Abstract Excess adsorption is usually used to measure the adsorption capacity for methane in porous clays and to compare with experiments. The commonly used definition of excess adsorption neglects water-occupied volume in moist clays. Such approximation leads to negative excess adsorption for nanoporous adsorbents with high water content, which is unphysical and deviates from experiments. Based on Monte-Carlo and molecular dynamics computations on montmorillonites with various slit apertures, a modified definition is proposed for the excess adsorption of methane in the nanoslit systems by taking the water-occupied volume into account. The modified model produces positive excess adsorption values that match better with the available observations.

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含水率对蒙脱石中甲烷过量吸附的影响

摘要 过量吸附通常用于测量多孔粘土中甲烷的吸附能力并与实验进行比较。常用的过量吸附定义忽略了潮湿粘土中的含水量。这种近似导致对高含水量的纳米多孔吸附剂产生负过量吸附，这是非物理的并且偏离实验。基于蒙特卡罗和分子动力学对具有各种狭缝孔径的蒙脱石的计算，通过考虑水占据体积，提出了纳米狭缝系统中甲烷过量吸附的修正定义。修改后的模型产生与可用观察结果更好匹配的正过量吸附值。