“Two‐in‐One” Anion Engineering Strategy for One‐Step Ethylene Purification From a Ternary Mixture

ABSTRACT One‐step purification of C 2 H 4 from a C 2 H 2 /CO 2 /C 2 H 4 mixture represents a significant industrial challenge. However, conventional ligand engineering strategies struggle to simultaneously enhance adsorption capacity and separation selectivity. Herein, we present an innovative “two‐in‐one” anion engineering strategy involving the substitution of SiF 6 2− with ZrF 6 2− , which enhances CO 2 capture while effectively shields C 2 H 4 adsorption at the fluorine sites. Compared to SIFSIX‑1‑Cu‑(CH 3 ) 2 , ZrFSIX‑1‑Cu‑(CH 3 ) 2 exhibits a dramatically enhanced CO 2 uptake (from 35.3 to 87.3 cm 3 /g). More importantly, the adsorption preference shifts from C 2 H 4 ‐selective to CO 2 ‐selective, with the CO 2 /C 2 H 4 (50/50) ideal adsorbed solution theory (IAST) selectivity increasing from 0.59 to 1.66. Dynamic breakthrough experiments demonstrate the exceptional separation performance of ZrFSIX‑1‑Cu‑(CH 3 ) 2 for a C 2 H 2 /CO 2 /C 2 H 4 (1/9/90) mixture. Theoretical calculations reveal that the highly electronegative F atoms on the ZrF 6 2− anions enhance the interactions with CO 2 , while ligand rotation‐induced pore contraction and methyl steric effects act synergistically to hinder C 2 H 4 from accessing the fluorine sites. This study provides a new paradigm for the design of materials aimed at purifying C 2 H 4 from multi‐component mixtures.