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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.
11

Super GTA: Urban Implications of Ontario's Greenbelt

Martin, Edward Johnson January 2006 (has links)
In early 2005, increasing social and infrastructural costs associated with the rapidly expanding Greater Toronto Area [GTA] pressed the Province of Ontario to initiate a growth management strategy for the region. The Provincial <em>Growth Plan</em>, coupled with its <em>Greenbelt Plan</em>, effectively legislates a minimum of 40 per cent infill development by 2015 and limits land supply until 2031. This book explores the extents and implications of this legislation, with a particular focus on the Town of Milton, a key community west of downtown Toronto, where city and Greenbelt meet. <br>    The structure of suburban communities can and should be modified to improve their sense of identity, and reduce their environmental impact and dependency on automobiles. The thesis aims to reflect the policies inherent in the Provincial Growth Plan, which advocates placing walkable infill development in close proximity to public transit. A design proposal links natural corridors and recreational spaces with a public thoroughfare along the existing railway line in Milton, Ontario. A dense new community flanks this public armature which connects the public realm network of this rapidly developing town to the larger network of the Metropolitan Greenbelt. <br>    The Town of Milton becomes a test case for scenarios which are common within the GTA, and examines the human impact on environmental systems moving towards symbiosis. The context of this city-building predicts a fundamental conceptual shift in the priorities of urban living, where residents understand the value of the natural environment and their relationship to it. That is to say, its context is one in which nature matters.
12

Evolving the Urban Dwelling

Gauthier, Martin 15 January 2012 (has links)
In examining the Canadian residential fabric, this thesis advocates for the design of urban dwellings which respond directly to a number of contemporary urban challenges. A number of these challenges stem from the largely suburban nature of North American cities; there are major concerns about the relative isolation and automobile dependence of contemporary suburbs, their spread into conurbations, and their environmental impacts. On the other hand, there are challenges with many typical urban infill developments as well; they are often developed for a limited range of households, lack much in the way of connections to the outdoors, and, in contrast to some of the key arguments for intensification, often perform below the level of energy efficiency we might reasonably expect in a compact, contemporary, and sustainable urban form. All of these challenges are further discussed and evaluated in chapter three of the thesis. In attempting to address these challenges in a holistic manner, this thesis makes a case for conscientiously increasing the density of the many existing low-density areas within our urban fabric, in a form which incorporates varied outdoor spaces, varied uses, varied unit types and sizes, within a relatively energy efficient form and skin. Chapter four looks at design principles, strategies, and precedents, as well as schematic designs which attempt to integrate and synthesize these objectives. In order to illustrate the application of these principles and schematic designs to an existing low density urban area, chapter five proposes a more detailed design on a large site in Westboro, Ottawa, an evolving semi-suburban area whose development dates largely from early and mid 20th century.
13

Perceptions on small-scale agricultural development : A qualitative case study made in Babati District, Manyara Region, Tanzania

Philipsson, Amanda January 2015 (has links)
This Bachelor’s thesis examines if and how the perceptions towards agricultural development differs between small-scale farmers, agricultural advisors and entrepreneurs with various age and level of knowledge. The case study was conducted in Babati District, Tanzania, during three weeks in the spring of 2015. Twelve semi-structured interviews were conducted, and to analyze the empirical results a theoretical framework was created to explain how poverty traps occur and point at possible strategies to dissolve them. The majority of the respondents expressed that the biggest obstacles and needs for small-scale farmers to be able to develop their farming is lack of capital to invest in inputs and knowledge on how to intensify their land use. The perception towards agricultural development seem to differ between generations, in that young farmers are taking part of new technology and methods when cultivating, unlike the older generation. The respondents’ general attitude towards foreign investments was predominantly negative, arguing that local knowledge is of importance if sustainable agricultural development is to be reached. To ease the agricultural development, increased knowledge on how to intensify the agricultural production and how to organize farmers’ associations is suggested.
14

Property size preferences and the value of private and public outdoor spaces amid a shift to high-density residential development: A case study of Kitchener-Waterloo, Ontario

