Guest Cation Functionalized Metal Organic Framework for Highly Efficient C₂H₂/CO₂ Separation

The removal of carbon dioxide (CO 2 ) from acetylene (C 2 H 2 ) production is critical yet difficult due to their similar physicochemical properties. Despite extensive research has been conducted on metal‐organic frameworks (MOFs) for C 2 H 2 /CO 2 separation, approaches to designing functionalized MOFs remain limited. Enhancing gas adsorption through simple pore modification holds great promise in molecular recognition and industrial separation processes. This study proposes a guest cation functionalization strategy using the anionic framework SU‐102 as the prototype material. Specifically, the guest cation Li + is introduced into the skeleton by ion exchange to obtain SU‐102‐Li + . This strategy generates strong interactions between Li + and gas molecules, thereby elevating C 2 H 2 uptake to 49.18 cm 3 g −1 and CO 2 uptake to 29.88 cm 3 g −1 , marking 20.3% and 36.9% improvements over the parent material, respectively. In addition, ideal adsorbed solution theory selectivity calculations and dynamic breakthrough experiments confirmed the superior and stable separation performance of SU‐102‐Li + for C 2 H 2 /CO 2 (25 min g −1 ) and C 2 H 2 productivity (1.55 mmol g −1 ). Theoretical calculations further reveals the unique molecular recognition mechanism between gas molecules and guest cations.