Guest Cation Functionalized Metal Organic Framework for Highly Efficient C 2 H 2 /CO 2 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.