Department of Chemical and Biological Engineering, Princeton University , Princeton, New Jersey 08544, United States.
Chemical Engineering Program, Texas A&M University at Qatar , P.O. Box 23874, Doha, Qatar.
J Phys Chem B. 2017 Feb 16;121(6):1386-1395. doi: 10.1021/acs.jpcb.6b12791. Epub 2017 Feb 2.
Phase equilibria of water/CO and water/n-alkane mixtures over a range of temperatures and pressures were obtained from Monte Carlo simulations in the Gibbs ensemble. Three sets of Drude-type polarizable models for water, namely the BK3, GCP, and HBP models, were combined with a polarizable Gaussian charge CO (PGC) model to represent the water/CO mixture. The HBP water model describes hydrogen bonds between water and CO explicitly. All models underestimate CO solubility in water if standard combining rules are used for the dispersion interactions between water and CO. With the dispersion parameters optimized to phase compositions, the BK3 and GCP models were able to represent the CO solubility in water, however, the water composition in CO-rich phase is systematically underestimated. Accurate representation of compositions for both water- and CO-rich phases cannot be achieved even after optimizing the cross interaction parameters. By contrast, accurate compositions for both water- and CO-rich phases were obtained with hydrogen bonding parameters determined from the second virial coefficient for water/CO. Phase equilibria of water/n-alkane mixtures were also studied using the HBP water and an exponenial-6 united-atom n-alkanes model. The dispersion interactions between water and n-alkanes were optimized to Henry's constants of methane and ethane in water. The HBP water and united-atom n-alkane models underestimate water content in the n-alkane-rich phase; this underestimation is likely due to the neglect of electrostatic and induction energies in the united-atom model.
通过 Gibbs 系综中的蒙特卡罗模拟，获得了在一定温度和压力范围内水/CO 和水/正烷烃混合物的相平衡数据。我们将三组 Drude 型可极化水模型（BK3、GCP 和 HBP 模型）与可极化高斯电荷 CO（PGC）模型相结合，以表示水/CO 混合物。HBP 水模型明确描述了水和 CO 之间的氢键。如果对水和 CO 之间的色散相互作用使用标准组合规则，则所有模型都会低估 CO 在水中的溶解度。通过优化色散参数来匹配相组成，BK3 和 GCP 模型能够表示 CO 在水中的溶解度，但 CO 富相中的水组成被系统低估。即使优化交叉相互作用参数，也无法准确表示富水相和富 CO 相的组成。相比之下，通过确定水/CO 第二维里系数来确定氢键参数，可以获得富水相和富 CO 相的准确组成。我们还使用 HBP 水模型和指数-6 统一原子正烷烃模型研究了水/正烷烃混合物的相平衡。优化了水和正烷烃之间的色散相互作用，以匹配甲烷和乙烷在水中的亨利常数。HBP 水模型和统一原子正烷烃模型低估了正烷烃富相中的含水量；这种低估可能是由于统一原子模型忽略了静电能和诱导能。
