CO₂ adsorption and separation from natural gason phosphorene surface : Combining DFT and GCMC calculations

We have examined the performance of phosphorene-based material, phosphorene slit pores (PSP), in CO₂ adsorption and separation from natural gas by using Density Function Theory (DFT) calculation and Grand Canonical Monte Carlo (GCMC) simulations. First, the adsorption of CH₄ and CO₂ molecules on phosphorene sheet were conducted by DFT study. Then, adsorption performances of natural gas components as well as their binary CO₂ /CH₄ gas mixture were investigated at 300 K with the pressure up to 3.0 MPa. The effects of slit pore width, H, and mole ratio of CO₂ /CH₄ in the gas phase on the separation of CO₂ from mixtures of CO₂ /CH₄ were also investigated. Our DFT calculation results show that the CO₂ moleculehas higher adsorption energy than that of CH₄ , which implies that it can be easily adsorbed to the phosphorene surface than CH₄. Detailed GCMC simulations reveal that the phosphorene slit pore has a high performance in separating CO₂ fromnature gas and achieves the highest gas selectivity at H = 1.0 nm at pressures lower than 0.1 MPa. Moreover, the selectivity of CO₂ overCO₂ /CH₄ gas mixture increases with increasing the mole ratio of CO₂ /CH₄ due to the enhanced adsorbate-adsorbent interactions for the favorable component. Therefore, it is suggested that the phosphorene is a promising candidate for natural gas purification and possessing practical potential applications in gas adsorption.