Neste trabalho foi realizado o estudo de transformações de óleo de soja com o catalisador VO(acac)2 em meio homogêneo e heterogêneo. Estes processos catalíticos estão de acordo com os conceitos de química limpa, no sentido de economia de reagentes e diminuição de subprodutos, enquanto que a matéria-prima, óleo vegetal, foi escolhida por ser de fonte renovável, sustentável e abundante no Rio Grande do Sul e no Brasil. A reação de transesterificação do óleo de soja foi realizada através do sistema VO(acac)2 e VO(acac)2 suportado em uma argila celadonita, cujo depósito localiza-se na região de Ametista do Sul – RS. O sistema heterogêneo foi caracterizado pelas técnicas de DRX, BET, BJH, ATG, FTIR, CHN, MEV/EDS e ICP/OES. O teor de vanádio impregnado na argila foi de 1,06 %. O melhor rendimento das reações de transesterificação foi de 36 % e 30 % para os sistemas homogêneo e heterogêneo, respectivamente, para as condições de 2 % em mol e 5 % em mol de vanádio, a 65 ºC de temperatura e 48 horas de reação. Alguns testes foram realizados em reações de epoxidação. Do sistema celadonita/VO(acac)2 foi obtido conversão de 44 %, 15 % de monoepóxido e 34 % de seletividade, em 3 horas de reação. A avaliação quantitativa das reações foi realizada por RMN de 1H. / This work presents the study of soybean oil reactions with VO(acac)2 in homogeneous and heterogeneous catalytic systems. The catalytic systems follow the green chemistry principles of economy of reagents and reduction in sub-products of the reaction while the starting material, soybean oil, was chosen as a renewable source, sustainability of its crop and abundancy. Soybean oil transesterification reactions were done with the catalytic system VO(acac)2 and VO(acac)2 supported in celadonita, which is a mineral found in Ametista do Sul / RS. The heterogeneous system was characterized by the XRD, BET, BJH, TGA, FTIR, CHN, SEM/EDX and ICP/OES techniques. The amount of vanadium impregnated in the clay it was 1,06%. The best conditions for transesterification reaction gave 36 % yield for homogeneous system and 30 % yield for heterogeneous system, using 2 % molar and 5 % molar of vanadium, respectively, at 65 ºC of temperature and 48 hours of reaction. Some tests on epoxidation reactions were performed. With celadonita/VO(acac)2 system it was obtained a conversion of 44%, 15% of monoepoxide and 34 % of selectivity after 3 hours of reaction. The quantitative evaluation of the reactions was made by 1H NMR.

Graduation date: 1997

Neste trabalho foi realizado o estudo de transformações de óleo de soja com o catalisador VO(acac)2 em meio homogêneo e heterogêneo. Estes processos catalíticos estão de acordo com os conceitos de química limpa, no sentido de economia de reagentes e diminuição de subprodutos, enquanto que a matéria-prima, óleo vegetal, foi escolhida por ser de fonte renovável, sustentável e abundante no Rio Grande do Sul e no Brasil. A reação de transesterificação do óleo de soja foi realizada através do sistema VO(acac)2 e VO(acac)2 suportado em uma argila celadonita, cujo depósito localiza-se na região de Ametista do Sul – RS. O sistema heterogêneo foi caracterizado pelas técnicas de DRX, BET, BJH, ATG, FTIR, CHN, MEV/EDS e ICP/OES. O teor de vanádio impregnado na argila foi de 1,06 %. O melhor rendimento das reações de transesterificação foi de 36 % e 30 % para os sistemas homogêneo e heterogêneo, respectivamente, para as condições de 2 % em mol e 5 % em mol de vanádio, a 65 ºC de temperatura e 48 horas de reação. Alguns testes foram realizados em reações de epoxidação. Do sistema celadonita/VO(acac)2 foi obtido conversão de 44 %, 15 % de monoepóxido e 34 % de seletividade, em 3 horas de reação. A avaliação quantitativa das reações foi realizada por RMN de 1H. / This work presents the study of soybean oil reactions with VO(acac)2 in homogeneous and heterogeneous catalytic systems. The catalytic systems follow the green chemistry principles of economy of reagents and reduction in sub-products of the reaction while the starting material, soybean oil, was chosen as a renewable source, sustainability of its crop and abundancy. Soybean oil transesterification reactions were done with the catalytic system VO(acac)2 and VO(acac)2 supported in celadonita, which is a mineral found in Ametista do Sul / RS. The heterogeneous system was characterized by the XRD, BET, BJH, TGA, FTIR, CHN, SEM/EDX and ICP/OES techniques. The amount of vanadium impregnated in the clay it was 1,06%. The best conditions for transesterification reaction gave 36 % yield for homogeneous system and 30 % yield for heterogeneous system, using 2 % molar and 5 % molar of vanadium, respectively, at 65 ºC of temperature and 48 hours of reaction. Some tests on epoxidation reactions were performed. With celadonita/VO(acac)2 system it was obtained a conversion of 44%, 15% of monoepoxide and 34 % of selectivity after 3 hours of reaction. The quantitative evaluation of the reactions was made by 1H NMR.

