Excess adsorption is usually used to measure the adsorption capacity of porous materials. Negative excess adsorption, which is unphysical and deviates from experiments, is noted in the usual computational model for methane adsorption in moist silica with nano-sized pores. Water-occupied volume, which is usually neglected in macro-porous models, is responsible for such deviations. A modified model for computing excess adsorption of methane in moist and nano-porous is proposed by taking into account the effect of water-occupied volume, which becomes significant in a small pore with a high water content. The modified model produces positive excess adsorption that matches better with available experiments. The proposed modification would be helpful for the prediction of methane reserves and productions.

过量吸附通常用于测量多孔材料的吸附能力。负过量吸附是非物理的并且偏离实验，在具有纳米孔的湿二氧化硅中甲烷吸附的常规计算模型中已注意到。在大孔模型中通常忽略了水占用量，这是造成这种偏差的原因。考虑到水占据体积的影响，提出了一种用于计算甲烷在潮湿和纳米孔中过量吸附的改进模型，该模型在含水量高的小孔中变得非常重要。修改后的模型产生正的过量吸附，与现有实验更好地匹配。拟议的修改将有助于甲烷储量和产量的预测。