Made available in DSpace on 2014-12-17T15:42:28Z (GMT). No. of bitstreams: 1 MariaJFC_TESE.pdf: 4007652 bytes, checksum: 7bb363c54641679d79bbff5c76de539f (MD5) Previous issue date: 2013-06-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The processing of heavy oil produced in Brazil is an emergency action and a strategic plan to obtain self-sufficiency and economic surpluses. Seen in these terms, it is indispensable to invest in research to obtain new catalysts for obtaining light fraction of hydrocarbons from heavy fractions of petroleum. This dissertation for the degree of Doctor of Philosophy reports the materials preparation that combine the high catalytic activity of zeolites with the greater accessibility of the mesoporosity, more particularly the HZSM-5/MCM-41 hybrid, done by synthesis processes with less environmental impact than conventional ones. Innovative methodologies were developed for the synthesis of micro-mesoporous hybrid material by dual templating mechanism and from crystalline zeolitic aluminosilicate in the absence of organic template. The synthesis of hybrid with pore bimodal distribution took place from one-single organic directing agent aimed to eliminate the use of organic templates, acids of any kind or organic solvents like templating agent of crystalline zeolitic aluminosilicate together with temperature-programmed microwave-assisted, making the experimental procedures of preparation most practical and easy, with good reproducibility and low cost. The study about crystalline zeolitic aluminosilicate in the absence of organic template, especially MFI type, is based on use of H2O and Na+ cation playing a structural directing role in place of an organic template. Advanced characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Highresolution Transmission Electron Microscopy (HRTEM), Adsorption of N2 and CO2, kinetic studies by Thermogravimetric Analysis (TGA) and Pyrolysis coupled to Gas Chromatography/Mass Spectrometry (Pyrolysis-GC/MS) were employed in order to evaluate the synthesized materials. Achieve the proposed objectives, has made available a set of new methodologies for the synthesis of zeolite and hybrid micro-mesoporous material, these suitable for catalytic pyrolysis of heavy oils aimed at producing light fraction / O processamento do petr?leo pesado produzido no Pa?s ? uma a??o emergencial e estrat?gica para obter a auto-sufici?ncia e super?vits econ?micos. Neste sentido, ? indispens?vel o investimento em pesquisas de novos catalisadores para obten??o de derivados leves a partir de fra??es pesadas do petr?leo. O trabalho de doutorado aqui reportado dedicouse ? prepara??o de materiais que combinem, numa ?nica estrutura, a elevada atividade catal?tica de ze?litas, com melhor acessibilidade de materiais mesoporosos, como a estrutura h?brida HZSM-5/MCM-41, utilizando processos de s?ntese com menor impacto ambiental que os convencionais. Metodologias inovadoras foram desenvolvidas para a s?ntese do catalisador h?brido micro-mesoporoso ou ze?lito-mesoporoso por mecanismo de direcionamento estrutural via duplo agente diretor org?nico e tamb?m a partir de estrutura zeol?tica sintetizada na aus?ncia total de direcionador org?nico. Esse ?ltimo, tamb?m chamado de s?ntese do h?brido com distribui??o bimodal de poros a partir de um ?nico agente diretor org?nico, visou eliminar o uso dos direcionadores org?nicos, ?cidos de qualquer natureza ou solventes org?nicos como molde estrutural da estrutura zeol?tica em conjunto com o m?todo hidrot?rmico assistido por irradia??o via micro-ondas, tornando o procedimento experimental de prepara??o pr?tico e simples, com boa reprodutibilidade e menor custo. A metodologia de prepara??o da ze?lita MFI do tipo ZSM-5 utiliza H2O e c?tions Na+ no papel de direcionamento estrutural e compensa??o de cargas na estrutura. T?cnicas relevantes de caracteriza??o, como Difra??o de Raios-X (XRD), Espectroscopia no Infravermelho com Transformada de Fourier (FTIR), Microscopia Eletr?nica de Varredura (SEM), Microscopia Eletr?nica de Transmiss?o de Alta Resolu??o (HRTEM), Adsor??o de N2 e CO2, estudos cin?ticos via An?lises Termogravim?tricas (TGA) e Pir?lise acoplada ? Cromatografia Gasosa/Espectrometria de Massas (Pyrolysis-GC/MS), foram empregadas no intuito de avaliar os materiais sintetizados. Alcan?ados os objetivos propostos, disponibilizou-se um conjunto de novas metodologias para s?ntese de catalisadores zeol?ticos e h?bridos micromesoporosos, estes adequados para pir?lise catal?tica de ?leos pesados visando ? produ??o de derivados leves