Neste trabalho foi realizado o estudo de transformações de óleo de soja com o catalisador VO(acac)2 em meio homogêneo e heterogêneo. Estes processos catalíticos estão de acordo com os conceitos de química limpa, no sentido de economia de reagentes e diminuição de subprodutos, enquanto que a matéria-prima, óleo vegetal, foi escolhida por ser de fonte renovável, sustentável e abundante no Rio Grande do Sul e no Brasil. A reação de transesterificação do óleo de soja foi realizada através do sistema VO(acac)2 e VO(acac)2 suportado em uma argila celadonita, cujo depósito localiza-se na região de Ametista do Sul – RS. O sistema heterogêneo foi caracterizado pelas técnicas de DRX, BET, BJH, ATG, FTIR, CHN, MEV/EDS e ICP/OES. O teor de vanádio impregnado na argila foi de 1,06 %. O melhor rendimento das reações de transesterificação foi de 36 % e 30 % para os sistemas homogêneo e heterogêneo, respectivamente, para as condições de 2 % em mol e 5 % em mol de vanádio, a 65 ºC de temperatura e 48 horas de reação. Alguns testes foram realizados em reações de epoxidação. Do sistema celadonita/VO(acac)2 foi obtido conversão de 44 %, 15 % de monoepóxido e 34 % de seletividade, em 3 horas de reação. A avaliação quantitativa das reações foi realizada por RMN de 1H. / This work presents the study of soybean oil reactions with VO(acac)2 in homogeneous and heterogeneous catalytic systems. The catalytic systems follow the green chemistry principles of economy of reagents and reduction in sub-products of the reaction while the starting material, soybean oil, was chosen as a renewable source, sustainability of its crop and abundancy. Soybean oil transesterification reactions were done with the catalytic system VO(acac)2 and VO(acac)2 supported in celadonita, which is a mineral found in Ametista do Sul / RS. The heterogeneous system was characterized by the XRD, BET, BJH, TGA, FTIR, CHN, SEM/EDX and ICP/OES techniques. The amount of vanadium impregnated in the clay it was 1,06%. The best conditions for transesterification reaction gave 36 % yield for homogeneous system and 30 % yield for heterogeneous system, using 2 % molar and 5 % molar of vanadium, respectively, at 65 ºC of temperature and 48 hours of reaction. Some tests on epoxidation reactions were performed. With celadonita/VO(acac)2 system it was obtained a conversion of 44%, 15% of monoepoxide and 34 % of selectivity after 3 hours of reaction. The quantitative evaluation of the reactions was made by 1H NMR.

Inputs of the major element potassium into the ocean from rivers and on-axis high temperature hydrothermal systems have likely varied on geological timescales. Variable uptake of potassium into lavas altered in low-temperature, off-axis, hydrothermal systems could keep the potassium concentration in seawater within the narrow range (~9.5 to 11 mmol L-1) observed in the Phanerozoic. To test this hypothesis a better understanding of the timing of alteration, and of the role of changing environmental conditions on seawater/basalt reactions is required. The age of 69 samples of the secondary, potassium-rich, phyllosilicate mineral celadonite from lavas in the Troodos ophiolite were determined using Rb-Sr radiometric dating to test whether potassium uptake occurs within a specific time interval. Measurements used tandem quadrupole ICP-MS/MS. Combined with published radiometric ages the dataset revealed regional differences in the duration of celadonite formation in the Troodos ophiolite lavas. In one area, where significant hydrothermal sediments were deposited on the lavas, celadonite formed as much as ~40 Myr after the crust accreted, whereas in an area with rare hydrothermal sediments celadonite formation was largely limited to the first ~20 Myr after crustal accretion. These differences in duration of celadonite formation in the upper oceanic crust are interpreted as reflecting differences in distribution of hydrothermal sediments that act as a source of labile Fe that is needed for celadonite formation. To test if there are significant variations of duration and timing of celadonite formation on various scales in the upper oceanic crust I measured the first in-situ Rb-Sr ages of celadonite in lavas from DSDP and ODP drill cores. These ages show that ~80% of celadonite formed from pervasive fluid flow within the first ~20 Myr after the oceanic crust accreted. All celadonite ages roughly correlate with the cumulative heat flow removed from the oceanic lithosphere in the same time interval. In combination the >100 new celadonite ages presented here provide strong evidence that most celadonite forms in the first ~20 Myr after crustal accretion and environmental conditions could be significant in controlling potassium uptake. To determine whether the potassium sink from seawater into altered seafloor lavas varied over time I compile a dataset of the potassium content of lavas from DSDP and ODP drill cores (0 to 180 Myr age range). Estimates of the average potassium content of individual holes reveal that this varies with age. However, holes of similar age show a similar magnitude of variability to that which occurs over this time. To investigate the source of the variability of potassium in altered lavas I modelled the effects of bottom seawater temperature and pH using PHREEQC. The models indicate that if the fluid is in equilibrium with K-feldspar, Na-beidellite and calcite, an increase in bottom seawater temperature and/or decrease in pH would lead to the potassium concentration in the off-axis fluid to increase significantly. This emphasizes the need for future studies to investigate feedback mechanisms between low-temperature hydrothermal alteration in response to changing environmental conditions. / Graduate / 2022-07-12