Selective Dynamic CO2 Separations on Mg-MOF-74 at Low Pressures: A Detailed Comparison with 13X

This study investigates the potential of the well-known metal–organic framework (MOF) Mg-MOF-74 for low-pressure CO2 separations under dynamic conditions. We developed a technique to make pellets of Mg-MOF-74 without large capacity loss and measured CO2 and CH4 isotherms on these pellets up to 40 bar in the temperature range of 293–338 K. Dynamic breakthrough separation experiments with mixtures of CO2 and CH4 on a column packed with Mg-MOF-74 pellets at 308 K and 1 bar indicated a higher CO2 capacity and separation efficiency for the MOF with respect to the benchmark 13X zeolite. The MOF regains 81% of its original capacity when purging with helium at 308 K during 10 min and can be fully regenerated at 353 K, which indicates the facile desorption of CO2 on this material. However, the performance of Mg-MOF-74 severely deteriorates upon long-term exposure to relevant impurities in CO2 separations at low pressures such as water and oxygen.