Effect of water occupancy on the excess adsorption of methane in montmorillonites
L Wang and DB Wang and CH Cai and N Li and L Zhang and ML Yang, JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING, 80, 103393 (2020).
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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