Navegando por Autor "Silva, Maxwell G."
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Artigo Influence of porosity in a packed-bed tubular reactor on biodiesel production from soybean oil and supercritical ethanol: an experimental and phenomenological investigation(American Chemical Society, 2019-07-31) Souza, Domingos Fabiano de Santana; Santiago, Luiz E. P.; Rebouças, Érica G.; Silva, Maxwell G.; Oliveira, Katherine C.; Jesus, Anderson A.; Aguiar, Emerson Moreira de; Oliveira, Jackson A.In the present study, the transesterification of soybean oil with ethanol under supercritical conditions was investigated using a packed-bed tubular reactor. The experiments were performed with an oil/alcohol molar ratio of 1:40, a pressure of 15 MPa, and different conditions of temperature (573−673 K), flow rate (0.5−1.0 mL/min), and bed porosity (0.32−1.0). A phenomenological model was developed to describe and analyze the results. The highest ester yield (98.99%) was obtained for the lower bed porosity (0.32), under 673 K and 0.5 mL/min with a residence time of 5.44 min. The kinetic and dispersion coefficients were estimated using the particle swarm optimization algorithm, and the model fitted the experimental data with an R2 coefficient of 0.97. The proposed kinetic model followed the behavior of the Arrhenius equations. Low values of dispersion were observed under conditions of lower flow rate and porosity. An analysis of the model allowed us to verify that the increase of the ester yield produced occurs at small values of the Reynolds number and high Peclet numbersArtigo Mathematical modeling and simulation of biodiesel production in a semibatch bubble reactor(American Chemical Society, 2018-08-16) Souza, Domingos Fabiano de Santana; Silva, Maxwell G.; Nobre, Lucas Rafael Pinto; Santiago, Luiz Eduardo Pereira; Deus, Marcell Santana; Jesus, Anderson Alles; Oliveira, Jackson Araújo deA mathematical model of an isothermal semi-batch bubble reactor has been developed to describe the esterification reaction of free fatty acids with superheated alcohol vapor. The proposed model accounts for the effects of mass transfer followed by chemical reaction in the liquid phase. The fluid physical properties are calculated by published correlations and the partition coefficient of alcohol vapor was estimated based on thermodynamic models of vaporliquid equilibria. Experimental data of acid-catalyzed esterification of oleic acid with superheated ethanol vapor at different conditions of temperature and gas superficial velocities was used to estimate the liquid side mass transfer coefficient and kinetic parameters. The results obtained showed that the model satisfactorily fits the experimental data for all operating conditions and was also able to simulate and predict experimental results for intermediate conditions with a coefficient of determination R2 of 0.987. In addition, the estimated values of the mass transfer coefficient agreed with data reported in literature for gas-liquid reactors