Effect of Pore Geometry on Gas Adsorption: Grand Canonical Monte Carlo Simulation Studies

Abstract

In this study, we investigated the pure geometrical effect of porous materials in gas adsorption using the grand canonical Monte Carlo simulations of primitive gas-pore models with various pore geometries such as planar, cylindrical, and random pore geometries. Although the model does not possess atomistic level details of porous materials, our simulation results provided many insightful information in the effect of pore geometry on the adsorption behavior of gas molecules. First, the surface curvature of porous materials plays a significant role in the amount of adsorbed gas molecules: the concave surface such as in cylindrical pores induces more attraction between gas molecules and pore, which results in the enhanced gas adsorption. On the contrary, the convex surface of random pores gives the opposite effect. Second, this geometrical effect shows a nonmonotonic dependence on the gas-pore interaction strength and length. Third, as the external gas pressure is increased, the change in the gas adsorption due to pore geometry is reduced. Finally, the pore geometry also affects the collision dynamics of gas molecules. Since our model is based on primitive description of fluid molecules, our conclusion can be applied to any fluidic systems including reactant-electrode systems.

A Grand Canonical Monte Carlo Simulation for the Evaluation of Pore Size Distribution of Nuclear-Grade Graphite from Kr Adsorption Isotherms

“…Modern methodologies, such as the Non-Localized Density Functional Theory (NLDFT) [17][18][19] and Grand Canonical Monte Carlo (GCMC) [14,[20][21][22], represent an alternative approach for the evaluation of PSD from gas adsorption data. Gas adsorption and phase equilibria in simulated porous materials with various pore geometries, such as cylinders, hexagonal pores, wedges and slits can be investigated using GCMC [11,14,23,24].…”