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Thermogravimetric analysis of the degradation of black copolyesters and block copolyamides containing cyclohexane and benzene ringsOkoh, Fred I. 01 December 1982 (has links)
No description available.
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Síntese, caracterização e estudo do comportamento térmico dos 2-metoxicinamalpiruvatos de lantanídeos (III), exceto promécio, e ítrio (III) no estado sólido /Carvalho, Cláudio Teodoro de. January 2010 (has links)
Orientador: Massao Hionashiro / Banca: Lazaro Moscardini D'Assunção / Banca: Nedja Suely Fernandes / Banca: José Marques Luiz / Banca: Salvador Claro Neto / Resumo: Sintetizou-se o ácido 2-metoxicinamalpirúvico (2-MeO-HCP), através da reação de condensação aldólica do 2-metoxicinamaldeído (CH3O-C6H4-(CH)2-CHO), 96 % de pureza com o piruvato de sódio, (Na-2-MeO-CP), 99% puro, ambos da Aldrich. A pureza do ácido 2-metoxicinamalpirúvico sintetizado foi determinada por DSC através do pico de fusão em 125 ºC. O ácido 2-metoxicinamalpirúvico foi convertido a uma solução de aproximadamente 0,15 mol L-1 de 2-metoxicinamalpiruvato de sódio (pH~7,5). Com esse sal foram sintetizados os compostos no estado sólido (Ln-2-MeO-CP.nH2O), sendo que Ln representa os lantanídeos trivalentes e Y(III), 2-MeO-CP o ligante 2-metoxicinamalpiruvato e n o número de moléculas de água com n = 1,5 para o composto de túlio e itérbio e para os demais compostos n = 1. Os Ln-2-MeO-CP.nH2O foram obtidos no estado sólido por adição lenta do ligante aos respectivos cloretos metálicos ou nitratos sob agitação contínua até a total precipitação dos íons metálicos. Os precipitados foram filtrados em papel de filtro Whatman n 42 lavando-se os mesmos com água destilada até a obtenção de teste negativo para cloretos com AgNO3 em meio nítrico e difenilamina para nitratos. Posteriormente os precipitados foram secos em temperatura ambiente e armazenados em dessecador contendo cloreto de cálcio. Técnicas instrumentais utilizadas no estudo dos compostos: Termogravimetria e Análise Térmica Diferencial Simultânea (TG-DTA) e Calorimetria Exploratória Diferencial (DSC) e Complexometria com EDTA (padrão de 1,000 x 10-2 mol L-1 ) forneceu informações sobre grau de hidratação, comportamento térmico e estequiometria; Difratometria de Raios X pelo método do pó, informações da cristalinidade e Espectroscopia de Absorção na Região do Infravermelho sugeriu a forma de coordenação dos compostos sintetizados. Na caracterização do ácido... (resumo completo, clicar acesso eletrônico abaixo) / Abstract: The 2-methoxycinnamylidenepyruvic acid (2-MeO-HCP) was synthesized through the reaction of aldolic condensation of 2-methoxycinnamaldehyde (CH3O-C6H4-(CH) 2-CHO), 96% purity, with sodium pyruvate, (Na-2 - MeO-CP) 99% pure, both from Aldrich. The purity of 2-methoxycinnamylidenepyruvic synthesized was determined by DSC through the melting peak at 125 ºC. The 2-methoxycinnamylidenepyruvic acid was converted to a solution of about 0.15 mol L-1 of the sodium 2-methoxycinnamylidenepyruvate (pH ~ 7.5). With this salt were synthesized the solid compounds (Ln-2-MeO-CP.nH2O), where Ln represents trivalent lanthanides and Y (III), 2-MeO-CP is the methoxycinnamylidenepyruvate ligand and n the number of water molecules with n = 1.5 for the compound thulium, ytterbium and for the other compounds, n = 1. The Ln-2-MeO-CP.nH2O were obtained in the solid state by slow addition of the ligand to the respective metal chlorides or nitrates on continuous stirring until total precipitation of metal ions. The precipitates