Adsorption Separation of CO2/CH4/N2/CO/H2 and Water-Gas Shift Reaction (CO + H2O ⇄ CO2 + H2) Equilibrium in Activated Carbon

Grand canonical Monte Carlo (GCMC) simulations were performed to investigate adsorption in slits and to fit the pure CO2 adsorption isotherms on activated carbon, from which the pore size distribution (PSD) was obtained. Combining GCMC with PSD, we predicted the adsorption isotherms for CH4 and N2, which were consistent with the experiment. We employed the Dual-Site Langmuir-Freundlich equation to fit the pure-component adsorption isotherms and used the Ideal Adsorbed Solution Theory to predict the separation of CH4/N2, CO2/N2, and CO2/CH4 mixtures, aligning well with experimental results. Additionally, we predicted the adsorption and separation of CO2/CO/H2 and used the reactive canonical Monte Carlo method to forecast the chemical equilibrium of the reaction in slits and activated carbon. At 3 MPa, CO2 mole fraction in optimal-width slit pores rose by 111% compared to the bulk phase, highlighting the importance of selecting the optimal pore width for enhancing CO2/H2 selectivity and CO2 uptake.