DeFields, Emma January 2013 (has links)
Planning policies in Ontario, such as the Provincial Policy Statement and the Growth Plan for the Greater Golden Horseshoe, enforce urban growth boundaries to preserve natural and agricultural lands while improving neighbourhood and city vibrancy. Consequently, urban areas must be intensified through high-density development, which will limit the land available for public green spaces and large private yards. As a result, homebuyers looking for spacious properties will have to rely mainly on the turnover of older homes. Therefore, this thesis explores how residents currently living in homes with private yards value private and public outdoor space, and whether they have interest in upsizing or downsizing their homes in the future. Neighbourhood and property attributes that may be influential in homebuyer decision-making are also investigated. The cities of Kitchener and Waterloo (“Kitchener-Waterloo”) were chosen as the study location, as both cities are affected by the Growth Plan and are currently being intensified. From March to August, 2012, a random sample of 1272 households living in homes with private yards were invited to participate in a survey on yard landscaping and maintenance practices and property preferences, after which a total of 206 surveys were analyzed. Most respondents were living in medium-sized homes with medium-sized yards, and results indicated that homes and yards of medium size would be the most commonly preferred options if residents were to move (considering their household size, health, finances, etc.). On the whole, the target market for high-density homes (i.e. condominiums, small houses, and small yards) came mainly from the aging population. Nevertheless, when asked if they would ever live with less yard space in the future (when their household conditions could differ from what they were at the time of the survey), 58% of all respondents indicated that they may live in a home with a small yard and 41% indicated that they may live with no yard. Such a finding further indicated that residents may find high-density dwellings more appealing as they age. Based on findings, ways of increasing the appeal of compact dwellings are discussed, such as including a small yard or balcony, providing privacy, ensuring access to public green spaces, and being located in a safe neighbourhood. Landscapes neat in appearance and designed with grass, colourful vegetation, trees, and natural gardens are also expected to increase property appeal. Overall, if development is to remain restricted to built-up areas, developers and planners will have to create desirable high-density homes located in communities that accommodate the lifestyles of potential residents. This thesis addresses such a challenge by delineating target market groups with the potential to move to high-density homes, and by providing insight into the variables that may increase the appeal of properties as landscapes are intensified.
15

Evolving the Urban Dwelling

Gauthier, Martin 15 January 2012 (has links)
In examining the Canadian residential fabric, this thesis advocates for the design of urban dwellings which respond directly to a number of contemporary urban challenges. A number of these challenges stem from the largely suburban nature of North American cities; there are major concerns about the relative isolation and automobile dependence of contemporary suburbs, their spread into conurbations, and their environmental impacts. On the other hand, there are challenges with many typical urban infill developments as well; they are often developed for a limited range of households, lack much in the way of connections to the outdoors, and, in contrast to some of the key arguments for intensification, often perform below the level of energy efficiency we might reasonably expect in a compact, contemporary, and sustainable urban form. All of these challenges are further discussed and evaluated in chapter three of the thesis. In attempting to address these challenges in a holistic manner, this thesis makes a case for conscientiously increasing the density of the many existing low-density areas within our urban fabric, in a form which incorporates varied outdoor spaces, varied uses, varied unit types and sizes, within a relatively energy efficient form and skin. Chapter four looks at design principles, strategies, and precedents, as well as schematic designs which attempt to integrate and synthesize these objectives. In order to illustrate the application of these principles and schematic designs to an existing low density urban area, chapter five proposes a more detailed design on a large site in Westboro, Ottawa, an evolving semi-suburban area whose development dates largely from early and mid 20th century.
16

The form and function of general extenders in English interactive disscourse

Overstreet, Maryann E (Maryann Elizabeth) January 1995 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 314-330). / Microfiche. / ix, 330 leaves, bound 29 cm
17

Agricultural intensification and ecosystem function in a brigalow (Acacia harpophylla)landscape: implications for ecosystem services

