Peng Junjie, Liu Zewei, Wu Ying, Xian Shikai, Li Zhong
School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, P. R. China.
Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, Xili, Nanshan, Shenzhen 518055, P. R. China.
ACS Appl Mater Interfaces. 2022 May 11;14(18):21089-21097. doi: 10.1021/acsami.2c04779. Epub 2022 Apr 27.
Selective CO capture is of great significance for environmental protection and industrial demand. Here, we report a stable and flexible metal-organic framework (MOF) with excellent water/moisture stability, namely, ZnDatzBdc, that enables high-performance selective CO capture from N and CH via a discriminatory gate-opening effect. ZnDatzBdc shows reversible structural transformation between the open-phase (OP) state and the close-phase (CP) state, owing to the synergistic effect of breakage/re-formation of intraframework hydrogen bonds and the rotation of the phenyl rings. Significantly, ZnDatzBdc exhibits S-shaped isotherms toward CO, resulting in a large CO theoretical working capacity of 94.9 cm/cm under typical pressure vacuum swing adsorption (PVSA) operations, which outperforms other flexible MOFs showing the CO selective gate-opening effect except for the miosture-sensitive ELM-11. In addition, CO uptake of ZnDatzBdc is well maintained upon multiple water/moisture exposure, indicating its excellent stability. Moreover, ZnDatzBdc establishes remarkable CO selectivity with ultrahigh uptake ratios of CO/N (107 at 273 K and 129 at 298 K) and CO/CH (35 at 273 K and 44 at 298 K) at 100 kPa. The in situ gas sorption PXRD experiment verifies that the gate-opening effect takes place in the atmospheric environment of CO but not for N or CH. Molecular simulation suggests the selective gate-opening of CO comes from its strong electrostatic interactions with the amino groups. Furthermore, effective breakthrough performance and easy regeneration are further confirmed. Hence, combined with excellent separation performance and remarkable stability, ZnDatzBdc can serve as a potential industrial adsorbent for selective CO capture.
选择性捕获一氧化碳对于环境保护和工业需求具有重要意义。在此，我们报道了一种具有出色水/湿气稳定性的稳定且灵活的金属有机框架（MOF），即ZnDatzBdc，它能够通过独特的门控开启效应从氮气和甲烷中高效选择性捕获一氧化碳。由于框架内氢键的断裂/重新形成以及苯环的旋转之间的协同作用，ZnDatzBdc在开放相（OP）状态和封闭相（CP）状态之间呈现可逆的结构转变。值得注意的是，ZnDatzBdc对一氧化碳呈现S形等温线，在典型的变压真空吸附（PVSA）操作下，其一氧化碳理论工作容量高达94.9 cm³/cm³，除了对湿气敏感的ELM-11外，这一表现优于其他具有一氧化碳选择性门控开启效应的柔性MOF。此外，在多次暴露于水/湿气后，ZnDatzBdc对一氧化碳的吸附量保持良好，表明其具有出色的稳定性。此外，在100 kPa下，ZnDatzBdc展现出显著的一氧化碳选择性，一氧化碳/氮气的超高吸附比（273 K时为107，298 K时为129）以及一氧化碳/甲烷的超高吸附比（273 K时为35，298 K时为44）。原位气体吸附PXRD实验证实，门控开启效应在一氧化碳的大气环境中发生，而对氮气或甲烷则不发生。分子模拟表明，一氧化碳的选择性门控开启源于其与氨基的强静电相互作用。此外，还进一步证实了有效的突破性能和易于再生。因此，结合出色的分离性能和显著的稳定性，ZnDatzBdc可作为一种潜在的工业吸附剂用于选择性捕获一氧化碳。
