EXTENSION OF GCA-EOS TO BINARY MIXTURES CONTAINING R134A

ZACUR JOSÉ L.; GONZO ELIO E.

Iguazú, Misiones - Argentina

Conferencia; I Iberoamerican Conference on Supercritical Fluids-PROSCIBA2007; 2007

PROSCIBA

Abstract. In recent years, the solvency properties of 1,1,1,2 tetrafluorethane (R134a) have been under examination, with the focus being on the properties as subcritical and supercritical fluid for natural products extraction. Halocarbons (between them R134a) are molecules that present a higher polarity than CO2, allowing specific intermolecular interaction like donor-acceptor proton relationships. It would facilitate higher solubility toward oxygenated compounds than the CO2, replacing the use of volatile polar modifiers in supercritical fluid extractions. In this work, GCA-EOS parameter matrix is extended, utilizing experimental data, in order to describe phase equilibrium behavior of propane, phenylalkanes and dimethyl ether (DME) in binary mixtures with R134a in subcritical and near-critical conditions. The effectiveness of the new group parameters GCA-EOS was tested estimating VLE equilibrium of these binary mixtures, comparing with EOS used for other authors to correlate the behavior of its own reported experimental information and predicting VLE behavior of similar compound not included in interaction parameters data base. Propane and DME are two homomorphic molecules that differ by the presence of oxygen in DME. The difference of molecular interaction with R314a is evidenced in the VLE behavior of its binary mixtures. The molecular interaction strength for the R134a+DME system is estimated trough homomorph concept, and the excess Gibbs energy of this mixture is compared with that corresponding to the R134a + propane system. Keywords: R134a, molecular interaction, thermodynamic modeling, Association, Group contribution