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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Otimização da produção de hidrogênio e ácidos orgânicos em reator em batelada a partir de consórcio de bactérias autóctones e alóctones do bagaço de cana-de-açúcar / Optimization of hydrogen and organic acids productions with autochthonous and allochthonous bacteria from sugarcane bagasse in batch reactors

Rabelo, Camila Abreu Borges da Silva 09 February 2018 (has links)
Nessa pesquisa avaliou-se a produção fermentativa de hidrogênio e ácidos orgânicos a partir do bagaço de cana-de-açúcar (BCA) usado como substrato em reatores em batelada. Três condições de pré-tratamento (hidrotérmico, autoclave e hidrotérmico mais autoclave) do BCA e condição in natura foram avaliadas a fim de favorecer a produção de hidrogênio. Verificou-se produção molar de hidrogênio de 3,79 mmol/L, 3,47 mmol/L, 1,67 mmol/L e 1,01 mmol/L para BCA autoclavado, BCA in natura, BCA pré-tratado em sistema hidrotérmico e BCA pré-tratado em sistema hidrotérmico seguido de autoclave, respectivamente. A partir desses valores, optou-se por usar o BCA autoclavado como substrato para otimização da produção de hidrogênio e ácidos orgânicos a partir de metodologias de delineamento do composto central e superfície de resposta. Foram monitorados 10 reatores em batelada (R1 a R10), em triplicatas, com diferentes concentrações de substrato (0,8 a 9,2 g/L) e pH (de 4,6 a 7,4). A maior produção de hidrogênio (24,1 mmol/L) e 6,4 g/L de ácidos orgânicos foram obtidos em R4 (8,0 g BCA/L e pH 7,0). Os açúcares glicose, arabinose, xilose, manose e galactose foram observados ao longo do tempo de operação em todos os reatores, sendo arabinose observado em maior concentração nas condições dos reatores R3 (8,0 g BCA/L e pH 5,0) e R8 (5,0 g BCA/L e pH 7,4), respectivamente, 1.415,3 e 1.372,5 mg/L. A produção de hidrogênio foi concomitante à formação de ácidos orgânicos, principalmente butírico (de 14,6 a 33,8% em R1 e R6, respectivamente) e succínico (de 19,5 a 26,4% em R3 e R9, respectivamente). Os dois fatores analisados, concentração de substrato e pH, exerceram efeitos significativos na produção de hidrogênio, ácido butírico e succínico. A partir dos resultados obtidos com o planejamento fatorial, foi possível verificar que o valor máximo de produção de hidrogênio estimado pelo modelo foi de 23,10 mmol/L, para 7,0 g BCA/L e pH 7,2. O valor obtido no experimento de otimização (Rotm) foi de 19,84 mmol/L, com grau de precisão do modelo de 85,9% para produção de hidrogênio a partir de BCA autoclavado. Sequenciamento massivo via plataforma Illumina (Miseq) foi realizado para a identificação de bactérias do reator do ponto central, (R9, 5,0 g BCA/L e pH 6,0), do reator otimizado (Rotm, 7,0 g BCA/L e pH 7,2), de amostras do BCA autoclavado e inóculo. No inóculo foram identificadas principalmente bactérias semelhantes a Clostridium bifermentans (62,69% de abundância relativa), Bacillus coagulans (31,67%) e Enterobacter aerogenes (2,72%). No BCA foram identificadas bactérias semelhantes a C. bifermentans (31,91%), C. cellobioparum (32,29%), C. cellulolyticum (5,69%), C. sartagoforme (14,63%) e Paenibacillus spp. (11,67%). Estas bactérias não foram favorecidas sob as condições impostas em R9 (5,0 g BCA/L e pH 6,0) e Rotm (7,0 g BCA/L e pH 7,2), uma vez que a abundância relativa das bactérias nas amostras dos reatores foram completamente diferentes. Em R9, bactérias semelhantes a Lactobacillus paracasei e Escherichia hermannii foram as principais identificas com 37,50 e 34,32% de abundância relativa, respectivamente. Em Rotm, as principais bactérias identificadas foram semelhantes a Bacteroides sp. e Enterobacter aerogenes, com 37,35 e 27,72% de abundância relativa, respectivamente. Assim, as populações bacterianas, bem como a produção de metabólitos, foram alteradas em função das condições impostas; ou seja, concentração de BCA, pH em reatores em batelada com BCA autoclavado como substrato. / This study evaluated the hydrogen and organic acids fermentative productions from sugarcane bagasse (SCB) as substrate in batch reactors. Three pre-treatment conditions (hydrothermal, autoclave and hydrothermal plus autoclave) of BCA and the in natura condition were evaluated in order to favor the hydrogen production. Hydrogen molar productions of 3.79 mmol/L, 3.47 mmol/L, 1.67 mmol/L and 1.01 mmol/L was found for SCB pretreated in autoclave, BCA in natura, SCB pretreated in hydrothermal system and SCB pretreated in hydrothermal system followed by autoclaving, respectively. From these values, it was decided to use autoclaved BCA as a substrate for optimization of hydrogen and organic acids productions from the design methodologies of the central compound and response surface. Ten batch reactors (R1 to R10) were monitored in triplicates with different substrate concentrations (0.8 to 9.2 g/L) and pH (4.6 to 7.4). The highest production of hydrogen (24.06 mmol/L) and 6.42 g/L of organic acids were obtained in R4 (8.0 g BCA/L and pH 7.0). Glucose, arabinose, xylose, mannose and galactose were produced and consumed throughout the operating time of all reactors, and arabinose was observed at higher concentration, 1,415.26 and 1,372.45 mg/L in R3 (8.0 g BCA/L and pH 5.0) and R8 (5.0 g BCA/L and pH 7.4), respectively. The production of hydrogen was concomitant to the formation of organic acids, mainly butyric (from 14.6 to 33.8% in R1 and R6, respectively) and succinic (from 19.5 to 26.4% in R3 and R9, respectively). The two factors analyzed, substrate concentration and pH, had significant effects on the production of hydrogen, butyric acid and succinic acid. From the results obtained with the factorial design, it was possible to verify that the maximum value of hydrogen production estimated by the model was 23.10 mmol/L, to 7.0 g BCA L and pH 7.2. The value obtained in the optimization experiment (Rotm) was 19.84 mmol/L, with an accuracy of 85.9% for hydrogen production from autoclaved BCA. Sequencing by the Illumina platform (Miseq) was performed for the identification of bacteria from the central point reactor (R9, 5.0 g BCA/L and pH 6.0), optimized reactor (Rotm, 7.0 g BCA/L and pH 7.2), autoclaved BCA and inoculum samples. In the inoculum were identified mainly bacteria similar to Clostridium bifermentans (62,69% of relative abundance), Bacillus coagulans (31,67%) and Enterobacter aerogenes (2,72%). Bacteria similar to C. bifermentans (31.91%), C. cellobioparum (32.29%), C. cellulolyticum (5.69%), C. sartagoforme (14.63%) and Paenibacillus spp. (11.67%). These bacteria were not favored under the conditions imposed on R9 (5.0 g BCA/L and pH 6.0) and Rotm (7.0 g BCA/L and pH 7.2), since the relative abundance of the bacteria in the reactor samples were completely different. In R9, bacteria similar to Lactobacillus paracasei and Escherichia hermannii were the main identified with 37.50 and 34.32% of relative abundance, respectively. In Rotm, the main bacteria identified were similar to Bacteroides sp. and Enterobacter aerogenes, with 37.35 and 27.72% relative abundance, respectively. Thus, bacterial populations, as well as the production of metabolites, were altered as a function of the imposed conditions; ie, BCA concentration, pH in batch reactors with autoclaved BCA as substrate.
32

