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Optimization of bio-oil steam reforming process by thermodynamic analysis
(2020) Rodrigues, Caroline Teixeira; Alonso, Christian Gonçalves; Machado, Guilherme Duenhas; Souza, Thiago Leandro de
A straightforward thermodynamic analysis of bio-oil steam reforming was carried out in the context of hydrogen and syngas production, employing Gibbs energy minimization method to determine equilibrium composition and global reaction heat. The bio-oil model compound was a mixture of acetic acid, phenol, and acetone. The effects of process variables, such as temperature and inlet S/C molar ratio, were investigated over a wide range of conditions. Thermodynamic analysis was performed using the software Aspen Plus v.11. It was identified the best operational conditions that could maximize syngas and further hydrogen production considering energy efficiency. The optimum production of hydrogen is 2.28 mol per carbon mole at S/C = 10 and 850 K, and syngas is 2.37 mol per carbon mole at S/C = 10 and 900 K. It has been demonstrated that the equilibrium calculations can be used to simulate these steam reforming reactions, given the catalyst's behavior.
Nb2O5 supported catalysts for cross-coupling reactions
(2020) Souza, Guilherme Botelho Meireles de; Ribeiro, Thiago Soares Silva; Mourão, Lucas Clementino; Pereira, Mariana Bisinotto; Leles, Maria Inês Goncalves; Liao, Luciano Morais; Oliveira, Guilherme Roberto de; Alonso, Christian Gonçalves
Palladium and nickel supported on Nb2O5 were synthesized via wet impregnation method and tested for the Suzuki-Miyaura reaction. The catalysts were characterized by X-ray fluorescence, textural analysis, scanning and transmission electron microscopy, thermogravimetry/differential thermal analysis and X-ray diffraction. Palladium catalyst resulted in high isolated yields (91%). Satisfactory yields (48%) were achieved employing the nickel catalyst. Hot filtration experiments were performed to evaluate the reaction heterogeneity. The catalysts were submitted to consecutive reactions runs to assess recyclability. Deactivation was attributed to catalyst loss by filtration between cycles, minor leaching of the active phase and poisoning by inorganic species.
Estudo das propriedades de estados excitados de porfirinas: formação de estados tripletos e oxigênio singlete
(Universidade Federal de Goiás, 2023-08-22) França, Andrew Gabriel Boaventura; Gonçalves, Pablo José; Gonçalves, Pablo José; Souza, Márcio Adriano Rodrigues; Marquezin, Cássia Alessandra
Photophysics has been gaining more and more importance, both in the academic area and in the technological area. In particular, we highlight its importance in Photomedicine, where photophysical controls are fundamental to explain Photodynamic Therapy, a new therapeutic modality used for the treatment of microorganisms and even tumors. This therapy employs the use of a photosensitizing compound, which in its excited state after absorption of visible light, produces reactive oxygen species that can lead to cell death of specific targets. In this course conclusion work, a study of the dynamics of excited states of organic signals, the main characteristics of excited states of porphyrins and a brief review of the experimental techniques involved for the proper characterization of a photosensitizer compound were carried out.Experimentally, the efficiency of triplet state formation was obtained, analyzing the effects of the concentration of photosensitizers and the concentration of oxygens on the phosphorescence emission of singlet oxygen, one of the main reactive oxygen species involved in the photodynamic action. It was also verified the importance of adjusting the absorption of the sample under study to 0.2 and a time of 20 to 30 minutes of bubbling oxygen for saturation of the solution.
On the magnetic properties of the multiferroic ceramics Bi0:99Y0:01Fe1-xNixO3 Bi0:99Y0:01Fe1 xNixO3
(2018) Ratkovski, Danilo Roberto; Ribeiro, P. R. T.; Machado, Fernando Luis de Araujo; Banerjee, Prasun; Franco Júnior, Adolfo
Multiferroic ceramics of Bi0:99Y0:01Fe1 xNixO3 with 0:01 6 x 6 0:05 were synthesized by using a modified solid state reaction method. The crystalline structure and the morphology of the samples were investi gated by X-ray diffraction (XRD) and by scanning electron microscopy (SEM). The addition of Y and Ni to the bismuth ferrite (BiFeO3) was found to decrease the average grain size. Ac magnetic susceptibility and the zero-field-cooled (ZFC) and field-cooled (FC) magnetizations were measured for temperatures in the range 5 6 T 6 300 K. Hysteresis loops and an irreversible behavior in the temperature dependence of the magnetization not present in pure BiFeO3 were observed in the doped samples. However, the ferro magnetism was found more likely to be due to the presence of small amounts of magnetite. Nevertheless, the determination of the amount of Fe3O4 in these composite materials is important because it influences the magnetoelectric coupling which is important for some technological applications
A new halogen-chalcone with potential for application in biofuels
(2020) Faria, Eduardo Coelho da Mata; Duarte, Vitor Santos; Silva, Aline Magalhães da; Fernandes, Fernanda de Sousa; Oliveira, Guilherme Roberto de; Napolitano, Hamilton Barbosa
Fossil fuels, which represent an important villain for the terrestrial ecosystem, are non-renewable sources of energy, which prompt many discussions about how long petroleum will remain available for use. As an alternative, new energy sources have been explored, including biofuels, such as biodiesel and ethanol. However, their use can raise some problems, such as lower storage stability associated with poor oxidation stability and lower energy availability, which affect consumption, emissions, and energy efficiency. In this context, a comprehensive study with structural description, theoretical calculations, and calorific power test was performed for a new halogen chalcone 4-(4-chlorophenyl)-1-[4-(2-oxo-2-phenylethoxy)phenyl]butan-2-one to understand its supramolecular arrangement and physicochemical properties. The structural description was carried out by X-ray diffraction with the contribution of Hirshfeld surfaces. The theoretical calculations were carried out using density functional theory with the contribution of calorific power determined by a calorimetric pump. All observed results characterize the new chalcone as a potential additive for biofuels.