Let us briefly summarize what is known about CO 2 /N 2 separation and how it is different from the kinetics-driven processes. Firstly, CO 2 and N 2 have relatively similar kinetic diameters (d CO2 = 0.33 nm and d N2 = 0.364 nm, respectively) and the arguments in the foundation of the kinetics-based theories play a diminished role here. However, transport effects do play an important role in CO 2 /N 2 separation. This is easy to show by naively assuming that