CO ₂ Chemical Trap and Electronegative Microenvironment Enable Metal–Organic Framework with One‐Step Ethylene Purification from Quaternary Mixture

Abstract One‐step purification of C ₂ H ₄ from a four‐component CO ₂ /C ₂ H ₆ /C ₂ H ₂ /C ₂ H ₄ mixture with a single adsorbent is of great significance but very challenging. Herein a feasible and general strategy is reported for constructing chemical traps in MOF featuring an electronegative microenvironment in the pore wall for one‐step purification of C ₂ H ₄ from the four‐component mixture. The enzyme‐mimicking Zn‐OH sites in CFA‐Zn‐OH, acting as a CO ₂ chemical trap, can efficiently fix CO ₂ while the electronegative pore wall in MOF ensures the preferential adsorption of C ₂ H ₂ and C ₂ H ₆ impurities, thus leading to the one‐step purification of C ₂ H ₄ from a four‐component mixture. Mechanism studies reveal that the Zn‐OH sites in CFA‐Zn‐OH can chemically fix CO ₂ impurity in a reversible manner to form bicarbonate Zn‐HCO ₃ , mimicking the carbonic anhydrase. In addition, the negative electrostatic potential of the pore wall allows CFA‐Zn‐OH to preferentially capture C ₂ H ₂ , and C ₂ H ₆ impurities, thus ensuring one‐step C ₂ H ₄ purification from the four‐component mixture. Column breakthrough experiments validated its ability for one‐step C ₂ H ₄ purification on from the four‐component mixture and C ₂ H ₄ with a purity of 99.9% can be directly harvested.