Collard, Stuart J. January 2007 (has links)
[Abstract]: Agricultural intensification, involving habitat fragmentation and modification, typically leads to a decline in biodiversity and ecosystem function. While most studies concentrate on remnant patches, the less intensively managed components of agricultural landscapes may also provide biodiversity values and ecosystem services. This study examines the contribution of different categories of land management to biodiversity and ecosystem function along a gradient of agricultural intensification. Differences within these land management categories are also examined. Research results are interpreted in the broad context of ecosystem services and their resilience in agro-ecosystems.
18

The application of phytolith and starch grain analysis to understanding formative period subsistence, ritual, and trade on the Taraco Pennisula, Highland Bolivia

Logan, Amanda Lee. January 2006 (has links)
Thesis (M.A.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 21, 2009) Includes bibliographical references.
19

Intensificaçao do cultivo do camarão rosa Farfantepenaeus paulensis no sul do Brasil

Fóes, Geraldo Kipper January 2011 (has links)
Tese(doutorado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2011. / Submitted by Cristiane Gomides (cristiane_gomides@hotmail.com) on 2013-11-26T20:09:31Z No. of bitstreams: 1 Geraldo.pdf: 5132055 bytes, checksum: ce116c1d809521acaf04fd07406d526b (MD5) / Approved for entry into archive by Sabrina Andrade (sabrinabeatriz@ibest.com.br) on 2013-11-27T11:39:16Z (GMT) No. of bitstreams: 1 Geraldo.pdf: 5132055 bytes, checksum: ce116c1d809521acaf04fd07406d526b (MD5) / Made available in DSpace on 2013-11-27T11:39:16Z (GMT). No. of bitstreams: 1 Geraldo.pdf: 5132055 bytes, checksum: ce116c1d809521acaf04fd07406d526b (MD5) Previous issue date: 2011 / O camarão rosa Farfantepenaeus paulensis, é uma espécie que possui grande importância econômica e ecológica no oceano Atlântico Sul. Pesquisas anteriores demonstraram a viabilidade técnica de cultivo desta espécie em estruturas alternativas de baixo custo e também em sistemas convencionais de cultivo extensivos, entretanto com baixo rendimento econômico. Nesta tese foram realizados estudos sobre a possibilidade da intensificação do cultivo desta espécie, utilizando sistemas convencionais e também sistemas considerados amigáveis ao ambiente, na tentativa de se obter maiores índices de produtividade. Um dos sistemas foi a utilização de substratos verticais para a formação de biofilme microbiano na fase de engorda. O outro sistema foi o de flocos microbianos (BFT), onde há a reciclagem dos nutrientes liberados na água de cultivo para a formação de flocos microbianos, os quais reduzem a necessidade de renovação de água e também servem de alimento aos organismos cultivados na fase de engorda. No primeiro capítulo se abordou a importância do sedimento nos parâmetros físico e químicos, na comunidade microbiana e no desempenho zootécnico de juvenis de F. paulensis cultivados em elevada densidade de estocagem. No segundo capítulo foi abordada a utilização de sistemas de cultivo ambientalmente amigáveis para o camarão rosa F. paulensis, que foram o sistema de cultivo utilizando substratos verticais para formação do biofilme e o sistema de flocos microbianos. O biofilme é um consórcio de microorganismos formado sobre superfícies submersas, que contribui na produção de organismos aquáticos, pois é uma excelente fonte nutricional. Além disso, os microorganismos presentes no biofilme também contribuem para a manutenção da qualidade da água do cultivo. O sistema de flocos microbianos combina a remoção de nutrientes da água, com a produção de biomassa microbiana que pode ser utilizada como uma fonte nutricional adicional para os camarões. Foi analisada a importância destes sistemas nos parâmetros de qualidade de água, na comunidade de microorganismos e no desempenho zootécnico de F. paulensis. No terceiro e quarto capítulos foram abordadas a utilização do sistema de flocos microbianos em berçário e na engorda do camarão rosa F. paulensis em diferentes densidades de cultivo. No quinto capítulo foi abordada a influência do declínio da temperatura durante o ciclo de cultivo para o camarão rosa F. paulensis em diferentes densidades de estocagem. Nos resultados obtidos no capítulo 1 evidenciou-se que o sedimento possui importância nos parâmetros físicos e químicos da água, na estrutura da comunidade de microorganismos e no desempenho zootécnico dos camarões cultivados em densidades elevadas, havendo diferenças significativas (p<0,05) no peso médio e na produtividade entre os tratamentos. Nos resultados obtidos no segundo capítulo foi demonstrado que os substratos verticais e principalmente o sistema de flocos microbianos