Metal–organic frameworks (MOFs) have emerged as attractive options for the nonthermal separation of hexane isomers due to their variable channel environments and structural diversity. Here, we report three robust Al-MOFs, KMF-1, MIL-160, and CAU-23, which have nanochannels functionalized with heteroatoms (N, O, and S) for the adsorptive separation of hexane isomers. The adsorption isotherms reveal that these three Al-MOFs can simultaneously adsorb linear, mono-, and dibranched isomers due to their relatively large pore sizes, while showing distinct thermodynamic adsorption behaviors. Significantly, CAU-23, constructed with “S”-atom-functionalized ligands, boasts a notable n-hexane uptake of 3.4 mmol·g^–1, coupled with n-hexane/3-methylpentane and n-hexane/2,2-dimethylbutane uptake ratios of 1.2 and 1.7 at 298 K and a pressure of 19 kPa, respectively, surpassing those of most reported thermodynamically separated MOF materials. Breakthrough measurements demonstrate that CAU-23 effectively separates an n-hexane/3-methylpentane/2,2-dimethylbutane mixture system into linear, mono-, and dibranched components, achieving n-hexane purity levels of up to 99.9%, while providing sufficient retention time between n-hexane, 3-methylpentane, and 2,2-dimethylbutane. The configurational bias Monte Carlo and density functional theory calculations confirmed atomic-scale interactions between heteroatom sites within Al-MOF nanochannels and various isomers, leading to distinct distributions and adsorption characteristics. Moreover, CAU-23 offers a benchmark balance among separation performance, regeneration ability, cost of production, and scalability, highlighting its potential for further research in industrial adsorptive separation of hexane isomers.

中文翻译：

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具有杂原子官能化纳米通道的稳定铝基金属-有机框架吸附剂，用于正己烷异构体分离


金属-有机框架 （MOF） 由于其可变的通道环境和结构多样性，已成为己烷异构体非热分离的有吸引力的选择。在这里，我们报道了三种稳定的 Al-MOF，即 KMF-1、MIL-160 和 CAU-23，它们具有用杂原子（N、O 和 S）官能化的纳米通道，用于正己烷异构体的吸附分离。吸附等温线表明，由于这三种 Al-MOF 的孔径相对较大，它们可以同时吸附线性、单支化和双支化异构体，同时表现出不同的热力学吸附行为。值得注意的是，由“S”原子官能化配体构建的 CAU-23 具有 3.4 mmol·g^–1 的正己烷吸收率，在 298 K 和 19 kPa 压力下，正己烷/3-甲基戊烷和正己烷/2,2-二甲基丁烷的吸收率分别为 1.2 和 1.7，超过了大多数报道的热力学分离 MOF 材料。突破性的测量表明，CAU-23 可有效地将正己烷/3-甲基戊烷/2,2-二甲基丁烷混合物体系分离成线性、单支链和双支链组分，实现高达 99.9% 的正己烷纯度水平，同时在正己烷、3-甲基戊烷和 2,2-二甲基丁烷之间提供足够的保留时间。构型偏差蒙特卡洛和密度泛函理论计算证实了 Al-MOF 纳米通道内杂原子位点与各种异构体之间的原子级相互作用，导致不同的分布和吸附特性。 此外，CAU-23 在分离性能、再生能力、生产成本和可扩展性之间提供了基准平衡，突出了其在己烷异构体工业吸附分离方面进一步研究的潜力。