La limitation de perméation des gaz aux bordes de l’encapsulation des photovoltaïques organiques flexibles a été adressée par l’identification des chemins de perméation du vapeur d’eau et par la formulation des nanocomposites adhésives. Une version modifiée du test de calcium optique a été développée pour identifier l’importance des chemins de perméation différents présent dans l’encapsulation des modules photovoltaïques organiques flexibles. Les nanoparticules des phyllosilicates et les nanoparticules des zéolithes ont été dispersées dedans les formulations des adhésifs différents incluant les adhésifs acryliques sensibles à pression et les adhésifs UV réticulables. Les propriétés mécaniques, optiques, et barrières de vapeur d’eau des nanocomposites ont été caractérisés en plus de leur photo-stabilité sous irradiation UV. Les nanocomposites ont été également utilisés pour encapsuler les cellules photovoltaïques organiques et la stabilité des dispositifs a été évaluer sous les conditions de vieillissement accélérés d’humidité et température. / In order to address the issue of lateral water and oxygen permeation through the sides of the encapsulation and into flexible organic photovoltaic (OPV) devices, the water vapor permeation pathways were identified and several adhesive nanocomposites formulated and tested to limit these pathways. To identify the relative importance of the various water vapor permeation pathways present in the encapsulation of flexible OPV devices, a modified version of the optical calcium test was developed. Passive nanoparticles (phyllosilicates) and active nanoparticles (zeolites) were both evaluated dispersed in UV curing acrylate adhesives and acrylic block copolymer pressure sensitive adhesives. The nanocomposites were characterized for their mechanical and optical properties as well as their water vapor permeation and UV photostability. The adhesives were also used to encapsulate OPV devices and tested in accelerated humidity aging.

<p>Selective catalytic reduction (SCR) of NO_xusing NH₃as a reductant (4NH₃+ 4NO + O₂ 6H₂O + 4N₂) over Cu-SSZ-13 zeolites is a commercial technology used to meet emissions targets in lean-burn and diesel engine exhaust. Optimization of catalyst design parameters to improve catalyst reactivity and stability against deactivation (hydrothermal and sulfur poisoning) necessitates detailed molecular level understanding of structurally different active Cu sites and the reaction mechanism. With the help of synthetic, titrimetric, spectroscopic, kinetic and computational techniques, we established new molecular level details regarding 1) active Cu site speciation in monomeric and dimeric complexes in Cu-SSZ-13, 2) elementary steps in the catalytic reaction mechanism, 3) and deactivation mechanisms upon hydrothermal treatment and sulfur poisoning.</p><p>We have demonstrated that Cu in Cu-SSZ-13 speciates as two distinct isolated sites, nominally divalent Cu^IIand monovalent [Cu^II(OH)]⁺complexes exchanged at paired Al and isolated Al sites, respectively. This Cu site model accurately described a wide range of zeolite chemical composition, as evidenced by spectroscopic (Infrared and X-ray absorption) and titrimetric characterization of Cu sites under <i>ex situ </i>conditions and <i>in situ </i>and <i>operando </i>SCR reaction conditions. Monovalent [Cu^II(OH)]⁺complexes have been further found to condense to form multinuclear Cu-oxo complexes upon high temperature oxidative treatment, which have been characterized using UV-visible spectroscopy, CO-temperature programmed reduction and dry NO oxidation as a probe reaction. Structurally different isolated Cu sites have different susceptibilities to H₂and He reductions, but are similarly susceptible to NO+NH₃reduction and have been found to catalyze NO_xSCR reaction at similar turnover rates (per Cu^II; 473 K) via a Cu^II/Cu^Iredox cycle, as their structurally different identities are masked by NH₃solvation during reaction. </p><p><br></p><p>Molecular level insights on the low temperature Cu^II/Cu^Iredox mechanism have been obtained using experiments performed <i>in situ</i>and <i>in operando </i>coupled with<i></i>theory. Evidence has been provided to show that the Cu^II to Cu^Ireduction half-cycle involves single-site Cu reduction of isolated Cu^IIsites with NO+NH₃, which is independent of Cu spatial density. In contrast, the Cu^I to Cu^IIoxidation half-cycle involves dual-site Cu oxidation with O₂to form dimeric Cu-oxo complexes, which is dependent on Cu spatial density. Such dual-site oxidation during the SCR Cu^II/Cu^Iredox cycle requires two Cu^I(NH₃)₂sites, which is enabled by NH₃solvation that confers mobility to isolated Cu^Isites and allows reactions between two Cu^I(NH₃)₂species and O₂. As a result, standard SCR rates depend on Cu proximity in Cu-SSZ-13 zeolites when Cu^Ioxidation steps are kinetically relevant. Additional unresolved pieces of mechanism have been investigated, such as the reactivity of Cu dimers, the types of reaction intermediates involved, and the debated role of Brønsted acid sites in the SCR cycle, to postulate a detailed reaction mechanism. A strategy has been discussed to operate either in oxidation or reduction-limited kinetic regimes, to extract oxidation and reduction rate constants, and better interpret the kinetic differences among Cu-SSZ-13 catalysts.