Synthesis And Electrochromic Properties Of Conducting Polymers Of Succinic Acid Bis-(2-thiophen-3-yl-ethyl)ester And Their Use In Electrochromic Devices

Sacan, Lale 01 June 2006 (has links) (PDF)
ABSTRACT SYNTHESIS AND ELECTROCHROMIC PROPERTIES OF CONDUCTING POLYMERS OF SUCCINIC ACID BIS-(2-THIOPHEN-3-YL-ETHYL) ESTER AND THEIR USE IN ELECTROCHROMIC DEVICES Sa&ccedil / an, Lale M.Sc., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare June 2006, 59 pages A new monomer / succinic acid bis-(2-thiophen-3-yl-ethyl)ester (SATE) was synthesized through the esterification reaction of 2-thiophen-3-yl-ethanol and succinyl chloride. The chemical structure of monomer was characterized via Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Electrochemical behaviors of SATE alone and SATE in the presence of thiophene were studied by cyclic voltammetry (CV). The synthesis of homopolymer and copolymer were achieved via constant potential electrolysis. Both homopolymer (PSATE) and copolymer [P(SATE-co-Th)] were characterized by various techniques including cyclic voltammetry, FTIR, Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravimetry Analysis (TGA) and UV-VIS Spectrophotometer. Conductivities of samples were measured by four probe technique. The electrochromic properties of the polymers were investigated via spectroelectrochemistry, colorimetry and switching studies. In addition, dual type electrochromic devices (ECDs) composed of PSATE, P(SATE-co-Th) and poly(3,4-ethylenedioxythiophene) (PEDOT) were constructed and evaluated. Spectroelectrochemistry, switching ability and stability of the devices were investigated by UV-Vis Spectrophotometer and Cyclic Voltammetry. They have shown to possess good switching times, reasonable contrasts, high stabilities and optical memories.
33

