Interlayer Expansion in a Layered Metal-Organic Framework Enhances CO2 Capture and CO2/N2 Separation

Developing efficient CO2 adsorbent materials and technologies is significant to reduce the increasing greenhouse gases concentration in the atmosphere. Herein, a layered MOF with a porous kagome lattice (kgm), which owned three phases (kgm-1, kgm-2, and kgm-3) via interlayer expansion, was evaluated as a promising CO2 capture and separation material by using grand canonical Monte Carlo simulations. Results showed that the interlayer expansion provided additional pore volume, which played a considerable role in CO2 adsorption and separation. The CO2 adsorption capacity and CO2/N-2 selectivity followed the sequence kgm-3>kgm-2>kgm-1, and kgm-3 exhibited an excellent CO2 adsorption capacity of 8.7 mmol g(-1) at 1 bar with a CO2/N-2 selectivity of 130.3 at 20 bar and 298 K. Gas distribution analysis showed that CO2 and N-2 are adsorbed only in the channels in kgm-1, whereas they could be adsorbed between layers in kgm-2 and kgm-3 due to the interlayer expansion. The adsorption heat and interactions between CO2 and frameworks were analyzed to elucidate the effect of interlayer expansion. Results of this work highlighted that appropriate interlayer expansion can be an effective approach for framework adsorbents to improve CO2 capture ability and separation performance at the same time.