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Orientadores: Elizabete Jordão, Wagner Alves Carvalho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-16T19:26:07Z (GMT). No. of bitstreams: 1 Zanin_CristianeImenesdeCamposBueno_M.pdf: 1177792 bytes, checksum: 1d486d6f780a5b8b17b181686be89bd5 (MD5) Previous issue date: 2010 / Resumo: O aproveitamento do glicerol tem se tornado assunto de grande importância, uma vez que ele é um subproduto da síntese do biodiesel. Além de fatores econômicos e políticos, a partir da década de 1990, devido a um aumento da conscientização acerca dos problemas ambientais causados pela queima de combustíveis fósseis, o biodiesel tem sido apontado como alternativa, fazendo com que a produção de glicerol aumente cada vez mais, diminuindo assim o seu preço. Contudo, é de grande importância sua transformação em produtos com maior valor agregado como os dióis, com interesse voltado para a indústria petroquímica. Com a finalidade de se expandir a produção de biodiesel, torna-se necessário o desenvolvimento de uma ?nova química do glicerol?, sendo a hidrogenólise para diálcoois bastante promissora. O presente trabalho tem o objetivo de estudar a influência da quantidade de catalisador, pressão de H2 e da temperatura na velocidade inicial das reações, bem como na seletividade e no total de conversão do substrato, a partir de catalisadores de Pt, Pd e Ru suportados em argila pilarizada (A?-PilC). Os catalisadores foram preparados através de impregnação em suspensões aquosas, a partir dos precursores Pt (NH3)4Cl2.0,68H2O, PdCl2 e RuCl3.1,37H2O, respectivamente, de modo a obter um catalisador com teor nominal de 2% em peso. Os catalisadores preparados foram caracterizados por meio das técnicas: área superficial específica (B.E.T.), redução à temperatura programada (TPR), difração de raios X (DRX), espectroscopia na região do infravermelho (FTIR) de piridina adsorvida e dessorção de piridina a temperatura programada. O desempenho dos catalisadores foi avaliado na reação de hidrogenólise do glicerol em fase líquida, empregando-se um reator Parr de alta pressão. Os resultados obtidos indicam que o uso de catalisadores bifuncionais metal-ácido é uma forma de tornar a hidrogenólise mais efetiva, uma vez que favorecem as reações de desidratação e hidrogenação para a produção de 1,2-propanodiol / Abstract: The use of glycerol has become a subject of great importance, since it is a byproduct of the synthesis of biodiesel. Besides economic and political factors, from the 1990s, due to environmental problems caused by burning fossil fuels, biodiesel has been become an alternative, making the production of glycerol increases more, thereby lowering its price. However, it is of great important its transformation into products with higher added value such as diols, with interest focused on the petrochemical industry. In order to expand the production of biodiesel, it becomes necessary to develop a "new chemistry of glycerol?, and the hydrogenolysis to dialcohols is promising. The present work aims to study the influence of substrate concentration, amount of catalyst, H2 pressure and temperature on initial velocity of reactions, as well as selectivity and total conversion of substrate, using catalysts based on Pt, Pd and Ru supported on pillared clay (A?-PILC). The catalysts were prepared by impregnation with aqueous suspensions, from the precursor Pt (NH3)4Cl2.0, 68H2O, PdCl2 and RuCl3.1, 37H2O, respectively, to obtain a catalyst with nominal content of 2% ww. The catalysts were characterized by the methods: specific surface area (B.E.T.), temperature programmed reduction (TPR), X-ray diffraction (DRX), infrared spectroscopy (FTIR) of adsorbed pyridine and the pyridine desorption temperature. The performance of the catalysts was evaluated in the reaction of hydrogenolysis of glycerol in the liquid phase, using a high pressure Parr reactor. The results indicate that the use of bifunctional metal-acid catalysts is a way to make the hydrogenolysis more effective, because it favors the dehydration and hydrogenation reactions to produce 1,2-propanediol / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Neste trabalho foram preparados nanocompósitos de Poliestireno (PS) e argilas organofílicas. As argilas, inicialmente hidrofílicas, foram modificadas organicamente utilizando três sais quaternários de amônio diferentes: Cloreto de hexadecil trimetil amônio (CTAC), Cloreto de alquil dimetil benzil amônio (Dodigen) e Cloreto de dimetil dioctadecil amônio (Praepagen). A argila organofílica Cloisite 20A foi também utilizada neste estudo. Os nanocompósitos foram preparados por intercalação no polímero fundido por três técnicas diferentes: adição de argila em suspensão de álcool etílico por uma bomba dosadora de líquidos durante a extrusão, adição de argila em pó por um alimentador mecânico durante a extrusão e adição de suspensão de argila em álcool etílico durante obtenção por batelada. Os materiais obtidos foram caracterizados por difração de raios-X (DRX), microscopia óptica (MO) e microscopia eletrônica de transmissão (MET) e ensaios reológicos de Cisalhamento Oscilatório de Pequenas Amplitudes (COPA). As propriedades térmicas foram analisadas por análise termogravimétrica (TG) e as propriedades mecânicas foram analisadas por ensaios de tração e impacto Izod. As três técnicas se mostraram eficazes na preparação dos nanocompósitos, e seus resultados apresentaram uma similaridade muito grande. Os resultados de DRX e microscopia mostraram que a maioria dos nanocompósitos apresentou estruturas compostas de fases intercaladas e esfoliadas. As análises térmicas mostraram que a adição de argila ao PS o tornou mais estável termicamente, suportando maiores temperaturas antes de iniciar o processo de degradação. Os ensaios reológicos de COPA e ensaios mecânicos dos nanocompósitos obtidos não apresentaram grandes variações em relação ao PS puro. / In this work nanocomposites of polystyrene (PS) and organophilic clays were prepared. The clays were organically modified using three different ammonium quaternary salts: cetyltrimethyl ammonium chloride (commercial name: CTAC), alquildimethyl benzyl ammonium chloride (commercial name: Dodigen) and distearyl dimethyl ammonium chloride (commercial name: Praepagen). The organoclay Cloisite 20 A was also used in this work. The nanocomposites were prepared by melt intercalation using three different techniques: adding the organoclay as a diluted organic solvent supension to the extruder using a motor-driven metering pump, adding the organoclay as powder to the extruder using a mechanical feeder and adding the organoclay as a diluted organic solvent suspension to the mixer. The materials obtained were characterized by X-ray diffraction (XRD), optical microscopy (OM), transmission electron microscopy (TEM) and by rheological studies through small amplitude oscillatory shear tests (SAOS). The thermal properties were studied by thermogravimetrical analyses (TG) and the mechanical properties were studied by tensile and impact Izod strength tests. The three techniques were efficient to prepare nanocomposites, and their results were very similar. The DRX and microscopy results showed that the most nanocomposites presented structures composed by intercalated and exfoliated phases. The thermal analyses showed that the addition of organoclay turned PS more thermally stable, increasing their degradation temperatures. The results of rheological studies (SAOS) and the mechanical tests did not present significant variations compared to the neat PS.

