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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.
121

Gasification-based Biorefinery for Mechanical Pulp Mills

He, Jie January 2014 (has links)
The modern concept of “biorefinery” is dominantly based on chemical pulp mills to create more value than cellulose pulp fibres, and energy from the dissolved lignins and hemicelluloses. This concept is characterized by the conversion of biomass into various bio-based products. It includes thermochemical processes such as gasification and fast pyrolysis. In thermo-mechanical pulp (TMP) mills, the feedstock available to the gasification-based biorefinery is significant, including logging residues, bark, fibre material rejects, bio-sludges and other available fuels such as peat, recycled wood and paper products. On the other hand, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost. The huge amount of purchased electricity can be compensated for by self-production of electricity from gasification, or the involved cost can be compensated for by extra revenue from bio-transport fuel production. This work is to study co-production of bio-automotive fuels, bio-power, and steam via gasification of the waste biomass streams in the context of the mechanical pulp industry. Ethanol and substitute natural gas (SNG) are chosen to be the bio-transport fuels in the study. The production processes of biomass-to-ethanol, SNG, together with heat and power, are simulated with Aspen Plus. Based on the model, the techno-economic analysis is made to evaluate the profitability of bio-transport fuel production when the process is integrated into a TMP mill.The mathematical modelling starts from biomass gasification. Dual fluidized bed gasifier (DFBG) is chosen for syngas production. From the model, the yield and composition of the syngas and the contents of tar and char can be calculated. The model has been evaluated against the experimental results measured on a 150 KWth Mid Sweden University (MIUN) DFBG. As a reasonable result, the tar content in the syngas decreases with the gasification temperature and the steam to biomass (S/B) ratio. The biomass moisture content is a key parameter for a DFBG to be operated and maintained at a high gasification temperature. The model suggests that it is difficult to keep the gasification temperature above 850 ℃ when the biomass moisture content is higher than 15.0 wt.%. Thus, a certain amount of biomass or product gas needs to be added in the combustor to provide sufficient heat for biomass devolatilization and steam reforming.For ethanol production, a stand-alone thermo-chemical process is designed and simulated. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost. The calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built over 200 MW.In TMP mills, wood and biomass residues are commonly utilized for electricity and steam production through an associated CHP plant. This CHP plant is here designed to be replaced by a biomass-integrated gasification combined cycle (BIGCC) plant or a biomass-to-SNG (BtSNG) plant including an associated heat & power centre. Implementing BIGCC/BtSNG in a mechanical pulp production line might improve the profitability of a TMP mill and also help to commercialize the BIGCC/BtSNG technologies by taking into account of some key issues such as, biomass availability, heat utilization etc.. In this work, the mathematical models of TMP+BIGCC and TMP+BtSNG are respectively built up to study three cases: 1) scaling of the TMP+BtSNG mill (or adding more forest biomass logging residues in the gasifier for TMP+BIGCC); 2) adding the reject fibres in the gasifier; 3) decreasing the TMP SEC by up to 50%.The profitability from the TMP+BtSNG mill is analyzed in comparison with the TMP+BIGCC mill. As a major conclusion, the scale of the TMP+BIGCC/BtSNG mill, the prices of electricity and SNG are three strong factors for the implementation of BIGCC/BtSNG in a TMP mill. A BtSNG plant associated to a TMP mill should be built in a scale above 100 MW in biomass thermal input. Comparing to the case of TMP+BIGCC, the NR and IRR of TMP+BtSNG are much lower. Political instruments to support commercialization of bio-transport fuel are necessary. / Gasification-based Biorefinery for Mechanical Pulp Mills
122

