Correlation of solubilities if coal liquefaction products in supercritical carbon dioxide and solubility enhancements using equation by state

Iwai, Y., Yamamoto, H., Shimizu, T. and Arai, Y., 1990. Correlation of solubilities of coal liquefaction products in supercritical carbon dioxide and solubility enhancements using equation of state. The solubility behavior in the supercritical region is essentially important in process design of supercritical fluid extraction. An entrainer is often used to enhance the solubilities of high boiling components in the gas phase. The cubic equation of state having three constants, recently proposed by Yu et al., was applied to correlate the solubilities of coal liquefaction products (solid components) in supercritical CO₂ and the solubility enhancements by entrainers. Conventional mixing rules were adopted for calculation of cross factors a_ij, b_ij, and c_ij. Binary parameters k_ij for calculation of a_ij, and l_ij for b_ij and c_ij were used. The binary parameters k_ij and l_ij (i.e. cross factors a_ij, b_ij, and c_ij) were determined to represent well the solubility data. Further, they were correlated with pure component properties of supercritical CO₂ and solid components such as critical volume, solid volume, number of atoms in molecule except for hydrogen, and solubility parameter. By using the empirical equations for calculation of the binary parameters k_ij and l_ij, the solubilities of solid components in supercritical CO₂ were calculated with good accuracy.