The methane uptakes of six double halogen substituted covalent organic frameworks (COFs) based on COF-102 were simulated with grand canonical Monte Carlo simulation at 298 K and pressure ranges from 1 to 80 bar. The simulation shows that COF-102-1,4-2I reaches the DOE target of 180 V(STP)/V for methane delivery. The current study highlights the correlation between the structure and the adsorption property of the double halogen substituted COF-102. In COF-102-1,4-2I, the triangle arrangement of the six I atoms around the central B3O3 ring brings close contact between I atom and B3O3 ring, and thus enhances the attraction of CH4 with high CH4 density in the vicinity above and below this region, especially in particular adsorption sites. Such favorable structural arrangement, altogether with the strongest I–CH4 attraction among the halogen substituent in this study, gives the highest isosteric heat as well as the CH4 uptakes at 298 K and 35 bar in the hypobaric region. The result in this study demonstrates that double halogen substituted COF-102 is capable of increasing CH4 uptakes for practical applications.

Shale is rich in nanopores with organic matter, but few studies have researched them in combination with molecular simulation and quantum mechanics. The organic matter was simplified into graphite and the graphene structure, and Grand Canonical Monte Carlo and Molecular Dynamics methods have been used to study methane adsorption in the different apertures of graphite; then, adsorption characteristics were calculated and analyzed by Density Functional Theory. The simulation results show that methane molecules form a tight adsorption layer near the wall with different orientations. The density distribution shows an obvious adsorption layer, and the interaction distance is 1 to 6 Å. The adsorption energy is distributed in the range of −0.2200 to −0.1080 eV, which states physical adsorption, and can be divided into two segments: 1–3 and 4–6 Å. Density of states (DOS) of systems are distributed within the range of −20 to 5 eV. II B5 and III B1 are different only at −5.0 to −3.6 eV, and DOS of adsorbents coincided before and after adsorption, while DOS of methane shift to the lower energy region after adsorption.

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