Made available in DSpace on 2015-05-14T13:21:44Z (GMT). No. of bitstreams: 1 parte1.pdf: 1266396 bytes, checksum: a4c7a57bd0fd6230873b3e69c5c52c4f (MD5) Previous issue date: 2010-12-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Molecular sieves have been applied to the processing of triacylglycerols, to produce biofuels. In this context, the mesoporous catalyst Al-MCM-41 was proposed in this work as an alternative to acid heterogeneous transesterification of cottonseed oil with ethanol. This material was prepared using various Si/Al molar ratios (25, 50, 75 and 100) with reaction times of 8, 10, 12 or 14 hours at 170°C. The solids were characterized by XRD, FTIR, 29 Si and 27Al MAS NMR, TG/DTA and nitrogen adsorption, which confirmed the mesoporous phase and allowed an estimate of the acidity associated whit the increase of aluminum content in the structure of MCM-41. The catalytic runs were carried out in a PAAR 4843 reactor, with an oil:ethanol molar ratio of 1:9 and catalyst loading of 1,5% at 200°C for 0-180 min; the reaction product was characterized by gas chromatography and 1H and 13C NMR. Gas chromatographic analysis, shoed that the conversion to ethyl esters is linearly dependent on catalyst loading, and Al-MCM-41 (Si/Al=50) was the most active material under the conditions tested. The results of GC-FID and 1H NMR analysis were corroborated by thermal analysis (TGA) and FTIR measurements, which were used to evaluate the Brønsted acidity of the materials. Overall, the yeld of the fatty acid ethyl ester (FAEE) transesterification increased with an increase in catalyst acidity. / Peneiras moleculares têm sido aplicadas para o processamento de triacilgliceróis, visando à produção de biocombustíveis. Nesse contexto, no presente trabalho, o catalisador mesoporoso Al-MCM-41 foi proposto como uma alternativa para a transesterificação ácida heterogênea do óleo de algodão com etanol. Esse material foi preparado variando a razão molar Si/Al (25, 50, 75 e 100) nos tempos de 8, 10, 12 e 14 horas sob temperatura de 170°C. Os sólidos obtidos foram caracterizados por DRX, FTIR, RMN MAS 29Si e 27Al, TG/DTA e área superficial por adsorção de nitrogênio, de modo que se pôde confirmar a fase mesoporosa e estimar a acidez gerada do incremento de alumínio na estrutura do MCM-41. O teste catalítico foi realizado num reator PAAR 4843, com razão molar óleo:etanol de 1:9, 1,5% de catalisador, a 200°C nos tempos de 0-180 min., sendo o produto obtido caracterizado por cromatografia gasosa e RMN 1H e 13C. Através da análise cromatográfica pôde-se verificar que os catalisadores apresentaram perfis lineares de conversão em etil ésteres, sendo o Al-MCM-41 (Si/Al=50) o material mais ativo nas condições utilizadas. Os resultados observados por CG-FID e RMN 1H, foram corroborados pela análise térmica (TG) e FTIR previstos para a geração de acidez de Bronsted, mostrando que o rendimento em FAEE da reação de transesterificação etílica aumenta com o incremento da acidez nos catalisadores.

Orientador: Carlos Alberto Luengo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-05T03:13:34Z (GMT). No. of bitstreams: 1 Capobianco_Gino_D.pdf: 12351248 bytes, checksum: f4842f51b128dadf5f45b6fa8ce145c4 (MD5) Previous issue date: 2005 / Resumo: Este trabalho consiste no estudo de um processo híbrido para obtenção de peneiras moleculares de carbono (PMC) a partir de madeiras e ou resíduos agrícolas tais como: casca de macadâmia e mesocarpo do coco verde que são insumos de origem renovável. A seguir descrevem-se as seguintes etapas do processo: seleção e conformação da matéria-prima; carbonização e pré-ativação (envolvendo tecnologias convencionais de ativação física ou química) e finalmente a obtenção de PMC em um reator de plasma com catodo oco para ativação. O estudo incluiu o projeto e construção de equipamentos para sua implementação em uma unidade piloto, a realização dos testes operacionais, a apreciação da influência dos parâmetros de processo (monitorados com caracterizações dos precursores em cada etapa) até a obtenção das PMC. Também a avaliação de possíveis aplicações em indústrias energo intensivas (eletro-metal e químicas), realizou-se através de estudo de caso (a remoção de metais pesados nos efluentes industriais), comparando o desempenho das PMC com os de amostras comerciais disponíveis no mercado. Finalmente, para análise da viabilidade técnico-econômico-financeira, foram realizados um levantamento da evolução da exportação e importação de carvão ativado (CA) no Brasil, sua demanda e oferta, assim como aquelas dos principais consumidores (setor industrial e setores ligados ao saneamento básico e saúde). Observa-se a que o país é auto-suficiente na produção do CA convencional, entretanto a produção de CAs com características e propriedades especificas, tipo PMC, ainda é incipiente, sendo necessário à importação de 3.000 toneladas/ano. Então, para a realização dos cálculos considera-se a capacidade de atender inicialmente, até 10 % da demanda nacional, correspondente a uma planta industrial de 300 toneladas/ano. As PMC produzidas podem ser utilizadas nas mais diversas aplicações, tais como: tratamento de efluentes líquidos e gasosos, tanques de sorção para remoção e recuperação de solventes orgânicos, entre outras. Por isso este projeto insere-se, no desenvolvimento de novas