Adsorption Behavior of Methane on Kaolinite

In this work, the adsorption Behaviors of CH4 in slit-like kaolinite pores were investigated using the grand canonical Monte Carlo method. The research results show that the isosteric heat of adsorption of CH4 decreases with increasing pore size and that CH4, adsorption on kaolinite can be characterized as physical adsorption. The potential energy between CH4 and kaolinite was found to decrease with increasing pressure or decreasing pore size, indicating that the adsorption sites of CH4 changed from higher-energy adsorption Sites to lower-energy adsorption sites. The CH4 adsorption capacity decreased with increasing pore size in mesopotes. With increasing temperature, the isosteric heat of adsorption of CH4 decreased, and the adsorption sites of CH4 changed from higher-energy adsorption sites to lower-energy adsorption sites, resulting in a decrease of the CH4 adsorption capacity. As a result of van der Waals force interactions, Coulomb force interactions, and hydrogen-bonding interactions, the water molecules in the kaolinite pores occupies the pore walls in a directional manner, causing the water molecules in the kaolinite pores to accumulate. With increasing accumulation of water, the water molecules occupied adsorption spates and adsorption sites of CH4, leading to a decrease of the CH4 adsorption capacity. The gas adsorption capacity on kaolinite was found to decrease in the following order: CO2 > CH4 > N-2. With increasing mole fraction of N-2 or CO2, the mole fraction of CH4 in the gas phase decreased, the adsorption sites of CH4 changed, and the adsorption space of CH4 decreased, resulting in a decrease of CH4 adsorption capacity.