</p><p><br></p><p>The stability of active Cu sites upon sulfur oxide poisoning has been assessed by exposing model Cu-zeolite samples to dry SO₂and O₂streams at 473 and 673 K, and then analyzing the surface intermediates formed via spectroscopic and kinetic assessments. Model Cu-SSZ-13 zeolites were synthesized to contain distinct Cu active site types, predominantly either divalent Cu^IIions exchanged at proximal framework Al (Z₂Cu), or monovalent [Cu^IIOH]⁺complexes exchanged at isolated framework Al (ZCuOH). SCR turnover rates (473 K, per Cu) decreased linearly with increasing S content to undetectable values at equimolar S:Cu ratios, consistent with poisoning of each Cu site with one SO₂-derived intermediate. Cu and S K-edge X-ray absorption spectroscopy and density functional theory calculations were used to identify the structures and binding energies of different SO₂-derived intermediates at Z₂Cu and ZCuOH sites, revealing that bisulfates are particularly low in energy, and residual Brønsted protons are liberated at Z₂Cu sites as bisulfates are formed. Molecular dynamics simulations also show that Cu sites bound to one HSO₄^-are immobile, but become liberated from the framework and more mobile when bound to two HSO₄^-. These findings indicate that Z₂Cu sites are more resistant to SO₂poisoning than ZCuOH sites, and are easier to regenerate once poisoned.</p><p><br></p><p>The stability of active Cu sites on various small-pore Cu-zeolites during hydrothermal deactivation (high temperature steaming conditions) has also been assessed by probing the structural and kinetic changes to active Cu sites. Three small-pore, eight-membered ring (8-MR) zeolites of different cage-based topology (CHA, AEI, RTH) have been investigated. With the help of UV-visible spectroscopy to probe the Cu structure, in conjunction with measuring differential reaction kinetics before and after subsequent treatments, it has been suggested that the RTH framework imposes internal transport restrictions, effectively functioning as a 1-D framework during SCR catalysis. Hydrothermal aging of Cu-RTH results in complete deactivation and undetectable SCR rates, despite no changes in long-range structure or micropore volume after hydrothermal aging treatments and subsequent SCR exposure, highlighting beneficial properties conferred by double six-membered ring (D6R) composite building units. Exposure aging conditions and SCR reactants resulted in deleterious structural changes to Cu sites, likely reflecting the formation of inactive copper-aluminate domains. Therefore, the viability of Cu-zeolites for practical low temperature NO_xSCR catalysis cannot be inferred solely from assessments of framework structural integrity after aging treatments, but also require Cu active site and kinetic characterization after aged zeolites are exposed to low temperature SCR conditions.</p>

In this thesis, geometry is used as a basis for conducting experiments aimed at growing and arranging inorganic minerals on curved interfaces. Mineralisation is directed using crystalline and liquid-crystalline metallic soaps and surfactant/water systems as templates.¶ A review of the history, syntheses, structure and liquid crystallinity of metallic soaps and other amphiphiles is presented as a foundation to understanding the interfacial architectures in mesostructured template systems in general.¶ In this study, a range of metallic soaps of varying chain length and cation type are synthesised and characterised to find potentially useful templates for mineral growth. These include alkaline-earth, transition metal, heavy metal and lanthanide soaps. These are systematically characterised using a variety of analytical techniques, including chemical analyses, x-ray diffraction (XRD) infrared spectroscopy (IR) and differential scanning calorimetry (DSC). Their molecular and crystal structures are studied using transmission electron microscopy (TEM), cryo-TEM, electron diffraction (ED), electron paramagnetic spin resonance (EPR), absorption spectroscopy (UV-VIS), high resolution laser spectroscopy, atomic force microscopy (AFM), nuclear magnetic resonance spectroscopy, scanning electron microscopy (SEM), electron dispersive x-ray analysis (EDXA), thermal gravimetric analysis (TGA) and magnetic measurements. Models for the molecular and crystal structures of metallic soaps are proposed. The soaps are predominantly lamellar crystalline or liquid crystalline lamellar rotor phases with tilted and/or untilted molecular constituents. These display evidence of varying degrees of headgroup organisation, including superstructuring and polymerisation. A single crystal structure is presented for a complex of pyridine with cobalt soap. Simple models for their structure are discussed in terms of their swelling properties in water and oils. Experiments are also presented to demonstrate the sorbent properties of aluminium soaps on oil spills.¶ The thermotropic liquid crystallinity of alkaline earth, transition metal, heavy metal and lanthanide soaps is investigated in detail. This is done to assess their suitability as templates, and to document their novel thermotropic behaviour, particularly the relatively unknown lanthanide soaps. Liquid crystalline behaviours are studied using high-temperature XRD (HTXRD), hot-stage optical microscopy and DSC. Models for a liquid crystalline phase progression from crystals to anisotropic liquids are discussed in terms of theories of self-assembly and interfacial curvature. The terminology required for this is drawn from various nomenclature systems for amphiphilic crystals and liquid crystals. General agreement with previous studies is reported for known soaps, while liquid crystallinity is demonstrated in the lanthanide and some non-lanthanide soaps for the first time. A general phase progression of crystalline lamellar through liquid crystalline lamellar to non-lamellar liquid crystalline is discussed in terms of models concerned with the molecular and crystal structures of the soaps and their phase transitions via headgroup and chain re-arrangements.¶ Experiments aimed at guiding growth of metal sulfides using metallic soaps as templates are described, and a model for this growth is discussed. Metal sulfides have been successfully grown by reacting crystalline and liquid crystalline transition metal and heavy metal soaps with H2S gas at room temperature and at elevated temperature. These have been characterised using XRD, TEM, ED and IR. Sulfide growth is demonstrated to be restricted and guided by the reacting soap template architecture. Zinc, cadmium, indium and lead soaps formed confined nanoparticles within the matrix of their reacting soap template. In contrast, curved and flat sheet-like structures, some resembling sponges were found in the products of sulfided iron, cobalt, nickel, copper, tin and bismuth soaps. A model to explain this behaviour is developed in terms of the crystal and liquid crystal structures of the soaps and the crystal structures of the metal sulfide particles.¶ Liquid crystalline iron soaps have been subjected to controlled thermal degradation yielding magnetic iron oxide nanoparticles. Some XRD and TEM evidence has been found for formation of magnetic mesostructures in heat-treated iron soaps. Models for the molecular and liquid crystalline structure of iron soaps, their thermotropic phase progression and eventual conversion to these magnetic products are discussed. Systematic syntheses of mesoporous silicates from sheeted clays are discussed.¶The templates that have been used are cationic surfactants and small, organic molecular salts. Experiments are reported where a cooperative self-assembly of surfactant/water/kanemite plus or minus salt and oils yields 'folded sheet materials' (FSM'S). Templating of kanemite has also been achieved using cobalt cage surfactants. A theoretical prediction of the specific surface areas and specific volumes of homologous sets of FSM's gave excellent agreement with measured values. The geometry and topology of the mesostructures are discussed. A theoretical model is also discussed regarding the curvature found in the sheets of natural clays , and results of templating clays and silica using metallic soaps are presented. Experiments and a model for low temperature nucleation and growth of microporous silicalite-1 are described in terms of silica templating by water clathrates.¶ Finally, the problem of finding minimal surface descriptions of crystal networks is addressed. Combinatoric methods are used to disprove the existence of possible embeddings of type I and II clathrate networks in non-self intersecting periodic minimal surfaces. The crystal network of the clathrate silicate, melanophlogite is successfully embedded in the WI-10 self-intersecting surface. Details of a previously unreported, genus-25 periodic surface with symmetry Im3m are discussed.

