Habibi Parsa, Dey Poulumi, Vlugt Thijs J H, Moultos Othonas A
Engineering Thermodynamics, Process and Energy Department, Faculty of Mechanical Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628 CB Delft, The Netherlands.
Department of Materials Science and Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands.
J Chem Phys. 2024 Aug 7;161(5). doi: 10.1063/5.0221004.
Vapor-Liquid Equilibria (VLE) of hydrogen (H2) and aqueous electrolyte (KOH and NaCl) solutions are central to numerous industrial applications such as alkaline electrolysis and underground hydrogen storage. Continuous fractional component Monte Carlo simulations are performed to compute the VLE of H2 and aqueous electrolyte solutions at 298-423 K, 10-400 bar, 0-8 mol KOH/kg water, and 0-6 mol NaCl/kg water. The densities and activities of water in aqueous KOH and NaCl solutions are accurately modeled (within 2% deviation from experiments) using the non-polarizable Madrid-2019 Na+/Cl- ion force fields for NaCl and the Madrid-Transport K+ and Delft Force Field of OH- for KOH, combined with the TIP4P/2005 water force field. A free energy correction (independent of pressure, salt type, and salt molality) is applied to the computed infinite dilution excess chemical potentials of H2 and water, resulting in accurate predictions (within 5% of experiments) for the solubilities of H2 in water and the saturated vapor pressures of water for a temperature range of 298-363 K. The compositions of water and H2 are computed using an iterative scheme from the liquid phase excess chemical potentials and densities, in which the gas phase fugacities are computed using the GERG-2008 equation of state. For the first time, the VLE of H2 and aqueous KOH/NaCl systems are accurately captured with respect to experiments (i.e., for both the liquid and gas phase compositions) without compromising the liquid phase properties or performing any refitting of force fields.
氢气（H₂）与水性电解质（KOH和NaCl）溶液的气液平衡（VLE）对于众多工业应用至关重要，如碱性电解和地下氢气储存。进行了连续分数组分蒙特卡罗模拟，以计算298 - 423 K、10 - 400 bar、0 - 8 mol KOH/kg水和0 - 6 mol NaCl/kg水条件下H₂与水性电解质溶液的VLE。使用针对NaCl的非极化马德里-2019 Na⁺/Cl⁻离子力场以及针对KOH的马德里传输K⁺和OH⁻的代尔夫特力场，结合TIP4P/2005水的力场，对KOH和NaCl水溶液中水的密度和活度进行了精确建模（与实验偏差在2%以内）。对计算得到的H₂和水的无限稀释过量化学势应用了自由能校正（与压力、盐类型和盐质量摩尔浓度无关），从而在298 - 363 K的温度范围内，对H₂在水中的溶解度和水的饱和蒸气压做出了准确预测（与实验误差在5%以内）。水和H₂的组成是根据液相过量化学势和密度，通过迭代方案计算得出的，其中气相逸度使用GERG - 2008状态方程计算。首次在不影响液相性质或不对力场进行任何重新拟合的情况下，相对于实验准确捕捉到了H₂与KOH/NaCl水溶液体系的VLE（即液相和气相组成）。
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