Valorisation catalytique d’un acide carboxylique issu de l’industrie sucrière / Catalytic valorization of a carboxylic acid derived from sugarcane industry

Hneine, Waël 21 June 2016 (has links)
Ces travaux de thèse ont porté sur la conversion catalytique de l'acide aconitique (un co-produit de la filière canne à sucre) en molécules d'intérêt industriel. Par deux voies catalytiques. 1) Par catalyse homogène, hydrogénation de l'acide en polyols, a été étudiée dans un réacteur Batch à l'aide d'un complexe catalytique actif à base de Ru [Ru(acac)3/Triphos]. L'optimisation des différents paramètres réactionnels a été effectuée sur une réaction modèle, l'hydrogénation de l'acide succinique en 1,4-butanediol. Ultérieurement, ces conditions réactionnelles optimales ont été utilisées pour l'hydrogénation de l'acide aconitique et ont permis l'obtention d'un produit majoritaire, le 2-méthyl 1,4-butanediol. 2) Par catalyse hétérogène, la réaction d'hydro-cyclisation de l'acide aconitique en MTHF ou en lactones, a été réalisée en réacteur continue en présence de catalyseurs à base de cuivre en partant de solutions d'acide aconitique dans l'éthanol. Les conditions de test catalytiques et la synthèse du catalyseur ont été optimisées. Les caractéristiques des différents catalyseurs testés ont été réalisées en faisant recours à des techniques analytiques complémentaires (SBET, Analyse chimique, DRX, XPS et MET) afin de corréler les propriétés de surface à l'activité catalytique / This thesis is focused on the catalytic conversion of aconitic acid (a co-product of sugarcane industry) into molecules of industrial interest, by two catalytic ways. 1) By homogeneous catalysis, the acid hydrogenation into polyols, was carried out in a batch reactor using a Ru complex [Ru(acac)3/Triphos]. The various reaction parameters was optimized in the model reaction of hydrogenation of succinic acid into 1.4-butanediol. Subsequently, these optimal reaction conditions were used for the hydrogenation of aconitic acid and resulted to a predominant formation of 2-methyl 1,4-butanediol. 2) By heterogeneous catalysis, the hydro-cyclization reaction of aconitic acid into MTHF or lactones, was performed in a continuous reactor in the presence of copper catalysts, using aconitic acid solutions in ethanol as substrate. The different conditions of the catalytic test and catalyst synthesis was optimized. Furthermore, the different catalysts tested in this thesis work was characterized using complementary techniques (BET, Elementary analysis, XRD, XPS and TEM) in order to correlate the superficial properties to the catalytic activity
34

Estudo da degradação de reagentes liofilizados para radiodiagnóstico por cromatografia líquida de alta eficiência (HPLC) e espectrometria de massas (MS) / Study of degradation of lyophilized reagents for radiodiagnosis by high performance liquid chromatography (HPLC) and mass spectrometry (MS)

ALMEIDA, ERIKA V. de 22 October 2015 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-10-22T16:54:02Z No. of bitstreams: 0 / Made available in DSpace on 2015-10-22T16:54:02Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
35

Estudo da degradação de reagentes liofilizados para radiodiagnóstico por cromatografia líquida de alta eficiência (HPLC) e espectrometria de massas (MS) / Study of degradation of lyophilized reagents for radiodiagnosis by high performance liquid chromatography (HPLC) and mass spectrometry (MS)

