JOAO COUTINHO FERREIRA

JOAO COUTINHO FERREIRA

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Synthesis of dibenzo-15-crown-5 - DMSO resin – silica used for isotopic separation of the lithium
2024 - FERREIRA, J.C.; BERGAMASCHI, V.S.; OTOMO, J.I.; SOUZA, R.F. de; SANTOS, D.G.; MORAES, T.S.; VEGA, J.B.
The development of new materials and ligands based on crown ethers capable of mono- and binuclear coordination compounds, free or linked to silica matrices, has been studied by several authors for the isotopic separation of lithium 6/lithium 7. The present work shows the synthesis of dibenzo-15-crown-5 in high-purity silica gel polymeric material, pore size 60 Å, 70–230 mesh. B15C5 was dissolved in a mixture of 15 g of phenol in 250 mL of methanol and 100 mL of DMSO in a reaction vessel, and approximately 50 g of porous silica granules were added to the solution, which was stirred for approximately 10 minutes by a rotoevaporator shaker under reduced pressure at room temperature. After the evaporation of methanol, approximately 10 g of formalin, 70 mL of formic acid, and 1 mL of sulfuric acid were added to the reaction flask and left to form the polymerization for 24 h under reduced pressure at 70?C. The pressure decreased further near the boiling point of the reactant solution by removing the reactant solution. The silica resins with a yellowish color were washed with water repeatedly until the neutral pH of the washing water was reached. The characterization of the dry resin spheres under reduced pressure was carried out via thermogravimetric analysis, infrared and ultraviolet spectroscopy, and nuclear magnetic resonance to verify the presence of carbon and hydrogen. The prepared material was placed in a chromatographic column positioned in series, forming stages, in the form of a cascade, for isotopic separation of the 99.98% purity lithium solution. Isotopic separation using the prepared material was evaluated by a quadrupole mass spectrometer.
Nickel, ceria and niobium catalysts are supported on alumina in the steam reforming of ethanol to obtain hydrogen
2024 - FERREIRA, J.C.; BERGAMASCHI, V.S.; SILVA, E.M.; SOUZA, R.F. de; MORAES, T.S.
Heterogeneous catalysts of nickel, niobium and cerium supported on alumina were prepared by the co-precipitation method in different chemical compositions. After the synthesis of the catalysts, the samples were calcined at 800 °C for 4 hours in a muffle furnace. Then, the obtained samples were analyzed by different characterization methods, such as X-ray Diffraction (XRD), X-ray Dispersive Spectrometry (EDS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Programmed Temperature Reduction (TPR), and Thermogravimetric Analysis (TG). The characterized catalysts were evaluated in catalytic tests using steam reforming of ethanol to produce hydrogen. A quartz fixed-bed catalytic reactor with an internal diameter of 6 mm was used. The catalytic reactor was filled with 100 mg of catalyst, and then the catalyst was activated using a hydrogen flow of 30 mL.min-1. After activating the catalyst, ethanol was steam reformed under the following operating conditions. Water/ethanol molar ratio equal to 3:1, Reaction temperature of 600 °C. The synthesis gases obtained in the reaction, such as hydrogen, carbon monoxide, carbon dioxide and methane, were analyzed in a gas chromatograph, coupled online to the catalytic reactor. The chromatograph used is equipped with two detectors, a thermal conductivity detector (TCD) and another for ionic conductivity (FID), in addition to two gas separation columns, a molecular column serving 5 A and another Porapak column.
Reforma do etanol para obtenção do hidrogênio utilizando catalisadores de CoCeCu/ZRO2-Y2O3
2022 - FERREIRA, JOAO C.; BERGAMASCHI, V.S.; ARCANJO, G.d.; MORAES, T.S.
Os catalisadores sintetizados neste trabalho foram preparados por complexação metal–quitosana ancoradas em sais de Cobalto, Cobre e Cério com diferentes massas sólidas dos metais de transição na forma de microesferas. Os denominados metais ativos foram suportados em solução de zircônio-ítrio e calcinados a 600 oC. Foram caracterizados por Difração de Raios –X (DRX), Espectrometria Dispersiva de Raios-X (EDS), Microscopia Eletrônica de Varredura (MEV), Microscopia Eletrônica de Transmissão (TEM), Temperatura Programada de Redução (TPR), Analise Termogravimétrica (TG). Os métodos de confecção catalítica foram comparados e avaliados através da reforma a vapor de etanol utilizando um reator tubular de quartzo de leito fixo (5 mm de diâmetro interno) acondicionado com 100 mg de catalisador colocado em um forno vertical sob pressão atmosférica. Foram tratados termicamente a 500 °C, durante 1 h com uma taxa de fluxo do H2 de 30 mL min-1. Água e etanol com relação molar de 1:3 e alimentados e reator usando um sistema com dois aparelhos saturadores com N2 como gás de transporte com fluxo de 20 mL.min- 1. Os reagentes e os produtos foram analisados por um Cromatógrafo a gás (Agilent 7890A).
