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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.
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    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.
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    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.
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    Treatment of hormones in wastewater from the pharmaceutical industry by continuous flow supercritical water technology
    (2021) Mourão, Lucas Clementino; Souza, Guilherme Botelho Meireles de; Dias, Isabela Milhomem; Andrade, Laiane Alves de; Souza, Paula Letícia de Melo; Cardozo Filho, Lúcio; Oliveira, Guilherme Roberto de; Oliveira, Sérgio Botelho de; Alonso, Christian Gonçalves
    Hormones are bioactive, ubiquitous, and persistent organic molecules that demand effective treatment when released in the environment. However, most conventional treatments are inefficient or not suitable for large-scale applications. This study describes the use of supercritical water (SCW) technology in the degradation of hormones in wastewater from the pharmaceutical industry. Initially, the treatment was developed with synthetic wastewater (SW) containing hormone prepared from commercial desogestrel pills and, later, with real industrial wastewater (IW). All the experimental tests were conducted in a continuous flow reactor in the absence of catalysts. Both liquid and gas phases generated during the process were analyzed by instrumental techniques. The liquid phase was characterized by total organic carbon (TOC), chemical oxygen demand (COD), high-performance liquid chromatography (HPLC), and phytotoxicity assays. The gas phase was characterized by gas chromatography (GC). TOC reductions of SW and IW samples, both treated at 700 °C and feed flow rate of 10 mL min−1 were 87.2% and 88.4%, respectively. Phytotoxicity assays indicated a significant reduction in the toxicity of the IW treated at 700 °C. Thus, considering the gas production, especially hydrogen, and the high toxicity mitigation, the IW treatment via SCW is quite promising.
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    Supercritical water technology: an emerging treatment process for contaminated wastewaters and sludge
    (2022) Souza, Guilherme Botelho Meireles de; Pereira, Mariana Bisinotto; Mourão, Lucas Clementino; Santos, Mirian Paula dos; Oliveira, José Augusto de; Aldaya Garde, Ivan Aritz; Alonso, Christian Gonçalves; Jegatheesan, Veeriah; Cardozo Filho, Lúcio
    The destruction of toxic, persistent, refractory, and hazardous organic compounds, often present at high concentrations in both industrial and municipal wastewaters, remains a major challenge to be overcome, mainly due to the inefficiencies of conventional processes. Notwithstanding, the search for novel treatment methods has received great attention recently. Supercritical water technology has proved to be a very promising treatment method for contaminated wastewaters and sludges. Performances of supercritical water technology in treating wastewaters from a wide variety of industries including pulp and paper, pharmaceutical, textile, pesticides, dairy, petrochemical, explosives, and distillery were reviewed. Furthermore, the effects of main operating conditions, namely temperature, pressure, residence time on the treatment efficiency, usually reported in terms of total organic carbon and chemical oxygen demand removal were summarized. In addition, well-known technical challenges faced by supercritical water processes such as corrosion, salt deposition, clogging, elevated running costs and possible solutions to mitigate those challenges have been discussed. At last, the future scope of the supercritical water technology is expected to be driven by policies aiming at the reduction of greenhouse gas emissions, environmental protection, mitigation of climate changes and the production of commercial gases from highly efficient treatment of contaminated organic wastewaters and sludges.