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MODELAGEM CINÉTICA DA PRODUÇÃO DE PROPENO A PARTIR DE ACETONA EM UMA ÚNICA ETAPA / KINETIC MODELING OF PROPYLENE PRODUCTION FROM ACETONE IN A SINGLE STEPEnzweiler, Heveline 19 February 2014 (has links)
Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / Propylene is a chemical compound with high value added, widely used in the industry and
usually obtained from petroleum. However, there is the need of the development of alternative
routes for the production of this compound from renewable sources. The use of acetone for
the production of propylene is a good option, because this oxygenated compound can be
obtained by biomass conversion. The use of a one step process also adds an advantage to the
propylene production from acetone, uniting in a single reactor two consecutive reactions:
acetone hydrogenation, followed by dehydration of the formed isopropanol. For this, there are
necessary two catalysts with distinct properties, one containing metallic sites, for
hydrogenation, and another where there are acidic sites, for dehydration. The main objective
of this work is to obtain propylene from acetone in one single step, using Cu/Zn/Al mixed
oxide derived from hydrotalcite-like compounds and acid form of Beta zeolite as catalysts.
For that, the catalysts were obtained by the coprecipitation method at variable pH followed by
calcination, for the mixed oxide, and by hydrothermal synthesis, for the zeolite. The catalysts
were also characterized as their with distinct properties. The hydrogenation and dehydration
reactions have been studied individually and together by varying the catalyst or mixture of
catalysts employed and the composition and flow rate of the feed. First, they were evaluated
the thermodynamic boundaries of the reaction systems in which was observed that the acetone
hydrogenation is strongly limited by the equilibrium and which are the preferential products
of each reaction. For the reaction test, it was used the factorial experimental design, where the
feeding conditions and reaction temperature were varied, and as response variables it was
obtained the composition of the organic fraction at the reactor outlet. In the hydrogenation
reaction, only isopropanol was obtained and the acetone conversion was close to that of
equilibrium. In the dehydration reaction of isopropanol, propylene was preferably formed,
with only small concentrations of diisopropyl ether at low temperatures, being obtained
complete alcohol conversion in some experimental conditions. The complete process of
acetone conversion into propylene was carried out at eleven distinct experimental conditions
and the olefin fraction was up to 65 % of the organic fraction. It was possible the parameters
estimation of simplified kinetic models, considering the Langmuir-Hinshelwood hypothesis,
appropriate to the prediction of the molar fractions of the compounds in the organic fraction
for both individual as simultaneous reactions. The kinetic models were used to the analysis of
the effect of process variables on the reaction products in the three reaction systems
considered. / O propeno é um composto químico de alto valor agregado, largamente empregado na
indústria e obtido, geralmente, a partir do petróleo. Entretanto, há a necessidade do
desenvolvimento de rotas alternativas para a produção deste composto a partir de fontes
renováveis. A utilização de acetona para a produção de propeno é uma boa opção, pois este
composto oxigenado pode ser obtido através de conversão da biomassa. A utilização de
processo em uma única etapa acrescenta, ainda, mais uma vantagem à produção de propeno a
partir de acetona, unindo em um único reator duas reações consecutivas: hidrogenação de
acetona, seguida da desidratação do isopropanol formado. Para tanto, são necessários dois
catalisadores com propriedades distintas, um deles contendo sítios metálicos, para a
hidrogenação, e outro onde haja sítios ácidos, para a desidratação. O objetivo principal deste
trabalho é a obtenção de propeno a partir de acetona em uma única etapa, utilizando óxido
misto de Cu/Zn/Al derivado de material do tipo hidrotalcita e forma ácida da zeólita Beta
como catalisadores. Para isso, os catalisadores foram obtidos pelo método de coprecipitação a
pH variável seguido de calcinação, para o óxido misto, e pela síntese hidrotérmica, para a
zeólita. Os catalisadores foram, ainda, caracterizados quanto às suas propriedades físicoquímicas.