Economic Policy and Resource Implications of Biofuel Feedstock Production

Adusumilli, Naveen 2012 August 1900 (has links)
Dramatically higher fuel prices and massive petroleum imports from politically unstable countries have contributed to a major national initiative to generate renewable fuels in the United States. Often, such policies are enacted and implemented with huge taxpayer expenditures without due diligence to the consequences. The evaluation of the water quality impacts of converting pastureland to intensive biomass production for fuel in a southern Texas watershed suggest significant increases erosion and nutrient loadings to water bodies. The Best Management Practices (BMPs), cover crop and filter strips when implemented individually failed to produce status-quo reduction levels. Combined BMPs implementation produced improved mitigation, at substantially higher costs, highlighting the issue of sustainability related to the economics of renewable fuels. The estimation of the net energy of biomass ethanol accounting for the production input data indicate a greater than one energy return for biomass crops. However, the policy results indicate that only 70 percent in net contribution to the energy supply is achieved due to relatively lower energy returns compared to conventional fossil fuels. In addition, because the ethanol produced has to have the energy used deleted from the total, the cost of producing a gallon of biomass ethanol is substantially higher than that of gasoline. The impacts of an exogenously-specified biofuel mandate fulfilled by the production of a dedicated biomass crop and its consequent effects on commodity prices and overall welfare are estimated. Net farm income increased due to an increase in crop prices; however, both consumer surplus and total surplus decreased. The analysis is extended to estimate the sensitivity of Conservation Reserve Program (CRP) acres returning to crop production and the potential of higher biomass yields. The results indicate that net farm income decreased and consumer surplus increased due to a decrease in crop prices, resulting in an increase in overall welfare. This current research evaluates the unintended consequences of the U.S. energy policy and provides interesting insights of the potential economic and environmental impacts. These results suggest policy makers should be cautious before enacting energy policy and consider multiple alternative energy sources in an economic and financial context to achieve a sustainable energy goal.
123

Upgraded biofuels-effects of quality on processing, handling characteristics, combustion and ash melting /

Paulrud, Susanne, January 2004 (has links) (PDF)
Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.
124

Avaliação do potencial de diferentes cultivares de sorgo sacarino (Sorghum bicolor (L.) Moench) para produção de etanol de 1ª e 2ª geração

