Liquid-liquid equilibrium correlations using lattice fluid equation of state with hydrogen bonding

Abstract

The nonrandom lattice equation of state with hydrogen bonding (NLF-HB EOS) was examined for the correlation of liquid-liquid equilibria (LLE) for binary alcohol and hydrocarbon mixture in a wide pressure range. For hydrocarbon + alcohol mixtures the consideration of a hydrogen-bonding term in the lattice equation of state clearly improves the prediction for vapor-liquid equilibrium (VLE) as shown in previous works, but the prediction of LLE is still in question. In this paper, LLE data for alcohols (methanol and ethanol) + hydrocarbons (n-hexane to n-hexadecane) were correlated by NLF-HB EOS and results were compared with a cubic equation of state (Peng-Robinson EOS with the T-K Wilson based G E model). Both equations of state showed similar degree of accuracies but with different number of adjustable parameters. The Peng-Robinson EOS based approach requires six temperature dependent coefficients for accurate calculation whereas NLF-HB EOS requires only two temperature dependent coefficients. The effects of varying hydrogen-bonding energies for NLF-HB EOS are discussed. (C) 2008 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.