ALMEIDA, ERIKA V. de 22 October 2015 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-10-22T16:54:02Z No. of bitstreams: 0 / Made available in DSpace on 2015-10-22T16:54:02Z (GMT). No. of bitstreams: 0 / A utilização de radiofármacos no diagnóstico de doenças do organismo humano tem aumentado de forma significativa nas últimas décadas. O crescente desenvolvimento de novos reagentes liofilizados (RL) para a preparação de radiofármacos, embora proporcionem uma maior variedade para o mercado de radiofármacos, deixa evidente uma das lacunas na pesquisa radiofarmacêutica: a identificação de produtos de degradação. No presente trabalho, foram identificados os principais produtos de degradação dos RL de ácido 2,3-Dimercaptosuccínico (DMSA) e Etilenodicisteína Dietil Éster (ECD) utilizando as técnicas de cromatografia líquida de alta eficiência com Detecção por Arranjo de Diodos (HPLC-DAD) e cromatografia líquida acoplada à espectrometria de massas de múltiplos estágios (LC-MSn). Realizou-se o estudo de degradação forçada do RL de DMSA e do RL de ECD nas condições de estresse hidrolítico, fotolítico, oxidativo e termodegradação. As análises foram realizadas em equipamento HPLC-DAD Shimadzu e espectrômetro de massas Bruker Daltonics. Todas as análises foram desenvolvidas utilizando coluna cromatográfica Shim-Pack VP-ODS (150 mm x 4,6 mm; 5 μm). O DMSA apresentou tempo de retenção de 5,58 minutos e m/z 204,8. A hidrólise ácida do DMSA não apresentou produtos de degradação. O perfil de degradação do DMSA após hidrólise alcalina apresentou três picos cromatográficos com características mais apolares que o DMSA. No espectro de fragmentação do íon de m/z 204,8 (MS2) pode-se observar a presença do fragmento de m/z 172,9, correspondente ao aduto sodiado de ácido mercaptosuccínico (MSA); e o fragmento de m/z 139,0 (MS3), correspondente ao aduto sodiado do ácido fumárico. O íon estanho (Sn) apresentou-se coordenado ao DMSA em todos os produtos de degradação após hidrólise alcalina do RL de DMSA. As amostras submetidas à hidrólise neutra não apresentaram degradação. Nos estudos de fotólise do DMSA, o íon de m/z 267,1 pode ser identificado como o ácido diacetil dimercaptosuccínico (BATSA). O íon de m/z 127,1 foi associado ao ácido hidroximetil fosfônico e observado nos estudos de oxidação. A termodegradação do DMSA e do RL de DMSA, não apresentou uma relação de decaimento da concentração do DMSA em função do tempo. Quanto ao RL de ECD, foi observado o ECD protonado em 5,55 minutos (m/z 325,6). As análises por LC-MSn do ECD sob hidrólise alcalina mostraram que o pico com tempo de retenção de 1,71 minutos foi identificado como o íon protonado do EC ([M+H]+) em m/z 269,2. Os picos com tempo de retenção de 3,34 e 3,69 minutos foram identificados como o íon protonado do ECD na forma monoéster (ECDM). A degradação alcalina do RL de ECD apresentou os íons de m/z 441,9 (ECD-Sn) e m/z 737,9 ([ECD2+Sn]-C2H2-2H). ECD monoester monoácida (ECDM) de m/z 295,2; ECD oxidado de m/z 323,5; ECD oxidado com duas pontes dissulfeto de m/z 389,1 e dímero de ECD de m/z 645,9 foram observados da degradação oxidativa. Conclui-se que as análises por HPLC-DAD e LC-MSn podem ser utilizadas no estudo de estabilidade de RL, identificando suas impurezas e produtos de degradação. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
36

Otimização da produção de hidrogênio e ácidos orgânicos em reator em batelada a partir de consórcio de bactérias autóctones e alóctones do bagaço de cana-de-açúcar / Optimization of hydrogen and organic acids productions with autochthonous and allochthonous bacteria from sugarcane bagasse in batch reactors