SILVA, Marcio José Vasconcelos da. 23 March 2018 (has links)
Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-03-23T20:07:03Z No. of bitstreams: 1 MARCIO JOSÉ VASCONCELOS DA SILVA – TESE (PPGEP) 2017.pdf: 2886790 bytes, checksum: 4e2912ac8b6df6d1df2aeb12d63b2646 (MD5) / Made available in DSpace on 2018-03-23T20:07:03Z (GMT). No. of bitstreams: 1 MARCIO JOSÉ VASCONCELOS DA SILVA – TESE (PPGEP) 2017.pdf: 2886790 bytes, checksum: 4e2912ac8b6df6d1df2aeb12d63b2646 (MD5) Previous issue date: 2017-12-05 / Na busca por fontes de energia renováveis e alternativas que reduzam a emissão de gases nocivos ao meio ambiente, diminuindo assim o uso de combustíveis fósseis em face da conscientização global, os biocombustíveis são uma fonte alternativa de energia, sendo principal destaque o etanol de 1ª e 2ª geração. Objetivou-se neste trabalho avaliar o potencial de diferentes cultivares de sorgo doce (Sorghum bicolor (L.) Moench.) para produção de etanol de 1ª geração a partir da fermentação do caldo dos colmos e etanol de 2ª geração a partir do substrato (bagaço). Para obtenção dos açúcares fermentescíveis a partir do bagaço, utilizou-se pré-tratamento ácido seguido de básico com auxílio de uma matriz de planejamento experimental 2³+3 pontos centrais para avaliar os efeitos das variáveis de entrada, tempo, temperatura e concentrações de ácido e base, verificando a solubilização da hemicelulose e lignina. Para avaliar a hidrólise enzimática verificou-se, por meio da aplicação de uma matriz de planejamento experimental 2²+3 pontos centrais, o efeito da carga enzimática e a razão massa seca de bagaço de sorgo e extrato enzimático. Foram usadas as enzimas comerciais Celluclast 1.5L da Novozyme e betaglicosidase da Prozyn na hidrólise enzimática para obtenção de açúcares fermentescíveis. A pesquisa foi desenvolvida no laboratório de engenharia bioquímica – LEB, na Universidade Federal de Campina Grande – UFCG, no estado da Paráiba e no Instituto Agronômico de Pernambuco – IPA, ambas localizadas na região do nordeste Brasileiro, a colheita das progens foi realizada na Estação Experimental do IPA no município de Vitória de Santo Antão, localizado na Zona da Mata de Pernambuco (lat: 35° 22' W, long: 08° 08' S, altitude: 146 m) no período de março/2013 a setembro/2017. Os resultados referentes aos dados agronômicos apresentaram diferenças significativas para um intervalo de confiança de 95% pelo teste Tukey. Dentre as sete cultivares pesquisadas as que obtiveram maiores teores de sólidos solúveis totais em campo foram entre BRS506, IPA2502, IPA EP17, IPA P222, IPA P134, IPA P228 e IPA SF15 com valores entre 12,3±0,08; 5,1±0,10; 16,8±0,40; 14,8±0,11; 7,1±0,10; 9,2±0,10 e 13,6±0,27 ºBrix, respectivamente. Os resultados referentes a fração sacarina (caldo do sorgo sacarino) foram analisados usando o teste de Tukey para um intervalo de confiança de 95%. Nos dados encontrados para concentração de etanol de 1ª geração, obtidos na fermentação dos caldos das cultivares que se destacaram foram IPA SF15, BRS506, IPA EP17, IPA P222 e IPA P134 com valores entre 55,72 ± 0,24; 45,46 ± 1,5; 44,6 ± 0,18; 33,78 ± 0,57 e 31,78 ± 0,28 g.L-1 respectivamente. As frações (bagaço) para avaliação na produção de etanol de 2ª geração, as cultivares IPA EP17 e BRS506, após pré-tratamento ácido seguido de básico, mostraram-se eficientes em concentrar a celulose, pela solubilização da hemicelulose e lignina, acarretando um aumento da celulose de 31,70 ± 0,49 para 60,42 ± 0,91% na variedade IPA-EP17 e para variedade BRS506 de 40,6 ± 1,1 para 64,52 ± 0,82% respectivamente. Os resultados encontrados no processo de hidrólise enzimática dos bagaços das variedades IPA EP17 para produção de glicose foi de 26,23 g L-1, nas condições de carga enzimática e razão (relação massa seca de bagaço) por volume de meio reacional (25 FPU/g e 2%) no tempo de 36 h de hidrólise e rotação constante de 150 RPM, e para BRS506 a produção de glicose foi de 25,17 g L-1, nas condições de carga enzimática e razão (relação massa seca de bagaço) por volume de meio reacional (25 FPU/g e 2%) no tempo de 36 h de hidrólise. / In the search for renewable energy sources and alternatives that reduce the emission of harmful gases to the environment, thus reducing the use of fossil fuels in the face of global awareness, biofuels present as an alternative, the main highlight being ethanol. The objective of this work was to evaluate the potential of different cultivars of sweet sorghum (Sorghum bicolor (L.) Moench.) For the production of ethanol of 1st generation from the fermentation of the broth the 2st generation ethanol from the substrate (bagasse). To obtain the fermentable sugars from the bagasse, acid pretreatment followed by base with the aid of experimental planning 2³ + 3 central points was applied to evaluate the effects of the variables of entry, time, temperature and acid and base concentrations, verifying the solubilization of hemicellulose and lignin. In order to evaluate the enzymatic hydrolysis, the effect of the enzymatic loading and the dry mass ratio of sorghum bagasse and enzyme extract wereverified using experimental planning design 2² + 3 central points. The commercial enzymes Celluclast 1.5L from Novozyme and beta-glucosidase from Prozyn wereused in the enzymatic hydrolysis to obtain fermentable sugars. The research was carried out at the biochemical-engineering laboratory - LEB, at the Federal University of Campina Grande - UFCG, in the state of Paráiba and at the Agronomic Institute of Pernambuco - IPA, both located in the northeast region of Brazil. The progenies were collected at the IPA Experimental Station in the city of Vitória de Santo Antão, located in the Zona da Mata of Pernambuco (lat: 35 ° 22 'W, long: 08 ° 08' S, altitude: 146 m) from March / 2013 to September / 2017. The results concerning agronomic data presented significant differences for a 95% confidence interval by the Tukey test. Among the seven cultivars studied, the highest soluble solids in the field were BRS506, IPA2502, IPA EP17, IPA P222, IPA P134, IPA P228 and IPA SF15 with values between 12,3 ± 0,08; 5,1 ± 0,10; 16,8 ± 0,40; 14,8 ± 0,11; 7,1 ± 0,10; 9,2 ± 0,10 and 13,6 ± 0,27 °Brix, respectively. Results for saccharin fraction (sorghum broth) were analyzed using the Tukey's test for a 95% confidence interval. In the data obtained for the concentration of ethanol of 1st generation, obtained in the fermentation of the broths of the cultivars that stood out were IPA SF15, BRS506, IPA EP17, IPA P222 and IPA P134 with values between 55,72 ± 0,24; 45,46 ± 1,5; 44,6 ± 0,18; 33,78 ± 0,57 and 31,78 ± 0,28 g.L-1 respectively. The fractions (bagasse) for evaluation in the production of second generation ethanol, IPA EP17 and BRS506, after acid pretreatment followed by basic, were efficient in concentrating the cellulose by the solubilization of hemicellulose and lignin, resulting in an increase of cellulose from 31,70 ± 0,49 to 60,42 ± 0,91% in the variety IPA-EP17 and for the BRS506 variety from 40,6 ± 1,1 to 64,52 ± 0,82% respectively. The results obtained in the enzymatic hydrolysis process for the IPA EP17 variety in the glucose production were 26,23 g L-1, for enzyme loading conditions and ratio (bagasse dry mass ratio) per reaction medium volume (25 FPU / and 2%) in the time of 36 hours of hydrolysis and constant rotation of 150 RPM, for BRS506 variety the glucose production was 25,17 g.L-1, for the conditions of enzymatic loading and ratio (bagasse dry mass ratio) by volume of reaction medium (25 FPU / g and 2%) in the time of 36 hours of hydrolysis.
125

