N-donating and water-resistant Zn-carboxylate frameworks for humid carbon dioxide capture from flue gas

Abstract

Carbon capture from flue gases is one of the crucial routines for reducing current CO2 emissions and mitigating the greenhouse effect. Metal-organic frameworks (MOFs) have received a lot of interest as efficient solid adsorbents for CO2/N2 separation in flue gas treatment. However, many MOF materials are susceptible to the presence of water vapor, which has a significant impact on their adsorption efficacy and moisture stability. Here in this work, we reported two pillar-layered Zn-MOFs with N-donors, i.e., Zn2(TRZ)2(Fuma) and Zn2(TRZ)2(BDC), which demonstrated high CO2 uptakes (3.92 and 1.52 mmol/g) and CO2/N2 (132 and 20.5) adsorption selectivities at 298 K and 101 kPa, among the best comprehensive results reported by far. After seven days of exposure to a 100 % RH environment, it was found that, the Zn-N pillar contributes to the robust structure of MOFs. Furthermore, in-depth theoretical calculations indicated the guest-framework interactions, and dynamic sorption tests confirmed high working capacities (2.78 and 1.14 mmol/g), sufficient water stability and remarkable cycling performance of the studied MOFs under humid ambient conditions. We believe this work provides a routine to prepare robust and promising candidates to address the challenge in carbon capture under humid conditions.