Camila Abreu Borges da Silva Rabelo 09 February 2018 (has links)
Nessa pesquisa avaliou-se a produção fermentativa de hidrogênio e ácidos orgânicos a partir do bagaço de cana-de-açúcar (BCA) usado como substrato em reatores em batelada. Três condições de pré-tratamento (hidrotérmico, autoclave e hidrotérmico mais autoclave) do BCA e condição in natura foram avaliadas a fim de favorecer a produção de hidrogênio. Verificou-se produção molar de hidrogênio de 3,79 mmol/L, 3,47 mmol/L, 1,67 mmol/L e 1,01 mmol/L para BCA autoclavado, BCA in natura, BCA pré-tratado em sistema hidrotérmico e BCA pré-tratado em sistema hidrotérmico seguido de autoclave, respectivamente. A partir desses valores, optou-se por usar o BCA autoclavado como substrato para otimização da produção de hidrogênio e ácidos orgânicos a partir de metodologias de delineamento do composto central e superfície de resposta. Foram monitorados 10 reatores em batelada (R1 a R10), em triplicatas, com diferentes concentrações de substrato (0,8 a 9,2 g/L) e pH (de 4,6 a 7,4). A maior produção de hidrogênio (24,1 mmol/L) e 6,4 g/L de ácidos orgânicos foram obtidos em R4 (8,0 g BCA/L e pH 7,0). Os açúcares glicose, arabinose, xilose, manose e galactose foram observados ao longo do tempo de operação em todos os reatores, sendo arabinose observado em maior concentração nas condições dos reatores R3 (8,0 g BCA/L e pH 5,0) e R8 (5,0 g BCA/L e pH 7,4), respectivamente, 1.415,3 e 1.372,5 mg/L. A produção de hidrogênio foi concomitante à formação de ácidos orgânicos, principalmente butírico (de 14,6 a 33,8% em R1 e R6, respectivamente) e succínico (de 19,5 a 26,4% em R3 e R9, respectivamente). Os dois fatores analisados, concentração de substrato e pH, exerceram efeitos significativos na produção de hidrogênio, ácido butírico e succínico. A partir dos resultados obtidos com o planejamento fatorial, foi possível verificar que o valor máximo de produção de hidrogênio estimado pelo modelo foi de 23,10 mmol/L, para 7,0 g BCA/L e pH 7,2. O valor obtido no experimento de otimização (Rotm) foi de 19,84 mmol/L, com grau de precisão do modelo de 85,9% para produção de hidrogênio a partir de BCA autoclavado. Sequenciamento massivo via plataforma Illumina (Miseq) foi realizado para a identificação de bactérias do reator do ponto central, (R9, 5,0 g BCA/L e pH 6,0), do reator otimizado (Rotm, 7,0 g BCA/L e pH 7,2), de amostras do BCA autoclavado e inóculo. No inóculo foram identificadas principalmente bactérias semelhantes a Clostridium bifermentans (62,69% de abundância relativa), Bacillus coagulans (31,67%) e Enterobacter aerogenes (2,72%). No BCA foram identificadas bactérias semelhantes a C. bifermentans (31,91%), C. cellobioparum (32,29%), C. cellulolyticum (5,69%), C. sartagoforme (14,63%) e Paenibacillus spp. (11,67%). Estas bactérias não foram favorecidas sob as condições impostas em R9 (5,0 g BCA/L e pH 6,0) e Rotm (7,0 g BCA/L e pH 7,2), uma vez que a abundância relativa das bactérias nas amostras dos reatores foram completamente diferentes. Em R9, bactérias semelhantes a Lactobacillus paracasei e Escherichia hermannii foram as principais identificas com 37,50 e 34,32% de abundância relativa, respectivamente. Em Rotm, as principais bactérias identificadas foram semelhantes a Bacteroides sp. e Enterobacter aerogenes, com 37,35 e 27,72% de abundância relativa, respectivamente. Assim, as populações bacterianas, bem como a produção de metabólitos, foram alteradas em função das condições impostas; ou seja, concentração de BCA, pH em reatores em batelada com BCA autoclavado como substrato. / This study evaluated the hydrogen and organic acids fermentative productions from sugarcane bagasse (SCB) as substrate in batch reactors. Three pre-treatment conditions (hydrothermal, autoclave and hydrothermal plus autoclave) of BCA and the in natura condition were evaluated in order to favor the hydrogen production. Hydrogen molar productions of 3.79 mmol/L, 3.47 mmol/L, 1.67 mmol/L and 1.01 mmol/L was found for SCB pretreated in autoclave, BCA in natura, SCB pretreated in hydrothermal system and SCB pretreated in hydrothermal system followed by autoclaving, respectively. From these values, it was decided to use autoclaved BCA as a substrate for optimization of hydrogen and organic acids productions from the design methodologies of the central compound and response surface. Ten batch reactors (R1 to R10) were monitored in triplicates with different substrate concentrations (0.8 to 9.2 g/L) and pH (4.6 to 7.4). The highest production of hydrogen (24.06 mmol/L) and 6.42 g/L of organic acids were obtained in R4 (8.0 g BCA/L and pH 7.0). Glucose, arabinose, xylose, mannose and galactose were produced and consumed throughout the operating time of all reactors, and arabinose was observed at higher concentration, 1,415.26 and 1,372.45 mg/L in R3 (8.0 g BCA/L and pH 5.0) and R8 (5.0 g BCA/L and pH 7.4), respectively. The production of hydrogen was concomitant to the formation of organic acids, mainly butyric (from 14.6 to 33.8% in R1 and R6, respectively) and succinic (from 19.5 to 26.4% in R3 and R9, respectively). The two factors analyzed, substrate concentration and pH, had significant effects on the production of hydrogen, butyric acid and succinic acid. From the results obtained with the factorial design, it was possible to verify that the maximum value of hydrogen production estimated by the model was 23.10 mmol/L, to 7.0 g BCA L and pH 7.2. The value obtained in the optimization experiment (Rotm) was 19.84 mmol/L, with an accuracy of 85.9% for hydrogen production from autoclaved BCA. Sequencing by the Illumina platform (Miseq) was performed for the identification of bacteria from the central point reactor (R9, 5.0 g BCA/L and pH 6.0), optimized reactor (Rotm, 7.0 g BCA/L and pH 7.2), autoclaved BCA and inoculum samples. In the inoculum were identified mainly bacteria similar to Clostridium bifermentans (62,69% of relative abundance), Bacillus coagulans (31,67%) and Enterobacter aerogenes (2,72%). Bacteria similar to C. bifermentans (31.91%), C. cellobioparum (32.29%), C. cellulolyticum (5.69%), C. sartagoforme (14.63%) and Paenibacillus spp. (11.67%). These bacteria were not favored under the conditions imposed on R9 (5.0 g BCA/L and pH 6.0) and Rotm (7.0 g BCA/L and pH 7.2), since the relative abundance of the bacteria in the reactor samples were completely different. In R9, bacteria similar to Lactobacillus paracasei and Escherichia hermannii were the main identified with 37.50 and 34.32% of relative abundance, respectively. In Rotm, the main bacteria identified were similar to Bacteroides sp. and Enterobacter aerogenes, with 37.35 and 27.72% relative abundance, respectively. Thus, bacterial populations, as well as the production of metabolites, were altered as a function of the imposed conditions; ie, BCA concentration, pH in batch reactors with autoclaved BCA as substrate.
37

