Thermodynamic Models To Predict Gas−Liquid Solubilities in the Methanol Synthesis, the Methanol−Higher Alcohol Synthesis, and the Fischer−Tropsch Synthesis via Gas−Slurry Processes

Abstract

Various thermodynamic models were tested concerning their applicability to predict gas−liquid solubilities, relevant for synthesis gas conversion to methanol, higher alcohols, and hydrocarbons via gas−slurry processes. Without any parameter optimization the group contribution equation of state (GCEOS) turns out to be the best model with an average, relative deviation of 19.0%. If a single binary interaction parameter is optimized for each binary system, the Peng−Robinson equation of state, the regular solutions theory, and the Flory−Staverman model all give good predictions with average, relative deviations of 4.0, 10.4, and 10.0%, respectively. As expected, the predictions from these models improve further and agree excellently with the experimental values by optimizing two binary interaction parameters for each binary system (average relative deviations < 2% for all models). The gas−liquid solubilities could also be correlated accurately to the temperature (average relative deviation = 2.1%) by assuming a constant enthalpy of solution (CEOS) model. For particular binary systems the Flory−Staverman model and the CEOS model give also reasonably accurate predictions of the gas−liquid solubilities by calculating the binary interaction parameters from pure component properties. Such an approach is promising for predicting as yet unknown gas−liquid solubilities without the need for experimental data.