Llovell Fèlix, Vega Lourdes F
Institut de Ciència de Materials de Barcelona, (ICMAB-CSIC), Consejo Superior de Investigaciones Científicas, Campus de la U.A.B., Bellaterra, 08193 Barcelona, Spain.
J Phys Chem B. 2006 Jan 26;110(3):1350-62. doi: 10.1021/jp0551465.
We present here the extension of the crossover soft-statistical associating fluid theory (soft-SAFT) equation of state to mixtures, as well as some illustrative applications of the methodology to mixtures of particular scientific and technological interest. The procedure is based on White's work (White, J. A. Fluid Phase Equilib. 1992, 75, 53) from the renormalization group theory, as for the pure fluids, with the isomorphism assumption applied to the mixtures. The equation is applied to three groups of mixtures: selected mixtures of n-alkanes, the CO2/n-alkane homologous series, and the CO2/1-alkanol homologous series. The crossover equation is first applied to the pure components of the mixtures, CO2 and the 1-alkanol family, while an available correlation is used for the molecular parameters of the n-alkane series (Llovell et al. J. Chem. Phys 2004, 121, 10715). A set of transferable molecular parameters is provided for the 1-alkanols series; these are accurate for the whole range of thermodynamic conditions. The crossover soft-SAFT equation is able to accurately describe these compounds near to and far from the critical point. The theory is then used to represent the phase behavior and the critical phenomena of the selected mixtures. We use binary interaction parameters xi and eta for dissimilar mixtures. These parameters are fitted at some particular conditions (one subcritical temperature or binary critical data) and used to predict the behavior of the mixture at different conditions (other subcritical conditions and/or critical conditions). The equation is able to capture the continuous change in the critical behavior of the CO2/n-alkane and the CO2/1-alkanol homologous series as the chain length of the second compound increases. Excellent agreement with experimental data is obtained, even in the most nonideal cases. The new equation is proved to be a powerful tool to study the global phase behavior of complex systems, as well as other thermodynamic properties of very challenging mixtures.
我们在此展示了交叉软统计缔合流体理论（soft-SAFT）状态方程对混合物的扩展，以及该方法在具有特定科学和技术意义的混合物中的一些示例性应用。该过程基于重整化群理论中怀特的工作（怀特，J. A.《流体相平衡》，1992年，75卷，53页），对于纯流体而言，将同构假设应用于混合物。该方程应用于三组混合物：正构烷烃的选定混合物、二氧化碳/正构烷烃同系物系列以及二氧化碳/一元醇同系物系列。交叉方程首先应用于混合物的纯组分，即二氧化碳和一元醇族，而对于正构烷烃系列的分子参数则使用现有的关联式（洛维尔等人，《化学物理杂志》，2004年，121卷，10715页）。为一元醇系列提供了一组可转移的分子参数；这些参数在整个热力学条件范围内都是准确的。交叉软-SAFT方程能够准确描述这些化合物在临界点附近和远离临界点的情况。然后，该理论用于表示选定混合物的相行为和临界现象。对于不同的混合物，我们使用二元相互作用参数xi和eta。这些参数在某些特定条件下（一个亚临界温度或二元临界数据）进行拟合，并用于预测混合物在不同条件下（其他亚临界条件和/或临界条件）的行为。该方程能够捕捉随着第二种化合物链长增加，二氧化碳/正构烷烃和二氧化碳/一元醇同系物系列临界行为的连续变化。即使在最不理想的情况下，也能与实验数据取得极好的一致性。新方程被证明是研究复杂系统全局相行为以及极具挑战性混合物的其他热力学性质的有力工具。