melhoram a qualidade da água e o desempenho zootécnico dos camarões F. paulensis em elevada densidade de estocagem. No terceiro e quarto capítulos também foi detectado que o sistema de flocos microbianos é importante para a manutenção da qualidade da água, sobrevivência e desempenho zootécnico do camarão rosa F. paulensis em densidades elevadas. Houve diferenças significativas entre as diferentes densidades de estocagem em relação ao peso médio final, sendo este maior nas densidades mais baixas. A produtividade foi mais elevada nas maiores densidades de estocagem. No quinto capítulo foi verificado que a densidade de estocagem influenciou o crescimento e produtividade. Foi também demonstrado a influência negativa da diminuição da temperatura no crescimento dos camarões. Entretanto, se evidenciou que com a redução da temperatura reduziu também a influência da densidade de estocagem no crescimento, pois quando a temperatura diminuiu, os crescimentos foram semelhantes entre os tratamentos. De uma maneira geral, os resultados dos experimentos demonstraram a importância dos sistemas de cultivo ambientalmente amigáveis para o aumento da produtividade da criação do camarão rosa F. paulensis comparativamente com as produtividades nos sistemas convencionais. / The pink shrimp Farfantepenaeus paulensis, has a great economic and ecological importance in the South Atlantic Ocean. Previous research has demonstrated the technical feasibility of the culture of this species into alternative structures and in conventional shrimp farmers. However, in these systems F. paulensis has presented a low economic performance. In order to achieve higher productivity rates in the culture systems, studies were conducted to evaluate of the intensification of F. paulensis rearing using environmentally friendly systems. It was analyzed the use of vertical substrates for microbial Biofilm formation. Other study was carried out to analyze the use of the Biofloc system technology (BFT) in F. paulensis culture. In this system nutrient of the water is used for the microbial floc formation. In the first chapter it was discussed the importance of sediment in the physical and chemical water parameters, in the microbial community and on the performance of juveniles of F. paulensis reared in high stocking density. In the second chapter it was discussed the use of environmentally friendly culture systems for the pink shrimp F. paulensis, when used substrates for biofilm formation and Biofloc system. The biofilm is a consortium of microorganisms adhered to surfaces under water. It can contribute to the production of aquatic organisms, it is also an excellent nutritional source. Furthermore, the microorganisms present in the biofilm also contribute to the maintenance of water quality of the culture. The biofloc system combines the removal of nutrients from the water, with the production of microbial biomass that can be used as an additional nutritional source for the shrimp. In the third and fourth chapters were discussed the use of the biofloc system in the nursery and grow out of pink shrimp F. paulensis at different stocking densities. In the fifth chapter discussed the influence of decline of temperature in the culture of pink shrimp F. paulensis at different stocking densities. The results achieved in Chapter 1 demonstrated that the sediment has important physical and chemical parameters of the water. It was detected significant differences in the community structure of microorganisms on the performance of shrimp reared (p<0.05) in different treatment. The results obtained in the second chapter shown that the vertical substrates and especially the bioflocs improve water quality parameters and zootechnical performance of the shrimp F. paulensis in high stocking density. In the third and fourth chapters it was shown that the system of biofloc is important for the maintenance of water quality parameters, survival and zootechnical performance of the pink shrimp F. paulensis reared at high densities. Significant differences were found between the different stocking densities where the final average weight was higher in lower densities. The productivity was highest in the highest stocking densities. In the fifth chapter it was showed that stocking density influenced the growth and productivity. It was also demonstrated the negative influence of the reduced temperature in the growth of shrimp. However, it was evidenced that with decreasing water temperature also decreased the influence of stocking density on growth, when the temperature decreased, the growth were similar among treatments. Then, in general results showed the importance of the environmentally friendly culture systems to increase the productivity of the pink shrimp F. paulensis in high stocking densities.
20