were filtered through filter paper Whatman number 42, washing them with distilled water to obtain a negative test for chloride with AgNO3 in nitric acid and diphenylamine to nitrates. Subsequently the precipitates were dried at room temperature and stored in a desiccator containing calcium chloride. Instrumental techniques used in the study of compounds: Thermogravimetry and differential thermal analysis (TG-DTA), Differential Scanning Calorimetry (DSC) and Complexometry with EDTA (standard padrão de 1,000 x 10-2 mol L-1 ) provided information on degree of hydration, thermal behavior and stoichiometry; X-ray Diffractometry by the method of powder provided information about crystallinity, and Absorption Spectroscopy in the Infrared Region suggested the form of coordination of the compounds synthesized. In the characterization of 2-methoxycinnamylidenepyruvic, apart from the DSC... (Complete abstract click electronic access below) / Doutor
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Investigating Thermal Transformations of Ligand-Stabilized Gold Nanoparticles: Influence of the Structural Attributes of the Nanoparticle and Its Environment on Thermal StabilitySmith, Beverly 18 August 2015 (has links)
Ligand-stabilized metal nanoparticles (LSNPs) have garnered significant attention for use in applications including sensing, catalysis, and thin film fabrication. Many uses rely on the size-dependent properties of the metal nanoparticle core. Therefore, preservation of nanoparticle core size is of paramount importance. In other uses, the low processing temperatures afforded by metal LSNPs make them attractive as precursors for conductive thin films. In these distinctly different applications, understanding nanoparticle thermal stability is crucial.
A key finding of this research is that nanoparticle sintering is dependent upon both core size and ligand functionality. Multi-technique analysis of four types of gold nanoparticles (AuNPs) with different ligand compositions and core sizes illustrates that more volatile ligands reduce the onset temperature for sintering. Also, AuNPs of larger core size with the same ligand composition exhibit lower sintering onset temperatures. Correlation between measurements reveals that only a small amount of ligand loss is necessary to trigger rapid sintering and that ligands are excluded to the surface of the porous gold films.
AuNPs with ligand shells composed of two alkanethiols of different chain length and volatility indicate that the onset temperature of sintering can be tuned further through incorporation of a small amount of more volatile alkanethiol into a ligand shell of lower volatility. Mixed LSNPs further reveal that AuNP thermal stability depends upon the ligand shell composition and its intermolecular interactions, which can result in markedly different sintering behavior for different ligand compositions. Long-chain alkanethiol AuNPs sinter after only a small amount of ligand loss, whereas short-chain alkanethiol AuNPs sinter following complete ligand loss and the formation of metastable bare AuNPs. Heated AuNP films prepared with mixed-ligand AuNPs exhibit ligand-dependent differences in film morphology.
To probe AuNP thermal stability in 2D-assemblies, self-assembly using larger ‘marker’ nanoparticles enables the study of small 1.5 nm AuNP arrays with successive TEM monitoring throughout ex situ heating. Monitoring images of the same area shows short-range (1-2 nm) nanoparticle migration/coalescence. In contrast to 3D assemblies, AuNP growth occurs at temperatures as low as 60 °C.