tecnologias para o país / Abstract: This work is presented an study of a hybrid process to obtain carbon molecular sieves (CMS) from pine wood or agricultural residues such as macadamia shell or green coconut mesocarp, alI of them are renewable precursors. This process embraces the following stages: selection and conformation of the raw material, carbonization and pré-activation, involving conventional physical or chemical activation technologies, finally activation using the hollow cathode plasma technology to obtain the CMS. The experimental part included design and equipment construction for implementation in a pilot unit, including operational tests, studies of the influence of process parameters, monitored with characterizations of the precursors in each stage, until obtaining CMS. To evaluate possible applications in intensive energy industries such as metal-electric industries or chemistries it was developed a case study in which the CMS efficiency for the removal of heavy metaIs in the industrial effluents was compared with that obtained using samples commercially available. For analyzing the techno economic feasibility, it was obtained the historical evolution of export and import quantities of activated carbon (AC) in Brazil, the evolution of demand and offer, as well as those of main consumer sections, industrial section and those related to basic sanitation and health.Through this analysis, it was observed that the country is self-sufficient in the production of the conventional AC, however the production of AC with special characteristic and properties, like CMS, is still incipient, being needed to import around 3.000 ton/year. Thus, the calculations are for a manufacturing capacity capable to attend up to 10% of the demand, corresponding to an industrial plant with a capacity for CMS production of 300 ton/year. The produced CMS has several applications, such as: treatment of liquid and gas effluents, sorption tanks for removal and recovery of wasted organic solvents, among others. So, this whole work, may be thought as the development of a new technology for the country / Doutorado / Doutor em Planejamento de Sistemas Energéticos

Orientadores: João Alexandre Ferreira da Rocha Pereira, Celio Loureiro Cavalcante Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-07T04:00:20Z (GMT). No. of bitstreams: 1 Lucena_SebastiaoMardonioPereirade_D.pdf: 7623397 bytes, checksum: 81ccae9f0728f1f2c499cc1d4fadbef6 (MD5) Previous issue date: 2006 / Resumo: Devido a grande importância dos processos industriais de separação de xilenos por adsorção, técnicas de simulação molecular foram usadas para estudar as causas da orto-seletividade de isômeros C8 em peneiras moleculares aluminofosfatadas. Aplicaram-se campos de força aproximados e otimizados do tipo AA no ensemble grande canônico com algoritmos Monte Carlo (GCMC) convencional e dirigido. Foram calculadas isotermas monocomponentes, calores de adsorção a baixa concentração e realizamos uma detalhada análise estrutural para definir sítios de adsorção e posicionamentos moleculares nos poros das peneiras AlPO4-5, AlPO4-8, AlPO4-11 e VPI-5. Obteve-se acordo quantitativo entre as isotermas experimentais e simuladas para o sistema xilenos/AlPO4-5 e um acordo qualitativo para o sistema xilenos/AlPO4-11. A análise estrutural levou em conta as variações no interior dos poros dos aluminofosfatos que ocorre em duas regiões: uma mais larga, denominada região de grades, e outra mais estreita, que corresponde à região de janelas. A orto-seletividade evidenciada experimentalmente é causada pela forte interação xileno-peneira e pela modulação dos canais. Este conjunto de fatores determina o posicionamento das moléculas dentro dos poros. Para o orto-xileno este microambiente provoca um posicionamento face-a-face na região das grades, enquanto o para-xileno posiciona-se verticalmente nas janelas. É esta diferença de posicionamento que origina o fenômeno da orto-seletividade para as peneiras AlPO4-5, AlPO4-8 e VPI-5. Nas simulações com o-xileno, o AlPO4-8 apresenta uma fração de posicionamentos face-a-face e por isso, apresentou capacidade de adsorção em média 14% maior para o o-xileno. O VPI-5 não apresentou adsorção preferencial para nenhum dos xilenos devido o não favorecimento da posição face-a-face. No AlPO4-11 a orto-seletividade se dá por um menor comprimento da molécula de o-xileno na direção cristalográfica c. Uma forte interação entre os radicais metila dos xilenos e os oxigênios da grade foi identificada com base na análise estrutural. Propõe-se que esta interação provoque deformações e/ou mudança de estrutura na peneira AlPO4-11. Na segunda parte do trabalho analisou-se o comportamento de moléculas cíclicas, lineares e ramificadas quanto ao posicionamento e sítios de adsorção utilizando-se as mesmas técnicas de simulação molecular. Benzeno, ciclohexano, o-xileno, butano, n-pentano, n-hexano, 2-metil-butano e 2,4-dimetil-butano foram estudados em AlPO4-5 com diferentes modelos de campos de força. Foram utilizados campos de força AA, UA e AUA todos no ensemble grande canônico com o algoritmo GCMC convencional. A análise estrutural mostrou que as moléculas de benzeno posicionam-se tanto face-a-face como paralelamente ao eixo cristalográfico c. Ao contrário do que a literatura propunha, o ciclohexano não apresentou nenhum tipo de