The Past And Future of Biofuels a Case Study of the United States Using the Institutional Analysis and Development Framework

January 2010 (has links)
abstract: In recent years, the world has debated the idea of biofuels as a solution to energy security, energy independence, and global climate change. However, as the biofuels movement has unfolded, crucial issues emerged regarding biofuels efficacy and efficiency. The deployment of biofuels of marginal benefit has raised questions about how countries like the USA may have found themselves so invested in a potentially failing technology. In order to better understand and evaluate these issues, this study utilizes the Ostrom Institutional Analysis and Development (IAD) framework to better evaluate these issues and analyze interacting institutions that shape US biofuel policy. The IAD framework is a model that enables one to study, conceptualize, compare, and make connections across decision arenas that would otherwise be distinct from each other. By analyzing the interactions of relevant institutions, one can see how different dynamic interests interacted to shape biofuel policy in the USA today. Conclusions from this analysis include: the IAD framework is ideal for analyzing the political and economic case for biofuels. The five action arenas identified in this thesis are sufficient to understand corn bioethanol policy. A compelling case for supporting bioethanol is not made. An international agreement to reduce GHG emissions could change the landscape for biofuels. Finally, there is little prospect for biofuels playing a significant role in the near term without greater alignment among the action arenas. / Dissertation/Thesis / M.S. Sustainability 2010
126

Avalia??o do potencial de leveduras selvagens para a fermenta??o alco?lica de D-xilose

