ARACELI JARDIM SILVA
7 resultados
Resultados de Busca
Agora exibindo 1 - 7 de 7
Artigo IPEN-doc 29680 Conversão de metano em metanol com co-geração de energia elétrica a partir de catalisadores de paládio suportados em carbono2023 - SILVA, ARACELI J.; ZAMBIAZI, PRISCILLA J.; GOMES, PAULO V.R.; NANDENHA, JULIO; GODOI, CAMILA M.; SOUZA, RODRIGO F.B. de; NETO, ALMIR O.; AZEREDO, NATHALIA F.B.The application of solid electrolyte reactors for methane oxidation and energy co-generation is attractive, especially with the use of catalysts synthesized from noble metals such as palladium. In this work, we prepared three different compositions of palladium on carbon support to evaluate the composition that had the greatest potential for energy generation. Catalysts in the proportions of 5, 10 and 20% of Pd/C were tested for the conversion of greenhouse gases into organic molecules of higher added value using electrochemical fuel cell solid electrolyte reactors. The focus of this work was the conversion of methane into methanol, using the fuel cell as a reactor and the commercial Pd/C as electrocatalyst. The electrocatalysts were tested at the anode, analyzed by infrared (IR) spectroscopy and their activities verified by experiments with rotating ring disk electrode (RRDE). Higher levels of palladium (Pd/C 20%) favored obtaining electrical power, and the intermediate composition (Pd/C 10%) showed a greater production of less oxidized compounds, such as methanol, in addition to generating electricity.Dissertação IPEN-doc 29250 Desenvolvimento de eletrocatalisadores baseados em paládio ou platina aplicados em reatores de eletrólitos poliméricos - tipo célula a combustível2022 - SILVA, ARACELI J.A aplicação de reatores de eletrólitos sólidos para oxidação de metano e cogeração de energia é atrativa, principalmente com o uso de catalisadores sintetizados a partir de metais nobres como o paládio (Pd). Neste trabalho, preparamos três diferentes composições de paládio, 5%, 10% e 20%, em suporte de carbono (Pd/C), no método da redução via borohidreto de sódio para avaliarmos a composição com maior potencial de geração de energia e produtos de maior valor agregado. Os catalisadores foram preparados nas proporções de 5%, 10% e 20% de Pd em suporte de carbono (Pd/C). O principal foco deste trabalho foi a conversão de metano em metanol. Os eletrocatalisadores prepados foram testados como ânodo, seus efluentes foram analisados por espectroscopia no infravermelho (IR) e suas atividades verificadas por experimentos com eletrodo de disco de anel rotatório (RRDE). As composições mais ativas foram 10% e 20% de paládio, com maiores taxas de reação próximas ao potencial de circuito aberto. Nós também preparamos eletrocatalisadores de PtPb/C, nas proporções 10:90, 70:30, 50:50, pelo método da redução via borohidreto de sódio e testamos esses materiais para a oxidação do etanol em meio alcalino e oxidação do ácido fórmico em meio ácido, nossos resultados mostraram para ambas reações estudadas o efeito benéfico da adição do chumbo à platina, esse efeito poderia ser atribuído ao mecanismo bifuncional e ao efeito eletrônico.Artigo IPEN-doc 28849 Application of binary PdSb/C as an anode in a polymeric electrolyte reactor-fuel cell type for electrosynthesis of methanol from methane2022 - GODOI, CAMILA M.; SANTOS, MONIQUE C.L.; NUNES, LIVIA C.; SILVA, ARACELI J.; RAMOS, ANDREZZA S.; SOUZA, RODRIGO F.B. de; NETO, ALMIR O.PdSb catalyst prepared in different compositions were applied as an anode in a polymeric electrolyte reactor - fuel cell type (PER-FC) to convert methane into oxygenated products and energy in mild conditions. The PER-FC polarization curves for Pd90Sb10/C presented maximum current density about 0.92 mW cm-2 about 15% higher than PdSb materials. However, the material Pd50Sb50/C showed higher reaction rate for methanol generation than the other materials occurring close to the OCV (r ~ 7 mol L-1 h-1). The qualitative analyses of PER-FC effluent by FT-IR identified products as methanol, carbonate and formate ions from the partial oxidation of methane for all materials.Artigo IPEN-doc 28325 Conversion of methane to methanol using WO3/TiO2 porous photocatalyst2021 - YOVANOVICH, MARCOS; SILVA, ARACELI J. da; SOUZA, RODRIGO F.B. de; USSUI, VALTER; NETO OLIVEIRA, ALMIR; LAZAR, DOLORES R.R.The conversion of methane into methanol is one of the great challenges in the photocatalysis. In this investigation WO3/TiO2 photocatalysts was synthesized by sodium borohydride (NaBH4) method. The