Adsorption of light gases in covalent organic frameworks: comparison of classical density functional theory and grand canonical Monte Carlo simulations

A classical density functional theory (cDFT) based on the PC-SAFT equation of state is proposed for calculation adsorption equilibria pure substances and their mixtures in covalent organic frameworks (COFs). Adsorption isotherms methane, ethane, n-butane nitrogen COFs TpPa-1 2,3-DhaTph are calculated compared to results from grand canonical Monte Carlo (GCMC) simulations. Mixture investigated methane/ethane methane/n-butane binary systems. Excellent agreement between DFT GCMC obtained all up pressures 50 bar. The cDFT formalism accurately predicts selective accumulation longer hydrocarbons considered COFs. This application shows substantial predictive power solved three-dimensional geometries suggest method can future also be applied efficient optimization force field parameters or structural properties porous material an analytical as opposed a stochastic simulation.