Intensification of methane dehydroaromatization process on catalytic reactors

Zanón González, Raquel 19 June 2017 (has links)
The present thesis has focused on the intensive study of the methane dehydroaromatization process under non-oxidative conditions for producing benzene and H2 in a direct way. Nevertheless, MDA process is thermodynamically limited and, moreover, the catalyst quickly accumulates large amounts of carbonaceous deposits, which hinders its commercialization. Therefore, this thesis has as fundamental purposes the improvement of the catalytic activity and the stability of the catalyst on MDA reaction. The catalysts widely used on MDA reaction are Mo/zeolite, which are bifunctional, i.e., Mo sites are involved in the methane dehydrogenation and formation of CHx species, which are dimirized to C2Hy species, and Brønsted acid sites of the zeolite oligomerize these C2Hy species, forming mostly benzene and naphthalene. Thereby, different Mo/zeolite catalysts were prepared using commercial zeolites as well as zeolites synthesized on the laboratory. Thus, observing that the zeolite and the Mo content employed on the catalyst affected significantly the MDA performance. The topology and the channel dimensions of the zeolite as well as its Si/Al ratio and crystal size were also important on the MDA results obtained. Concretely, the best MDA performance was achieved by the 6%Mo/MCM-22 catalyst. Different catalyst activation procedures were tested, achieving the best MDA performance and catalyst stability using a gas mixture of CH4:H2, 1:4 (vol. ratio) during 1 h up to 700 ºC and maintaining this temperature for 2 h. This catalyst activation leads to the pre-carburization and pre-reduction of the Mo species, obtaining the most active and stable on MDA reaction. Moreover, the effect of the space velocity was studied in the present thesis. The best MDA results were reached at 1500 mL¿h-1¿gcat-1, as at higher space velocities methane barely can interact with the catalytic sites. While at lower space velocities the condensation of the heavy aromatic hydrocarbons is facilitated, causing higher coke accumulation on the catalyst. Furthermore, higher catalyst stability was obtained by co-feeding H2O, H2 and CO2 separately using the 6%Mo/HZSM-5 catalyst as well as the 6%Mo/MCM-22, due to the partial suppression of coke deposited. However, the catalytic activity was worsen by adding these co-reactants because of, on one hand, thermodynamically the addition of H2O, H2 or CO2 to the methane feed is detrimental and, on the other hand, H2O and CO2 partially re-oxidize the Mo species of the catalyst. Thermodynamically, H2 causes an equilibrium shift and, therefore, a decrease on the methane conversion; H2O favors the methane reforming reaction and coke gasification; and CO2 promotes the methane reforming reaction and the reverse Boudart reaction. The development and implementation of a catalytic membrane reactor (CMR) that integrates the 6%Mo/MCM-22 catalyst and the BZCY72 tubular membrane has been carried out on the present thesis. The MDA performance and the stability of the catalyst were exceptionally improved using this CMR by imposing a current to the electrochemical cell, changing or not the standard operating conditions. These good results were obtained due to the simultaneous H2 removal from MDA reaction side and O2 injection to this side through the BZCY72 tubular membrane. Thus, the H2 extraction results in the thermodynamic equilibrium displacement of MDA reaction, which causes the increase of the methane conversion and in turn of the aromatics yield. Moreover, the O2 injection involves the formation of H2O in low concentration, which reacts with coke accumulated (coke gasification), rising the stability of the catalyst. / La presente tesis se ha centrado en el estudio intensivo del proceso de deshidroaromatización de metano en condiciones no oxidativas para producir benceno e