Computer simulation of the adsorption of light gases in covalent organic frameworks

Grand canonical Monte Carlo simulations of argon, hydrogen, and methane adsorption in four covalent organic frameworks are presented. Argon adsorption isotherms from computer simulations overestimate the amount adsorbed by 25% upon saturation, with respect to the available experiments at T = 87 K. Hydrogen adsorption isotherms show that these materials might attain a 30% increase for the uptake when compared with analogous simulations performed for metal organic frameworks at T = 77 K and T = 298 K. Methane adsorption isotherms give a strong indication that at least one material in this class, COF-102, could meet or exceed the Department of Energy's target of 180 cm3 (STP)/cm3 for P = 35 bar and room temperature. The origin of this large affinity for methane is investigated by analyzing the structure of the potential energy surface of interaction between the adsorbate and the adsorbent.