ordenação particular, seu posicionamento variou de forma caótica ao longo dos poros do AlPO4-5. As moléculas de benzeno e ciclohexano se mostraram muito mais sensíveis às alterações do campo de força que o o-xileno. Esta sensibilidade pode estar relacionada à condição geométrica crítica denominada efeito levitação. As moléculas de n¿hexano adsorvem preferencialmente na região das janelas e o butano na região de grades. Elas posicionam-se respectivamente, paralelamente e horizontalmente com relação ao eixo cristalográfico c. As moléculas ramificadas testadas posicionam-se horizontalmente com relação ao eixo c na região de grades. O n-pentano apresentou um comportamento complexo quanto a posicionamentos e sítios de adsorção. Este comportamento complexo pode também estar relacionado ao efeito levitação. Em todos os modelos testados uma forte interação entre os grupos metila das extremidades das moléculas e os oxigênios das grades influenciou o posicionamento e os sítios de adsorção / Abstract: Molecular simulation techniques were used to study the ortho-selectivity causes of C8 isomers in aluminophosphate molecular sieves structures. Approximated and optimized force fields of the AA type were applied in the grand canonical ensemble with biased and conventional Monte Carlo algorithms (GCMC). We simulated pure-components isotherms, adsorption heats at low loading and made a detailed structural analysis to define adsorption sites and molecular positionings in the AlPO4-5, AlPO4-8, AlPO4-11 and VPI-5 pores. We obtained quantitative agreement between experimental and simulated isotherms for the system xylenes / AlPO4-5 and a qualitative agreement for the system xylenes/AlPO4-11. The structural analysis of the adsorbed phases was performed considering the dimensional variations inside the aluminophosphates pores that are composed of two regions: a wide region (fences) and a narrow region that corresponds to the 12-ring oxygen windows areas. The ortho-selectivity experimentally evidenced was caused by the strong interaction xylene-sieve and the channels modulation. These two factors determine the molecules positioning inside the pores. For ortho-xylene this micro-environment provokes a face-to-face positioning in the wide regions, while para-xylene was positioned almost parallel to the c-axis in the windows. This positioning difference originates the ortho-selectivity phenomenon for the AlPO4-5, AlPO4-8, and VPI-5 sieves. In the o-xylene simulations, AlPO4-8 presents a fraction of the face-to-face positioning and thus shows a lighter adsorption capacity for o-xylene (14%). In VPI-5 we can not find any fraction of face-to-face position, so it did not present preferential adsorption for none of the xylenes. In AlPO4-11 the ortho-selectivity comes from the o-xylene molecule smaller length in the c-axis direction. A strong interaction between the xylenes methyl radicals and the wide region oxygen atoms, was identified based in the structural analysis. We proposed that this interaction causes deformations and/or structural changes in the AlPO4-11 sieve. In the second part of this study the behavior of cyclic, linear and branched molecules was analyzed with relation to the positioning and adsorption sites. We used the same molecular simulation techniques. Benzene, cyclohexane, o-xylene, butane, n-pentane, n-hexane, 2-methylbutane and 2,4-dimethylbutane were studied in AlPO4-5 with different force field models. We applied AA, UA and AUA force fields in the grand canonical ensemble with the conventional GCMC algorithm. The structural analysis of the cyclic molecules showed that benzene was face-to-face and c-axis parallel positioned. As opposed to other previous studies, cyclohexane did not present any particular order, the molecules positioning in a chaotic way along the pores of AlPO4-5. The benzene and cyclohexane molecules were much more sensible to the kind of force field than o-xylene. This sensibility can be related to the critical geometric condition denominated levitation effect. The n -hexane molecules adsorb preferably in the window region and butane in the wide region. They are positioned respectively, parallel and horizontally to the c-axis plane. The branched molecules are positioned horizontally in the pore wide region. The n-pentane presented a complex behavior in relation to positioning and adsorption sites. This complex behavior can also be related to the levitation effect. In all tested models a strong interaction between the methyl groups of the molecules extremities and the wide region oxygens influenced the positioning and the adsorption sites / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química

"Grupo de peneiras moleculares micro e mesoporosas" / Orientadores: Heloise de Oliveira Pastore, Marco Andre Fraga / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T13:56:16Z (GMT). No. of bitstreams: 1 Ruiz_JuanAlbertoChavez_D.pdf: 9318678 bytes, checksum: 0b11ace77679aab815eebe6b5abaed29 (MD5) Previous issue date: 2005 / Doutorado / Quimica Inorganica / Doutor em Quimica

