https://doi.org/10.1016/j.ccst.2022.100039
“When the adsorbent has a pore size close to the CO2 diameter, the adsorption of CO2 will be promoted (Seredych et al., 2014). Currently, the kinetic diameter of CO2 is considered as 0.33 nm, smaller than CH4 (0.38 nm) and N2 (0.364 nm). In order to obtain a high selectivity of CO2, the pore size of the adsorbent is required to be controlled between 0.33 and 0.36 nm. On the other hand, CO2 adsorption is found to increase with the increase of total micropore volume (Querejeta et al., 2018). Moreover, the increased CO2 adsorption at a smaller pore volume indicates that the adsorption of CO2 by ultra micropores is governed by pore filling. In the experiment of Parshetti et al. (Parshetti et al., 2015), a higher adsorption capacity of CO2 was achieved with a higher surface area and micropore volume, suggesting a characteristic pore-filling mechanism and physical adsorption behavior.”