New association scheme for 1-alcohols in alcohol/water mixtures with sPC-SAFT: The 2C association scheme
A new association scheme for sPC-SAFT, denoted as 2C, is presented for more-accurate predictions of 1-alcohol/water phase equilibria than with the 2B or 3B association schemes. This 2C association scheme consists of one bipolar association site and one negative electron donor site and is a combination of the 1A and 2B/3B association schemes. The performance of the 2C scheme is evaluated and compared to the 2B and 3B schemes by modeling the vapor-liquid equilibria and liquid-liquid equilibria of alcohol/water, alcohol/alcohol and alcohol/alkane mixtures. Liquid-liquid equilibria of multicomponent systems are also considered. Compared to sPC-SAFT with the 2B or 3B schemes, sPC-SAFT-2C provides improved phase equilibria predictions for the investigated alcohol/water vapor-liquid systems, as well as for liquid-liquid equilibria of water/alcohol/alkane and water/alcohol/alcohol ternary systems. However, a slight deterioration in the prediction of binary alcohol/alkane phase equilibria is observed with the 2C scheme, compared to the 2B scheme. Furthermore, related VLE predictions with sPC-SAFT-2C compare well to predictions with the Cubic-Plus-Association (CPA) equation of state. © 2011 American Chemical Society.