Navegando por Autor "Nascimento, José Carlos"
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Artigo Determination of reactivity and thermodynamic analysis of nickel-based oxygen carriers for chemical-looping combustion(Brazilian Society of Chemical Engineering, 2019) Figueiredo, Adolfo Lopes de; Carvalho, Fabiola Correia de; Nascimento, José Carlos; Ruiz, Juan A. C.; Chiavone Filho, Osvaldo; Courtial, Camila Gambini PereiraThis work aimed to study nickel-based oxygen carriers (OC) for Chemical Looping Combustion (CLC) using H2 and CH4 as fuel. The reactivity and reaction kinetics of the OC were investigated, applying the shrinking core, nucleation and diffusion models in three dimensions, as well as whether the OC is thermodynamically favorable for the reaction. The results showed that the OC achieved high conversion for both fuels, proving to be quite reactive, while the fuel gas concentration and the temperature have a strong effect on the solids conversion. For the H2 combustion, the reaction rate can be described well by the shrinking core model, whereas for CH4 the nucleation model may better represent the experimental data. With respect to reactions that occur in the reduction reactor with the NiO/Ni redox system, it was observed that, for the investigated temperatures used in CLC, high values of the equilibrium constant were obtained, showing that practically complete conversion of the fuels is possibleArtigo Synthesis and characterization of bifunctional transition-metal/silica-alumina catalysts for the chloromethane conversion to hydrocarbons(ABPG, 2008) Rojas, Leopoldo Osvaldo Alcazar; Nascimento, José Carlos; Ruiz, Juan Alberto Chavez; Benachour, Monhad; Sousa, João Fernandes deIn this work bifunctional (metal-acid) catalysts of Fe, Ni, Fe2O3 and NiO over amorphous silica alumina support were characterized (acidity) and evaluated for the conversion of chloromethane in a fixed bed reactor. Temperature program tests TPD (Temperature Programmed Desorption) and TPR (Temperature Programmed Reduction) were performed to characterize the quimissorption sites for the impregnated and unimpregnated support. New adsorption sites were created on the metal supported catalysts. The conversion yield of chloromethane was evaluated for the five materials. The highest conversion conversion (85%) was observed for the unmodified support (SiAl) after 6 of reaction at 860 K and a WHSV (Weight Hourly Space Velocity) of 4,5 h-1. The best selectivity toward desirable hydrocarbons (C3, C4) was found for the Fe-SiAl catalyst. C3 was also found in the products stream when Ni/SiAl and NiO/SiAl catalyts were tested. Ni catalysts were the most favorable to methane production. The catalytic tests showed coke formation in all materials. For the SiAl support the desorption energy of chloromethane, determined by TPD runs, was 101,9 KJ/mol. The metals presented lower desorption energies (75,2 KJ/mol for Ni and 133,4 KJ/mol for Fe) than the oxides (190,1 KJ/mol for Fe2O3 and 322,4 KJ/mol for NiO)Artigo Synthesis and characterization of CuCl2/SiO2 catalyst for the oxychlorination of methane(Brazilian Association of Research and Development in Petroleum and Gas (ABPG), 2011) Nascimento, José Carlos; Sousa, João Fernandes de; Rojas, Leopoldo Osvaldo Alcazar; Fontes, Francisco de Assis OliveiraCuCl2 catalysts supported on silica were used in the oxychlorination of methane. The materials were synthesized by the ion-exchange technique in a basic solution, using a copper-ammonia complex with 3 and 6 % of nominal copper load. The materials where characterized by Thermogravimetry (TG), X-ray Fluorescence Spectroscopy (XRF), Temperature Programmed Reduction (TPR), Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS), BET specific area, and Pore Distribution. The characterization confirmed the presence of copper on the support surface, concluding that the ion-exchange technique was adequate for the catalyst synthesis. During reaction assays, an oxychlorination bench-scale unit was employed. The tests were carried out at 673 and 773 K. The results demonstrated the influence of temperature and catalyst copper content on methane conversion