摘要
In this work we examined the prediction of vaporx2013;liquid equilibria (VLE) of mixtures from the combined use of the Pengx2013;Robinson equation of state (PR EOS) and the COSMO-SAC liquid activity coefficient model (LM). Based on the results of quantum mechanical calculations, it has been shown that the COSMO-SAC model is capable of predicting VLE of mixtures away from the critical point of any constituent component. Following the Wongx2013;Sandler mixing rule, we found that the combined model is capable of predicting the VLE of binary mixtures, including alkane and alkane, alkane and alcohol, alkane and ketone, and alcohol and water, over a wide range of temperature (183.15x2013;623.15 K) and pressure (0.1x2013;19 MPa). Furthermore, it is found that the accuracy can be greatly improved when the Stavermannx2013;Guggenheim combinatorial term in the COSMO-SAC model is ignored. The average error in both the pressure and vapor phase composition from the latter approach, denoted as PR + WS + COSMOSACres, is lowered by more than 50%compared to that from the PR EOS with the van der Waals one fluid mixing rule (PR + VDW). Our results show that PR + WS + COSMOSACres is a promising approach for mixture VLE predictions over a large range of conditions.