It is very important today to address the impacts of climate change as its effects can be observed every day. Nowadays many scientists believe that earth's climate is changing as a result of human-caused greenhouse gas emissions such as carbon dioxide and methane. Global energy demand is also rapidly evolving. A sustainable approach that balances economic growth with social and environmental responsibility should be considered as an effective and long-term strategy. Carbon dioxide is the foremost greenhouse gas of anthropogenic origin, responsible for the majority of the earth's warming effects. It is estimated that around 60% of the global warming impact can be traced back to the release of carbon dioxide into the atmosphere. Lowering methane emissions offers a range of notable advantages in terms of energy, safety, economy, and the environment. Firstly, since methane is a potent greenhouse gas (25 times more powerful than CO2 over a 100-year period), reducing methane emissions will contribute significantly to mitigating climate change in the short term. Additionally, methane is the primary component of natural gas and biogas, which means collecting and utilizing methane can be a valuable source of clean energy that fosters local economic growth and minimizes local environmental pollution. Generating energy through methane recovery eliminates the need for traditional energy resources, thus lessening end-user and power plant CO2 and air pollutant emissions. Physical adsorption separation processes have proven to be an effective technique for simultaneous carbon dioxide capture and methane enrichment applications. The objective of this study is to conduct a thorough assessment of the adsorption separation of methane and carbon dioxide gases employing a commercially available carbon molecular sieve, CMS(C), and an activated carbon, AC(B). The accomplishment of the objective involved conducting an in-depth characterization of the adsorbents. Part of the characterization included measurements of the internal surface area and pore size distributions, as well as the measurements of the equilibrium adsorption isotherms using gravimetric techniques. These isotherms enabled detailed kinetic analyses, such as evaluating diffusivity and mass transfer coefficients at various temperatures and pressure steps. The prediction of binary isotherms were based on theoretical models, which can describe the gas mixture adsorption equilibria using pure component equilibrium data. Breakthrough curves were generated to describe the dynamic response of an adsorption column under different pressures, temperatures, and flow rates. A mechanistic model was developed utilizing gPROMS simulation software for adsorption breakthrough process and it was validated by comparing its results to the experimental breakthrough curves. Parametric studies were conducted to determine the optimal operating conditions for gas adsorption separation of CO2 and CH4 gases. By examining the data obtained from breakthrough curves, pure and predicted binary adsorption equilibria, we calculated adsorption capacities, selectivity, sorbent selection parameter (S parameter), and the adsorbent performance indicator (API). These calculations were carried out to evaluate the initial potential for gas adsorption separation of the carbon molecular sieve (CMS(C)) and the activated carbon (AC(B)) under a range of operating conditions. Increasing pressure, decreasing temperature, and reduced feed flow improved breakthrough time and adsorption capacity for both gases on these adsorbents. CMS(C) showed superior selectivity, while AC(B) had a higher API value at specific conditions. The API was considered a more practical parameter for evaluating the initial gas separation potential. CMS(C) proved to be the better choice for methane purification, achieving the longest purification time under optimal conditions. Additionally, the study explored the kinetic behavior of methane and carbon dioxide with these adsorbent materials, revealing faster carbon dioxide uptake rates and the potential advantages of activated carbon in reducing adsorption/desorption cycle times in separation processes. At a pressure of 1 atm, a temperature of 294 K, and a flow rate of 400 ml min-1, CMS(C) had the highest values of selectivity and the S parameter, while AC(B) had the highest API value at 9 atm of pressure, a temperature of 294 K, and a flow rate of 400 ml min-1. The API was considered a more practical parameter for evaluating the initial gas separation potential. CMS(C) proved to be the better choice for methane purification, achieving the longest purification time of 420 seconds at a pressure of 9 atm, a temperature of 294 K, and a flow rate of 400 ml min-1. Additionally, the study explored the kinetic behavior of methane and carbon dioxide with these adsorbent materials, revealing faster carbon dioxide uptake rates and the potential advantages of activated carbon in reducing adsorption/desorption cycle times in separation processes. The analysis of the study, when compared to existing literature, reveals a coherent and logical progression. Our results align with similar studies, validating key points such as the improvement of methane purification through reduced feed flow rates and increased pressures, enhanced adsorption separation performance at lower temperatures and pressures, the superior adsorption capacity of activated carbon over carbon molecular sieves, and the greater selectivity of carbon molecular sieves over activated carbon and faster diffusion of carbon dioxide compared to methane within the carbon porous materials.

