Fluid phase equilibria modeling of CO2 with polar solvents using GCA-EoS

MARIANA GONZÁLEZ PRIETO; FRANCISCO A. SÁNCHEZ; SELVA PEREDA

Eindhoven

Congreso; 27th European Symposium of Applied Thermodynamics (ESAT 2014); 2014

Eindhoven University of Technology

Carbon dioxide is one of the most studied chemical compounds present in nature. It is a product of biological life cycle, fuel and biomass combustion, as well as other biomass processing like pyrolysis, hydrolysis or gasification. It is present in nature in a wide range of conditions from atmospheric to petrochemical reservoirs, in mixtures with hydrocarbons, water and different organic compounds. It plays a major role in a wide variety of process like enhanced oil recovery, carbon dioxide sequestration and injection in ocean waters as a disposal method. Also, its mixtures with alcohols are used as cosolvents in the feed and pharmaceutical industry. Moreover, because of its near room critical temperature, low reactivity, toxicity and cost, it has been proposed for many processes as supercritical fluid extract agent. In this context, an accurate representation of thermodynamic properties of these systems is required for the design and operation of separation units. Furthermore, a predictive thermodynamic model for properties estimation is a highly useful tool for exploratory purposes in the emerging technologies for biomass processing.In this work, the group-contribution with association equation of state, namely GCA-EoS [1], has been successfully applied to represent vapor-liquid and liquid-liquid equilibria of carbon dioxide mixtures. Previous parameter table [2] was revisited in order to model multicomponent mixtures of carbon dioxide with n-alkanes, alcohols and water. Parameters for hydrocarbons and polar compounds were taken from previous work [3]. Using a single set of parameters obtained from binary data, the model is able to predict the phase behavior of binary mixtures not included in the parameterization procedure. The model is able to predict the change in type of phase behavior, according to van Konynenburg and Scott [4], in all analyzed cases. Moreover, good predictions are obtained also for ternary mixtures analyzed. Model parameters were tested against an experimental database covering temperatures from 250 K to 647 K, and pressures up to 1500 bar. This work is also part of a broader project to develop a thermodynamic tool for predicting the phase behavior of biomass derived compounds from highly variable feedstocks and through wide processing conditions. References[1]    H.P. Gros, S.B. Bottini, E.A. Brignole, Fluid Phase Equilib., 1996, 116, 535-544.[2]    S. Espinosa, G.M. Foco, T. Fornari, Fluid Phase Equilib. 2000, 172, 129-143.[3]    T.M. Soria, F.A. Sánchez, S. Pereda, S.B. Bottini, Fluid Phase Equilib., 2010, 296, 116-124.[4]    P.H. van Konynenburg, R.L. Scott, Philos. Trans. R. Soc. A Math. Phys. Eng. Sci., 1980, 298, 495-540.