Navegando por Autor "Lago, Rochel Montero"
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Item Alcoxycle : a novel route for glycerol reform into H2 and COx inseparate stages.(2016) Paula, Fabiano Gomes Ferreira de; Rosmaninho, Marcelo Gonçalves; Teixeira, Ana Paula de Carvalho; Souza, Patterson Patrício de; Lago, Rochel MonteroIn this paper, it is proposed a new route, named “Alkoxycle”, for the conversion of glycerol from biodieselproduction into H2and CO/CO2in different and separate stages. In this process, glycerol first reacts withNaOH to form an alkoxide that, in a second step, undergoes controlled thermal decomposition. Analysesof glycerol:NaOH precursor mixtures (molar ratios of 1:1, 1:2, 1:3 and 1:5) by TG, XRD, SEM, TEM, Raman,total carbon and GC–MS showed that the decomposition of the alkoxide at 400◦C leads to the formationof three fractions: liquid, gas and solid. The liquid products were formed only in very small amountswhereas an important gas fraction (12–16 wt%) was produced consisting mainly of H2(95% selectivity).In the second stage, the solid products (70–86 wt%) consisting of Na2O, carbon and mostly Na2CO3canbe decompose by heating at 700◦C to procuce CO2and especially CO. At the end of the Alcoxycle process,the NaOH used in the reaction and also the NaOH present in the biodiesel glycerol can be recovered andreused.Item Carbon nanostructures-modified expanded vermiculites produced by chemical vapor deposition from ethanol.(2011) Purceno, Aluir Dias; Barrioni, Breno Rocha; Dias, Anderson; Costa, Geraldo Magela da; Lago, Rochel Montero; Moura, Flávia Cristina CamiloIn this work, chemical vapor deposition using ethanol and FeMo catalysts at 600, 700, 800 and 900 °C was used to modify the surface of expanded vermiculite (EV). Scanning electron microscopy, Raman spectroscopy, X-ray diffraction, Mössbauer spectra, N2-BET surface areas, and carbon elemental analyses suggested that the FeMo catalyst promoted 2–3% growth of carbon in different forms, mainly nanofibers, on the EV surface. The amount of 2–3% carbon produced by ethanol/CVD process on EV produced a 500% increase in the absorption of soybean, diesel and engine oil, with a concomitant decrease on water absorption. These results were discussed in terms of a hydrophobization of the EV surface by the carbon structures and a “sponge-like” effect due to the entangled nanofibers structure, as it was observed by microscopy, and an increase of N2-BET surface area from 3 m2 g−1 for EV up to 21 m2 g–1 for the ethanol CVD-treated EV.Item Catalytic carbon deposition-oxidation over Ni, Fe and Co catalysts : a new indirect route to store and transport gas hydrocarbon fuels.(2013) Oliveira, Patrícia E. F.; Ribeiro, Leandro Passos; Rosmaninho, Marcelo Gonçalves; Ardisson, José Domingos; Dias, Anderson; Oliveira, Luiz Carlos Alves de; Lago, Rochel MonteroIn this work, a new two-step route to store and transport associated natural gas, promoted by Ni, Fe and Co supported catalyst was presented. Initially, CH4 is converted into carbon deposits (M/C composite), being Fe catalyst the most active catalyst. In Step 2, M/C composite reacts with H2O producing H2, CO and CH4. TPO experiments showed that efficiency and selectivity of oxidation depends on the metal. Ni catalyst produced mainly H2 and CO, while Fe system was more selective to convert carbon into CH4. The formation of C2 and C3 compounds suggests the presence of a Fischer Tropsch like process.Item Conversion of fatty acids into hydrocarbon fuels based on a sodiumcarboxylate intermediate.