Barbosa, Gabriela Maria Pereira 19 May 2017 (has links)
Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-08-30T17:21:18Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gabriela_maria_pereira_barbosa.pdf: 2753973 bytes, checksum: e196ae4be05114b62809f147ce9f80df (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-08-30T18:48:30Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gabriela_maria_pereira_barbosa.pdf: 2753973 bytes, checksum: e196ae4be05114b62809f147ce9f80df (MD5) / Made available in DSpace on 2017-08-30T18:48:30Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) gabriela_maria_pereira_barbosa.pdf: 2753973 bytes, checksum: e196ae4be05114b62809f147ce9f80df (MD5) Previous issue date: 2017 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / As pentoses oriundas da hidr?lise da fra??o hemicelul?sica de biomassas vegetais podem ser fermentadas a etanol. Entretanto, s?o poucas as esp?cies conhecidas de micro-organismos capazes de converter pentoses a etanol e, mesmo essas, mostram-se ineficientes e suscept?veis ? presen?a de inibidores produzidos durante o pr?-tratamento das biomassas lignocelul?sicas. Neste contexto, o presente trabalho teve por objetivo identificar e avaliar seis linhagens de leveduras isoladas a partir de biomassas vegetais quanto a capacidade de realizar a fermenta??o alco?lica da D-xilose utilizando diferentes formula??es de meios sint?ticos. As linhagens foram submetidas a identifica??o morfol?gica e molecular. Os processos fermentativos foram conduzidos em batelada simples em frascos c?nicos sob agita??o a 150 rpm e temperatura de 30?C por at? 145 horas. Os bioprocessos foram monitorados a intervalos regulares de tempo quanto ? concentra??o de a??cares redutores, glicose, etanol e biomassa celular. Ao final do processo, foram determinados os valores das vari?veis de resposta rendimento (YP/S), produtividade (QP) e taxa de consumo de a??cares (qS). Todas as linhagens avaliadas foram capazes de produzir ?lcool em meio sint?tico contendo somente xilose como carboidrato. Os maiores valores de produ??o e rendimento alc?olico foram obtidos em meios que continham al?m da xilose, a glicose. O maior valor de YP/S observado foi de 0,38, em condi??es experimentais com produ??o de 3,33 g L-1 de etanol. A composi??o de microelementos e fontes de nitrog?nio afetou a fermenta??o alc?olica. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The pentoses from the hydrolysis of the hemicellulosic fraction of plant biomass can be fermented to ethanol. However, few known species of microorganisms are capable of converting pentoses to ethanol, and even those, are inefficient and susceptible to the presence of inhibitors produced during pretreatment of lignocellulosic biomasses. In this context, main objective of this work is to identify and evaluate six yeast strains isolated from plant biomasses in order to perform the alcoholic fermentation of D-xylose using different formulations of synthetic media. The strains were submitted to morphological and molecular identification at the species level. The fermentative processes were conducted in single batch in conical flasks under agitation at 150 rpm and at 30 ?C for up to 145 hours. The bioprocesses were monitored at regular intervals for the concentration of reducing sugars, glucose, ethanol and cell biomass. At the end of the process, the values of the response variables YP/S, QP e qS were determined. All the evaluated strains were able to produce alcohol in synthetic medium containing only xylose as a carbohydrate. The highest values of production and alcoholic yield were obtained in media that contained beyond xylose, glucose. The highest value of YP/S observed was 0.38, under experimental conditions with production of 3.33 g L-1 of ethanol. The composition of microelements and nitrogen sources affected the alcoholic fermentation.
127