Préparation et caractérisation de catalyseurs bimétalliques Re-Pd/TiO2 pour l'hydrogénation de l'acide succinique issu de la biomasse / Preparation and characterization of Re-Pd/TiO2 bimetallic catalysts for the hydrogenation of succinic acid from biomass

Tapin, Benoît 29 November 2012 (has links)
L'objectif de ce travail est de mettre au point des catalyseurs bimétalliques Re-Pd/TiO2 actifs et suffisamment robustes en milieu hydrothermal pour hydrogéner sélectivement l'acide succinique (SUC) en 1,4-butanediol (BDO). Dans un premier temps, des catalyseurs monométalliques 2%Pd/TiO2 sont préparés et caractérisés par diverses techniques physico-chimiques. Les résultats montrent l'importance d'un certain nombre de paramètres sur les propriétés des catalyseurs et leurs performances catalytiques. Les catalyseurs à base de palladium sont très sélectifs en γ-butyrolactone mais très peu en BDO. Différentes teneurs en rhénium sont ensuite déposées sur les catalyseurs 2%Pd/TiO2 (par imprégnation successive (IS) et par réduction catalytique (RC)). L'existence d'une interaction entre les deux métaux Pd-Re est mise en évidence par plusieurs techniques de caractérisation (chimisorption H2, réaction modèle de déshydrogénation du cyclohexane, RTP, XPS, MET-EDX). L'ajout de rhénium permet d'augmenter la vitesse de la réaction de transformation du SUC et améliore la sélectivité en BDO. Pour les catalyseurs préparés par IS, des quantités importantes de rhénium (3-4%) sont nécessaires pour avoir un effet optimum, alors que le dépôt par la méthode RC doit être limité à des teneurs plus faibles (< 1%). Néanmoins, les catalyseurs préparés par IS conduisent à une meilleure activité et sélectivité en BDO. / The objective of this work is to synthesize bimetallic catalysts Re-Pd/TiO2 active and strong enough in hydrothermal environment to hydrogenate selectively the succinic acid (SUC) to 1,4-butanediol (BDO). At first, monometallic 2%Pd/TiO2 catalysts are prepared and characterized by various physico-chemical methods. The results show the importance of several parameters on the catalyst properties and catalytic performances. Palladium catalysts are very selective to γ-butyrolactone but few to BDO. Various rhenium contents are then deposited on 2%Pd/TiO2 catalysts (by successive impregnation (SI) and catalytic reduction (CR)). The existence of an interaction between both Pd-Re metals is revealed using several techniques of characterization (H2 chemisorption, model reaction of cyclohexane dehydrogenation, TPR, XPS, TEM-EDX). Adding rhenium both allows enhancing the reaction rate of SUC transformation and improving the selectivity to BDO. For catalysts prepared by SI, important quantities of rhenium (3-4%) are needed for optimal effect, while the deposit must be limited to lower contents (< 1%) when using the CR method. Nevertheless, catalysts prepared by SI lead to better activity and selectivity to BDO.
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Produção biotecnólogica de ácido succínico a partir de casca de arroz / Biotecnological production of succinic acid from rice husks