This dissertation includes previously published and unpublished co-authored material. / 10000-01-01
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Um estudo da sorção de \'SO IND.2\' por calcário em analisador termogravimétrico e na combustão de carvão em leito fluidizado / A Study of the \'SO IND.2\' sorption by limestone in thermogravimetric analyser and coal combustion in fluidized bedÁvila, Ivonete 29 August 2008 (has links)
Nesta tese investiga-se a sorção de \'SO IND.2\' por um calcário dolomítico brasileiro em duas diferentes configurações experimentais: um analisador termogravimétrico e um combustor de carvão em leito fluidizado atmosférico borbulhante. Os experimentos termogravimétricos foram realizados em condições tão próximas quanto possível àquelas observadas no processo de combustão em leito fluidizado. Coeficientes intrínsecos de taxa de reação, efetividades e conversões foram determinados através de termogravimetria em atmosfera contendo 65% de ar sintético, 15% de \'CO IND.2\' e 20% de \'SO IND.2\', para quatro diferentes granulometrias do calcário dolomítico (385, 545, 725 e 775 µm) em quatro diferentes temperaturas de processo (800, 830, 860 e 890 graus Celsius). Os coeficientes intrínsecos de taxa de reação, na condição de máxima taxa de reação, resultaram entre 3,86 x \'10 POT.-3\' e 7,07 x \'10 POT.-3\' m/s. As efetividades médias para 200 segundos de reação resultaram entre 0,37 e 0,49/s. As conversões após 600 segundos de sulfatação resultaram entre 0,40 e 0,49 kmol(\'SO IND.2\')/kmol(\'CA\'+\'MG\') . Nos experimentos em combustor de leito fluidizado obteveram-se coeficientes globais de taxa de reação, conversões e eficiência de sorção de \'SO IND.2\'. Considerou-se um calcário dolomítico em cinco diferentes granulometrias médias (385, 545, 718, 725 e 775 µm) e um carvão mineral brasileiro (CE4500) com granulometria média de 385 µm. Aplicaram-se temperaturas entre 798,2 e 886,6 graus Celsius, U/Umf entre 5,6 e 10,8 m/s, e relações molares (\'CA\'+\'MG\')/S na alimentação entre 3,7 e 11,9 kmol(\'CA\'+\'MG\')/kmol(s). O coeficiente global de taxa de reação resultou entre 0,009 e 0,072 m/s, a conversão resultou entre 0,020 e 0,064 kmol(\'SO IND.2\')/kmol(\'CA\'+\'MG\'), e a eficiência de sorção de \'SO IND.2\' resultou entre 46,4 e 83,9%. Os coeficientes globais de taxa de sulfatação obtidos em leito fluidizado foram comparados com os coeficientes intrínsecos de taxa de reação obtidos via termogravimetria. Concluiu-se que condições termogravimétricas mais realistas são necessárias para que a composição de coeficientes de taxa de reação intrínsecos e globais permita análises de controle de reação em reatores de leito fluidizado. / This thesis investigates the sorption of \'SO IND.2\' by a brazilian dolomite in two different experimental setups: a thermogravimetric analyzer and an atmospheric bubbling fluidized bed coal combustor. The thermogravimetric experiments were carried out in conditions as close as possible to those observed in the fluidized bed combustion process. Intrinsic coefficient of reaction rate, effectiveness and conversion were determined through thermogravimetry in synthetic atmosphere containing 65% of air 15% of \'CO IND.2\' and 20% of \'SO IND.2\' for four different dolomite particle sizes (385, 545, 725 and 775 µm) and four different temperatures (800, 830, 860 and 890 Celsius degrees). The results of the intrinsic reaction rate coefficient in the maximum reaction rate conditions were between 3.86 x \'10 POT.-3\' and 7.07 x \'10 POT.-3\' m/s, while the resuls of the average effectiveness for 200 seconds of reaction were between 0.37 and 0.49/s. The values of conversion after 600 seconds of sulfation were between 0.40 and 0.49 kmol(\'SO IND.2\')/kmol(\'CA\'+\'MG\') . Global reaction rate coefficient, conversion and \'SO IND.2\' sorption efficiency were obtained from the fluidized bed combustor experiments for five different dolomite particulate sizes (average diameters of 385, 545, 718, 725 and 775 µm) and a brazilian coal (CE4500) with particle size of 383 \'mü\'m. Temperatures between 798.2 and 886.6 Celsius degrees, U/Umf between 5.6 and 10.8 m/s, and (\'CA\'+\'MG\')/S molar feeding ratios between 3.7 and 11.9 kmol(\'CA\'+\'MG\')/kmol(s) were applied. The results of the global reaction rate coefficient were between 0.009 and 0.072 m/s, the ones of the conversion were between 0.020 and 0.064 kmol(\'SO IND.2\')/kmol(\'CA\'+\'MG\'), and those of the \'SO IND.2\' sorption efficiency were between 46.4 and 83.9%. The global sulfation rate coefficients obtained in fluidized bed were compared to the intrinsic reaction rate coefficients obtained through thermogravimetry. It was concluded that more realistic thermogravimetric conditions are required so that the composition of intrinsic and global reaction rate coefficients can allow for the analyses of reaction rate control in fluidized bed reactors.