Desenvolvimento de tecnologias para compressão de biogás

Souza, José de January 2010 (has links)
O crescimento do potencial energético a partir da biomassa estimula o desenvolvimento e a criação de novas tecnologias neste setor. Neste trabalho realizou-se uma ampla pesquisa da produção, compressão e acondicionamento do biogás. Constatou-se durante essa pesquisa a necessidade da busca por alternativas que possibilitem a utilização eficiente deste biocombustível. Analisou-se a possibilidade da fabricação de um compressor alternativo para biogás que possa ser aplicado em pequenas unidades de produção por meio da modelagem das partes componentes. Primeiro efetuou-se a escolha do material considerando-se as características adequadas para construção do sistema de compressão. Depois disto dimensionou-se a camisa de compressão e a sua modelagem tridimensional com software Inventor 2010 (versão Student), além de válvulas e matrizes para fabricação. Complementarmente foi simulado o funcionamento do compressor (gráfico do deslocamento, velocidade e força com o software FluidSim da Festo Didatic). Por último executou-se o projeto eletropneumático, energização e lista de dispositivos necessários para montagem do compressor. Observou-se que essa tecnologia pode ser aplicada em pequenas plantas de produção de biogás. A comparação com outros sistemas de compressão revelou vantagens como a não haver contaminantes na compressão e acionamento, além da compressão poder se dar em ambiente separado do seu acionamento. / The growth of the energy potential from the biomass stimulates development and creation of new technologies in this sector. In this work is carried out extensive research in production, compression and biogas bottling. The need to search for alternatives has been evidenced during the research to make possible the efficient use of biofuel. After it analyzed the possibility of manufacturing of an alternative compressor for biogas which can be applied in small production units through the modeling of the contracting parties. At first it was effected the material choice considering the characteristics for the construction of the compression system. After this, was dimensioned a compression jacket, valves and matrices with the Student software Inventor 2010. Moreover the functioning of the compressor was simulated (its graphical of the displacement, speed and force with a FluidSim software from Festo Didatic). Finally was made a pneumatic project and was executed a list of necessary devices for the compressor assembly. It was observed to that this technology can be applied in small plants of production of biogas. The comparison with other systems of compression demonstrates that tis compressor haven’t contaminants, beyond the compression to be able to give itself in separate environment of its drive.
128

Desenvolvimento de tecnologias para compressão de biogás

Souza, José de January 2010 (has links)
O crescimento do potencial energético a partir da biomassa estimula o desenvolvimento e a criação de novas tecnologias neste setor. Neste trabalho realizou-se uma ampla pesquisa da produção, compressão e acondicionamento do biogás. Constatou-se durante essa pesquisa a necessidade da busca por alternativas que possibilitem a utilização eficiente deste biocombustível. Analisou-se a possibilidade da fabricação de um compressor alternativo para biogás que possa ser aplicado em pequenas unidades de produção por meio da modelagem das partes componentes. Primeiro efetuou-se a escolha do material considerando-se as características adequadas para construção do sistema de compressão. Depois disto dimensionou-se a camisa de compressão e a sua modelagem tridimensional com software Inventor 2010 (versão Student), além de válvulas e matrizes para fabricação. Complementarmente foi simulado o funcionamento do compressor (gráfico do deslocamento, velocidade e força com o software FluidSim da Festo Didatic). Por último executou-se o projeto eletropneumático, energização e lista de dispositivos necessários para montagem do compressor. Observou-se que essa tecnologia pode ser aplicada em pequenas plantas de produção de biogás. A comparação com outros sistemas de compressão revelou vantagens como a não haver contaminantes na compressão e acionamento, além da compressão poder se dar em ambiente separado do seu acionamento. / The growth of the energy potential from the biomass stimulates development and creation of new technologies in this sector. In this work is carried out extensive research in production, compression and biogas bottling. The need to search for alternatives has been evidenced during the research to make possible the efficient use of biofuel. After it analyzed the possibility of manufacturing of an alternative compressor for biogas which can be applied in small production units through the modeling of the contracting parties. At first it was effected the material choice considering the characteristics for the construction of the compression system. After this, was dimensioned a compression jacket, valves and matrices with the Student software Inventor 2010. Moreover the functioning of the compressor was simulated (its graphical of the displacement, speed and force with a FluidSim software from Festo Didatic). Finally was made a pneumatic project and was executed a list of necessary devices for the compressor assembly. It was observed to that this technology can be applied in small plants of production of biogas. The comparison with other systems of compression demonstrates that tis compressor haven’t contaminants, beyond the compression to be able to give itself in separate environment of its drive.
129