The objective of this research was to determine an appropriate adsorbent for the separation of CH₄ from CO₂, N₂, and O₂. To screen different adsorbents for this purpose, pure component adsorption isotherms and gas mixture isotherms were measured. Adsorption isotherms are critical data for modeling adsorption processes. Thus, determining an accurate and reliable method of measuring gas adsorption isotherms is crucial. Concentration pulse chromatography can be used to measure the slope of the isotherm. In the case of pure component adsorption, the slope at different partial pressures of adsorbate can be integrated to determine the adsorption isotherm. The accuracy of the concentration pulse chromatography method was compared to that of gravimetric analysis to find an appropriate technique to obtain pure component gas adsorption isotherms by measuring CH₄ isotherms on activated carbon at 25°C and up to 6.3 atm. Isotherm results from concentration pulse chromatography were identical to gravimetric results, but the use of a sufficiently long column for concentration pulse chromatography was crucial. Afterwards, gravimetric analysis was used to determine the performance of activated carbon (AC A-C) and carbon molecular sieve (CMS A-D) adsorbents for adsorbing CO₂ and N₂. Additionally, O₂ adsorption isotherms were measured for CMS's. At 25°C and above atmospheric pressure, AC-B showed the highest CO₂ capacity and CO₂/N₂ selectivity. The isosteric heat of adsorption values of CO₂, N₂, and O₂ for the CMS's were calculated; CMS-A and CMS-C had high isosteric heat of adsorption values for CO₂, above 40 kJ mol⁻¹. Finally, the performance of activated carbon in separating a binary mixture of CO₂ and N₂ was experimentally measured by obtaining binary gas mixture adsorption isotherms using concentration pulse chromatography technique between 30-70°C and 1-5 atm total pressure. The OLC activated carbon showed selectivity for CO₂ over N₂, with the experimental results showing a slight deviation from theoretical predictions of the binary adsorption isotherms. Compared to other adsorbents in the literature, OLC had similar CO₂ and N₂ adsorption capacities but higher CO₂/N₂ selectivity.

The goal of this research was to identify and fabricate zeolitic membranes that can separate radioisotope krypton-85 (half-life 10.72 years) and xenon gas released during spent nuclear fuel reprocessing. In spent nuclear fuel reprocessing, fissionable plutonium and uranium are recovered from spent nuclear fuel and recycled. During the process, krypton-85 and xenon are released from the spent nuclear fuel as process off-gas. The off-gas also contains NO, NO2, 129I, 85Kr, 14CO2, tritium (as 3H2O), and air and is usually vented to the atmosphere as waste without removing many of the radioactive components, such as 85Kr. Currently, the US does not reprocess spent nuclear fuel. However, as a member of the International Framework for Nuclear Energy Cooperation (IFNEC, formerly the Global Nuclear Energy Partnership), the United States has partnered with the international nuclear community to develop a “closed” nuclear fuel cycle that efficiently recycles all used nuclear fuel and safely disposes all radioactive waste byproducts. This research supports this initiative through the development of zeolitic membranes that can separate 85Kr from nuclear reprocessing off-gas for capture and long-term storage as nuclear waste. The implementation of an 85Kr/Xe separation step in the nuclear fuel cycle yields two main advantages. The primary advantage is reducing the volume of 85Kr contaminated gas that must be stored as radioactive waste. A secondary advantage is possible revenue generated from the sale of purified Xe. This research proposed to use a zeolitic membrane-based separation because of their molecular sieving properties, resistance to radiation degradation, and lower energy requirements compared to distillation-based separations. Currently, the only commercial process used to separate Kr and Xe is cryogenic distillation. However, cryogenic distillation is very energy intensive because the boiling points of Kr and Xe are -153 °C and -108 °C, respectively. The 85Kr/Xe separation step was envisioned to run as a continuous cross-flow filtration process (at room temperature using a transmembrane pressure of about 1 bar) with a zeolite membrane separating krypton-85 into the filtrate stream and concentrating xenon into the retentate stream. To measure process feasibility, zeolite membranes were synthesized on porous α-alumina support discs and permeation tested in dead-end filtration mode to measure single-gas permeance and selectivity of CO2, CH4, N2, H2, He, Ar, Xe, Kr, and SF6. Since the kinetic diameter of krypton is 3.6 Å and xenon is 3.96 Å, zeolites SAPO-34 (pore size 3.8 Å) and DDR (pore size 3.6 Å) were studied because their pore sizes are between or equal to the kinetic diameters of krypton and xenon; therefore, Kr and Xe could be separated by size-exclusion. Also, zeolite MFI (average pore size 5.5 Å) permeance and selectivity were evaluated to produce a baseline for comparison, and amorphous carbon membranes (pore size < 5 Å) were evaluated for Kr/Xe separation as well. After permeation testing, MFI, DDR, and amorphous carbon membranes did not separate Kr and Xe with high selectivity and high Kr permeance. However, SAPO-34 zeolite membranes were able to separate Kr and Xe with an average Kr/Xe ideal selectivity of 11.8 and an average Kr permeance of 19.4 GPU at ambient temperature and a 1 atm feed pressure. Also, an analysis of the SAPO-34 membrane defect permeance determined that the average Kr/Xe selectivity decreased by 53% at room temperature due to unselective defect permeance by Knudsen diffusion. However, sealing the membrane defects with polydimethylsiloxane increased Kr/Xe selectivity by 32.8% to 16.2 and retained a high Kr membrane permeance of 10.2 GPU at ambient temperature. Overall, this research has shown that high quality SAPO-34 membranes can be consistently fabricated to achieve a Kr/Xe ideal selectivity >10 and Kr permeance >10 GPU at ambient temperature and 1 atm feed pressure. Furthermore, a scale-up analysis based on the experimental results determined that a cross-flow SAPO-34 membrane with a Kr/Xe selectivity of 11.8 and an area of 4.2 m2 would recover 99.5% of the Kr from a 1 L/min feed stream containing 0.09% Kr and 0.91% Xe at ambient temperature and 1 atm feed pressure. Also, the membrane would produce a retentate stream containing 99.9% Xe. Based on the SAPO-34 membrane analysis results, further research is warranted to develop SAPO-34 membranes for separating 85Kr and Xe.

