Multi-Scale insights into competitive adsorption of CO2-CH4-N2 ternary mixtures on MIL-101(Cr): From molecular behaviour to process simulation

• Adsorption capacity of MIL-101 is primarily governed by its topological structure. • CO 2 and N 2 occupy from the edge inward, while CH 4 fills from the center outward. • CH 4 alters the spatial distribution and sequence of CO 2 and N 2 adsorption. • Excess gas reduces the self-diffusion of other gases while enhancing its own rate. • A novel method is developed to predict gas mixture breakthrough curves across scales. Understanding competitive adsorption behaviors and pore-filling mechanisms of multicomponent gas mixtures in metal–organic frameworks (MOFs) is essential for advancing gas separation technologies. This study explores the adsorption dynamics of CO 2 , CH 4 , and N 2 in MIL-101(Cr), demonstrating how its unique topological structure determines adsorption capacity and governs competitive interactions. Pure CO 2 and N 2 exhibit edge-to-center pore-filling sequences, while CH 4 fills from the center outward. In mixed gas systems, CH 4 dominates by reshaping the spatial distribution and filling sequence of CO 2 and N 2 , while its own adsorption remains stable. Excess CO 2 or CH 4 inhibits competing gases from accessing adsorption sites, whereas excess N 2 enhances CH 4 adsorption, revealing a nuanced interplay of competitive effects. Furthermore, these interactions influence gas mobility, with excess molecules reducing the self-diffusion coefficients of other gases while increasing their own. This work also introduces a novel computational framework that integrates molecular-scale simulations with process-scale modelling to predict breakthrough curves of gas mixtures with high accuracy. The proposed two-stage adsorption process highlights MIL-101(Cr)’s exceptional potential for purifying CH 4 from coal bed methane and biogas under ambient conditions. These findings underscore the utility of MIL-101(Cr) and computational innovations for sustainable energy applications and greenhouse gas mitigation.