tungsten concentration was studied in the range of 5 to 20 atomic ratio. XRD results revealed a TiO2 anatase phase and WO3 peaks near the background noise. However, WO3 presence has been highlighted by Raman spectroscopy, indicating the existence of both orthorhombic and amorphous phase.The photocatalyst experiments showed that all materials enable the methanol production in UVC irradiation, and only the materials with WO3 content produced the alcohol in white light irradiation. The high conversion was observed for WO3(10)/TiO2(90) with 3.5 mmol h-1. The conversion of methane to methanol was most promising using WO3(10)/TiO2(90) due high conversion and no other products observed in FTIR spectra.Artigo IPEN-doc 27709 Methane conversion to higher value‑added product and energy co‑generation using anodes OF PdCu/C in a solid electrolyte reactor2021 - GODOI, C.M.; SANTOS, M.C.L.; SILVA, A.J.; TAGOMORI, T.L.; RAMOS, A.S.; SOUZA, R.F.B. de; OLIVEIRA NETO, A.PdxCuy/C catalysts combinations were employed to CH4 partial oxidation in mild condition using a solid electrolyte reactor—alkaline fuel cell type. The differential mass spectroscopy on line method was used to monitor the oxidation products obtained as methanol, dimethyl ether, methyl formate and potassium formate. It was observed that as the electrical potential of the reactor increases, the generation of products decreases. The best results for conversion of methane into methanol and energy co-generation was obtained from Pd90Cu10/ C and Pd50Cu50/ C due to better H2O activation effects and adsorption site for CH4 oxidation.Artigo IPEN-doc 27246 Conversion of methane into methanol using the [6,6′-(2,2′-bipyridine-6,6′-diyl)bis(1,3,5-triazine-2,4-diamine)](nitrato-O)copper(II) complex in a solid electrolyte reactor fuel cell type2020 - GARCIA, LUIS M.S.; RAJAK, SANIL; CHAIR, KHAOULA; GODOY, CAMILA M.; SILVA, ARACELI J.; GOMES, PAULO V.R.; SANCHES, EDGAR A.; RAMOS, ANDREZZA S.; SOUZA, RODRIGO F.B. de; DUONG, ADAM; NETO, ALMIR O.The application of solid electrolyte reactors for methane oxidation to co-generation of power and chemicals could be interesting, mainly with the use of materials that could come from renewable sources and abundant metals, such as the [6,6′- (2, 2′-bipyridine-6, 6′-diyl)bis (1,3,5- triazine-2, 4-diamine)](nitrate-O)copper (II) complex. In this study, we investigated the optimal ratio between this complex and carbon to obtain a stable, conductive, and functional reagent diffusion electrode. The most active Cu-complex compositions were 2.5 and 5% carbon, which were measured with higher values of open circuit and electric current, in addition to the higher methanol production with reaction rates of 1.85 mol L−1 h−1 close to the short circuit potential and 1.65 mol L−1 h−1 close to the open circuit potential, respectively. This activity was attributed to the ability of these compositions to activate water due to better distribution of the Cu complex in the carbon matrix as observed in the rotating ring disk electrode experiments.Resumo IPEN-doc 26798 Development of non-fluorinated membranes based on PBI for application in high temperature fuel cells (HT-PEM)2019 - SILVA, R.P.; SOUZA, R.F.B. de; SANTOS, C.M.G.; SILVA, A.J.; SANTIAGO, E.I.Most of Proton Exchange Membrane Fuel Cells (PEMFCs) use the Nafion as electrolyte, which has a limitation in the operating temperature. Usually, these cells operate up to 80°C since the proton conduction is dependent on water molecules carriers. The increase in the operating temperature of a PEMFC cell is desired due to the contribution of the temperature in the acceleration of the electrochemical reactions, which are thermoactivated processes. In the context of searching alternative polymeric electrolytes, PBI (polybenzimidazole) membranes have been considered a promising membrane for high temperature operating PEMFC (HT-PEMFC) due to the combination of satisfactory proton conduction in conditions of low relative humidity (RH) and excellent thermal stability. Pure PBI membranes were prepared by casting a solution of PBI / N, N'-dimethylacetamide (DMAc) and doped with phosphoric acid at different times (1, 3, 5, 7 10 and 15 days). Each membrane was evaluated in Fuel Cell tests, doping level and online Raman tests in order to determine effects of doping level, chemical degradation and fuel cell performance. The electrodes were optimized by studying different catalytic layer composition and the cell tested at different operational conditions.