Hydrothermal Organic Reduction and Deoxygenation

January 2018 (has links)
abstract: Organic reactions in natural hydrothermal settings have relevance toward the deep carbon cycle, petroleum formation, the ecology of deep microbial communities, and potentially the origin of life. Many reaction pathways involving organic compounds under geochemically relevant hydrothermal conditions have now been characterized, but their mechanisms, in particular those involving mineral surface catalysis, are largely unknown. The overall goal of this work is to describe these mechanisms so that predictive models of reactivity can be developed and so that applications of these reactions beyond geochemistry can be explored. The focus of this dissertation is the mechanisms of hydrothermal dehydration and catalytic hydrogenation reactions. Kinetic and structure/activity relationships show that elimination occurs mainly by the E1 mechanism for simple alcohols via homogeneous catalysis. Stereochemical probes show that hydrogenation on nickel occurs on the metal surface. By combining dehydration with and catalytic reduction, effective deoxygenation of organic structures with various functional groups such as alkenes, polyols, ketones, and carboxylic acids can be accomplished under hydrothermal conditions, using either nickel or copper-zinc alloy. These geomimetic reactions can potentially be used in biomass reduction to generate useful fuels and other high value chemicals. Through the use of earth-abundant metal catalysts, and water as the solvent, the reactions presented in this dissertation are a green alternative to current biomass deoxygenation/reduction methods, which often use exotic, rare-metal catalysts, and organic solvents. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2018
130

Análise das potencialidades e barreiras referentes ao desenvolvimento e à implementação do biodiesel a partir do óleo de palma na Colômbia / Analysis of potentials and barriers for the development and implementation of biodiesel from palm oil in Colombia.

Ariel Augusto Amaya Avila 27 November 2009 (has links)
A Colômbia, a partir de 2003, prevendo um déficit na sua produção de combustíveis e tentando reativar a economia rural, iniciou seu programa nacional de biocombustíveis apoiado em políticas, regulamentos e incentivos econômicos para o novo setor energético. É assim que esta dissertação tem como objetivo descrever e analisar o processo de implementação do programa de biodiesel na Colômbia a partir de óleo de palma, determinando a capacidade produtiva do país e discutindo as barreiras existentes para o seu desenvolvimento. Para isto são descritos aspectos relacionados à produção de biodiesel na Colômbia como: a fase agrícola e industrial, a produção de biodiesel, o setor de combustíveis na Colômbia, a legislação criada para o biodiesel, assim como os mecanismos econômicos para sua continuidade. A partir dessas informações foram construídos três cenários possíveis até 2020, nos quais são analisados os objetivos do programa e o potencial de produção. Conclui-se que o biodiesel de óleo de palma oferecerá benefícios econômicos, sociais e ambientais caso o governo oriente esforços e recursos às populações pobres e à agricultura familiar. Adicionalmente, a Colômbia tem potencial para substituir a totalidade do diesel consumido no país e ter excedentes de dois milhões de litros de biodiesel para exportação. / Since 2003, Colombia, predicting a deficit in fuel production and trying to revive the rural economy, begins its national biofuels program based on policies, regulations and economic incentives for the new energy sector. This dissertation aims to describe and to analyze the process of implementing the biodiesel program from palm oil in Colombia, determining the country\'s productive capacity and discussing the barriers to its development. Therefore describes the different areas related to the biodiesel production in Colombia as agricultural and industrial stage; biodiesel production; the Colombian fuel sector; legislation developed for biodiesel; as well as economic mechanisms for continuity. From this information were built three possible scenarios until 2020, which analyze the program\'s objectives and production potential. It is concluded that biodiesel from palm oil offers economic, social and environmental benefits if the focus would be in poor population and small farms. In addition, Colombia has the potential to replace all diesel consumed in the country and have over two million liters of biodiesel for export.

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