Generation of Cu(I) Sites in Y Zeolite via In Situ Ethylene Reduction for Ethylene/Ethane Separation

Ethylene (C2H4) serves as a core petrochemical feedstock, but its separation from ethane (C2H6) is energy-intensive due to their nearly identical molecular diameters and closely matched boiling points. Cu(I)-based adsorbents offer a solution by selectively capturing C2H4 through π-complexation, delivering a superior separation performance compared to traditional methods. However, conventional Cu(I)-based adsorbents preparation typically relies on high-temperature self-reduction (HTSR, ≥450 °C), resulting in high energy consumption but low Cu(I) yield. In this study, we present an in situ C2H4 reduction (IER) strategy to selectively convert Cu(II) in Y zeolite to Cu(I) at a much lower temperature of 170 °C under a flowing C2H4 atmosphere. The obtained CuY-170 adsorbent achieved an impressive 84.5% Cu(I) yield, obviously outperforming the HTSR method. Density functional theory (DFT) calculations indicate that the IER strategy reduces the reduction energy barrier from 510 kJ mol–1 in the HTSR method to 362 kJ mol–1, thus reducing the energy consumption. Benefiting from the abundant Cu(I) sites, CuY-170 demonstrates a C2H4 adsorption capacity of 4.27 mmol g–1 and a C2H4/C2H6 selectivity of 41.2, far surpassing previously reported Cu-containing adsorbents, such as CuCl/NaX (1.90 mmol g–1, selectivity 3.6), 1.5 CuCoM-DS (2.25 mmol g–1, selectivity 2.6), and Cu-MCM-48 (0.50 mmol g–1, selectivity 3.8). Moreover, CuY-170 maintains a high C2H4 adsorption capacity, even after multiple cycles. The present adsorbents, possessing good adsorption performance and stability while being prepared through the efficient, energy-saving IER approach, provide promising alternatives for practical C2H4/C2H6 separation.