(2016) Perígolo, Deise Morone; Paula, Fabiano Gomes Ferreira de; Rosmaninho, Marcelo Gonçalves; Souza, Patterson Patrício de; Lago, Rochel Montero; Araujo, Maria HelenaIn this work, it was investigated the conversion of fatty acids into hydrocarbon based on the reaction withNaOH followed by a controlled thermal decomposition. FTIR, Raman, UV–vis, XRD, TG-MS, SEM/TEM, CHN,GC–MS showed that precursors based on NaOH/oleic acid (molar ratios 0.7, 1.0, 1.5 and 2.0) decomposedat 550◦C to produce three fractions, i.e. liquid (5–37 wt%), gas (52–70 wt%) and solid (10–31 wt%). Theliquid fraction was composed of a complex mixture containing mainly aromatic compounds. On the otherhand, the major gas fraction showed a remarkable selectivity for propane (56–61 wt%) with some C1, C2,C4, H2and COx. The solid fraction showed the presence of Na2CO3, Na2O and particles of amorphousand graphene like carbon. Upon treatment at 800◦C the carbonate decomposes to CO2, oxidizes thecarbon and regenerated the Na2O which can potentially be used for a new reaction cycle. These resultsare preliminary discussed in terms of a catalytic effect of the basic sodium oxide to promote cracking,dehydrogenation and H-transfer reactions.Item Effect of Sn on methane decomposition over Fe supported catalysts to produce carbon.(2011) Freitas, Patrícia Elizabeth de; Ribeiro, Leandro Passos; Rosmaninho, Marcelo Gonçalves; Ardisson, José Domingos; Dias, Anderson; Lago, Rochel MonteroIn this work, alumina-supported Sn containing Fe catalysts were investigated in CVD reactions (Chemical Vapor Deposition) using methane for carbon production. The catalysts were prepared with 10 wt.% of Fe (as Fe2O3) and 3, 6 and 12 wt.% of Sn (as SnO2) supported on Al2O3 named hereon Fe10Sn3A, Fe5Sn6A and Fe10Sn12A, respectively. These catalysts were characterized by SEM, TPCVD, TPR, TG, Raman,XRDand 57Fe and 119Sn Mössbauer spectroscopy.Methane reacts with Fe10A catalyst (without Sn) in the temperature range 680–900◦C to produce mainly Fe0, Fe3 C and 20 wt.% of carbon deposition. TPR and TPCVD clearly showed that Sn strongly hinders the CH4 reaction over Fe catalyst. 57Fe Mössbauer suggested that in the presence of Sn the reduction of Fe+3 by methane becomes very difficult. 119Sn Mössbauer showed Sn+4 species strongly interact with metallic iron after CVD, producing iron-tin phases such as Fe3SnC and FeSn2. This interaction Sn–Fe increases the CVD temperatures and decreases the carbon yield leading to the production of more organized forms of carbon such as carbon nanotubes, nanofibers and graphite.Item Facile preparation of carbon coated magnetic Fe3O4 particles by a combined reduction/CVD process.(2011) Tristão, Juliana Cristina; Oliveira, Aline A. S.; Ardisson, José Domingos; Dias, Anderson; Lago, Rochel MonteroIn this work, we report a simple method for the preparation of magnetic carbon coated Fe3O4 particles by a single step combined reduction of Fe2O3 together with a Chemical Vapor Deposition process using methane. The temperature programmed reactionmonitored by Mo¨ ssbauer, X-ray Diffraction and Raman analyses showed that Fe2O3 is directly reduced by methane at temperatures between 600 and 900 8C to produce mainly Fe3O4 particles coated with up to 4 wt% of amorphous carbon. Thesemagneticmaterials can be separated into two fractions by simple dispersion in water, i.e., a settled material composed of large magnetic particles and a suspended material composed of nanoparticles with an average size of 100–200 nm as revealed by Scanning Electron Microscopy and High-resolution Transmission Electron Microscopy. Different uses for these materials, e.g., adsorbents, catalyst supports, rapid coagulation systems, are proposed.Item K2MgSiO4 : a novel K+-trapped biodiesel heterogeneous catalystproduced from serpentinite Mg3Si2O5(OH)4.(2016) Ballotin, Fabiane Carvalho; Cibaka, Thérèse Ebambi; Benfica, Tatiana Aparecida Ribeiro dos Santos; Santos, Eleonice Moreira; Teixeira, Ana Paula de Carvalho; Lago, Rochel MonteroIn this study, a new catalyst for biodiesel synthesis, based on K2MgSiO4, was produced from the mineralserpentinite. TG, SEM, XRD, AA, BET analyses showed that serpentinite Mg3Si2O5(OH)4impregnated withKOH (5,10 and 20 wt%), and thermally treated at 500◦C, 700 and 900◦C, can be converted to the main crys-talline phase K2MgSiO4. Analyses by TPD-MS (CO2) and titration suggested the presence of weak/mediumbasic sites in relatively high concentrations. Biodiesel production using soybean oil (methanol:soybean oilratio of 1:12, 1:9; 1:6, 60◦C) showed yields higher than 95% with catalyst at 10 wt%, which can be reusedfor three consecutive times without significant decrease on the reaction yield. The obtained results arediscussed in terms of a new catalytic phase based on K+ions trapped in the cavities of the MgSiO42−structure containing negatively charged oxygen basic sites.Item Magnetic amphiphilic composites based on carbon nanotubes and nanofibers grown on an inorganic matrix : effect on water-oil interfaces.