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Application of the Statistical Associating Fluid Theory (SAFT) for the calculation of the vapour-liquid equilibrium: Modeling of the N2O4-NO2 reacting system

Belkadi, Abdelkrim and Gerbaud, Vincent and Hadj-Kali, Mohamed and Joulia, Xavier and Vega, Lourdes F. and Llovell, Felix Application of the Statistical Associating Fluid Theory (SAFT) for the calculation of the vapour-liquid equilibrium: Modeling of the N2O4-NO2 reacting system. (2007) In: Thermodynamics 2007, 25-27 September 2007, Rueil Malmaison, France .

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Abstract

Accurate thermophysical properties are mandatory for all industrial applications. However, experimental data are often scarce and models are needed for the estimation of the properties. Such is the case in supercritical processes like the selective oxidation of vegetal macromolecules in mixture NO2/N2O4 – supercritical CO2 [1]. Currently, the process optimization is incomplete due to the unability to assess experimental the fraction of free NO2 monomer in the reactor. Statistical Associating Fluid Theory (SAFT) is a powerful equation of state model for thermodynamic property and phase equilibria calculations for fluid mixtures. It has been used to describe with an equation of state approach non polar and polar compounds, with particular attention to associating compounds. In this work we use a modified version of the SAFT EOS, the so called soft-SAFT equation of state extended by a crossover treatment to take into account the long density fluctuation encountered when the critical region is approached [2]. The equation is applied to predict vapour liquid equilibria for NO2 that can self associate into N2O4 [3]. Both molecules NO2 and N2O4 are rigid molecules and the self association equilibrium is quickly achieved [4]. The procedure of modeling of such system consists in considering the monomer NO2 as an associating fluid with a strong association strength that represents the covalent bond between the N-N atoms. The system is successfully modeled by crossover soft-SAFT EOS by a set of parameters of only NO2 with a self association to form the dimmer (N2O4). The equation is also applied to a mixture NO2-N2O4/CO2 where good agreement is obtained with experimental data of the CO2 mass fraction.

Item Type:Conference or Workshop Item (Paper)
Audience (conference):International conference proceedings
Uncontrolled Keywords:
Institution:Other partners > Consejo Superior de Investigaciones Científicas - CSIC (SPAIN)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
Laboratory name:
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Deposited By: Vincent GERBAUD
Deposited On:20 Feb 2009 14:32

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