Made available in DSpace on 2017-07-25T19:30:47Z (GMT). No. of bitstreams: 1 Ariadne Waureck.pdf: 1552798 bytes, checksum: d207d66f92bd28ac1d16d99ac88a1093 (MD5) Previous issue date: 2015-02-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The seeds classification and the appropriate storage conditions are critical to maintaining quality, otherwise, the previous efforts to develop material and cultural techniques for seed production will not be valid. Accordingly, the objective of this study was to evaluate the interference of classification and storage on quality of barley seeds. Seed samples of four lots of BRS Cauê were used. The design was completely randomized with the treatments: group I - control - seeds unclassified; treatment II - seeds retained on the sieve 2.2 mm width x length 22.0mm; treatment III - seeds retained on the sieve 2.2 mm width x length 22.0mm + table of gravity; IV treatment - seeds retained on the sieve 2.5 mm width x length 22.0mm; treatment V - seeds retained on the sieve 2.5 mm width x length 22.0mm + table gravity. The evaluations were performed at the beginning of storage and 45, 90 , 150, 210 and 270 days after storage. The seeds remained stored in natural environment. To determine the quality of seeds were evaluated: the water content , the volumetric weight, thousand seed weight , the amount of infected seeds, germination, vigor, health and protein content. The infestation , test weight , moisture content and protein content , were not subjected to statistical analysis , the first three repetitions performed with two replications . The results of percentage of sanity test were transformed into arcsin √ ( x / 100 ) , and the other variables were subjected to analysis of variance and means were compared by Tukey test at 5 % significance level. In general, the results of seeds classified in sieve 2.5 x 22.0 mm associated with gravity table presented thousand seed weight and higher test weight in relation to the results of other treatments. However, these results were not observed for physiological and health parameters and protein content . Thus, it is concluded that , right for the barley seeds is the classification in the sieve 2.5 mm + table gravity. Besides, there was a reduction in the quality of barley seeds and the incidence of field fungi from 90 days of storage in a natural environment . / A classificação das sementes e as condições adequadas de armazenamento são fundamentais para manutenção da qualidade, caso contrário, os esforços anteriores para o desenvolvimento do material genético e as técnicas culturais para a produção das sementes não serão válidos. Nesse sentido, o objetivo desse trabalho foi avaliar a interferência da classificação e do armazenamento na qualidade das sementes de cevada. Foram utilizadas sementes de quatro lotes da cultivar BRS Cauê. O delineamento utilizado foi o inteiramente casualizado, sendo os tratamentos: I - controle – sementes não classificadas; II – sementes retidas na peneira 2,2 mm de largura x 22,0mm de comprimento; III – sementes retidas na peneira 2,2 mm de largura x 22,0mm de comprimento + mesa de gravidade; IV – sementes retidas na peneira 2,5 mm de largura x 22,0mm de comprimento; V – sementes retidas na peneira 2,5 mm de largura x 22,0mm de comprimento + mesa de gravidade. As avaliações foram realizadas no início do armazenamento e aos 45, 90, 150, 210 e 270 dias após armazenamento. As sementes permaneceram armazenadas em ambiente natural. Para a determinar a qualidade das sementes foram avaliados: o teor de água, o peso volumétrico, o peso de mil sementes, a quantidade de sementes infestadas, a germinação, o vigor, a sanidade e o teor de proteína. A infestação, peso hectolítrico, teor de água e teor de proteína, não foram submetidos a análise estatística, sendo os três primeiros realizados com duas repetições repetições. Os resultados de porcentagem do teste de sanidade foram transformados em arcsen √(x /100), e as demais variáveis foram submetidas a análise de variância e as médias comparadas pelo teste de Tukey a 5% de significância. Em geral, os resultados das sementes classificadas na peneira 2,5 X 22,0 mm associadas à mesa de gravidade apresentaram peso de mil sementes e peso hectolítrico superiores em relação aos resultados dos demais tratamentos. Porém, esses resultados não foram observados para os parâmetros fisiológico, sanitário e teor de proteína. Dessa forma, conclui-se que, o indicado para as sementes de cevada é a classificação na peneira 2,5mm + mesa de gravidade. Além disso, houve redução da qualidade das sementes de cevada e da incidência de fungos de campo a partir de 90 dias de armazenamento em ambiente natural. A classificação das sementes e as condições adequadas