hidrógeno de forma directa. Sin embargo, el proceso de MDA está limitado termodinámicamente y, además, el catalizador acumula rápidamente grandes cantidades de depósitos carbonosos, lo que dificulta su comercialización. Por tanto, esta tesis tiene como objetivos fundamentales la mejora de la actividad catalítica y la estabilidad del catalizador en la reacción MDA. Los catalizadores Mo/zeolita son ampliamente utilizados en la reacción MDA, los cuales son bifuncionales, es decir, los sitios de Mo están involucrados en la deshidrogenación del metano y la formación de las especies CHx, las cuales se dimerizan a especies C2Hy, y los sitios ácidos de Brønsted de la zeolita oligomerizan éstas especies C2Hy, formando principalmente benceno y naftaleno. Por lo que, diferentes catalizadores Mo/zeolita se prepararon utilizando zeolitas tanto comerciales como sintetizadas en el laboratorio. Observando así que la zeolita y el contenido de Mo utilizados en el catalizador afectan significativamente el rendimiento de la reacción MDA. Tanto la topología y las dimensiones de los canales de la zeolita como su relación Si/Al y su tamaño de cristal son también importantes en los resultados obtenidos de la reacción MDA. Concretamente, el mejor rendimiento de MDA fue obtenido por el catalizador 6%Mo/MCM-22. Se probaron diferentes procedimientos de activación del catalizador, obteniendo el mejor rendimiento de la reacción MDA y estabilidad del catalizador usando una mezcla gaseosa de CH4:H2, 1:4 (relación en volumen) durante 1 h hasta 700 ºC y manteniendo esta temperatura durante 2 h. Esta activación del catalizador provoca la pre-carburización y pre-reducción de las especies de Mo, obteniendo las más activas y estables en la reacción de MDA. Los mejores resultados de MDA se obtuvieron con 1500 mL¿h-1¿gcat-1, ya que con mayores velocidades espaciales el metano apenas puede interaccionar con los sitios catalíticos. Mientras que con menores velocidades espaciales la condensación de los hidrocarburos aromáticos pesados se ve favorecida, provocando una mayor acumulación de coque en el catalizador. Por otra parte, co-alimentando H2O, H2 y CO2 por separado se obtuvo una mayor estabilidad tanto del catalizador 6%Mo/HZSM-5 como del 6%Mo/MCM-22, debido a la supresión parcial del coque depositado. Sin embargo, la actividad catalítica empeoró al añadir estos co-reactivos ya que, por un lado, la adición de H2O, H2 y CO2 a la alimentación de metano es perjudicial termodinámicamente y, por otro lado, el H2O y el CO2 re-oxidan parcialmente las especies Mo del catalizador. Termodinámicamente, el H2 provoca un cambio en el equilibrio y, por tanto, una disminución de la conversión de metano; el H2O favorece la reacción de reformado de metano y la gasificación de coque; y el CO2 promueve la reacción de reformado de metano y la reacción inversa de Boudart. En la presente tesis se ha llevado a cabo el desarrollo y la implementación de un reactor catalítico de membrana (CMR) que integra el catalizador 6%Mo/MCM-22 y la membrana tubular BZCY72. El rendimiento de la reacción MDA y la estabilidad del catalizador fueron excepcionalmente mejorados usando este CMR imponiendo una corriente a la celda electroquímica, cambiando o no las condiciones de operación estándar. Estos buenos resultados fueron obtenidos debido a la simultánea extracción de H2 del lado de reacción y la inyección de O2 a este lado mediante la membrana tubular BZCY72. Así, la extracción de H2 se traduce en un desplazamiento del equilibrio termodinámico de la reacción MDA, lo que causa el aumento de la conversion de metano y a su vez del rendimiento de aromáticos. Además, la inyección de O2 implica la formación de agua en baja concentración, la que reacciona con el coque acumulado (gas / La present tesi s'ha centrat en l'estudi intensiu del procés de deshidroaromatització de metà en condicions no oxidatives per produir benzé i hidrogen de forma directa. No obstant