Preparation and characterization of high-performance Ni-based core-shell catalyst for ethanol steam reforming
2022 - MORAES, TAMARA S.; BERGAMASCHI, VANDERLEI S.; FERREIRA, JOAO C.; SPINACE, ESTEVAM V.
A core–shell catalyst, based on nickel nanoparticles supported on silica nanospheres and surrounded by ceria, was tested for ethanol steam reforming (ESR) reaction (H2O/ethanol: 3/1) under low-temperature conditions (400, 500 and 600 °C) in order to test its stability during the reaction. Two other catalysts of Ni supported in SiO2 and CeO2 were also synthesized to be compared with the core–shell catalyst in the ESR. All catalysts showed excellent activity at 500 and 600 °C with 100% ethanol conversion. Increasing the reaction temperature, carbon deposition on the surface of the catalysts decreases throughout the reaction. The core–shell catalyst showed high coke inhibition capacity in the ESR at 600 °C, without coke formation for at least 100 h of reaction. On the other hand, after 20 h of ESR at 600 °C, Ni–SiO2 and Ni/CeO2 catalysts showed formation of 6.3 and 5.2 mgC/(gcat.h) of coke, respectively. The strong redox capacity of ceria together with the change in catalyst structure due to the deposition of cerium oxide on top of Ni particles led to an excellent ESR activity of this catalyst.
Core-shell catalysts for ethanol steam reforming reaction
2020 - MORAES, T.S.; FERREIRA, J.C.; BERGAMASCHI, V.S.; SPINACE, E.V.
Hydrogen can be produced from the steam reforming (SR) of biomass-derived liquids such as bioethanol. The SR of ethanol for hydrogen production has several advantages. However, one of the main barriers to the commercialization of this technology is the deactivation of the catalysts due to the formation of carbon. Therefore, the development of catalysts that are stable and resistant to carbon formation is necessary. Several strategies have been used to avoid the deposition of carbon on the surface of the catalysts. Cerium oxide, at high temperatures or in the presence of reducers, can easily change oxidation state to form a non-stoichiometric oxygen deficient oxide. This oxide has a strong tendency to remain in the fluorite structure even after considerable oxygen loss, stabilizing the structure with a high number of oxygen vacancies. Other approach to minimize coke formation is to control the size of metallic particle through modifications in the catalyst structure. According to the mechanism reported in the literature, carbon formation in these reactions are favored in large sizes of metal particle. Therefore, controlling particle size is essential to reduce carbon accumulation on the catalyst surface during ethanol reforming reactions. One strategy for inhibiting the sintering process of metal particles in catalysts is the development of core-shell catalysts. These catalysts feature a metal core covered with an oxide layer, which gives them unique characteristics. The core-shell structure also accelerates the transformation processes of the carbon formed at the metal-oxide interface, favoring the gasification reaction and consequently its elimination in the form of CO2. Das et all have synthesized an innovative sandwiched core-shell structured Ni-SiO2@CeO2 catalyst that showed high activity and stability at dry reforming of biogas with negligible coke formation. The aim of this work is to investigate the performance of the structurally modified Ni-SiO2@CeO2 catalyst in the form of a sandwiched core-shell to inhibit the formation of carbon and increase the stability of the catalysts in the SR of ethanol reaction. This new form of catalyst synthesis has proved very efficient in other reactions but is still very little studied in the ethanol SR reaction. Silica nano-spheres were synthesized by the Stöber method and Ni-SiO2 catalysts were prepared via a Ni-phyllosilicate precursor route. Ni-SiO2@CeO2 will be prepare using the fresh Ni-phyllosilicate spheres that will be coated with a thin layer of CeO2 using a precipitation method. Silica nano-spheres and Ni-SiO2 were calcined at 1273 K for 1 hour with air. Samples were analyzed using transmission electron microscope (TEM) and x-ray diffraction (XRD). SR of ethanol was performed in a fixed-bed reactor at atmospheric pressure. Prior to reaction, catalysts were reduced under pure hydrogen at 923 K for 1 h. The reactions were carried out at 673K and H2O/ethanol molar ratio of 3.0.