Navegando por Autor "Oliveira, F. S."
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Artigo Effect of lanthanum replacement by strontium in lanthanum nickelate crystals synthetized using gelatin as organic precursor(Elsevier, 2010-12-31) Melo, Marcus Antônio de Freitas; Oliveira, F. S.; Pimentel, Patrícia Mendonça; Oliveira, Rosane Maria Pessoa Betânio; Melo, Dulce Maria de AraújoLa1-xSrxNiO3 (0 ≤ x ≤ 0.8) nanopowders were successfully synthesized using gelatin as a polymerization agent. Powders were calcined for 4 h at 700 and 900 °C and characterized using thermal analysis, X-Ray diffraction and scanning electron microscopy. Perovskite phase formation was achieved at 700 °C, with an increase in crystallinity and secundary phases forming in powders calcined at 900 °C. The structure of the lanthanum nickelate was confirmed as rhombohedral and transition to tetragonal structure occurred by partially substituting lanthanum with strontiumArtigo LayCu0.4Fe0.6O3 perovskite oxides: synthesis, characterization and catalytic reactivity in the fischer-tropsch synthesis(Brazilian Association of Research and Development in Petroleum and Gas (ABPG), 2011) Melo, Marcus Antônio de Freitas; Souza, José Roberto de; Silva, C. F.; Melo, Dulce Maria de Araújo; Rojas, Leopoldo Osvaldo Alcazar; Oliveira, F. S.The current natural gas production of 52 Mm3 d-1 and the large projects for its expansion has been setting new boundaries for the Brazilian industry of oil and gas. So far, one of the biggest challenges regards the logistics for gas transportation from offshore fields. Therefore, the transformation of natural gas into gasoline, diesel and/or olefins via Fischer-Tropsch synthesis would be an alternative to this matter. In this work, the production of hydrocarbons by Fischer-Tropsch synthesis in a slurry reactor was investigated and a perovskite-type catalyst (LayCu0,4Fe0,6O3) was used, where the lanthanum index “y” varies from 0 to 1 on a molar basis. The selection of the method to synthesize perovskite largely depends on its target application and desired properties. The synthesized perovskites were characterized by X-ray diffraction (XRD) and energy dispersive X-ray fluorescence (EDX). The reducibility of such oxides was studied by a temperature-programmed reduction (TPR) technique and the reactivity of the catalysts was evaluated in a slurry reactor. The selectivity toward hydrocarbons was better in materials with a lanthanum content ranging between 0.6 and 0.8 to produce hydrocarbons (C1-C6 and C17-C26) from syngas by the Fischer-Tropsch (FT) synthesis