CO2/N2 separation by vacuum swing adsorption using a metal-organic framework, CALF-20: Multi-objective optimization and experimental validation

In this paper, the ability of CALF-20, a hydrophobic metal-organic framework (MOF), to capture CO2 from dry flue gas (15/85 mol% of CO2/N2) using two different adsorption configurations, basic four-step vacuum swing adsorption (VSA), and four-step with light-product pressurization (LPP) was evaluated. Pareto curves, for the simultaneous maximization of CO2 purity and recovery, were generated. Five points from each Pareto curve representing five different process conditions were chosen to experimentally validate the model prediction. The experiments resulted in a CO2 purity and recovery of 95 %, and 70 %, respectively for the basic four-step cycle, while the four-step LPP resulted in 95.5 % purity and 88.1 % recovery. The temperature history, the pressure transient, and the flow rate of different steps were in good agreement with the model predictions. The results of this study confirmed that CALF-20 is capable of separating CO2 from dry flue gas, demonstrating the potential of the MOF for practical separations.