Computational Studies of CO2 Sorption and Separation in an Ultramicroporous Metal–Organic Material

Grand canonical Monte Carlo (GCMC) simulations of CO2 sorption and separation were performed in [Zn(pyz)2SiF6], a metal–organic material (MOM) consisting of a square grid of Zn2+ ions coordinated to pyrazine (pyz) linkers and pillars of SiF62– ions. This MOM was recently shown to have an unprecedented selectivity for CO2 over N2, CH4, and H2 under industrially relevant conditions. The simulated CO2 sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the experimental data for all the state points considered. CO2 saturation in [Zn(pyz)2SiF6] was achieved at near-ambient temperatures and pressures lower than 1.0 atm. Moreover, the sorbed CO2 molecules were representative of a liquid/fluid under such conditions as confirmed through calculating the isothermal compressibility, βT, values. The simulated CO2 uptakes within CO2/N2 (10:90), CO2/CH4 (50:50), and CO2/H2 (30:70) mixture compositions, characteristic of flue gas, biogas, and syngas, respectively, ...