论文标题
水+氢系统中界面特性的分子透视
Molecular Perspectives of Interfacial Properties in the Water+Hydrogen System in Contact with Silica or Kerogen
论文作者
论文摘要
包含H2的多相系统中的界面行为对于地下H2存储至关重要，但尚不清楚。进行了分子动力学模拟，以研究H2O+H2和H2O+H2+H2+二氧化硅/动力学系统的界面特性，该温度范围很广（298-523 K）和压力（1-160 MPA）。 H2模型与界面力场和TIP4P/2005 H2O模型的组合可以准确预测实验中的界面张力（IFTS）。来自模拟的IFT也与与状态的PC-SAFT方程相连的密度梯度理论的IFT也非常吻合。通常，IFT随压力和温度而降低。但是，在相对较高的温度和压力下，IFT随压力而增加。相反的压力效应可以通过H2相对吸附的符号的反转来解释。在密度曲线中观察到H2在界面区域的富集。同时，H2O+H2+二氧化硅系统中的接触角（CAS）的行为与H2O+H2+动型系统中的行为明显不同。 H2O+H2+二氧化硅和H2O+H2+动脉粥样硬化系统的H2O CAS随压力而增加，随着温度的降低。但是，对于低温下H2O+H2+二氧化硅系统，温度和压力对这些CA的影响不太明显。根据H2O+H2系统（流体流体相互作用）和粘附张力（流体固定相互作用）中的IFT的变化来理解CA的行为。此外，对原子密度曲线的分析表明，H2O液滴和二氧化硅/动物学表面之间的H2的存在几乎可以忽略不计。然而，H2O在H2O液滴外的二氧化硅表面上的吸附很强，而在动干表面上可以看到H2O的吸附较少。
Interfacial behaviours in multiphase systems containing H2 are crucial to underground H2 storage but are not well understood. Molecular dynamics simulations were conducted to study interfacial properties of the H2O+H2 and H2O+H2+silica/kerogen systems over a wide range of temperatures (298 - 523 K) and pressures (1 - 160 MPa). The combination of the H2 model with the INTERFACE force field and TIP4P/2005 H2O model can accurately predict the interfacial tensions (IFTs) from the experiment. The IFTs from simulations are also in good agreement with those from the density gradient theory coupled to the PC-SAFT equation of state. Generally, the IFTs decrease with pressure and temperature. However, at relatively high temperatures and pressures, the IFTs increase with pressure. The opposite pressure effect on IFTs can be explained by the inversion of the sign of the relative adsorption of H2. The enrichment of H2 in the interfacial regions was observed in density profiles. Meanwhile, the behaviours of contact angles (CAs) in the H2O+H2+silica system are noticeably different from those in the H2O+H2+kerogen system. The H2O CAs for the H2O+H2+silica and H2O+H2+kerogen systems increase with pressure and decrease with temperature. However, the effect of temperature and pressure on these CAs is less pronounced for the H2O+H2+silica system at low temperatures. The behaviours of CAs were understood based on the variations of IFTs in the H2O+H2 system (fluid-fluid interaction) and adhesion tensions (fluid-solid interaction). Furthermore, the analysis of the atomic density profiles shows that the presence of H2 in between the H2O droplet and the silica/kerogen surface is almost negligible. Nevertheless, the adsorption of H2O on the silica surface outside the H2O droplet is strong, while less H2O adsorption is seen on the kerogen surface.
