Functionalized Dual/Multiligand Metal–Organic Frameworks for Efficient CO<sub>2</sub> Capture under Flue Gas Conditions
Yangyang Guo, Li Xu, Jia‐Jia Zheng, Na Geng, Yaofeng Wang, Ming‐Shui Yao, Tingyu Zhu
Abstract
Reducing carbon dioxide (CO 2 ) emissions has become increasingly urgent for China, particularly in the industrial sector. Striking a balance between a high CO 2 adsorption capacity and long-term stability under practical conditions is crucial for effectively capturing CO 2 from flue gas. In this study, a series of functionalized MFM-136 adsorbents were synthesized in which -NO 2 and -NH 2 groups were grafted onto the kagome lattice of MFM-136. Modifications with -NH 2 groups were found to be highly effective for CO 2 adsorption, specifically, the CO 2 adsorption capacity peaked at 4.35 mmol/g for NH 2(0.6) -MFM-136, representing a 55% enhancement more than MFM-136. Concurrently, the CO 2 /N 2 selectivity for NH 2(0.6) -MFM-136 was increased 1.57 times. Verification of novel adsorption sites introduced by NH 2 –H 2 L 4 was conducted by using in situ DRIFT analysis and DFT calculations. It turns out that NH 2 –H 2 L 4 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 2 absorption capacity for NH 2(0.6) -MFM-136 was 34% less than that for MFM-136 after 24 h of exposure to simulated flue gas, making NH 2(0.6) -MFM-136 a promising candidate for the potential application of stable and selective CO 2 capture under industrial flue gas conditions.