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Pirólise de resíduos de embalagens cartonadas e seus componentes puros : uma avaliação cinéticaAlvarenga, Larissa Machado 06 September 2013 (has links)
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Previous issue date: 2013-09-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Muitos processos têm sido utilizados para a reciclagem dos resíduos de embalagens cartonadas. A pirólise se destaca como uma tecnologia promissora capaz de separar o alumínio do polietileno e gerar produtos com maior poder calorífico. Neste trabalho, realizou-se um estudo das reações de pirólise dos resíduos cartonados e de seus componentes puros, a fim de estimar os parâmetros cinéticos destas reações. Para isto, análises termogravimétricas isotérmicas e dinâmicas foram realizadas e dois diferentes tipos de modelos cinéticos foram
utilizados: os isoconversionais e o das reações paralelas independentes (RPI). Os modelos isoconversionais permitiram calcular a energia de ativação global da reação de pirólise dos materiais, de acordo com as suas conversões. Os valores de
energia de ativação obtidos com os modelos de Ozawa, K-A-S e Starink para a pirólise das embalagens cartonadas foram semelhantes (168,30; 166,54 e 166,78 kJ.mol-1), assim como aqueles encontrados para o polietileno (137,41; 132,49;
132,98 kJ.mol-1) e para o papel cartão (155,66; 153,46; 153,69 kJ.mol-1). Entretanto, o método de Kissinger estimou menores valores de energia de ativação para as embalagens cartonadas (121,42 kJ.mol-1) e para o papel cartão (144,89 kJ.mol-1), e um maior valor para a energia de ativação do polietileno (155,15 kJ.mol-1). O modelo RPI, por sua vez, permitiu calcular os parâmetros cinéticos de cada um dos
subcomponentes da embalagem cartonada e do papel cartão. Os valores estimados para os parâmetros cinéticos dos subcomponentes dos materiais permaneceram dentro da faixa de valores encontrada na literatura. A perda de massa dos materiais simulada com o modelo RPI apresentou um bom ajuste aos dados experimentais obtidos por termogravimetria, com valores de desvios na mesma ordem de grandeza daqueles encontrados em outros trabalhos na literatura. Foi realizada
ainda, uma análise de sensibilidade paramétrica do modelo RPI, através da qual se pode verificar que a energia de ativação afetou a conversão total dos materiais de forma mais acentuada do que o fator pré-exponencial. Em geral, este trabalho contribuiu na avaliação da qualidade dos ajustes dos modelos cinéticos utilizados e para o cálculo dos parâmetros cinéticos da pirólise dos materiais / Many processes have been used for recycling of carton packaging wastes. The pyrolysis highlights as a promising technology to be used for recovering the aluminum from polyethylene and generating products with high heating value. In this research, a study on pyrolysis reactions of carton packaging wastes and its pure components was performed in order to estimate the kinetic parameters of these reactions. For this, dynamic and isothermal thermogravimetric analyses were carried out and two different kinds of kinetic models were used: the isoconversional and Independent Parallel Reactions (IPR). Isoconversional models allowed to calculate the overall activation energy of the material pyrolysis reaction, in according to their conversions. The activation energy values obtained with Ozawa, KAS and Starink models for carton packaging pyrolysis were similar (168.30, 166.54 and 166.78
kJ.mol-1), as well as the results found for polyethylene (137.41, 132.49, 132.98 kJ.mol-1) and cardboard (155.66, 153.46, 153.69 kJ.mol-1). Nevertheless, the Kissinger method the method of Kissinger estimated lower values of activation
energy for carton packaging (121.42 kJ.mol-1) and cardboard (144.89 kJ.mol-1), and a higher value for polyethylene activation energy (155.15 kJ.mol-1). The IPR model, in turn, allowed the calculation of kinetic parameters of each one of the carton packaging and paperboard subcomponents. The estimated values for the kinetic parameters of the material subcomponents were within the range of values found in
the literature. The mass loss of materials simulated with the RPI model showed a good fit to the experimental data obtained by thermogravimetry, presenting deviation values in the same order of magnitude as those found in other literature studies. It was also performed a parametric sensitivity analysis of IPR model, that shown that the activation energy affected the total conversion of the material more strongly than the pre-exponential factor. In general, this work contributed to the quality evaluation of the kinetic models adjustment and for the calculation of the kinetic parameters of material pyrolysis
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Estudo da pirólise da microalga Chlorrella Vulgaris: determinação das classes de produtos e dos parâmetros cinéticos. / Pyrolysis study of microalgae Chlorella vulgaris: determination of classes of products and kinetic parameters.Rodrigues, Tâmira Tácita Maia 11 April 2017 (has links)
