Gong Wei, Cui Hui, Xie Yi, Li Yingguo, Tang Xianhui, Liu Yan, Cui Yong, Chen Banglin
School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules and Stat Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249-0698, United States.
J Am Chem Soc. 2021 Sep 15;143(36):14869-14876. doi: 10.1021/jacs.1c07191. Epub 2021 Aug 31.
Physical separation of CH from CO on metal-organic frameworks (MOFs) has received substantial research interest due to the advantages of simplicity, security, and energy efficiency. However, that CH and CO exhibit very close physical properties makes their separation exceptionally challenging. Previous work appeared to mostly focused on introducing open metal sites that aims to enhance the CH affinity at desired sites, whereas the reticular manipulation of organic components has rarely been investigated. In this work, by reticulating preselected amino and hydroxy functionalities into isostructural ultramicroporous chiral MOFs-Ni(l-asp)(bpy) () and Ni(l-mal)(bpy) ()-we targeted efficient CH uptake and CH/CO separation, which outperforms most benchmark materials. Explicitly, adsorbs substantial amount of CH with record storage density of 0.81 g mL at ambient conditions, which even exceeds the solid density of CH at 189 K. In addition, gave IAST selectivity of 25 toward equimolar mixture of CH/CO, which is nearly twice higher than that of . Notably, the adsorption enthalpies for CH at zero converge in both MOFs are remarkably low (17.5 kJ mol for and 16.7 kJ mol for ), which to our knowledge are the lowest among efficient rigid CH sorbents. The efficiencies of both MOFs for the separation of CH/CO are validated by multicycle breakthrough experiments. DFT calculations provide molecular-level insight over the adsorption/separation mechanism. Moreover, can survive in boiling water for at least 1 week and can be easily scaled up to kilograms eco-friendly and economically, which is very crucial for potential industrial implementation.
由于具有简单、安全和能源效率高的优点，在金属有机框架（MOF）上实现CH与CO的物理分离受到了广泛的研究关注。然而，CH和CO的物理性质非常接近，这使得它们的分离极具挑战性。先前的工作似乎大多集中在引入开放金属位点以增强目标位点对CH的亲和力，而对有机组分的网状结构调控研究较少。在这项工作中，我们通过将预选的氨基和羟基官能团引入到同构的超微孔手性MOF——Ni(l-asp)(bpy)（ ）和Ni(l-mal)(bpy)（ ）中，目标是实现高效的CH吸附和CH/CO分离，其性能优于大多数基准材料。具体而言， 在环境条件下吸附了大量的CH，记录存储密度为0.81 g/mL，甚至超过了189 K时CH的固体密度。此外， 对CH/CO等摩尔混合物的IAST选择性为25，几乎是 的两倍。值得注意的是，两种MOF中CH在零覆盖度下的吸附焓都非常低（ 为17.5 kJ/mol， 为16.7 kJ/mol），据我们所知，这是高效刚性CH吸附剂中最低的。通过多循环突破实验验证了两种MOF对CH/CO分离的效率。DFT计算为吸附/分离机制提供了分子水平的见解。此外， 在沸水中至少能存活1周，并且可以很容易地扩大到千克规模，既环保又经济，这对于潜在的工业应用至关重要。