de armazenamento são fundamentais para manutenção da qualidade, caso contrário, os esforços anteriores para o desenvolvimento do material genético e as técnicas culturais para a produção das sementes não serão válidos. Nesse sentido, o objetivo desse trabalho foi avaliar a interferência da classificação e do armazenamento na qualidade das sementes de cevada. Foram utilizadas sementes de quatro lotes da cultivar BRS Cauê. O delineamento utilizado foi o inteiramente casualizado, sendo os tratamentos: I - controle – sementes não classificadas; II – sementes retidas na peneira 2,2 mm de largura x 22,0mm de comprimento; III – sementes retidas na peneira 2,2 mm de largura x 22,0mm de comprimento + mesa de gravidade; IV – sementes retidas na peneira 2,5 mm de largura x 22,0mm de comprimento; V – sementes retidas na peneira 2,5 mm de largura x 22,0mm de comprimento + mesa de gravidade. As avaliações foram realizadas no início do armazenamento e aos 45, 90, 150, 210 e 270 dias após armazenamento. As sementes permaneceram armazenadas em ambiente natural. Para a determinar a qualidade das sementes foram avaliados: o teor de água, o peso volumétrico, o peso de mil sementes, a quantidade de sementes infestadas, a germinação, o vigor, a sanidade e o teor de proteína. A infestação, peso hectolítrico, teor de água e teor de proteína, não foram submetidos a análise estatística, sendo os três primeiros realizados com duas repetições repetições. Os resultados de porcentagem do teste de sanidade foram transformados em arcsen √(x /100), e as demais variáveis foram submetidas a análise de variância e as médias comparadas pelo teste de Tukey a 5% de significância. Em geral, os resultados das sementes classificadas na peneira 2,5 X 22,0 mm associadas à mesa de gravidade apresentaram peso de mil sementes e peso hectolítrico superiores em relação aos resultados dos demais tratamentos. Porém, esses resultados não foram observados para os parâmetros fisiológico, sanitário e teor de proteína. Dessa forma, conclui-se que, o indicado para as sementes de cevada é a classificação na peneira 2,5mm + mesa de gravidade. Além disso, houve redução da qualidade das sementes de cevada e da incidência de fungos de campo a partir de 90 dias de armazenamento em ambiente natural.

Made available in DSpace on 2014-12-17T15:41:45Z (GMT). No. of bitstreams: 1 MarcelaNBpdf.pdf: 2700913 bytes, checksum: 95100e939e95f8047d0ef3d50eb366ab (MD5) Previous issue date: 2009-08-12 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Emissions of CO2 in the atmosphere have increased successively by various mechanisms caused by human action, especially as fossil fuel combustion and industrial chemical processes. This leads to the increase in average temperature in the atmosphere, which we call global warming. The search for new technologies to minimize environmental impacts arising from this phenomenon has been investigated. The capture of CO2 is one of the alternatives that can help reduce emis ions of greenhouse gases. The CO2 can be captured through the process of selective adsorption using adsorbents for this purpose. Were synthesized by hydrothermal method, materials of the type MCM-41 and Al-MCM-41 in the molar ratio Si / Al equal to 50. The synthesis of gels were prepared from a source of silicon, sodium, water and aluminum in the case of Al-MCM-41. The period of synthesis of the materials was 5 days in autoclave at 100?C. After that time materials were filtered, washed and dried in greenhouse at 100 ? C for 4 hours and then calcined at 450 ? C. Then the calcined material was functionalized with the Di-isopropylamine (DIPA) by the method of wet impregnation. We used 0.5 g of material mesopores to 3.5 mL of DIPA. The materials were functionalized in a closed container for 24 hours, and after this period were dried at brackground temperature for 2 hours. Were subsequently subjected to heat treatment at 250?C for 1 hour. These materials were used for the adsorption of CO2 and were characterized by XRD, FT-IR, BET / BJH, SEM, EDX and TG / DTG. Tests of adsorption of CO2 was carried out under the following conditions: 100 mg of adsorbent, temperature of 75?C under flow of 100 mL/min of CO2 for 2 hours. The desorption of CO2 was carried out by thermogravimetry from ambient temperature to 900?C under flow of 25 mL min of He and a ratio of 10?C/min. The difratogramas X-ray for the synthesized samples showed the characteristic peaks of MCM-41, showing that the structure of it was obtained. For samples functionalized there was a decrease of the intensities of these peaks, with a consequent reduction in the structural ordering of the material. However, the structure was preserved mesopores. The adsorption tests showed that the functionalized