Ethylene Pretreatment Enhances Ethylene Adsorption and Separation over Cu@SAPO‐RHO Zeolite

Abstract Efficient ethylene/ethane (C 2 H 4 /C 2 H 6 ) separation using low‐energy technologies is crucial for the chemical industry yet remains challenging due to the lack of industrially applicable adsorbents. Cu(I)‐based adsorbents show significant potential; however, traditional synthesis methods often involve complex procedures or reduction steps. Herein, we report that Cu@SAPO‐RHO zeolite, synthesized for the first time via a one‐pot method with cyclam as the Cu(II) ligand, exhibits a remarkable C 2 H 4 /C 2 H 6 selectivity of 22.6, a C 2 H 4 uptake of 3.08 mmol g −1 , and a separation factor of 9.4 under ambient conditions by using a C 2 H 4 pretreatment, placing it among the best‐performing zeolitic materials. The C 2 H 4 pretreatment enhances separation efficiency by partially reducing Cu(II) to Cu(I) and water resistance through the formation of carbon species during pretreatment. Structural analysis using Rietveld refinement reveals that Cu 2+ ions occupy the corners of elliptical single 8‐rings ( s 8 r ). X‐ray absorption near‐edge structure analysis confirms a reduction in the Cu oxidation state, while X‐ray photoelectron spectroscopy corroborates the partial conversion of Cu(II) to Cu(I). Periodic density functional theory calculations further reveal that Cu(I) interacts more strongly with C 2 H 4 than Cu(II). With its straightforward synthesis and enhanced performance through C 2 H 4 pretreatment, Cu@SAPO‐RHO zeolite presents a promising solution for industrial‐scale C 2 H 4 /C 2 H 6 separation.