Utilizing the Gate-Opening Mechanism in ZIF-7 for Adsorption Discrimination between N2O and CO2

N2O is a greenhouse gas with tremendous global warming potential, and more importantly it also causes ozone depletion; thus, the separation of N2O from industrial processes has gained significant attention. We have demonstrated that N2O can be selectively separated from CO2 using the zeolite imidazolate framework ZIF-7. The adsorption/desorption isotherms of both N2O and CO2 in ZIF-7 indicate the gate-opening mechanism of this material, and surprisingly, the threshold pressure for the gate opening with N2O is lower than that with CO2. Theoretical calculations indicate that both gas-host and gas-gas interaction energies for N2O are more favorable than those for CO2, giving rise to the difference in the threshold pressure between N2O and CO2 in ZIF-7. Breakthrough experiments for N2O/CO2 mixtures confirm that ZIF-7 is capable of separating N2O and CO2 mixtures under the optimized conditions, in reasonable agreement with simulation results, making it a promising material for industrial applications.