The effect of microwave radiation on the prepared 0.5Fe/ZSM-5 catalysts as a post-synthesis modification step was studied in the methanol-to-hydrocarbons process using the temperature-programmed surface reaction (TPSR) technique. This was achieved by preparing a series of 0.5Fe/ZSM-5 based catalysts under varying microwave power levels (0–700 W) and over a 10 s period, after iron impregnating the HZSM-5 zeolite (Si/Al = 30 and 80). Physicochemical properties were determined by XRD, SEM, BET, FT-IR, C3H9N-TPSR, and TGA techniques. It was found that microwave radiation induced few changes in the bulk properties of the 0.5Fe/ZSM-5 catalysts, but their surface and catalytic behavior were distinctly changed. Microwave radiation enhanced crystallinity and mesoporous growth, decreased coke and methane formation, decreased the concentration of Brønsted acidic sites, and decreased surface area and micropore volume as the microwave power level was increased from 0 to 700 W. From the TPSR profiles, it was observed that microwave radiation affects the peak intensities of the produced hydrocarbons. Application of microwave radiation shifted the desorption temperatures of the MTH process products over the HZSM-5(30) and HZSM-5(80) based catalysts to lower and higher values respectively. The MeOH-TPSR profiles showed that methanol was converted to DME and subsequently converted to aliphatic and aromatic hydrocarbons. It is reasonable to suggest that microwave radiation would be an essential post-synthesis modification step to mitigate coke formation and methane formation and increase catalyst activity and selectivity. / Chemical Engineering / M. Tech. (Chemical Engineering)

Esse trabalho consiste na síntese, caracterização e potenciais aplicações de sílicas mesoporosas altamente ordenadas, estáveis térmica e hidrotermicamente. Esses materiais de estrutura cúbica do tipo FDU-1 foram sintetizados, em meio ácido, utilizando como fonte de sílica tetraetilortosilicato (TEOS) e como moldes os copolímeros tribloco B50-6600 (EO39BO47EO39) e Vorasurf 504&#174;. Os géis de síntese foram submetidos a tratamento hidrotérmico em forno de microondas e em seguida as amostras foram calcinados em atmosfera de N2 e ar, ou submetidos à extração por solvente. Os materiais foram caracterizados por termogravimetria (TG), análise elementar, espectroscopia de absorção no infravermelho, difração de raios X a baixo ângulo (SAXRD), microscopia eletrônica de transmissão de alta resolução (HRTEM), isotermas de adsorção de N2 e espectrometria de retroespalhamento de Rutherford (RBS). Os materiais FDU-1 foram empregados para o desenvolvimento dos seguintes estudos: i) aplicação do planejamento fatorial para definir um novo copolímero tribloco como direcionador de estrutura, o Vorasurf&#174; 504, a fim de substituir o B50-6600 não mais disponível no mercado. As respostas obtidas não foram significativas num nível de 95% de confiança para as variáveis escolhidas (tempo de agitação e tempo de microondas). O estudo demonstrou que é possível diminuir o tempo de síntese do FDU-1 e ainda assim obter materiais com boas propriedades estruturais e texturais. Para os planejamentos fatoriais 22 e 23 observou-se que a variável mais importante foi a temperatura do forno de microondas usada no tratamento hidrotérmico. Contudo, a concentração de HCl e a presença do etanol da mistura de síntese não apresentaram nenhum efeito significativo em um nível de 95% de confiança; ii) encapsulação de complexos luminescentes de európio [Eu(dbm)3.TPPO] e [Eu(pic)3.2.Leu.5H2O] nas sílicas pura e/ou modificadas com 3-aminopropiltrieto-xissilano (APTES). As amostras encapsuladas mantiveram as propriedades óticas e aumentaram a resistência térmica dos complexos, ambas propriedades foram medidas por espectroscocopia de emissão e excitação na região do visível e por TG; iii) incorporação nas sílicas FDU-1 de ácido húmico com diferentes concentrações (1.0; 1.5 e 2.0 mmols) empregando forno de microondas no tratamento hidrotérmico. As amostras foram testadas para remoção de Cd2+ em solução aquosa com pH = 6. Esses materiais apresentaram uma alta capacidade de adsorção dos íons cádmio; iv) síntese uma amostra de FDU-1 utilizando-se 1,3,4 trimetilbenzeno (TMB) como agente dilatador de poros. Esse material apresentou poro com diâmetro de 11,7 nm e foi utilizado para imobilização da enzima glicose oxidase (GOX) na presença de glutaraldeído. Sua atividade, medida por espectrofotometria e quimiluminescência, foi muito próxima para as soluções puras, 601 e 629 &#181;mol g-1, respectivamente. Para a amostra de glicose oxidase imobilizada na sílica FDU-1 a atividade enzimática, medida diretamente por quimiluminescência, foi estimada em 233 &#181;mol g-1; v) incorporação da zeólita TS-1 nas paredes da sílica mesoporosa FDU-1 empregando tratamento hidrotérmico em forno de microondas. As amostras foram tratadas termicamente visando à cristalização da zeólita. O teste para