NO and CO are two linear molecules, which have almost the same molecular size and similar physical properties (polarizability and quadrupole moment). Therefore, the separation of CO and NO is extremely challenging. Flexible metal organic frameworks exhibit a gate-opening phenomenon for one type of gas molecule, but not for another, thus enabling excellent selectivity for twin-like molecules. In this study, the separation of CO/NO by flexible metal organic frameworks with different structures was studied systematically using a combination of adsorption and breakthrough tests. The results show that the gate-opening pressure of CO is lower than that of NO on Cu(bpy)(BF) (ELM-11) and Cu(bpy)(OTf) (ELM-12), which are two-dimensional layered flexible MOFs, whereas NO has a lower gate-opening pressure than CO on MIL-53Al, a three-dimensional breathing structure with an adsorption capacity of up to 8 mmol/g was observed at 298 K and ~5 bar, indicating its good separation properties for NO from CO under high pressure. Breakthrough experiments for NO/CO mixtures confirmed that MIL-53Al is capable of separating NO and CO under the optimized conditions (8 bar), making it a promising material for industrial application.

中文翻译：

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柔性金属有机框架CO2-N2O分离研究


NO和CO是两种线性分子，它们具有几乎相同的分子大小和相似的物理性质（极化率和四极矩）。因此，CO和NO的分离极具挑战性。柔性金属有机骨架对一种类型的气体分子表现出开门现象，但对另一种气体分子则不然，从而对类孪生分子具有优异的选择性。本研究结合吸附和突破试验，系统地研究了不同结构的柔性金属有机骨架对CO/NO的分离。结果表明，二维层状Cu(bpy)(BF) (ELM-11)和Cu(bpy)(OTf) (ELM-12)上CO的开闸压力低于NO。 MIL-53Al 上的 MOF 具有柔性，而 NO 的开门压力低于 CO，在 298 K 和 ~5 bar 下观察到吸附容量高达 8 mmol/g 的三维呼吸结构，表明其具有良好的分离性高压下 CO 产生的 NO 的性质。 NO/CO 混合物的突破性实验证实，MIL-53Al 能够在优化条件（8 bar）下分离 NO 和 CO，使其成为一种有前景的工业应用材料。