Functionalized Dual/Multiligand Metal-Organic Frameworks for Efficient CO Capture under Flue Gas Conditions.

Reducing carbon dioxide (CO) emissions has become increasingly urgent for China, particularly in the industrial sector. Striking a balance between a high CO adsorption capacity and long-term stability under practical conditions is crucial for effectively capturing CO from flue gas. In this study, a series of functionalized MFM-136 adsorbents were synthesized in which -NO and -NH groups were grafted onto the kagome lattice of MFM-136. Modifications with -NH groups were found to be highly effective for CO adsorption, specifically, the CO adsorption capacity peaked at 4.35 mmol/g for NH-MFM-136, representing a 55% enhancement more than MFM-136. Concurrently, the CO/N selectivity for NH-MFM-136 was increased 1.57 times. Verification of novel adsorption sites introduced by NH-HL was conducted by using DRIFT analysis and DFT calculations. It turns out that NH-HL modification can effectively mitigate the chemical deposition from the impurity gases and significantly improve the adsorbent's hydrophobicity and its tolerance to impurity gases. Remarkably, the reduction in the CO absorption capacity for NH-MFM-136 was 34% less than that for MFM-136 after 24 h of exposure to simulated flue gas, making NH-MFM-136 a promising candidate for the potential application of stable and selective CO capture under industrial flue gas conditions.