a catálise de fenol em presença de radiação UV e H2O2 indicou que houve cerca de 90% de redução do fenol num período de 120 minutos. / This work consists of the synthesis, characterization and potentials applications of highly ordered mesoporous silica, thermal and hydrothermally stable. These materials of cubic structure of type FDU-1 were synthesized, in acid media, using as silica source tetraetilortosilicate (TEOS) and as poly(ethylene oxide)-poly(butylene oxide)-poly-(ethylene oxide) triblock copolymer B50-6600 (EO39BO47EO39) and Vorasurf 504&#174; templates. The synthesis gels were submitted the hydrothermal treatment in microwaves oven and after that the samples were calcined under N2 and air atmosphere or submitted to the solvent extration. The materials were characterized by thermogravimetry (TG), elementary analysis, infrared spectroscopy absorption, small-angle X ray diffraction (SAXRD), high-resolution transmission electronic microscopy (HRTEM), Nitrogen adsorption measurements and Rutherford Back-scattering spectrometry (RBS). FDU-1 materials were used for the development the following studies: i) application of the factorial design to define a new triblock copolymer as template, Vorasurf 504&#174;, in order to substitute the triblock copolymer B50-6600, that is not more available in the market. The supplied answers were not significant in a reliable level of 95% for the selected variables (stirring time and microwave time). This study demonstrated that is possible to diminish the time of synthesis of the FDU-1 and still to get materials with good structural and texture properties. For the 22 and 23 factorial designs was observed that the most important variable was the microwave oven temperature used in the hydrothermal treatment. However, the concentration of HCl and the presence of etanol of the synthesis mixture did not show no significant effect in a reliable level of 95%; ii) encapsulation of luminescent europium complexes [Eu(DBM3.TPPO] e [Eu(pic)3.2Leu.5H2O] in the pure and/or modified silicas with 3-aminopropyltriethoxysilane (APTES). The encapsulated samples kept the optic properties and increased the thermal resistance of the complexes, both properties were measured for Excitation and emission spectra and TG; iii) incorporation of humic acid with different concentrations (1.0; 1.5 and 2.0 mmols) using microwave oven in the hydrothermal treatment. The samples were tested for removal of Cd2+ from aqueous solutions at pH=6. These materials presented high adsorption capacity for cadmium ions; iv) synthesis of the material using 1,3,5-trimethylbenzene (TMB) as pore expanding agent. This material with pore 11.7 nm was used for immobilization of the glucose oxidase (GOX) enzyme in the presence of glutaraldehyde. Its activity, measured by spectrofotometry and quimilumi-nescence, was very near close for the pure solutions, 601 and 629 &#181;mol g-1, respectively. For immobilized glucose oxidase sample in silica FDU-1 the enzymatic activity, measured directly by quimiluminescence, was esteem in 233 &#181;mol g-1; v) incorporation of TS-1 zeolite in the walls of mesoporous silica using hydrothermal treatment in microwave oven. The samples were submitted the thermal treatment for the zeolite crystallization. The test for the phenol catalysis in presence of UV radiation and H2O2 indicated that it had about 90% of phenol reduction after 120 minutes.

Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.

Komposit-Adsorbentien, die aus einer mit hygroskopischem Salz imprägnierten Zeolithmatrix bestehen, bilden eine vielversprechende Materialklasse für die thermochemische Energiespeicherung (TCES). Sie vereinen die hohe Wärmespeicherdichte des Salzes und die einfache technische Handhabbarkeit des Zeoliths. Dabei verhindert die poröse Matrix das Auslaufen von Salzlösung und kompensiert volumenänderungen während der Ad- und Desorption. Das dynamische Sorptionsverhalten solcher Komposite unterscheidet sich jedoch von dem reiner Zeolithe. Speziell die Adsorptionskinetik ist langsamer, was zu Problemen wie einer geringeren und nicht konstanten thermischen Leistung sowie unvollständiger Adsorption und langen Adsorptionspasen von Energiespeichern auf Basis dieser Materialien führt. Numerische Modellierung hat sich als wichtiges Werkzeug erwiesen, um die Ursachen solcher Leistungseinschränkungen zu identifizieren. Dadurch erleichtert es die Entwicklung von thermochemischen Energiespeichern: Optimale Designs und Arbeitsbedingungen können per Simulation gefunden werden bevor Prototypen gebaut werden müssen. In dieser Arbeit wurde ein numerisches Modell einer Adsorbensschüttung in einer offenen Sorptionskammer entwickelt, in die Open-Sourve Finite-Elemente-Software OpenGeoSys implementiert und mittels experimenteller Daten validiert. Die Modellierungserebnisse zeigen, dass etablierte Sorptionskinetiken das dynamische Adsorptionsverhalten von Salz/Zeolith-Kompositen unter anwendungsrelevanten