Comparative study of semi-theoretical models for predicting infinite dilution activity coefficients of alkanes

C. B. CASTELLS; D. I. EIKENS; CARR, P. W.; BUSH, D. M.; ECKERT, C. A.

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Lugar: Washington; Año: 1999 vol. 38 p. 4104 - 4109

0888-5885

Five non-electrolyte solution models are used to predict infinite dilution activity coefficients (g¥) of five linear, four branched and two cyclic alkanes in 67 solvents at 25°C, and the results are compared with experimental data. The models use two distinct approaches to the prediction of g¥. The solution of groups concept provides the basis for three versions of the UNIFAC model: original UNIFAC,  g¥-based UNIFAC and modified UNIFAC (Dortmund). The MOSCED and the SPACE models avoid the group concept and use only pure component parameters. For a database of 737 limiting activity coefficients, the SPACE model gave an average absolute error of 8.1%, and in only 13.3% of the cases were the errors worse than 15%. The modified UNIFAC model gave an absolute average error of 9.8% and 32% of the predicted g¥ had errors larger than 15%. The SPACE approach also produced the most reliable estimations over a wide range of activity coefficient values.