Confined Water Determines Transport Properties of Guest Molecules in Narrow Pores.
Confined Water Determines Transport Properties of Guest Molecules in Narrow Pores.
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DOI：
10.1021/acsnano.6b02942
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发表时间：
2016-08
期刊：
影响因子：
17.1
通讯作者：
A. Phan;David R. Cole;R. G. Weiß;J. Dzubiella;A. Striolo
中科院分区：
文献类型：
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作者：
A. Phan;David R. Cole;R. G. Weiß;J. Dzubiella;A. Striolo
我们计算了甲烷通过1 nm宽的狭缝形孔雕刻出固体基板的运输。二氧化硅、氧化镁和氧化铝的模型用作固体基质。毛孔里充满了水。结果表明，甲烷通过水化孔隙的渗透率强烈依赖于固体基质。模拟系统的详细分析表明，当地的承压水，包括其结构，更重要的是，溶剂化自由能和氢键结构的演变是负责观察到的显着差异。模拟扩展到代表天然气的多组分系统，含有甲烷，乙烷和H2S。结果表明，所考虑的所有孔对H2S具有高亲和力，对甲烷具有中等亲和力，对乙烷具有低亲和力。通过水合氧化铝孔的H2S/甲烷传输选择性与现有商业膜报道的相当或上级。一个多尺度的方法，然后实施，以证明Smoluchowski一维模型是能够重现分子水平的结果时，局部自扩散系数的适当值被用作输入参数的短孔。我们建议，该模型可以扩展到预测甲烷通过均匀的宏观长度的水化孔隙传输。当通过实验验证时，我们的模拟结果可能在天然气脱硫和预测水力压裂页岩地层中的甲烷迁移等应用中具有重要意义。
We computed the transport of methane through 1 nm wide slit-shaped pores carved out of solid substrates. Models for silica, magnesium oxide, and alumina were used as solid substrates. The pores were filled with water. The results show that the methane permeability through the hydrated pores is strongly dependent on the solid substrate. Detailed analysis of the simulated systems reveals that local properties of confined water, including its structure, and more importantly, evolution of solvation free energy and hydrogen bond structure are responsible for the pronounced differences observed. The simulations are extended to multicomponent systems representative of natural gas, containing methane, ethane, and H2S. The results show that all pores considered have high affinity for H2S, moderate affinity for methane, and low affinity for ethane. The H2S/methane transport selectivity through the hydrated alumina pore is comparable, or superior, to that reported for existing commercial membranes. A multiscale approach was then implemented to demonstrate that a Smoluchowski one-dimensional model is able to reproduce the molecular-level results for short pores when appropriate values for the local self-diffusion coefficients are used as input parameters. We propose that the model can be extended to predict methane transport through uniform hydrated pores of macroscopic length. When verified by experiments, our simulation results could have important implications in applications such as natural gas sweetening and predictions of methane migration through hydraulically fractured shale formations.