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Results of drained and undrained triaxial compressions tests on a sensitive clay are presented in this thesis. Contours of water content from both drained and undrained tests are compared, and it appears that for the clay tested, there is not a unique relationship between effective stresses and water content as found by Rendulic and Henkel for remolded soil. The Roscoe concept of a state boundary surface, which is similar to the Rendulic concept is examined, and it also does not hold for the clay tested. The Roscoe energy equation is applied to the results of all tests and it appears to hold quite well. It indicates that for a soil which is yielding there is only one fundamental strength parameter, M, which is independent of both strain and strain rate. Methods of predicting stress-strain relationships are examined. The Roscoe method, which is based on the existence of a state boundary surface is not strictly applicable, but does yield results which are of the same order as the measured relationships. The Landanyi method does not appear to apply to the clay tested. A method for predicting residual pore pressures and or permeability in drained triaxial tests is derived. This enabled allowances to be made for the effect of residual pore pressures in drained tests. However, it is felt that the method may have more application in the examination of soil structure, since a comparison of the permeability of samples at the same void ratio and temperature yields a measure of structural difference. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

A review is given on the factors important to the build-up of a gel structure in clay suspensions. The effect of salt is especially stressed. The maximum yield stress of a 19.06 weight per cent washed Bentonite clay paste was measured with a Rotovisco viscometer as a function of the concentration of five salts which were added individually to the paste. The salt concentration was varied from .002 molality up to the coagulation concentration. Two groups of salts were studied; those which had cations in common with the caly: NaCl and CaCl₂, and those found only in trace amounts in clay: CuCl, MnCl₂ and CeCl₃. The behavior of the two groups of salt was quite different. The latter group produced a maximum developable yield value in the clay which was inversely proportional to the valence of the cation. Sodium Chloride produced the largest maximum yield value at a high salt concentration while no yield value could be found for clay with concentrations of CaCl₂ above 0.002M. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

A theoretical and experimental investigation into the creep of a sensitive clay under different deviator stresses is presented. The effect of deviator stress on pore-pressures within the soil is also studied. An explanation of the phenomenon of creep is offered which is based on a consideration of the micro-structure of the clay. Experimental evidence to support this explanation is presented. The experimental work consisted of standard triaxial "consolidated undrained tests" performed on cylindrical specimens. Pore-pressures were measured by means of a pore-pressure panel based on the M.I.T. design. The observed data show that, with other variables remaining constant, the strain rate increases with increase in applied stress. Experimental results do not conclusively prove the existence of an upper yield value for the clay tested, but they do suggest it as a possibility. With the temperature remaining constant, the test results show that the pore-pressure increases with increase in applied stress. Under a given applied deviator stress the pore-pressure increases at a decreasing rate and does not attain a maximum or constant value at any time during the test. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Many field problems in soils approximate plane strain conditions. Conventional laboratory practice, however, consistently uses triaxial compression testing for evaluating strength and deformation properties of soils. Possible differences between triaxial and plane strain behaviour of natural soils have so far received little attention. New plane strain and K₀-triaxial apparatuses have been designed in which it is now possible to shear samples under various stress paths. A series of triaxial and plane strain tests were performed on identically K₀-consolidated samples of an undisturbed, sensitive, marine clay. Drained and undrained compression and extension tests under both increasing and decreasing stresses were carried out. Similar series of tests were also made on heavily overconsolidated specimens. It is demonstrated that the use of triaxial test results where plane strain conditions prevail invariably leads to an overestimate of deformations and an underestimate of strength. Methods to estimate strains in undrained plane strain shear from the results of triaxial tests under identical stress paths have been developed. Similarly, strains during drained plane strain shear of normally consolidated clay could be predicted from drained and undrained triaxial results, using an extended form of Rendulic's hypothesis. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate