One-Step Purification of Polymer-Grade C ₂ H ₄ with Simultaneous Trace C ₂ H ₂ Recovery Enabled by a Low-Cost MOF with Finely Tuned Pore Electrostatics

The production of polymer-grade ethylene (C2H4) and the recovery of trace acetylene (C2H2) from complex gas mixtures remain highly energy-intensive in the chemical industry, relying predominantly on cryogenic distillation or selective hydrogenation. Herein, we report a sustainable and scalable metal–organic framework (MOF), ZMOF-Cd, that enables energy-efficient one-step purification of polymer-grade C2H4 together with the simultaneous recovery of trace C2H2 from ternary C2H2/CO2/C2H4 mixtures via finely tuned pore-surface electrostatics. ZMOF-Cd adopts a zeolitic RHO-type topology featuring abundant polar O/N sites and polarized hydrogen atoms, which collectively create well-matched electrostatic environments for the preferential recognition of C2H2 and CO2 over C2H4. Static adsorption isotherms, dynamic breakthrough experiments, and density functional theory (DFT) calculations consistently reveal a thermodynamically favorable affinity hierarchy of C2H2 > CO2 > C2H4, enabling efficient impurity capture and the production of high-purity C2H4. Notably, ZMOF-Cd directly delivers polymer-grade C2H4 (>99.99%) while efficiently recovering trace C2H2 under realistic ternary feed compositions, high flow rates, and humid conditions. Importantly, ZMOF-Cd can be synthesized via a scalable, water-based route using inexpensive precursors with a low estimated production cost of 137.2 $ kg–1. The framework further exhibits excellent chemical stability, moisture resistance, and processability into shaped adsorbents with smaller loss of porosity. This work demonstrates a green and scalable strategy for designing low-cost MOF adsorbents capable of energy-efficient one-step olefin purification and impurity recovery, offering a promising pathway toward the sustainable industrial deployment of adsorption-based separation technologies.