(2010) Oliveira, Aline A. S.; Teixeira, Ivo Freitas; Ribeiro, Leandro Passos; Tristão, Juliana Cristina; Dias, Anderson; Lago, Rochel MonteroNovos compósitos magnéticos anfifílicos foram preparados pelo crescimento de nanotubos e nanofibras de carbono contendo partículas magnéticas através de deposição química de vapor (CVD), utilizando etanol como fonte de carbono e lama vermelha (RM, subproduto do processo Bayer de produção de alumina) como suporte e catalisador. Monitoramento da reação CVD à temperatura programada (TPCVD), difração de raios X (XRD), espectroscopia Mössbauer, espectroscopia de energia dispersiva (EDS), espectroscopia Raman, termogravimetria (TG/DTA), análise elementar (CHN), determinação de área superficial (BET), microscopia eletrônica de varredura (SEM) e de transmissão (TEM) e medidas magnéticas mostraram que etanol reduz íons de ferro na RM para formar fases magnéticas, por exemplo Fe3O4 e Fe0, e depósitos de carbono (5-42 wt.%) na forma de nanotubos e nanofibras. A combinação de nanoestruturas hidrofóbicas de carbono com óxidos hidrofílicos de Al, Si e Ti presentes na lama vermelha produziu materiais anfifílicos com excelente interação com a interface água-óleo. Misturas de óleo de soja ou de decalina com água (completamente imiscíveis) foram emulsificadas facilmente na presença dos compósitos anfifílicos. Quando os compósitos foram adicionados a uma emulsão água-biodiesel estável, as partículas anfifílicas difundiram-se para a interface água- óleo. As partículas do compósito foram atraídas por ímãs e carregaram com elas as gotas de óleo, levando à completa desemulsificação e separação entre biodiesel e água.Item New heterogeneous catalyst for the esterification of fatty acid produced by surface aromatization/sulfonation of oilseed cake.(2015) Santos, Eleonice Moreira; Teixeira, Ana Paula de Carvalho; Silva, Flávia Gontijo da; Cibaka, Thérèse Ebambi; Araújo, Maria Helena; Oliveira, Willian Xerxes Coelho; Medeiros, Felipe; Brasil, Alex Nogueira; Oliveira, Leandro Soares de; Lago, Rochel MonteroIn this work, an efficient heterogeneous acid catalyst for the esterification of oleic acid was prepared directly from oilseed cake by a simple sulfonation with concentrated H2SO4. Characterization by SEM/EDS, IR, Raman, TG, TG/MS, potentiometric titration showed that treatment with H2SO4 for 1, 2 and 4 h at 120 _C partially dehydrates the cake to form a carbon/cellulose composite which is sulfonated to produce strong ASO3H acidic sites. These surface sites were active for the esterification of oleic acid with yields ca. 84%, 88% and 94% in the presence of 5, 10 and 20 wt% catalyst, respectively. These results are comparable to 98% yield obtained with 1 wt% H2SO4 and higher than 75% observed for a high surface area (880 m2 g_1) sulfonated activated carbon with similar number of ASO3H active groups. These results are discussed in terms of two effects: (i) the number of sulfonic surface acidic groups and (ii) the presence of a hydrophilic cellulosic fraction in the catalyst that adsorbs/traps water formed in the reaction shifting the esterification equilibrium and improving the yield.Item Production of nanostructured magnetic composites based on Fe0 nuclei coated with carbon nanofibers and nanotubes from red mud waste and ethanol.(2011) Oliveira, Aline A. S.; Tristão, Juliana Cristina; Ardisson, José Domingos; Dias, Anderson; Lago, Rochel MonteroIn this work, a catalytic CVD process using ethanol as carbon source was used to convert an iron rich waste, i.e. red mud (RM), in a magnetic composite. TPCVD (temperature programmed CVD), XRD, Mössbauer, EDS, magnetic measurements, TG/DTA, CHN, BET, Raman, SEM and TEM showed that ethanol gradually reduces the iron phases in the RM to Fe3O4 at 500 ◦C and to Fe1−xO at 600 ◦C. At higher temperatures Fe0 and Fe carbide are the main phases produced with the formation of large amounts of carbon (30–50 wt%) especially as nanotubes and nanofibers. These magnetic