Highly selective capture of methane from nitrogen is considered to be a feasible approach to improve the heating value of methane and mitigate the effects of global warming. In this work, an ultramicroporous squarate‐based metal‐organic framework (MOF), [Co₃(C₄O₄)₂(OH)₂] (C₄O₄²⁻ = squarate), with enhanced negative oxygen binding sites was synthesized for the first time and used as adsorbent for efficient separation of methane and nitrogen. Adsorption performance of this material was evaluated by single‐component adsorption isotherms and breakthrough experiments. Furthermore, density functional theory calculation was performed to gain the deep insight into the adsorption binding sites. Compared with the other state‐of‐the‐art materials, this material exhibited the highest adsorption selectivity (8.5–12.5) of methane over nitrogen as well as the moderate volumetric uptake of methane (19.81 cm³/cm³) under ambient condition. The unprecedented selectivity and chemical stability guaranteed this MOF as a candidate adsorbent to capture CH₄ from N₂, especially for the unconventional natural gas upgrading. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3681–3689, 2018

中文翻译：

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在基于方波的金属有机框架上高效分离甲烷和氮

从氮中高度选择性地捕获甲烷被认为是提高甲烷的热值并减轻全球变暖影响的可行方法。在这项工作中，是基于超微孔方金属金属框架（MOF）[Co ₃（C ₄ O ₄）₂（OH）₂ ]（C ₄ O ₄ ^2- =方形），首次合成了具有增强的负氧结合位点的化合物，并用作有效分离甲烷和氮气的吸附剂。通过单组分吸附等温线和突破实验评估了该材料的吸附性能。此外，进行密度泛函理论计算以深入了解吸附结合位点。与其他最先进的材料相比，该材料在环境条件下对甲烷的甲烷吸附选择性最高（8.5–12.5），并且对甲烷的吸收中等量（19.81 cm ³ / cm ³）。前所未有的选择性和化学稳定性保证了该MOF作为捕获CH ₄的候选吸附剂从N _2开始，特别是对于非常规天然气提质。©2018美国化学工程师学会AIChE J，64：3681–3689，​​2018