MCM-41 is presented as a material promising adsorbent, for CO2 capture, with a loss of mass on the desorption CO2 of 7,52%, while that in Al-MCM- 41 functionalized showed no such loss / As emiss?es de CO2 na atmosfera v?m aumentando sucessivamente devido a v?rios mecanismos provocados pela a??o humana, principalmente como a queima de combust?veis f?sseis e processos qu?micos industriais. Isso leva ao aumento da temperatura m?dia na atmosfera, a qual chamamos de aquecimento global. A busca por novas tecnologias para minimizar os impactos ambientais decorrentes deste fen?meno tem sido investigadas. A captura de CO2 ? uma das alternativas que podem ajudar a diminuir as emiss?es desses gases. O CO2 pode ser capturado atrav?s do processo de adsor??o utilizando adsorventes seletivos para este fim. Foram sintetizados pelo m?todo hidrot?rmico, materiais do tipo MCM-41 e Al- MCM-41 na raz?o molar Si/Al igual a 50. Os g?is de s?nteses foram preparados partindo deuma fonte de sil?cio, s?dio, ?gua destilada e alum?nio no caso do Al-MCM-41. O per?odo de s?ntese dos materiais foi de 5 dias em autoclave a 100?C. Ap?s esse tempo os materiais foram filtrados, lavados e secos em estufa a 100?C durante 4 horas, e posteriormente calcinados a 450?C. Em seguida os materiais calcinados foram funcionalizados com a Di-iso-propilamina (DIPA) atrav?s do m?todo de impregna??o por via ?mida. Foi utilizado 0,5 g de material mesoporoso para 3 mL de DIPA. Os materiais funcionalizados ficaram em um recipiente fechado durante 24 horas, e ap?s esse per?odo foram secos em temperatura ambiente durante 2 horas. Posteriormente foram submetidos a um tratamento t?rmico a 250?C durante 1 hora. Estes materiais foram utilizados para o processo de adsor??o de CO2 e foram caracterizados por DRX, FT-IR, BET/BJH, MEV, EDX e TG/DTG. Os ensaios de adsor??o de CO2 foram realizados nas seguintes condi??es: 100 mg de adsorvente, temperatura de 75?C sob fluxo de 100 mL/min de CO2 durante 2 horas. A dessor??o do CO2 foi realizada atrav?s da termogravimetria, da temperatura ambiente at? 900?C, sob fluxo de 25 mL/min de He e uma raz?o de 10?C/min. Os difratogramas de raios-X para as amostras sintetizadas apresentaram os picos caracter?sticos do MCM-41, evidenciando que a estrutura do mesmo foi obtida. Para as amostras funcionalizadas observou-se uma diminui??o das intensidades desses picos, consequentemente, uma diminui??o do ordenamento estrutural do material. No entanto, a estrutura mesoporosa foi preservada. Os testes de adsor??o mostraram que o MCM-41 funcionalizado se apresentou como um material adsorvente promissor, para captura de CO2, com uma perda de massa referente ? dessor??o do CO2 de 7,52 %, enquanto que no Al-MCM- 41 funcionalizado n?o apresentou essa perda

Current membrane technology, based on polymeric materials, is subject to a limiting tradeoff between productivity (permeability) and efficiency (selectivity). Other materials with better gas separation performance exist, such as zeolites and carbon molecular sieves, but the physical characteristics of these materials inhibit industrial scale membrane preparation. This research focuses on the application of hybrid membrane technology, which has shown the ability to combine the advantageous properties of these materials, to a system comprised of carbon molecular sieves dispersed in the upper bound polymer 6FDA-6FpDA. Hybrid membranes require effective mass transfer across the interface between the two phases. This work shows the sensitivity of the component materials to processing conditions and the importance of consistency in gas separation membrane production. In particular, milling the sieves to reduce the size and using chemical linkage agents to bond to the polymer have potential to alter the separation performance of the respective materials. Analysis of multiple factors in this work provides important information regarding the source of unexpected properties in the hybrid membranes. Hybrid membrane testing in this work shows a need for active control of particle agglomerates within the dope prior to casting for effective membrane production. Continual sonication during the preparation of the casting dope was able to prevent the excessive agglomerates present in earlier trials. Further reduction of stresses generated during the casting process was also necessary to produce membranes with enhanced selectivity. Annealing the hybrid films above the polymer Tg appears to repair the interfacial morphology and produce effective membranes. The application of this process to enhance the gas separation performance of 6FDA-6FpDA represents the first known report of successful selectivity improvement in an upper bound polymer using the hybrid membrane approach.