic precursor formaldehyde. Indeed, this formose reaction could be carried out successfully, although the yield was lower compared to the counterpart reaction under ambient conditions. However, striking differences regarding selectivity and necessary catalysts were observed. At moderate temperatures bases and catalytically active cations like Ca2+ are necessary and the main products are hexoses and pentoses, which accumulate due to their higher stability. In contrast, in high-temperature water no catalyst was necessary but a slightly alkaline solution was sufficient. Hexoses were only formed in negligible amounts, whereas pentoses and the shorter carbohydrates accounted for the major fraction. Amongst the pentoses there was some preference for the formation of ribose. Even deoxy sugars could be detected in traces.
The observation that catalysts can be avoided was successfully transferred to another reaction. In a green chemistry approach platform chemicals must be produced from sustainable resources. Carbohydrates can for instance be employed as a basis. They can be transformed to levulinic acid and formic acid, which can both react via a transfer hydrogenation to the green solvent and biofuel gamma-valerolactone. This second reaction usually requires catalysis by Ru or Pd, which are neither sustainable nor low-priced. Under hydrothermal conditions these heavy metals could be avoided and replaced by cheap salts, taking advantage of the temperature dependence of the acid dissociation constant. Simple sulfate was recognized as a temperature switchable base. With this additive high yield could be achieved by simultaneous prevention of waste. In contrast to conventional bases, which create salt upon neutralization, a temperature switchable base becomes neutral again when cooled down and thus can be reused. This adds another sustainable feature to the high atom economy of the presented hydrothermal synthesis.
In a last study complex decomposition pathways of biomass were investigated. Gas chromatography in conjunction with mass spectroscopy has proven to be a powerful tool for the identification of unknowns. It was observed that several acids were formed when carbohydrates were treated with bases at high temperature. This procedure was also applied to digest wood. Afterwards it was possible to fermentate the solution and a good yield of methane was obtained. This has to be regarded in the light of the fact that wood practically cannot be used as a feedstock in a biogas factory. Thus the hydrothermal pretreatment is an efficient means to employ such materials as well. Also the reaction network of the hydrothermal decomposition of glycine was investigated using isotope-labeled compounds as comparison for the unambiguous identification of unknowns. This refined analysis allowed the identification of several new molecules and pathways, not yet described in literature.
In summary several advantages could be taken from synthesis in high-temperature water. Many catalysts, absolutely necessary under ambient conditions, could either be completely avoided or replaced by cheap, sustainable alternatives. In this respect water is not only a green solvent, but helps to prevent waste and preserves resources. / In dieser Arbeit wurden chemische Reaktionen unter Hydrothermalbedingungen untersucht. Darunter versteht man Wasser als Reaktionsmedium, welches eine Temperatur über 100 °C aufweist. Der flüssige Zustand wird dabei durch erhöhten Druck aufrecht erhalten. Typischerweise wurden die Reaktionen bei 200 °C und einem Druck von 100 bar durchgeführt, also dem 100-fachen des Normaldrucks. Dieses System kann man auch mit einem Dampfdrucktopf vergleichen, wobei durch die erhöhten Temperaturen chemische Reaktionen sehr schnell ablaufen und überraschende Reaktivität auftritt. Die Motivation, Wasser als Lösemittel zu benutzen, ist auch in seiner Umweltfreundlichkeit gegenüber klassischen organischen Lösemitteln begründet.
Da solche Hydrothermalbedingungen auf der frühen Erde häufiger anzutreffen waren, wurde untersucht, ob wichtige Biomoleküle bei solch hoher Temperatur gebildet werden können. In der Tat konnten Zucker aus der sehr einfachen Verbindung Formaldehyd synthetisiert werden. Hierzu war lediglich eine leicht basische Lösung nötig und keine der bei moderaten Temperaturen essentiellen Katalysatoren.
Zucker stellen zudem den größten Teil der pflanzlichen Biomasse dar und können daher als Grundlage für eine nachhaltige Chemie dienen. Sie können relativ einfach zu Lävulin- und Ameisensäure umgesetzt werden. Aus diesen wiederum kann die wichtige Basischemikalie gamma-Valerolacton hergestellt werden. Der Schlüsselschritt, die Reduktion von Lävulinsäure, erforderte bisher die Zuhilfenahme seltener Edelmetalle wie Ruthenium. Es konnte nun gezeigt werden, dass unter Hydrothermalbedingungen diese Rolle von einfachen Salzen, z. B. Natriumsulfat, übernommen werden kann. Hierbei macht man sich zunutze, dass sie nur bei hoher Temperatur basisch wirken, nicht aber wenn die Lösung wieder abgekühlt ist.
Neben Kohlenhydraten besteht Biomasse auch aus Aminosäuren, von denen Glycin die einfachste darstellt. Unter Abspaltung von CO2 können aus ihnen synthetisch wichtige Amine hergestellt werden. Diese Reaktion findet unter Hydrothermalbedingungen statt, daneben treten jedoch noch andere Produkte auf. Unbekannte Verbindungen wurden mittels Massenspektroskopie identifiziert, wobei die Masse des Moleküls und bestimmter Molekülfragmente bestimmt wurde. Dies erlaubte es, bisher noch unbekannte Reaktionswege aufzuklären.
Zusammenfassend lässt sich sagen, dass Wasser unter Hydrothermalbedingungen eine interessante Alternative zu organischen Lösemitteln darstellt. Desweiteren können bestimmte Katalysatoren, die bei moderaten Temperaturen nötig sind, entweder vollständig eingespart oder ersetzt werden. In dieser Hinsicht ist Wasser nicht nur ein umweltfreundliches Lösemittel, sondern trägt dazu bei, Abfall zu vermeiden und Ressourcen zu schonen.
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HOMOGENEOUS TRIDENTATE RUTHENIUM BASED HYDROGENATION CATALYSTS FOR THE DEOXYGENATION OF BIOMASS DERIVED SUBSTRATES IN AQUEOUS ACIDIC MEDIAOswin, Chris 30 August 2013 (has links)
Project I: [Ru(OH2)3(4'-phenyl-2,2':6',2''-terpyridine)](OTf)2 as a Homogeneous Hydrogenation Catalyst for Biomass Derived Substrates.
The complex [Ru(OH2)3(4'-phenyl-2,2':6',2''-terpyridine)](OTf)2 has been shown to be an active ionic hydrogenation catalyst for selected carbonyls, diols and glycerol by the Schlaf group. It was postulated to also be active for other biomass derived substrates such as levulinic acid (LA), furfural and 5-hydroxymethyl furfural (HMF). Synthesis of the complex was optimized and full characterization carried out by 1H/13C –NMR. The complex was tested against LA in aqueous sulfolane medium and the furfural/HMF model system 2,5-hexanedione in water. Activity of the complex was compared to the analogous metal-ligand bifunctional (MLB) system described in
Project II. The complex exhibited good thermal stability up to 200 oC in 90/10 wt%
sulfolane/water mixtures and was capable of hydrogenation of LA to γ-valerolactone in 95% yield. Addition of protic acids to the reaction mixture and increasing proportions of water decreased the activity of the complex towards the hydrogenation of LA.
Project II: [Ru(OH2)3(di(picolyl)amine)](OTf)2 as an acid-, water- stable, metal-ligand bifunctional deoxygenation catalyst.
The complex [Ru(OH2)3(di(picolyl)amine)](OTf)2 was postulated to be an active MLB ionic hydrogenation catalyst under acidic aqueous conditions. Using the substantially labile [Ru(DMF)6](OTF)3 ruthenium complex as the precursor, the desired complex was prepared insitu by coordination of the DPA ligand and concomitant reduction of Ru3+ to Ru2+. The complex was characterized by 1H/13C-NMR and tested for the hydrogenation of LA, 2,5-hexanedione, furfural and HMF under acidic aqueous conditions. The complex exhibited thermal stability up to 150 oC and was active for the hydrogenation of carbonyls, as demonstrated by the conversion of 2,5-hexanedione to 2,5-hexanediol in 94% yield in water. Addition of H3PO4 as an acid cocatalyst resulted in nearly complete conversion to dimethyltetrahydrofuran (DMTHF) but further deoxygenation could not be achieved. Direct comparision of [Ru(OH2)3(di(picolyl)amine)](OTf)2 and [Ru(OH2)3(4'-phenyl-2,2':6',2''-terpyridine)](OTf)2 under identical conditions against LA and 2,5-hexanedione demonstrated that the[Ru(OH2)3(di(picolyl)amine)](OTf)2 catalyst is more active than the [Ru(OH2)3(4'-phenyl-2,2':6',2''-terpyridine)](OTf)2 complex in all cases, suggesting that the di(picolyl)amine complex operates through a MLB ionic hydrogenation mechanism. / NSERC
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Development and characterization of noble metal integrated polymeric membrane reactors for three-phase hydrogenation reactionsStanford, John Paul January 1900 (has links)
Doctor of Philosophy / Department of Chemical Engineering / Mary E. Rezac / Catalytic membrane reactors are a class of reactors that utilize a membrane to selectively deliver reactants to catalysts integrated in the membrane. The focus of this research has been on developing and characterizing polymeric catalytic membranes for three-phase hydrogenation reactions, where the membrane functions as a gas/liquid phase contactor allowing selective delivery of hydrogen through the membrane to reach catalytic sites located on the liquid side of the membrane. The benefit of conducting three-phase reactions in this manner is that delivering hydrogen through the membrane to reach catalytic sites avoids the necessity of hydrogen dissolution and diffusion in the liquid phase, which are both inherently low and often described as causing mass-transfer and reaction rate limitations for the reactive system.
