Abstract
Carbon capture through adsorption is acknowledged as a promising engineering solution, notable for its low energy consumption, high controllability, and compatibility with renewable energy sources. Metal-organic frameworks (MOFs) have gained significant attention as sorbents for low-energy CO2 separation from flue gases. In this study, we conducted molecular dynamics (MD) simulations to study the charge distribution of atoms in SIFSIX-3-M (where M = Ni, Co, Cu, Zn, Fe) with various pore parameters. Results indicated that SIFSIX-3-Cu possesses a large van der Waals surface and improved accessible solvent surface, suggesting the enhanced gas adsorption capabilities. Further analysis of the charge distribution and differential density maps for CO2 adsorption revealed that the primary adsorption site for CO2 within the pore is largely influenced by the strong interactions with the fluorine atoms in the framework. By calculating the radial distribution function (RDF) of the carbon atoms in CO2 relative to the silicon atoms in SIFSIX-3-Cu, we observed a notably strong interaction between the carbon atoms and the neighboring fluorine atoms near the silicon atoms at 5.75 Å, that provides a critical binding site for CO2 adsorption. Additionally, we employed computational fluid dynamics (CFD) simulations to study the breakthrough curves of N2-CO2 gas mixture passing through a porous packed bed constructed by SIFSIX-3-Cu. The results demonstrated effective separation of N2 and CO2, highlighting the strong selectivity of SIFSIX-3-Cu for CO2 adsorption. Moreover, SIFSIX-3-Cu exhibited excellent thermal stability, maintaining consistent CO2 uptake across multiple temperature swing adsorption (TSA) cycles. This study provides a solid foundation for further optimization of the SIFSIX series MOFs for advanced carbon capture applications.