A crescente necessidade de se obter fontes de energia e materiais mais sustentáveis tem aumentado o interesse em processos baseados na conversão de biomassa. Microalgas são particularmente interessantes por não competirem com alimentos e serem facilmente adaptáveis ao meio de crescimento. Além disso, microalgas podem ser processadas termicamente para geração tanto de biocombustíveis quanto de produtos químicos úteis. Estudos de conversão térmica de microalgas tem aparecido apenas em anos recentes, endereçando principalmente temperaturas entre 350 e 500 ºC. Neste estudo, a pirólise em temperaturas entre 500 e 900 ºC foi avaliada pelo interesse em se obter biocombustíveis e produtos químicos úteis. As classes de compostos obtidos a partir da pirólise isotérmica da microalga da espécie Chlorella vulgaris foram investigadas através de um sistema composto por um pirolisador conectado a um CG/MS. Dentre as classes identificadas, houve uma predominância de compostos aromáticos e nitrogenados, principalmente derivados de proteínas. Além disso, a maioria dos compostos identificados na corrente de produtos voláteis está presente em todas as temperaturas de reação estudadas. Os parâmetros cinéticos de energia de ativação aparente, constante de reação e ordem de reação foram determinados através de três modelos cinéticos conhecidos como K-A-S, Osawa e Freeman-Carroll, a partir de dados termogravimétricos. A energia de ativação determinada para Chlorella apresentou valores entre 60 e 206 kJ/mol, enquanto a ordem de reação teve como resultado valores entre segunda e décima ordem, de acordo com o modelo cinético. / The increasing need to obtain more sustainable sources of energy and raw materials has attracted attention to processes based on biomass conversion. Microalgae are particularly interesting because they do not compete with human food and they are easily adaptable to the growth medium. Besides, microalgae can be thermally processed to produce both biofuels and useful chemicals. Studies on thermal conversion of microalgae have appeared only in recent years, addressing mainly reaction temperatures between 350 and 500 °C. In this study, pyrolysis in temperatures ranging from 500 to 900 ºC have been investigated considering the interest in producing biofuels and useful chemical compounds. The classes of products obtained by isothermal pyrolysis of the Chlorella vulgaris microalgae have been investigated using a pyrolyzer directly connected to a GC/MS system. Among the classes identified, there was a predominance of aromatic and nitrogenous compounds, mainly protein derived compounds. In addition, most products identified in the volatile products stream are present in all reaction temperatures investigated. The kinetic parameters of apparent activation energy, reaction constant and order of reaction were determined through three kinetic models known as K-A-S, Osawa and Freeman-Carroll, calculated from thermogravimetric data. The activation energy for Chlorella presented values within the range of 60 and 206 kJ/mole, while the order of reaction resulted in values between second and tenth order, from the different methods.
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Measurement of gas evolution from PUNB bonded sand as a function of temperatureSamuels, Gregory James 01 July 2011 (has links)
The chemical binders used to make sand molds and cores thermally decompose and release gas when subjected to the high temperature conditions in sand casting processes. Computational models that predict the evolution of the binder gas are being introduced into casting simulations in order to better predict and eliminate gas defects in metal castings. These models require knowledge of the evolved binder gas mass and molecular weight as a function of temperature, but available gas evolution data are limited. In the present study, the mass and molecular weight of gas evolved from PUNB bonded sand are measured as a function of temperature for use with binder gas models. Thermogravimetric analysis of bonded sand is employed to measure the binder gas mass evolution as a function of temperature for heating rates experienced in molds and cores during casting. The volume and pressure of gas evolved from bonded sand are measured as a function of temperature in a specially designed quartz manometer during heating and cooling in a furnace. The results from these experiments are combined with the ideal gas law to determine the binder gas molecular weight as a function of temperature. Thermogravimetric analysis reveals that the PUNB binder significantly decomposes when heated to elevated temperatures, and the PUNB binder gas mass evolution is not strongly influenced by heating rate. During heating of PUNB bonded sand at a rate of 2°C/min, the binder gas molecular weight rapidly decreases from 375 g/mol at 115°C to 99.8 g/mol at 200°C. The molecular weight is relatively constant until 270°C, after which it decreases to 47.7 g/mol at 550°C. The molecular weight then steeply decreases to 30.3 g/mol at 585°C and then steeply increases to 47.2 g/mol at 630°C, where it remains constant until 750°C. Above 750°C, the binder gas molecular weight gradually decreases to 33.3 g/mol at 898°C. The present measurements are consistent with the molecular weights calculated using the binder gas composition data from previous studies. The binder gas is composed of incondensable gases above 709°C, and the binder gas partially condenses during cooling at 165°C if the bonded sand is previously heated below 507°C.