This work examines two types of membrane reactor systems, porous polytetrafluoroethylene and asymmetric Matrimid membranes, respectively, for the ruthenium catalyzed aqueous phase hydrogenation of levulinic acid. The highly hydrophobic PTFE material provides an almost impermeable barrier to the liquid phase while allowing hydrogen gas to freely transport through the pores to reach catalytic sites located at the liquid/membrane interface. Catalytic rates as a function of hydrogen pressure over the range 0.07 to 5.6 bar are presented and shown to be higher than those of a packed bed reactor under similar reaction conditions. An increasing catalytic benefit was obtained operating at temperatures up to 90 °C, which is attributed to increased hydrogen permeability and avoidance of the decreasing solubility of hydrogen in water with increasing temperature. The membrane reactor was shown to be stable with no decrease in catalytic activity over 200 hours of operation. The Matrimid membrane reactor work demonstrates the feasibility of applying an integrally-skinned asymmetric membrane for an aqueous phase hydrogenation reaction and focuses on the impact that membrane hydrogen permeance and catalyst loading have on catalytic activity. The non-porous nature of the separating layer in the Matrimid membrane allowed successful operation up to 150 °C. The overall catalytic rates were approximately an order of magnitude lower than those achieved in the PTFE membrane reactor system due primarily to significantly lower hydrogen permeances, nevertheless rates were still higher than control experiments.
This work also focuses on characterizing Matrimid/solvent thermodynamic relationships for a variety of organic solvents, looking at sorption, diffusion, and polymer relaxation behavior in thin films ranging from 0.1 to 2.0 µm in thickness using quartz crystal microbalance techniques. Diffusion coefficients at infinite dilution for water and C1-C6 alcohols are given as a function of van der Waals molar volume and a clear dependency is shown ranging from 2E-11 to 6.5E-13 cm²/s for water and hexanol, respectively, for 0.26 µm thick films. Diffusion coefficients for all studied vapor penetrants displayed a marked dependence on thickness spanning approximately two orders of magnitude for each respective vapor penetrant over the range 0.1 to 1.0 µm. Chemically cross-linking Matrimid is a method to mitigate some of the relatively high sorption and swelling behavior exhibited in the presence of sorbing species. An in-depth analysis on the vapor phase ethylenediamine cross-linking of Matrimid films and its impact on diffusion, sorption, and relaxation is also described.
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Produção de ácido levulínico por meio de hidrólise ácida da casca de arroz / Acids production by means of acid hydrolysis of rice huskBevilaqua, Daiane Balconi 08 February 2010 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The beginning of the 21st century has been characterized by a great interest about the use of renewable raw materials for the production of industrial feedstocks and technological products. This trend is followed by the concern about the huge amount of waste generated by the always increasing agricultural production. In this sense, the reuse of the residual rice husks (RH) of the rice production, which by inadequate management affects negatively the environment in several ways, can constitute an environmental solution and a source of income. In this work, it was used RH as a source of cellulose for the production of levulinic acid (AL), a versatile chemical
intermediate with many industrial applications, produced usually via chemical synthesis. The cellulose hydrolysis in acidic medium releases glucose monomers, which by heating under pressure dehydrate and form the intermediary 5-hydroxymethyl-2-furfural (5-HMF) - that, in turn, degraded generating AL. For the AL production, a 1.00 g of RH previously comminuted, selected, washed and dried in an oven, was hydrolyzed with 10.0 mL of HCl 4.5% (v/v) or 4%
H2SO4 (v/v) in a batch reactor under pressure (51 to 62 atm). The concentration of AL, as well as of 5-HMF, present in the acidic hydrolysate, were analyzed by HPLC-UV. The solid residue of the hydrolysis was characterized by SEM and FTIR. In order to evaluate the effect of the variables temperature, pressure and hydrolysis time
on the yield of the process of AL production, two factorial designs were performed: one, for the process using HCl, and another for the process using H2SO4, keeping constant the mass of RH and the used acid volume. After optimization of the time, pressure and temperature of hydrolysis, it was studied the effects of the acid concentration and of the RH pre-treatment on the production
of AL. It was investigated, therefore, the pre-treatment with hydrogen peroxide, sodium hypochlorite, oxalic acid, Soxhlet extraction in aqueous medium and Soxhlet extraction with a mixture of benzene-ethanol 1:1 (v/v).
It was verified that the AL production is maximum when the hydrolytic process was carried out at temperatures 160 °C, under pressure of 53 atm and reaction time of 70 min. The
best catalyst for the process was hydrochloric acid at a concentration of 4.5% (v/v). Among the pre-treatments applied to the RH, the Soxhlet aqueous extraction provided the best yield of AL (59.4%, w/w). / O início do século 21 tem se caracterizado por um grande interesse na utilização de matérias-primas renováveis para a produção de insumos e produtos tecnológicos. A esta
tendência soma-se à preocupação com a enorme quantidade de resíduos gerada pela sempre crescente produção agrícola. Neste sentido, o aproveitamento das cascas residuais da produção de arroz (CA) - cuja disposição inadequada leva a prejuízos ao meio ambiente, de várias maneiras pode constituir uma solução ambiental e possível fonte adicional de renda. Neste trabalho utilizou-se a CA como fonte de celulose para o processo de produção de ácido levulínico (AL),
intermediário químico muito versátil, com diversas aplicações industriais, produzido, em geral, via síntese química.
A hidrólise da celulose em meio ácido leva à liberação de monômeros de glicose, que, por aquecimento à pressão, se desidrata e forma o intermediário 5-hidroximetil-2-furfural (5-HMF) que, por sua vez, se degrada gerando o AL. Para o processo de produção do AL, uma fração de 1,00 g de CA, previamente cominuída, selecionada, lavada e seca em estufa, foi hidrolisada com 10,0 mL de HCl 4,5% (v/v) ou de
H2SO4 4% (v/v), em batelada, em reator à pressão (51 a 62 atm). A concentração de AL, bem como de 5-HMF, presente no hidrolisado ácido, foram analisadas por HPLC-UV. Já, o resíduo sólido da hidrólise foi caracterizado por meio de MEV e FTIR. Os efeitos da temperatura, pressão e tempo de hidrólise no processo de produção de AL foram avaliados através de planejamento fatorial utilizou-se metodologia de superfície resposta. Foram feitos dois planejamentos: um para o processo com HCl e outro para o processo com H2SO4, mantendo-se constantes a massa da CA e o volume de ácido utilizado. Após otimização do tempo, da pressão e da temperatura reacional, foram estudados os efeitos da concentração de ácido e do pré-tratamento inicial da CA na produção de AL. Foram investigados, assim, os prétratamentos
com peróxido de hidrogênio, clorito de sódio, ácido oxálico, extração por soxhlet em meio aquoso e extração por soxhlet com mistura benzeno-etanol 1:1 (v/v). Verificou-se que a produção de AL é máxima quando o processo hidrolítico foi realizado em temperatura de 160 °C, sob pressão de 53 atm e tempo reacional de 70 min. O melhor catalisador para o processo foi o ácido clorídrico, na concentração de 4,5% (v/v). Entre os prétratamentos aplicados à biomassa, a extração aquosa da CA, em soxhlet, levou ao melhor
rendimento em AL (59,4%, m/m).
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Glucose Levulinates as Bio-plasticizers / Glukos levulinater som biobaserade mjukningsmedelXuan, Wenxiang January 2017 (has links)
Glucose, as the most plentiful sugar in nature, is a renewable resource and possesses excellent record in health safety. Levulinic acid is a platform chemical which plays an important role in biomass transformation and reactive intermediates. Both glucose and levulinic acid can be produced by biomass conversion with green processing techno logies. Due to the rising needs for bio-based, eco-friendly and non-toxic plasticizers, glucose levulinates as bio plasticizers were synthesized from glucose and levulinic acid, by utilizing microwave radiation or conventional condensation reaction (direct-heating method ). Acid number for the reaction liquor was measured by acid-base titration to follow the decrease of acid groups due to the reaction and the trend in the acid number within reaction time displayed the process of esterification and possible sensitivity of the reaction rate to reaction scale. It showed that microwave radiation had superior ability in enhancing reaction speed but it was also more sensitive to reaction scale and generated more diverse prod ucts than the direct-heating method. Besides, the process of reaction and formation of ester bonds was followed and confirmed by FT IR. The achieved levulinate products were extracted by 2-pro panol and ethyl acetate. The practices showed several serio us problems in 2-propanol extraction, including high dosage required for NaCl and solvent and difficulties in purification. The ethyl acetate proved to be a suitable solvent for this study and the extrac ted product s from the Con-24hrs and Micro-3/4/5/6/7hrs were characterized by 1H NMR, 13C N :tvlR. and LDI-MS. The results from spectrum suggested the presence of GL,. and G J .'l. type of levulinates. That means the glucose levulinates were successfully synthesized although the dehydration side reaction of glucose was inevitable leading to the generation of glucosidic bonds. In addition, BG (mixture of glucose and glycosidic levulinates) was evaluated by so lution casting of starch and PVC. In order to minimize the microbial contaminations in solution casting of starch, a modified method was raised and applied. The results showed that 40% BG had goo d miscibility with starch and the conclusion was further proved by DSC measurements, while the BG performed poor miscibility with PVC.
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Metabolism of Levulinate and Conversion to the Drug of Abuse 4-HydroxypentanoateHarris, Stephanie R. 19 October 2011 (has links)
No description available.
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Uso de sólidos ácidos na conversão catalítica do ácido levulínicoOliveira, Gilmar de January 2015 (has links)
Orientador: Prof. Dr. Wagner Alves Carvalho / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Ciência e Tecnologia/Química, 2015. / O aumento da demanda energética e depreciação das reservas de combustíveis fósseis implicam na adoção de metodologias que estimulem a utilização de fontes alternativas na produção de combustíveis. A biomassa possui considerável importância neste cenário, sendo uma promissora fonte de energia renovável quando convertida a combustíveis e produtos químicos de importância industrial. Reações de desidratação e hidrogenação ocorrem em meio ácido, podendo ser catalisadas por sólidos ácidos.
O objetivo deste trabalho foi avaliar a atividade de catalisadores mono- e bimetálicos, contendo Sn e Ru suportados em carvão, assim como o impacto do aumento da acidez do meio utilizando sólidos sulfonados como co-catalisadores. As condições foram otimizadas para a reação com um catalisador comercial 5 % de Ru em carvão.
Neste trabalho foram testados nióbia (CBMM ¿ HY-340), argila pilarizada (Fluka) e carvão (Darco) sulfonado na conversão do ácido levulínico. Com o intuíto de otimizar a reação de hidrogenação avaliou-se o uso de carvão variando-se a relação metálica Sn/Ru. Os sólidos foram tratados com ácido sulfúrico fumegante concentrado, os carvões contendo metal sofreram impregnação sucessiva e impregnação simultânea. A presença de grupos sulfônicos e o aumento da acidez dos sólidos demonstram a adequação do processo de sulfonação. O melhor catalisador para reação de hidrogenação do ácido levulínico foi o carvão Darco contendo Sn-Ru 1:0,5, associado ao co-catalisador carvão sulfonado, apresentando conversão de 75% após duas horas de reação e 98% de seletividade para GVL, à 100 °C e pressão de 30 bar de hidrogênio. / Increasing energy demand and depreciation of the fossil fuels reserves implicate in the adoption of methodologies that stimulate the use of alternative sources in the production of fuels. Biomass has considerable importance in this scenario, being a promising source of renewable energy when converted to fuels and chemical products of industrial importance. Dehydration and hydrogenation reactions take place in acid medium, and may be catalyzed by acid solids.
The objective of this work was to evaluate the activity of monometallic and bimetallic catalysts, containing Sn and Ru supported on carbon, as well as the impact of the increase of the acidity in the reaction system using sulfonated solids as co-catalysts. Reaction conditions were optimized with a commercial catalyst, 5% of Ru supported on carbon.
In this work niobia (CBMM. HY -340), pillared clay (Fluka) and sulfonated carbon (Darco) were tested in the conversion of the levulinic acid. With the aim of optimizing the hydrogenation reaction the use of carbon was evaluated by varying the Sn/Ru metallic relationship. The solids were treated with concentrated fuming sulfuric acid, while the carbon containing both Sn and Ru was submitted to successive and simultaneous impregnation processes. The presence of sulfonic acid groups and the increase of the acidity of the solids demonstrate the viability of the sulfonation process. The best catalyst for reaction of levulinic acid hydrogenation was Darco carbon containing Sn-Ru 1:0,5, associated to the sulfonated carbon as co-catalyst, presenting conversion of 75% after 2 h reaction time and 98% of selectivity for GVL, under 100 °C and hydrogen pressure of 30 bar.
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