Bevilaqua, Daiane Balconi 16 December 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Rice husk is a subproduct of the food industry, rich in carbohydrates, which can be partially fractionated and converted into fermentable sugars. In this work, it was investigated the best conditions for the conversion of the residual biomass, rice husks, into succinic acid, an important start molecule for the synthesis of the chemo-pharmaceutical industry. With the goal of the separation of lignin and transformation of cellulose and hemicellulose into sugars, the rice husks were submitted, initially, to acid hydrolysis, in autoclave and in pressurized polytetrafluoroethylene reactor. The hydrolysis conditions were optimized by factorial design for the pressurized acid hydrolysis; temperature, time and acid catalyst concentration (HCl or H2SO4) were evaluated. For the acid hydrolysis in autoclave, it was optimized the ratio rice husks mass: acid volume, time and concentration of HCl or H2SO4. It was observed that the sugar production by using autoclave was lower than by the pressurized hydrolysis system, needing further concentration of the hydrolysate for the subsequent fermentation step. The best results were obtained with the polytetrafluoroethylene reactor, by 59 bar, with HCl 0,26 mol L-1, at 175°C and reaction time of 46 min, yielding 19.0 g L- 1 of glucose and 3.01 g L- 1 of xylose. The efficiency of different detoxification methods of the hydrolyzed rice husk were evaluated; the combined method of pH adjustment plus adsorption on active carbon was the most effective by eliminating inhibitors, without appreciable reduction of the sugar concentration. The detoxified hydrolysate was sterilized and adjusted at pH 7 and fermented with A. succinogenes at 37 ° C, in anaerobic medium, occurring the conversion of the two main monosaccharides, glucose and xylose, into succinic acid. The nutrient concentration and the agitation rate of the medium were also optimized by factorial design. As a result, after 54 h of static fermentation, the hydrolysate was supplemented with 8.40 g L-1 yeast extract and 1.40 g L -1 of NaHCO3, to yield 59.9% succinic acid. Almost all of the sugar at this time was consumed and converted to succinic acid; at the same time, acetic and formic acid are formed, but, in low concentrations related to the production of succinic acid, not compromising the yield of the process. For the succinic acid extraction and purification, the fermentate was submitted to the solid phase extraction procedure; cartridges with different extraction phases were tested, and among them, the ion exchange one was the only effective, with recoveries up to 96%. After solid phase extraction, the eluted solution, containing 12.05 g L- 1 succcinic acid, was lyophilized, and crystals of succinic acid with 80.7% (m m- 1) were obtained. The raw material used in the bioprocess has no commercial value, representing a zero cost carbon source, which reveals itself adequate to the succinic acid production by fermentation with A. succinogenes, after hydrolysis. The use of the residual rice husk can contribute to the mitigation of the environmental impact resulting from the illegal discharge in the environment. / A casca de arroz é um subproduto da indústria de alimentos, rico em carboidratos, que pode ser fracionada e, parcialmente, convertida em açúcares fermentescíveis. Neste trabalho, investigou-se as melhores condições para a conversão da biomassa residual, casca de arroz, em ácido succínico, importante insumo para a síntese industrial farmoquímica. Com o objetivo de separação da lignina e transformação da celulose e da hemicelulose em açúcares, a casca de arroz foi submetida, inicialmente, à hidrólise ácida em autoclave e em reator de politetrafluoretileno, à pressão. As condições de hidrólise foram otimizadas através de planejamento fatorial, sendo avaliado na hidrólise ácida pressurizada, a influência da temperatura, do tempo e da concentração do catalisador ácido (HCl ou H2SO4); já, na hidrólise em autoclave, otimizou-se a relação massa de casca de arroz : volume de solução ácida, tempo e concentração de HCl ou H2SO4. Observou-se que a produção de açúcares em autoclave é inferior à do sistema de hidrólise à pressão, necessitando, inclusive, concentração do hidrolisado para utilização na etapa fermentativa. Os melhores resultados foram obtidos com o reator de politetrafluoretileno, à pressão de 59 bar, com 0,26 mol L-1 de HCl, temperatura de 175 °C e tempo de reação de 46 min, produzindo-se 19 g L-1 de glicose e 3,01 g L-1 de xilose. Avaliou-se a eficiência de diferentes métodos de destoxificação do hidrolisado de casca de arroz, sendo o método combinado, de ajuste de pH seguido de adsorção em carvão ativado, o mais eficaz na eliminação de inibidores, sem redução apreciável da concentração de açúcares. O hidrolisado destoxificado foi esterilizado, ajustado a pH 7 e fermentado com A. succinogenes, à 37 ºC, em meio anaeróbio, ocorrendo a conversão dos monossacarídeos predominantes, glicose e xilose, em ácido succínico. A concentração dos nutrientes e a velocidade de agitação do meio também foram otimizadas por meio de planejamento fatorial. Após 54 h de fermentação estática do hidrolisado, suplementado com 8,40 g L-1 de extrato de levedura e 1,40 g L-1 de NaHCO3, o rendimento em ácido succínico foi de 59,9%. Praticamente, toda a concentração de açúcar é consumida neste tempo e convertida em ácido succínico; simultaneamente, formam-se ácido acético e fórmico, porém, em baixas concentrações em relação à produção de ácido succínico, não comprometendo o rendimento do processo. Para a extração e purificação do ácido succínico, o fermentado foi submetido ao procedimento de extração em fase sólida; cartuchos com diferentes fases extratoras foram testados, e, dentre eles, somente o de troca iônica se mostrou efetivo, com recuperação de até 96,0%. Após a extração, o eluido da extração em fase sólida, contendo 12,0 g L-1 de ácido succínico foi liofilizado, obtendo-se cristais com pureza de 80,7% (m m-1). A matéria-prima utilizada no bioprocesso, casca de arroz, não tem valor comercial, representando fonte de carbono de custo zero, que se revelou adequada à produção de ácido succínico por meio de fermentação com A. succinogenes, após hidrólise. O aproveitamento da casca de arroz residual pode contribuir para a mitigação do impacto ambiental resultante da disposição ilegal no ambiente.
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Synthesis and properties of polyesters based on poly(butylene succinate), a renewable polymer / Synthèse et propriétés des polyesters à base de poly (butylène succinate), un polymère renouvelables

