释放由稀缺 Fe4O2 核心构建的 3D 铁基金属有机框架的分离能力，用于升级天然气,Chemistry of Materials

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释放由稀缺 Fe4O2 核心构建的 3D 铁基金属有机框架的分离能力，用于升级天然气
Chemistry of Materials ( IF 7.2 ) Pub Date : 2023-09-27 , DOI: 10.1021/acs.chemmater.3c01777
Himan Dev Singh ₁ , Piyush Singh ₁ , Raviraju Vysyaraju ₂ , Bhubesh Murugappan Balasubramaniam ₂ , Deepak Rase ₁ , Pragalbh Shekhar ₁ , Aleena Jose ₁ , Arvind Rajendran ₂ , Ramanathan Vaidhyanathan ₁

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甲烷是一种重要的替代燃料，对其进行升级以提高燃料效率是当务之急。能够选择性地从天然气中去除主要杂质CO ₂和N _{2的固体吸附剂对此过程做出了巨大贡献。}我们报道了一种多孔3D铁-MOF，通过容易获得的对苯二甲酸酯和二氨基三唑配体连接稀缺的Fe ₄ O ₁₈ N ₂簇而构建。具有高密度极化胺基、芳香环和羧酸氧的一维通道吸附CO ₂和极化程度更低的CH ₄。MOF在273 K、1 bar下吸收4.7 mmol/g CO ₂，最佳吸附热约为24.5 kJ/mol，CO ₂ /N ₂ IAST选择性约为26。在较高压力下，MOF 对甲烷和氮气表现出 Langmuir 型等温线，CH ₄ /N ₂ IAST 选择性约为 4。MOF 优异的循环稳定性得到了 TGA 和异构循环的证实。模型研究提出了胺与CO ₂的相互作用，但更占主导地位的是CO ₂ ···CO ₂协同相互作用。在 20 bar 下，CH ₄通过弱色散相互作用与许多框架位点相互作用。相反，N ₂与三唑部分特异性相互作用；因此，财政部倾向于前者。使用 MD 模拟计算得出的CO ₂、CH ₄和 N ₂扩散系数非常有利（CO ₂的 Dc = 1.11 × 10 ^–6；CH ₄ = 9.04 × 10 ^–6；N ₂ = 1.875 × 10 ^–5厘米² /秒）。动态突破性研究证实了 Fe-MOF 分离气体混合物的潜力。凭借这种 Fe-MOF 的这些有利的吸附剂特性，我们建议将其用于天然气净化过程的两阶段 PSA，阶段 I：去除 CO ₂和阶段 II：去除 N ₂。结果表明，易于获得的铁基胺 MOF 作为天然气提质吸附剂的潜力。使用 4 步 PSA 进行的工艺优化验证了我们的 MOF 能够产生管道运输所需的>96% 纯度的 CH _{4 。}

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Unlocking the Separation Capacities of a 3D-Iron-Based Metal Organic Framework Built from Scarce Fe4O2 Core for Upgrading Natural Gas

Methane is an important alternative fuel, and upgrading it to improve fuel efficiency is an imperative target. Solid sorbents capable of selectively removing the major impurities CO₂ and N₂ from the natural gas contribute immensely to this process. We report a porous 3D iron-MOF built by linking scarce Fe₄O₁₈N₂ clusters through readily available terephthalate and diaminotrizaole ligands. The 1-D channels with a high density of polarizing amine groups, aromatic rings, and carboxylate oxygen adsorb CO₂ and the even less polarizable CH₄. The MOF uptakes 4.7 mmol/g of CO₂ at 273 K, 1 bar, with an optimal heat of adsorption of ≈24.5 kJ/mol and CO₂/N₂ IAST selectivity of ≈26. At higher pressures, the MOF exhibits a Langmuir type isotherm for methane and nitrogen with a CH₄/N₂ IAST selectivity of ≈4. The MOF’s excellent cyclic stability is affirmed by the TGA- and iso-cycling. Modeling studies propound the amine’s interactions with the CO₂, but more dominant is the CO₂···CO₂ cooperative interactions. At 20 bar, CH₄ interacts with many framework sites through weak dispersive interactions. In contrast, N₂ interacts specifically with the triazole moiety; thus, the MOF favors the former. The CO₂, CH₄, and N₂ diffusion coefficients, calculated using MD simulations, are quite favorable (Dc for CO₂ = 1.11 × 10^–6; CH₄ = 9.04 × 10^–6; N₂ = 1.875 × 10^–5 cm²/s). The dynamic breakthrough studies confirm the potential of the Fe-MOF to separate the gas mixtures. With these advantageous sorbent characteristics of this Fe-MOF, we propose using it in a two-stage PSA for the natural gas purification process, Stage I: removal of CO₂ and Stage II: removal of N₂. The outcomes point to the potential of a readily accessible iron-based amine MOF as sorbent for natural gas upgrading. A process optimization using a 4-step PSA validates the ability of our MOF to yield >96% purity of CH₄ as required for pipeline transportation.

更新日期：2023-09-27

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