As reações de hidrogenação e desidratação foram estudadas individualmente e em
conjunto variando-se o catalisador ou mistura de catalisadores empregados e a composição e
vazão da alimentação. Primeiramente, foram avaliados os limites termodinâmicos dos
sistemas reacionais, em que se observou que a hidrogenação de acetona é fortemente limitada
pelo equilíbrio e quais são os produtos preferenciais de cada reação. Para os testes reacionais
foi utilizado planejamento de experimentos fatorial, onde as condições de alimentação e
temperatura de reação foram variadas, e como variáveis resposta obteve-se a composição da
fração orgânica na saída do reator. Na reação de hidrogenação, apenas isopropanol foi obtido
e a conversão de acetona foi próxima daquela de equilíbrio. Na reação de desidratação de
isopropanol, o propeno foi formado preferencialmente, com apenas pequenas concentrações
de éter di-isopropílico a baixas temperaturas, sendo obtidas conversões completas do álcool
em algumas condições experimentais. O processo completo de conversão de acetona em
propeno foi realizado em onze condições experimentais distintas e a fração de olefina foi de
até 65 % da fração orgânica. Foi possível a estimação dos parâmetros de modelos cinéticos
simplificados, considerando as hipóteses de Langmuir-Hinshelwood, adequados à predição
das frações molares dos compostos na fração orgânica tanto para as reações individuais como
simultâneas. Os modelos cinéticos foram utilizados para a análise do efeito das variáveis de
processo sobre os produtos de reação nos três sistemas reacionais considerados.
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Characterisation of soluble components and PAH in PM10 atmospheric particulate matter in BrisbaneKumar, Annakkarage January 2008 (has links)
Fours sets of PM10 samples were collected in three sites in SEQ from December 2002 to August 2004. Three of these sets of samples were collected by QLD EPA as a part of their regular air monitoring program at Woolloongabba, Rocklea and Eagle Farm. Half of the samples were used in this study for the analysis of water-soluble ions, which are Na+, K+, Mg2+, Ca2+, NH4 +, Cl-, NO3 -, SO4 2-, F-, Br-, NO2 -, PO4 -3 and the other half was retained by QLD EPA. The fourth set of samples was collected at Rocklea, specifically for this study. A quarter of the samples obtained from this set of samples were used to analyse water-soluble ions; a quarter of the sample was used to analyse Pb, Cu, Al, Fe, Mn and Zn; and the rests were used to analyse US EPA 16 priority PAHs. The water-soluble ions were extracted ultrasonically with water and the major watersoluble anions as well as NH4 + were analysed using IC. Na+, K+, Mg2+, Ca2+ Pb, Cu, Al, Fe, Mn and Zn were analysed using ICP-AES while PAHs were extracted by acetonitrile and analysed using HPLC. Of the analysed water-soluble ions, Cl-, NO3 -, SO4 2-, Na+, K+, Mg2+ and Ca2+ were high in concentration and determined in all the samples. F-, Br-, NO2 -, PO4 -3 and NH4 + ions were lower in concentration and determined only in some samples. Na+ and Cl- were high in all samples indicating the importance of a marine source. Principal Component Analysis (PCA) was used to examine the temporal variations of the water-soluble ions at the three sites. The results indicated that there was no major difference between the three sites. However, comparing the average concentrations of ions and Cl-/Na+ it was concluded that Woolloongabba had more marine influence than the other sites. Al, Fe and Zn were detected in all samples. Al and Fe were high in all samples indicating the significance of a source of crustal matter. Cu, Mn and Pb were in low concentrations and were determined only in some samples. The lower Pb concentrations observed in the study than in previous studies indicate that the phasing-out of leaded petrol had an appreciable impact on Pb levels in SEQ. This study reports for the first time, simultaneous data on the water-soluble, metal ion and PAH levels of PM10 aerosols in Brisbane, and provides information on the most likely sources of these chemical species. Such information can be used alongside those that already exist to formulate PM10 pollution reduction strategies for SEQ in order to protect the community from the adverse effects of PM pollution.
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