Guest Cation Functionalized Metal Organic Framework for Highly Efficient CH/CO Separation.

The removal of carbon dioxide (CO) from acetylene (CH) production is critical yet difficult due to their similar physicochemical properties. Despite extensive research has been conducted on metal-organic frameworks (MOFs) for CH/CO 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 CH uptake to 49.18 cm g and CO uptake to 29.88 cm g, 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 CH/CO (25 min g) and CH productivity (1.55 mmol g). Theoretical calculations further reveals the unique molecular recognition mechanism between gas molecules and guest cations.