això, el procés de MDA està limitat termodinàmicament i, a més, el catalitzador acumula ràpidament grans quantitats de dipòsits carbonosos, el que dificulta la seva comercialització. Per tant, aquesta tesi té com a objectius fonamentals la millora de l'activitat catalítica i l'estabilitat del catalitzador en la reacció MDA. Els catalitzadors Mo/zeolita són àmpliament utilitzats en la reacció MDA, els quals són bifuncionals, és a dir, els llocs de Mo estan involucrats en la deshidrogenació del metà i la formació de les espècies CHx, les quals es dimeritzen a espècies C2Hy, i els llocs àcids de Brønsted de la zeolita oligomeritzan aquestes espècies C2Hy, formant principalment benzè i naftalè. Per tant, diferents catalitzadors Mo/zeolita es van preparar utilitzant zeolites tant comercials com sintetitzades al laboratori. Observant així que la zeolita i el contingut de Mo utilitzats en el catalitzador afecten significativament el rendiment de la reacció MDA. Tant la topologia i les dimensions dels canals de la zeolita com la seva relació Si/Al i el seu tamany de cristall són també importants en els resultats obtinguts de la reacció MDA. Concretament, el millor rendiment de MDA va ser obtingut pel catalitzador 6%Mo/MCM-22. Es van provar diferents procediments d'activació del catalitzador, obtenint el millor rendiment de la reacció MDA i estabilitat del catalitzador usant una mescla de gasos de CH4: H2, 1: 4 (relació en volum) durant 1 h fins a 700 ºC i mantenint aquesta temperatura durant 2 h. Aquesta activació del catalitzador provoca la pre-carburització i pre-reducció de les espècies de Mo, obtenint les més actives i estables en la reacció de MDA. A més, en la present tesi es va estudiar l'efecte de la velocitat espacial. Els millors resultats de MDA es van obtindre amb 1500 mL¿h-1¿gcat-1, ja que amb majors velocitats espacials el metà gairebé no pot interaccionar amb els llocs catalítics. Mentre que amb menors velocitats espacials la condensació dels hidrocarburs aromàtics pesants es veu afavorida, provocant una major acumulació de coc en el catalitzador. D'altra banda, co-alimentant H2O, H2 i CO2 per separat es va obtindre una major estabilitat tant del catalitzador 6%Mo/HZSM-5 com del 6%Mo/MCM-22, a causa de la supressió parcial del coc dipositat. No obstant això, l'activitat catalítica empitjorà en afegir aquests co-reactius ja que, d'una banda, l'addició d'H2O, H2 i CO2 a l'alimentació de metà és perjudicial termodinàmicament i, d'altra banda, el H2O i el CO2 re-oxiden parcialment les espècies Mo del catalitzador. Termodinàmicament, el H2 provoca un canvi en l'equilibri i, per tant, una disminució de la conversió de metà; l'H2O afavoreix la reacció de reformat de metà i la gasificació de coc; i el CO2 promou la reacció de reformat de metà i la reacció inversa de Boudart. En la present tesi s'ha dut a terme el desenvolupament i la implementació d'un reactor catalític de membrana (CMR) que integra el catalitzador 6%Mo/MCM-22 i la membrana tubular BZCY72. El rendiment de la reacció MDA i l'estabilitat del catalitzador van ser excepcionalment millorats usant aquest CMR imposant un corrent a la cel¿la electroquímica, canviant o no les condicions d'operació estàndard. Aquests bons resultats van ser obtinguts a causa de la simultània extracció d'H2 del costat de reacció i la injecció d'O2 a aquest costat per mitjà de la membrana tubular BZCY72. Així, l'extracció d'H2 es tradueix en un desplaçament de l'equilibri termodinàmic de la reacció MDA, el que causa l'augment de la conversió de metà i alhora del rendiment d'aromàtics. A més, la injecció d'O2 implica la formació d'aigua en baixa concentració, la qual reacciona amb el coc acumulat (gasificació de coc) / Zanón González, R. (2017). Intensification of methane dehydroaromatization process on catalytic reactors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/83124 / TESIS

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