Thermodynamics of biofuels: excess enthalpies and isothermal vapour-liquid equilibria of binary mixtures containing 1-pentanol and isoctane or heptane

A. Moreau1, J. Segovia1, M. Villamañán1, C. Chamorro1, R. Villamañán1 and M. Martín1

1Research Group TERMOCAL, University of Valladolid, Spain

Keywords: biofuels
property: excess enthalpies, VLE
material: 1-pentanol, heptane, isoctane

The transport sector accounts for more than 30 % of final energy consumption in the European Community and it is expanding, a trend which is bound to increase, along with carbon dioxide emissions. Greater use of biofuels for transport forms a part of the package of measures needed to comply with the Kyoto Protocol. There is a wide range of biomass that could be used to produce biofuels, deriving from agricultural and forestry products. The blending of biofuel with fossil fuels could facilitate a potential cost reduction in the distribution system in the Community. Contributing to the knowledge of the thermodynamic properties of the new fuel blends, the total pressure measurements and excess enthalpies are reported for the binary systems (1-pentanol + isooctane) and (1-pentanol + heptane). An automated quasi-isothermal flow calorimeter has been developed for the measurement of high accurate excess enthalpies over the range 250-400 K. The technique was checked for different test binary mixtures and the results were compared with the literature values available [1]. The technique allows to measure excess enthalpies with an estimated total uncertainty better than 1%. Both binary mixtures has been measured at T = (298.15 and 313.15) K. They show an exothermic behaviour which increases with temperature. The experimental results have been correlated with the Redlich–Kister polynomial equation. An isothermal total pressure cell has been employed for measuring the vapour-liquid equilibrium at 313.15 K [2]. Data reduction by Barker’s method provides correlations for GE using the Margules equation and Wilson, NRTL and UNIQUAC models. They have been applied successfully to both binary systems.

  1. J.J. Segovia, M.C. Martín, D. Vega-Maza, C.R. Chamorro, M.A. Villamañán, J. Chem. Thermodyn 41, 759 (2009)

  2. L.M. Lozano, E.A. Montero, M.C. Martín, M.A. Villamañán, Fluid Phase Equilib 110, 219 (1995)

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