We employed a combination of macroscopic approaches (Ideal Adsorption Solution Theory, IAST, and Two-Dimensional Equation of State, 2D-EOS) and microscopic molecular simulations to explore the adsorption and separation of N, CH, and CO in mesoporous materials CMK-1, CMK-3, and CMK-5. Our findings reveal that these behaviors are intricately linked to the material's structure, surface properties, and the adsorbed fluid type. For nonpolar N/CH supercritical fluid, both macroscopic theories align remarkably well with molecular simulations. For gas mixtures with a supercritical gas (N or CH) and a subcritical gas (CO), the impact of material structure on adsorption and separation varies. While both adsorption theories perform well for CMK-3, with excellent agreement to simulations, only IAST accurately predicts CMK-1. This discrepancy indicates that 2D-EOS has a less satisfactory predictive accuracy for CMK-1 compared to CMK-3 due to structural differences. The hexagonal arrangement of nanorods in CMK-3 leads to a more uniform adsorption site, while CMK-1's diverse adsorption sites, including nanorod surfaces and inter-rod grooves, contribute to a more complex adsorption behavior. In CMK-5, a unique jump in the CO adsorption selectivity is observed, attributed to a phase transition within the pores. Interestingly, this transition-induced jump defies accurate prediction by common theoretical models, except for IAST, which correctly predicts trends in selectivity and adsorption amounts. This phenomenon is specific to CMK-5's dual-pore structure, where most CO adsorption occurs inside the pipes until saturation, followed by adsorption on the external surface. Examining the impact of –COOH and –OH functional groups on adsorption behavior, we find minimal influence on separation in nonpolar N–CH fluid, independent of the material type. However, in CO-containing systems, the –COOH functional group has a substantial impact, highlighting its significance in influencing adsorption behavior.

中文翻译：

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CMK系列介孔碳材料的流体性质、孔结构和表面化学对N2/CH4/CO2分离的意义

我们采用宏观方法（理想吸附溶液理论，IAST和二维状态方程，2D-EOS）和微观分子模拟相结合来探索介孔材料CMK-1中N、CH和CO的吸附和分离、CMK-3 和 CMK-5。我们的研究结果表明，这些行为与材料的结构、表面特性和吸附流体类型密切相关。对于非极性 N/CH 超临界流体，两种宏观理论与分子模拟都非常吻合。对于超临界气体（N 或 CH）和亚临界气体（CO）的气体混合物，材料结构对吸附和分离的影响各不相同。虽然两种吸附理论对于 CMK-3 都表现良好，并且与模拟非常吻合，但只有 IAST 能够准确预测 CMK-1。这种差异表明，由于结构差异，与 CMK-3 相比，2D-EOS 对 CMK-1 的预测精度不太令人满意。 CMK-3 中纳米棒的六边形排列导致更均匀的吸附位点，而 CMK-1 的多样化吸附位点（包括纳米棒表面和棒间凹槽）有助于更复杂的吸附行为。在 CMK-5 中，观察到 CO 吸附选择性的独特跳跃，这归因于孔内的相变。有趣的是，这种转变引起的跳跃无法通过常见理论模型进行准确预测，但 IAST 除外，它可以正确预测选择性和吸附量的趋势。这种现象是 CMK-5 的双孔结构所特有的，其中大部分 CO 吸附发生在管道内部直至饱和，然后吸附在外表面。检查 –COOH 和 –OH 官能团对吸附行为的影响，我们发现对非极性 N-CH 流体中的分离影响最小，与材料类型无关。然而，在含CO系统中，-COOH官能团具有重大影响，突出了其在影响吸附行为方面的重要性。