Arbeitsbedingungen erfassen. Außerdem zeigen sie, dass der Hauptgrund für die Unterschiede zwischen dem Sorptionsverhalten der Komposite und reiner Zeolithe in ihren qualitativ unterschiedlichen Sorptionsgleichgewichten liegt. Ein zweiter Fokus dieser Arbeit liegt darauf zu untersuchen, ob ein begrenzter Umfang an experimentellen Daten genügt, um die entwickelten numerischen Modelle zu kalibrieren. Diese Möglichkeit wurde durch Simulationen von dynamischen Adsorptionsvorgängen an Komposit-Adsorbentien bestätigt. Zudem wurden Kriterien entwickelt, die die Rekonstruktion eines robusten Adsorptionsgleichgewichtsmodells aus einem beschränkten expermientellen Datensatz erlauben. Schließlich wurde im Kontext der Dubinin-Polanyi-Theorie der Adsorption in Mikroporen festgestellt, das die Wahl eines bestimmten Adsorbatdichtemodells nur einen kleinen Einfluss auf Vorhersagen der Leistungsfähigkeit von Adsorbentien für die TCES hat. Die Ergebnisse dieser Arbeit bilden eine fundierte Grundlage für die zukünftige numerische Untersuchung von Materialien, Reaktorgeometrien und Arbeitsbedingungen während der Entwicklung von thermochemischen Energiespeichern, die auf Zeolithen oder Komposit-Adsorbentien basieren.:Used symbols and abbreviations 1. Introduction 2. Foundations 2.1. Thermochemical energy storage 2.2. Zeolites and salt/zeolite composites 2.3. Dubinin-Polanyi theory 2.4. Multiphysical model of a fixed adsorbent bed 2.5. Experimental data 3. Assessment of adsorbate density models 4. Water loading lift and heat storage density prediction 5. Modelling of sorption isotherms based on sparse experimental data 6. Modelling sorption equilibria and kinetics of salt/zeolite composites 7. Summary 7.1. Main achievements 7.2. Conclusions and outlook Bibliography A. Publications A.1. Assessment of adsorbate density models A.2. A comparison of heat storage densities A.3. Water loading lift and heat storage density prediction A.4. Modelling of sorption isotherms based on sparse experimental data A.5. Modelling sorption equilibria and kinetics of salt/zeolite composites / Composite adsorbents consisting of a zeolite host matrix impregnated with a hygroscopic salt are a promising material class for thermochemical energy storage (TCES). They combine the high heat storage density of the salt with the easy technical manageability of the zeolite, which prevents the leakage of salt solution and inhibits volume changes upon ad- and desorption. The dynamic sorption behaviour of such composites, however, is different from the pure host matrix material. Particularly, the adsorption kinetics are slower, which leads to issues such as low and non-steady thermal output power, incomplete adsorption and long adsorption phases of TCES devices using these composite materials. Numerical modelling has proven to be a valuable tool to identify the causes for such performance limitations. Therefore, it facilitates the development of TCES devices: it allows to easily find optimum designs and operating procedures before actual prototypes have to be built. In this thesis a numerical model of a packed adsorbent bed in an open sorption chamber has been developed, implemented in the open-source finite element software OpenGeoSys and validated with experimental data. The modelling results show that established sorption kinetics models capture the dynamic sorption behaviour of salt/zeolite composites under application-relevant operating conditions. Moreover, they show that the main cause for the differences between the composites' and pure zeolite's sorption behaviour lies in their different sorption equilibria. A second focus of the thesis is to investigate the use of limited experimental data for the calibration of the numerical models. This possibility has been confirmed by dynamic sorption simulations of the composite materials. Furthermore, criteria were determined that allow the reconstruction of a robust adsorption equilibrium description from a reduced experimental data set. Finally, in the context of the Dubinin-Polanyi theory of adsorption in micropores, it has been found that the choice of a specific adsorbate density model has only a small influence on performance predictions of adsorbents for TCES. In summary, the results from this thesis will facilitate the screening of materials, reactor geometries and operating conditions via numerical simulations during the design of TCES devices based on zeolites and composite sorbents.:Used symbols and abbreviations 1. Introduction 2. Foundations 2.1. Thermochemical energy storage 2.2. Zeolites and salt/zeolite composites 2.3. Dubinin-Polanyi theory 2.4. Multiphysical model of a fixed adsorbent bed 2.5. Experimental data 3. Assessment of adsorbate density models 4. Water loading lift and heat storage density prediction 5. Modelling of sorption isotherms based on sparse experimental data 6. Modelling sorption equilibria and kinetics of salt/zeolite composites 7. Summary 7.1. Main achievements 7.2. Conclusions and outlook Bibliography A. Publications A.1. Assessment of adsorbate density models A.2. A comparison of heat storage densities A.3. Water loading lift and heat storage density prediction A.4. Modelling of sorption isotherms based on sparse experimental data A.5. Modelling sorption equilibria and kinetics of salt/zeolite composites