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The Influence of Rolling Oil Decomposition Deposits on the Quality of 55Al-43.4Zn-1.6Si Alloy CoatingsPillar, Rachel Joanne, rachel.pillar@flinders.edu.au January 2007 (has links)
Uncoated defects in hot dip metal-coated steel products result from non-wetting of the steel surface by the molten alloy. The occurrence of uncoated defects is highly detrimental to product quality and production efficiency; uncoated defects compromise the appearance and anti-corrosion performance of hot dip metal-coated steel products and causes time delays in the application of subsequent surface treatments. Although many studies have been directed towards evaluating the effect of steel pre-heat temperature and oxidation on the formation of uncoated defects, fewer investigations have analysed how oil-derived residues remaining on steel surface following the cold rolling and furnace cleaning processes impact upon hot dip metallic coating quality. Furthermore, although a considerable amount of research has focussed on the process of deposit formation in lubricants used in other applications, the composition of oily residues remaining after the continuous annealing process, and the origins of these residues in the original rolling oil formulation, are poorly understood.
The primary focus of the present work has been to gain an improved understanding of relationships between cold rolling oil composition, oil residue-formation characteristics and the occurrence of uncoated defects in 55Al-43.4Zn-1.6Si hot dip metallic coatings. Several key classes of rolling oil ingredients which decompose to leave high levels of thermally-stable residue have been identified. The thermal decomposition processes undergone by a variety ingredients within these classes have been studied under both oxidising and reducing conditions using Thermogravimetric Analysis (TGA) and Pressure Differential Scanning Calorimetry (PDSC) techniques, with chemical characterisation of the decomposition process and the resultant thermally-stable residue by infrared spectroscopy. Model blends of each ingredient in a typical cold rolling oil base ester have also been evaluated by TGA and PDSC to identify the impact of ingredient concentration and chemical structure on the amount of oily residue formed. The results of these investigations have been related to the impact of the ingredients on 55Al-43.4Zn-1.6Si hot dip metallic coating quality through the performance of industrial-scale hot dipping trials and hot dip simulation studies.
In order to translate these results into a context more closely aligned with industrial conditions, the effect of processing variables, including furnace atmosphere and the availability/concentration of iron in contact with the rolling oil at the steel surface, on the decomposition process of a fully-formulated commercial cold rolling oil has also been investigated. The information gained can potentially be used to tailor operating conditions within the cold rolling/continuous hot dip metallic coating processes to enhance steel surface cleanliness.
Finally, the deposit-forming tendencies of an array of different commercial cold rolling oils have been evaluated, leading to the development of a thermal analysis-based test for screening cold rolling oils with respect to their likely impact upon 55Al-43.4Zn-1.6Si hot dip metallic coating quality. This test, together with the understanding obtained on the effect of different rolling oil ingredients on hot dip metallic coating quality, can be used within the industry to formulate improved cold rolling oils.