Jacquel, Nicolas 15 December 2011 (has links)
Les polymères issus de la biomasse génèrent depuis quelques années un engouement certain puisqu’ils apparaissent comme de potentiels substituts aux polymères issus de l’industrie pétrolière. Parmi ces monomères récemment développés, l’acide succinique bio-sourcé a reçu une attention particulière notamment pour des applications dans le domaine des polyesters tels que le poly(butylène succinate). La présente thèse décrit la synthèse de ce polymère par estérification directe de l’acide succinique et du 1,4-butanediol dans un réacteur pilote de 7.5 L. Les principaux paramètres du procédé tels que l’excès de diol, la température de trans-estérification ainsi que la pureté de l’acide succinique ont été étudiés. Une attention particulière a été portée sur le choix du catalyseur (son type, la quantité utilisée …) afin d’observer son influence sur le procédé ainsi que sur la stabilité du polymère final. Puis différentes stratégies de modification du poly(butylene succinate) ont été testées pour améliorer à la fois sa mise en forme par extrusion gonflage et les propriétés des films obtenus. Dans ce but l’introduction d’agents de branchements, de silices nanométriques ainsi que des comonomères rigides a été étudiée. / Polymers issued from biomass present a growing interest, since they seem to be a suitable alternative to conventional petrochemical polymers. Among the newly developed monomers, bio-based succinic acid received a particular attention for its application in the synthesis of aliphatic polyesters such as poly(butylene succinate). The present thesis reports the synthesis of this polymer via the direct esterification of succinic acid and 1,4-butanediol in a 7.5 L pilote scale reactor. Main process parameters such as the diol exces, the trans-esterification temperature as well as the purity of succinic acid have been studied. In addition a special attention was taken to highlight the influence of the catalyst (its type, quantity ...) on the synthesis and on the stability of the resulting polymer. Then several strategies of modification of poly(butylene succinate) have been studied to improve the processability of the polymer via film extrusion blowing and to enhance the properties of polymer films. To that end the introduction of branching agents, silica nanofillers as well as rigid comonomers have been studied.
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Méthodologie générale pour la conception d'une extraction liquide-liquide réactive : application à la séparation d'un acide carboxylique issu d'un milieu fermentaire / General design methodology for reactive liquid-liquid extraction : application to carboxylic acid recovery in fermentation broth

Mizzi, Benoît 07 November 2016 (has links)
Le couplage fonctionnel des opérations de séparation et de réaction ainsi que les bio-procédés sont deux axes de recherche largement explorés. Cependant, l’industrie du génie des procédés a du mal à se tourner vers des technologies de ce type car il demeure un réel manque de connaissances et d’outils de conception pour ce genre de procédés. Une méthodologie de conception générale pour l'extraction liquide-liquide réactive est introduite dans cette étude. Elle est composée de trois étapes différentes: l'analyse de faisabilité, la synthèse ou dimensionnement du procédé et la validation par simulation. Cette méthodologie conduit à des paramètres structuraux et opératoires de la colonne étudiée à partir seulement des informations concernant le comportement physico-chimique du système étudié, en exploitant les équations d’équilibre chimique et entre phase ainsi que les bilans matières. Les résultats de cette méthode sont un bon point de départ pour une étude d'optimisation ou d'un processus de calcul d'investissement. Cette méthodologie a été appliquée à différentes études de cas: regroupant deux stratégies différentes d'extraction avec plusieurs solvants pour récupérer l'acide succinique dans un milieu de fermentation / The functional coupling of separation and reaction operations and bioprocesses are two widely explored areas of research. However, process engineering industry is struggling to turn to these technologies because it remains a real lack of knowledge and design tools for this kind of processes. A general design methodology for reactive liquid-liquid extraction is introduced in this study. It is composed of three different steps: feasibility analysis, pre-design determination and simulation validation. This methodology leads to the design specifications of the units from the information concerning the physicochemical behaviour of the studied system, exploiting the equilibrium and material balance equations. The results of this methodology are a good starting point for an optimization study or for an investment calculation process. This methodology has been applied to different case studies: two different strategies of extraction and several solvents to recover succinic acid in fermentation broth.

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