Molecular Simulation Study of the Adsorption and Diffusion of a Mixture of CO₂/CH₄ in Activated Carbon: Effect of Textural Properties and Surface Chemistry

In this study, the effect of pore textural property and surface functionalization in activated carbon (AC) on the competitive adsorption and diffusion of a binary mixture of CO₂/CH₄ was examined by grand canonical Monte Carlo simulations and equilibrium molecular dynamics. The simulation results indicated that AC with a high surface area exhibited a low CO₂/CH₄ selectivity, while a high CO₂ adsorption capacity was observed. To obtain high CO₂ adsorption capacity and high CO₂/CH₄ selectivity at the same time, surface chemistry (adsorbent-adsorbate interaction) and pore textural property (pore size) were investigated. On this basis, two types of AC were prepared: (I) with different pore sizes, attributed to building ordered pores and (II) with different surface chemistry properties, attributed to modification with different functional groups. The results showed that the effects of surface chemistry properties are factors more important for improving the CO₂/CH₄ capacity and selectivity. (Chemical Equation Presented).