Browsing by Author "Rodrigues, J."
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- An electrochemical process for the production of synthetic fuels at low temperatures [Resumo]Publication . Fernandes, Vitor; Furtado, Olívia; Rodrigues, J.; Rangel, C. M.Following work exploring the low temperature electrolysis in alkaline media, using graphite consumable anodes, from which syngas was obtained1, laboratory studies have been conducted in acid media pursuing higher efficiency in the production of hydrogen and synthetic fuels. Experiments were conducted in an own designed undivided planar cell with 25 cm2 geometrical area electrodes using a 0.5 M H2SO4 solution with and without Fe(II) additions. Fe2+ oxidizes to Fe3+ at the anode surface. The redox couple Fe3+/ Fe2+ acts as an oxidation mediator not only oxidizing the bulk and detached graphite but also the surface functional groups. The practical experimental potential for graphite oxidation is within the range for the electroxidation of the Fe redox couple giving as a result a 4-fold increase in the amount of produced CO2 at near room temperature, when using 0.025 M FeSO4.
- Macroestrutura varisca do Arco da Garraia, Santa Comba, Murça, NE de PortugalPublication . Rodrigues, J.; Ribeiro, António; Pereira, EuricoA unidade quartzítica que constitui os relevos residuais das serras da Garraia e Santa Comba forma uma macrodobra de 1ª fase varisca que apresenta um flanco inverso com mais de 10 km de extensão e importante variação da direcção das charneiras do dobramento. A cartografia dessa variação evidencia uma importante estrutura arqueada, agora designada por arco da Garraia - Santa Comba. A caracterização geométrica desta estrutura juntamente com os dados do único achado fóssil neste sector fazem com que não se exclua uma idade ordovícica para a unidade aflorante no núcleo desse anticlinal deitado e vergente para E a ESE.
- Organização tectonoestratigráfica do complexo parautóctone do NE de Portugal : uma propostaPublication . Rodrigues, J.; Ribeiro, António; Pereira, Eurico; Pinto de Meireles, Carlos AugustoCom base em características geométricas e estratigráficas apresenta-se, para o NE de Portugal, uma divisão interna no Complexo Parautóctone: o Parautóctone Inferior está estruturado num conjunto interno de acidentes inversos imbricados envolvendo unidades silúrico-devónicas; o Parautóctone Superior apresenta macrogeometrias do tipo manto-dobra, com flancos inversos que podem apresentar mais de 10 km de extensão e unidades com possível idade ordovícica no núcleo de grandes anticlinais deitados e vergentes para E a SE.
- Preliminary geochemical data of the 2014 erupted lavas and pyroclasts at Fogo Island (Cape Verde Archipelago)Publication . Mata, João; Martins, S.; Mattielli, Nadine; Madeira, J.; Silva, P.; Martins, L.; Caldeira, Rita; Moreira, M.; Ramalho, R.S.; Faria, Bruno V. E.; Rodrigues, J.; Victória, S.
- Synthetic fuels production by graphite-assisted electrolysisPublication . Fernandes, Vitor; Furtado, Olívia; Rodrigues, J.; Rangel, C. M.ABSTRACT: Hydrogen produced by water electrolysis is considered as the best energy carrier to adjust the balance between the generation of power source by renewable primary energy and energy demand for end-use. Further advantages are foreseen with the use of carbon-assisted electrolysis. This is due to the electrochemical participation of carbon in the reaction, the electrolysis process would potentially require about 1/3 the electrical energy with the balance of 2/3 coming from the chemical energy of carbon in comparison with conventional water electrolysis where all the energy input is electric. Carbon is oxidized to CO2 on the anode and hydrogen is produced at the cathode. Generally, carbon sources for anodic reaction are graphite, activated carbon and coal. In this work, low temperature electrochemical gasification of graphite in alkaline and acid solutions was explored, taking into account experimental conditions where the faradaic overall current has a significant contribution from carbon oxidation reactions. Results indicate adequate molar gases fraction for the production of syngas and the production of small chain hydrocarbons, obtained at laboratory prototype level.