Modeling and quantitative characterization of the non-constant multilayer adsorption structure of CO2 on organic pore surfaces: Based on the improved Ono-Kondo lattice model

F Miao and XT Chen and JZ Jia and XY Liu and YY Tu and D Wu, CHEMICAL ENGINEERING JOURNAL, 522, 167666 (2025).

DOI: 10.1016/j.cej.2025.167666

A deep understanding of CO2 adsorption behavior in nanopores is essential for accurately evaluating its storage and transport capabilities in nanoporous media. Focusing on organic nanopore surfaces, this study develops a variable adsorption phase width Ono-Kondo lattice (VAPW-OK) model by introducing the variable volume assumption of the adsorption phase into the classical Ono-Kondo lattice (OK) model. Supported by Grand Canonical Monte Carlo (GCMC) molecular simulations and an adsorption layer partitioning method, the model quantitatively characterizes the non-uniform multilayer adsorption structure of CO2 and reveals its evolution with changes in pressure and temperature. The results show that the width of the CO2 adsorption phase first increases and then decreases with bulk density, peaking at 0.3-0.4 g/cm3 before stabilizing. This peak is more pronounced at lower temperatures and can be well described by an empirical function. The absolute adsorption amount shows a trend of increase, decline, and slight recovery with pressure, while rising temperatures moderate this variation. A clear distinction exists between absolute and excess adsorption in the stable stage. The proposed VAPW-OK model effectively captures the response of multilayer adsorption structures to absolute adsorption isotherms, highlighting the importance of accounting for adsorption phase volume variation. With parameters calibrated from molecular simulations, the model accurately predicts CO2 adsorption on pore surfaces, providing a practical and efficient tool for analyzing gas adsorption mechanisms in nanoporous materials. Overall, the VAPW-OK model enables quantitative characterization of non-uniform multilayer adsorption on organic nanopores and offers theoretical support for simulating adsorption in applications such as CO2 geological storage.

Return to Publications page