Efficient Purification of Ethylene from C₂ Hydrocarbons with an C₂H₆/C₂H₂‑Selective Metal–Organic Framework

The separation of ethylene (C2H4) from C2 hydrocarbons is considered as one of the most difficult and important processes in the petrochemical industry. Heat-driven cryogenic distillation is still widely used in the C2 hydrocarbons separation realms, which is an energy intensive process and takes up immense space. In response to a greener, more energy-efficient sustainable development, we successfully synthesized a multifunction microporous Mg-based MOF [Mg2(TCPE)­(μ2-OH2)­(DMA)2]·solvents (NUM-9) with C2H6/C2H2 selectivity based on a physical adsorption mechanism, and with outstanding stability; especially, it is stable up to 500 °C under an air atmosphere. NUM-9a (activated NUM-9) shows good performances in the separation of C2H6/C2H2 from raw ethylene gases. In addition, its actual separation potential is also examined by IAST and dynamic column breakthrough experiments. GCMC calculation results indicate that the unique structure of NUM-9a is primarily conducive to the selective adsorption of C2H6 and C2H2. More importantly, compared with C2H4, NUM-9a prefers to selectively adsorb C2H6 and C2H2 simultaneously, which makes NUM-9a as a sorbent have the capacity to separate C2H4 from C2 hydrocarbon mixtures under mild conditions through a greener and energy-efficient separation strategy.从碳二烃（C2 hydrocarbons）中分离乙烯（C2H4），被视为石油化工行业中最具挑战性且至关重要的工艺之一。当前工业领域仍广泛采用热驱动低温精馏工艺开展碳二烃分离，但该工艺能耗高昂且占地面积巨大。为契合绿色低碳、节能高效的可持续发展需求，我们基于物理吸附机制，成功合成了一款具备C2H6/C2H2选择性的多功能微孔镁基金属有机框架（Metal-Organic Framework, MOF）[Mg₂(TCPE)(μ₂-OH₂)(DMA)₂]·溶剂（NUM-9），该材料具有优异的稳定性，尤其可在空气氛围下耐受最高500℃的高温。活化后的NUM-9（即NUM-9a）可高效实现原料气中C2H6、C2H2与乙烯的分离。此外，本研究通过理想吸附溶液理论（Ideal Adsorbed Solution Theory, IAST）与动态柱突破实验验证了其实际分离性能潜力。巨正则蒙特卡洛（Grand Canonical Monte Carlo, GCMC）计算结果表明，NUM-9a的独特结构使其可优先选择性吸附C2H6与C2H2。更为关键的是，相较于乙烯（C2H4），NUM-9a可同时选择性吸附C2H6与C2H2，这使得该材料作为吸附剂，能够在温和条件下通过绿色节能的分离策略，实现碳二烃混合物中乙烯的高效分离。