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Hydro/Solvothermal Synthesis, Structures and Properties of Metal-Organic Frameworks Based on S-Block MetalsVakiti, Raj Kishore 01 May 2012 (has links)
Carbon dioxide removal from flue gases of power plants is critical for reduction of greenhouse gas emissions implicated in global warming. Metal Organic Frameworks (MOFs) promising potential applications in carbon dioxide capture due to their unique structural properties such as high porosity and high thermal stability. These MOFs have application in separation processes and gas storage. By the assembly of the organic ligands and metal oxide clusters, porous MOFs can be synthesized. The use of s-block metals such as calcium, magnesium and rubidium in porous materials is appealing because their ionic binding characters with organic ligands will general flexible MOFs. The bonding interaction of s-block metal centers with carboxylate oxygen atoms is mainly ionic in nature due to large differences in electronegativity. The s-block elements can form low density frameworks which could increase the gas uptake capacity of small molecules.
This work focuses on synthesis of new metal organic frameworks (MOFs) using s-block metals. Different types of the carboxylic ligands were utilized for synthesis of MOFs. Four new calcium or rubdium metal organic frameworks, [Ca3(btc)2(H2O)12] (1) and [Ca2(btc)(pzc)(H2O)3] (2) (btc=benzene-1,3,5-tricarboxylate, pzc = pyrazine-2- carboxylate), [Ca(Hbtc)(H2O)]•H2O (6), and [Rb(Hbdc)] (7) have been synthesized using the hydro/solvothermal method and have been characterized using X-ray diffraction, IR, UV-vis, TGA and fluorescence analysis. The structures of compounds 1, 6 and 7are three-dimensional frameworks while that of compound 2 is a double layered network.
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Kinetic Modeling of the Adsorption of Mercury Chloride Vapor on Spherical Activated Carbon by Thermogravimetric AnaylysisCHEN, WEI-CHIN 25 August 2004 (has links)
This study investigated the adsorptive capacity and isotherm of HgCl2 onto spherical activated carbons (SAC) via thermogravimetric analysis (TGA). Activated carbon injection (ACI) is thought as the best available control technology (BACT) for mercury removal from flue gas. There are two major forms of vapor-phase mercury, Hgo and Hg2+, of which HgCl2 accounts for 60-95% of total mercury. Mercury emitted from the incineration of municipal solid wastes (MSW) could cause severely adverse effects on human health and ecosystem since it exists mainly in vapor phase due to high vapor pressure. Although the adsorptive capacity of HgCl2 onto activated carbon has been studied in previous adsorption column tests, only a few studies have thoroughly investigated the adsorption isotherms of HgCl2 onto SAC.
Equilibrium and kinetic studies are important towards obtaining a better understanding of mercury adsorption. Many investigations have addressed the relationship between sorption kinetics and equilibrium for different adsorbent/adsorbate combinations. For the removal of vapor-phase mercury, several bench-pilot, and full-scale tests have be proceeded to examine the influence of carbon types, carbon structures, carbon surface characteristics, injection methods (dry or wet), amount of carbon injected, and flue gas temperature on mercury removal. In addition, the dynamics of spherical activated carbons (SAC) adsorbers for the uptake of gas-phase mercury was evaluated as a function of temperature, influent concentration of mercury, and empty-bed residence time. However, only a few studies investigated the adsorption isotherms of HgCl2 onto activated carbons.
In this study, TGA was applied to obtain the adsorptive capacity of HgCl2 onto SAC with adsorption temperature (30~150oC) and influent HgCl2 concentration (50~1,000£gg/m3). Experimental results indicated that the adsorptive capacity of HgCl2 onto SAC was 0.67and 0.20 mg/gC at 30¡B70 and 150oC, respectively. This study investigated the adsorptive capacity of HgCl2 vapor onto SAC via TGA analysis. Experimental results indicated that the adsorptive capacity of SAC decreased with the increase of the adsorption temperature. Furthermore, the results suggested that that the adsorption of SAC on HgCl2 vapor was favorable equilibrium at 30 and 70¢J and unfavorable equilibrium at 150¢J. In comparison of the experimental data with isotherm equations, Freundlich isotherm fitted the experimental results better than Langmuir isotherm. The model simulations were found to fit very well to the high concentration experimental kinetic data for both adsorption and desorptionusing two adjust parameter, effective diffusivity, and the Freundlich isothermexponent.¡@The extracted model parameter, effective diffusivity and n, were then used to predict the experimental kinetic data for the same combination at other concentrations.
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