JOAO COUTINHO FERREIRA
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Resumo IPEN-doc 31331 Nickel, ceria and niobium catalysts are supported on alumina in the steam reforming of ethanol to obtain hydrogen2024 - 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.Artigo IPEN-doc 30849 Development of hydrophobic graphenoid layer on Portland cement for non-thermal plasma method2024 - PEREIRA FILHO, N.G.; SOARES, E.P.; FERREIRA, J.C.; SOUZA, R.F.B. de; ANDRADE, D.A.; NETO, A.O.This study focuses on the development of hydrophobic layer on Portland cement using graphenoid materials to enhance impermeability and hydrophobicity. X-ray diffraction analysis indicated that characteristic peaks associated with concrete, such as ettringite, calcium hydroxide, and calcite, remained intact. The application of graphenoid material produced by non-thermal plasma resulted in the formation of carbonaceous structures, minimally affecting the overall cement structure. Raman spectroscopy provided detailed insights into the composition, highlighting the presence of specific and indicating boundary defects. Moreover, contact angle measurements confirmed a substantial increase in hydrophobicity for the graphene-coated cement, with an average angle of 117° ± 4.72° demonstrated graphenoid material layers deposited over structural defects, effectively waterproofing and enhancing local hydrophobicity.Artigo IPEN-doc 29865 Graphene deposited on glass fiber using a non-thermal plasma system2023 - GOMES, PAULO V.R.; BONIFACIO, RAFAEL N.; SILVA, BARBARA P.G.; FERREIRA, JOAO C.; SOUZA, RODRIGO F.B. de; OTUBO, LARISSA; LAZAR, DOLORES R.R.; NETO, ALMIR O.This study reports a bottom-up approach for the conversion of cyclohexane into graphene nanoflakes, which were then deposited onto fiberglass using a non-thermal generator. The composite was characterized using transmission electron microscopy, which revealed the formation of stacked few-layer graphene with a partially disordered structure and a d-spacing of 0.358 nm between the layers. X-ray diffraction confirmed the observations from the TEM images. SEM images showed the agglomeration of carbonaceous material onto the fiberglass, which experienced some delamination due to the synthesis method. Raman spectroscopy indicated that the obtained graphene exhibited a predominance of defects in its structure. Additionally, atomic force microscopy (AFM) analyses revealed the formation of graphene layers with varying levels of porosity.Artigo IPEN-doc 29694 Effective phosphate removal from water by electrochemically mediated precipitation with coffee grounds biocarbon obtained by non-thermal plasma method2023 - SILVESTRIN, G.A.; GONCALVES, M.H.; GODOI, C.M.; MAIA, V.A.; FERREIRA, J.C.; GUILHEN, S.N.; NETO, A.O.; SOUZA, R.F.B. deThis study investigates the use of biocarbon electrodes, produced from coffee grounds through plasma pyrolysis, in the electrochemically mediated precipitation process for phosphorus removal in a flow reactor. The structural and electrochemical properties of biocarbon were analyzed using X-ray powder diffraction (XRD), Raman spectroscopy, and cyclic voltammetry. The results show that biocarbon consists of both graphene oxide and lignocellulose with surface OH groups that facilitate the breakdown of water, a key step in the electrochemically mediated precipitation process for phosphorus removal. The addition of graphite to the biocarbon paste was found to be necessary to obtain a response from the biocarbon in cyclic voltammetry. The Gr75BC25 electrode achieved higher phosphorus removal rates than other tested electrodes, particularly at low flows, due to the functional groups present in biocarbon enhancing the breakdown of water. However, electrodes with a greater amount of biocarbon exhibit lower rates of phosphorus removal and higher consumption of electrical power, which can be attributed to their higher electrical resistivity. Thus, to optimize its use, it is important to balance the benefits of increased phosphorus removal rates with the trade-off of increased energy consumption and decreased phosphorus removal at higher levels of biocarbon. The results suggest that biocarbon produced from coffee grounds by plasma pyrolysis has the potential to be used as an effective electrode material for electrochemically mediated precipitation processes.