Single-Step Ethylene Purification from Ternary C₂ Hydrocarbon Mixtures in a Scalable Metal–Organic Framework

Single-step purification of the ternary C₂ hydrocarbon mixture to produce ethylene (C₂H₄) directly using adsorption-based technologies is desirable for reducing large energy consumption. However, it is challenging to develop an appropriate adsorbent, having preferential adsorption characteristics toward ethane (C₂H₆) and acetylene (C₂H₂) rather than C₂H₄ coupled with high adsorption capacity owing to their similar physicochemical properties. Herein, we present a highly stable, cheap, and scalable CAU-23 adsorbent, which enables single-step production of high-purity C₂H₄ (>99.9%) from the ternary C₂ hydrocarbon mixture. CAU-23 exhibited higher uptake capacity of C₂H₆ (4.0 mmol g⁻¹) and C₂H₂ (4.7 mmol g⁻¹) compared to that of C₂H₄ (3.8 mmol g⁻¹). Further, it showed the reasonable selectivity for both C₂H₆/C₂H₄ (1.54) and C₂H₂/C₂H₄ (1.5) with an equimolar binary mixture, indicating that the separation performance of CAU-23 is comparable to the benchmark porous materials for separating C₂ ternary gas mixture. The breakthrough experiments demonstrated its capability to produce high-purity C₂H₄ (>99.9%) with various C₂H₆/C₂H₄/C₂H₂ compositions at 298 K and 1 bar with high recyclability. The origin of the separation performance was further explored by using computational simulations of the grand canonical Monte Carlo (GCMC) and density functional theory (DFT).