Made available in DSpace on 2014-12-17T15:41:45Z (GMT). No. of bitstreams: 1 MariaJFCpdf.pdf: 4931245 bytes, checksum: 45a7ea893d17f478c73adf56787579aa (MD5) Previous issue date: 2008-12-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The present work reports the study of nanoporous structures, aiming at their use in research directed to the current demand of the petroleum industry to value heavy oil. Initially, two ways were chosen for the synthesis of porous structures from the molecular sieves of type Si-MCM-41. In the first way, the structure MCM-41 is precursory for heteroatom substitutes of silicon, generating catalyst of the type Al-MCM-41 from two different methods of incorporation of the metal. This variation of the incorporation method of Aluminum in the structure of Si-MCM-41 was carried out through the conventional procedure, where the aluminum source was incorporated to the gel of synthesis, and the procedure post-synthesis, where the Aluminum source was incorporated in catalyst after the synthesis of Si-MCM-41. In the second way, the MCM-41 acts as a support for growth of nanocrystals of zeolite embedded in their mesoporous, resulting in hybrid MCM-41/ZSM-5 catalyst. A comparative analysis was carried through characterizations by XRD, FTIR, measures of acidity through n-butylamine adsorption for TGA, SEM-XRF and N2 adsorption. Also crystalline aluminosilicate with zeolitic structure MFI of type ZSM-5 was synthesized without using organic templates. Methodologies to the preparation of these materials are related by literature using conventionally reactants that supply oxides of necessary silicon and aluminum, as well as a template agent, and in some cases co-template. The search for new routes of preparation for the ZSM-5 aimed at, above all, the optimization of the same as for the time and the temperature of synthesis, and mainly the elimination of the use of organic templates, that are material of high cost and generally very toxic. The current study is based on the use of the H2O and Na+ cations playing the role of structural template and charge compensation in the structure. Characterizations by XRD, FTIR, SEM-XRF and N2 adsorption were also conducted for this material in order to compare the samples of ZSM-5 synthesized in the absence of template and those used industrially and synthesized using structuring / O presente trabalho relata o estudo de estruturas nanoporosas, visando o uso em pesquisas que atendam a atual demanda da ind?stria do petr?leo, de valorizar ?leos pesados. Inicialmente, optou-se por duas vertentes para a s?ntese de estruturas porosas a partir da peneira molecular do tipo Si-MCM-41. Na primeira vertente, a estrutura MCM-41 ? precursora para hetero?tomos substituintes do sil?cio, gerando catalisadores do tipo Al-MCM-41 a partir de dois diferentes m?todos de incorpora??o do metal. Essa varia??o do m?todo de incorpora??o do Alum?nio na estrutura do Si-MCM-41 se deu atrav?s do procedimento convencional, no qual a fonte de alum?nio foi incorporada ao gel de s?ntese e do procedimento p?s-s?ntese, no qual a fonte de Alum?nio foi incorporada ao catalisador ap?s a s?ntese do Si-MCM-41. Na segunda vertente, o MCM-41 age como suporte para o crescimento de nanocristais de ze?lita embutidos nos seus mesoporos, resultando no catalisador h?brido MCM-41/ZSM-5. Uma an?lise comparativa foi realizada atrav?s de caracteriza??es por XRD, FTIR, medidas de acidez atrav?s de dessor??o de n-butilamina por TGA, SEM-XRF e Adsor??o de N2. Tamb?m foi sintetizado um aluminossilicato cristalino com estrutura zeol?tica MFI do tipo ZSM-5, na aus?ncia total de direcionador org?nico. Metodologias relacionadas ? prepara??o desses materiais s?o relatadas pela literatura utilizando-se convencionalmente reagentes que forne?am os ?xidos de sil?cio e de alum?nio necess?rios, bem como um agente direcionador, e em alguns casos at? co-direcionadores. A busca por novas rotas de prepara??o para a ZSM-5 visou, sobretudo, a otimiza??o da mesma no que se refere ao tempo e ? temperatura de s?ntese, e principalmente a elimina??o do uso dos direcionadores org?nicos, que s?o materiais de alto custo e geralmente muito t?xicos. O atual estudo se baseia na utiliza??o da H2O e dos c?tions Na+ desempenhando o papel de direcionamento estrutural e compensa??o de cargas na estrutura. Caracteriza??es por XRD, FTIR, SEM-XRF e Adsor??o de N2 tamb?m foram realizadas para esse material, a fim de comparar as amostras de ZSM-5 sintetizadas na aus?ncia do direcionador e aquelas utilizadas industrialmente e sintetizadas utilizando estruturantes