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Neto A.F.G.,Federal University of Para | Lopes F.S.,Federal University of Para | Carvalho E.V.,Federal University of Para | Huda M.N.,University of Texas at Arlington | And 2 more authors.
Journal of Molecular Modeling | Year: 2015

This paper presents a theoretical study using density functional theory to calculate thermodynamics properties of major molecules compounds at gas phase of fuels like gasoline, ethanol, and gasoline–ethanol mixture in thermal equilibrium on temperature range up to 1500 K. We simulated a composition of gasoline mixture with ethanol for a thorough study of thermal energy, enthalpy, Gibbs free energy, entropy, heat capacity at constant pressure with respect to temperature in order to study the influence caused by ethanol as an additive to gasoline. We used semi-empirical computational methods as well in order to know the efficiency of other methods to simulate fuels through this methodology. In addition, the ethanol influence through the changes in percentage fractions of chemical energy released in combustion reaction and the variations on thermal properties for autoignition temperatures of fuels was analyzed. We verified how ethanol reduces the chemical energy released by gasoline combustion and how at low temperatures the gas phase fuels in thermal equilibrium have similar thermodynamic behavior. Theoretical results were compared with experimental data, when available, and showed agreement. [Figure not available: see fulltext.] © 2015, Springer-Verlag Berlin Heidelberg. Source


Da Mota S.D.P.,Laboratory of Separation Processes and Applied Thermodynamic TERM | Da Mota S.D.P.,Federal University of Para | Mancio A.A.,Laboratory of Separation Processes and Applied Thermodynamic TERM | Mancio A.A.,Federal University of Para | And 16 more authors.
Journal of Analytical and Applied Pyrolysis | Year: 2014

In this work, the production of light diesel like fractions by thermal catalytic cracking of crude palm oil (Elaeis guineensis, Jacq.) has been systematically investigated in pilot scale. The cracking reactions were carried out in a reactor of 143 L, operating in batch mode at 450 °C and atmospheric pressure, using 20% (w/w) sodium carbonate (Na2CO3) as catalyst. The reaction products called organic liquid products (OLP) were submitted to distillation using a laboratory scale column (Vigreux Column) of three stages in order to obtain light diesel like fractions. The catalyst has been characterized by X-ray diffraction, FTIR spectroscopy, TGA and DTG. The OLP and the green diesel fractions have been physical-chemical characterized by officials AOCS, ASTM, and ABNT/NBR methods in terms of acid value, saponification value, density, refraction index, kinematics viscosity, copper strip corrosion, carbon residue, flash point, and distillation curve. The chemical composition of green diesel has been determined by FTIR spectroscopy and GC-MS. The results show that the process yield on OLP was 65.86% (w/w) with an acid value of 1.02 mg KOH/g OLP and kinematic viscosity of 1.48 mm2/s, 30.24% (w/w) non-condensable gases, 2.5% (w/w) water, and 1.4% (w/w) coke. The yield on green diesel obtained by distillation average 24.9% (w/w), presenting an acid value of 1.68 mg KOH/g green diesel and kinematic viscosity of 1.48 mm2/s. The GC-MS analysis indicated that green diesel is composed of 91.38% (w/w) of hydrocarbons (31.27% normal paraffins, 54.44% olefins and 5.67% of naphthenics), and 8.62% (w/w) of oxygenates compounds. © 2014 Elsevier B.V. All rights reserved. Source

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