The results in Figure show that the presence of N2 influences the diffusion of CO2 in CALF-20. In these experiments, run 1 in He/N2 (Figure ) was completed first, followed by the runs in He only (Figure ), then the other 2 runs in He/N2 (Figure ), verifying that the adsorbed N2 caused the observed change in the mechanism. Thus, contrary to expectations, the small amount (< 0.3 mmol/g) 18 N2 loading at ambient temperatures and pressures on CALF-20 is enough to contribute to meaningful changes in adsorption behavior, which is approximated in this case by a single-component LDF model. Changes in the CO2 diffusion mechanism are likely occurring because N2 is adsorbing and producing a CO2/N2 mixed-gas adsorption environment.