materials can be separated into two fractions by simple dispersion in water, i.e. a settled material composed of large magnetic particles and the suspended material composed of nanoparticles with average size of 10–100 nm. The carbon in the composites can be activated with CO2 increasing the surface area from 79 to 185m2 g−1. The magnetic composites were used as adsorbent of model dyes methylene blue and indigo carmine showing excellent results. The composites were also used as support to produce a recyclable Pd catalyst. Tests for the 1,5-cyclooctadiene hydrogenation showed that the catalyst can be easily magnetically separated from the reaction medium and reused for five consecutive times with no deactivation or change in selectivity.Item As relações entre parques científicos e tecnológicos e agentes externos : uma abordagem multinível.(2021) Leite, Taiane Quaresma; Silva, Sergio Evangelista; Silva, André Luís; Silva, Sergio Evangelista; Silva, André Luís; Bouyer, Gilbert Cardoso; Lago, Rochel Montero; Silva, Joaquim Alexandre dos RamosOs PCTs (Parques Científicos e Tecnológicos) consistem em espaços físicos e sociais, cujo papel é dar suporte ao desenvolvimento de EBTs (Empresas de Base Tecnológica) que se encontram em um estágio maduro. Embora a literatura sobre PCTs já tenha mostrado como eles dão suporte, internamente, às EBTs, verifica-se ainda a necessidade de se explorar de modo mais sistemático quais são os agentes do ambiente externo dos PCTs e também como eles se relacionam para o desenvolvimento de cada um deles. Dessa maneira, surgem as seguintes questões de pesquisa: quais são os agentes do ambiente externo dos PCTs? Quais as relações estabelecidas entre os PCTs e estes agentes? Com o propósito de responder estas questões, o objetivo desta dissertação é apresentar uma visão sistemática dos agentes externos aos PCTs e quais as relações constituídas com os mesmos. Assim, estes agentes são analisados a partir de cinco perspectivas, que vão desde a municipal até a global. Da perspectiva metodológica, este estudo foi desenvolvido em duas fases. Na primeira, foram utilizados dados documentais de um total de 30 PCTs, dos quais, 16 estão localizados no Brasil, e 14 em Portugal. Na segunda fase, como forma de triangulação e validação dos dados obtidos na primeira, foram realizadas entrevistas por meio do uso de um protocolo de pesquisa semiestruturado. Como principais resultados, apresentamos uma visão detalhada dos vários tipos de agentes que permeiam o ambiente externo dos PCTs e identificamos os tipos de relações existentes entre eles. Como contribuição para a teoria, este estudo traz uma visão mais detalhada dos tipos de agentes externos dos PCTs e sobre a natureza das relações construídas. Da perspectiva prática, o modelo conceitual gerado pode ser utilizado como instrumento de autoavaliação e planejamento estratégico para os PCTs.Item Use of iron and bio-oil wastes to produce highly dispersed Fe/C composites for the photo-Fenton reaction.(2017) Mendonça, Fernanda Gomes de; Rosmaninho, Marcelo Gonçalves; Fonseca, Philipe Xavier da; Soares, Ricardo Reis; Ardisson, José Domingos; Tristão, Juliana Cristina; Lago, Rochel MonteroThis work describes the synthesis, characterization, and application of an active heterogeneous photo-Fenton system obtained from two different wastes, i.e., laterite (an iron mining waste) and the acid aqueous fraction (AAF) from biooil production. AAF with high acidity (ca. 3 molH+L−1) and organic concentration (25 wt.%) obtained from biomass flash pyrolysis was used for the efficient extraction of Fe3+ from laterite waste. After extraction, the mixture Fe3+/AAF was dried and treated at different temperatures, i.e., 500, 650, and 800 °C, to obtain Fe/C reactive composites. Mössbauer, XRD, TG, elemental analyses, and SEM/EDS showed the presence of highly disperse Fe oxide nanoparticles at 500 and 650 °C and Fe0 particles in the material obtained at 800 °C with carbon contents varying from 74 to 80 %. The three composites were tested as heterogeneous catalysts in the photo-Fenton reaction for the oxidation of the model dye contaminant methylene blue, showing high activities at neutral pH.