CO 2 -Selective Metal-Organic Frameworks for One-Step C 2 H 2 Purification

Abstract

The separation of acetylene (C 2 H 2 ) and carbon dioxide (CO 2 ) and is a critical step in the industrial production of high-purity C 2 H 2 . Traditional approaches such as liquid extraction and cryogenic distillation are energy-intensive and environmentally demanding. Metal-organic frameworks (MOFs), with their tunable pore geometries and surface chemistry, have emerged as promising adsorbents for this challenging task. In particular, CO 2 -selective MOFs enable one-step C 2 H 2 purification by preferentially capturing CO 2 , thereby avoiding the need for energy-costly desorption cycles. In this review, we first compare the physicochemical properties of CO 2 and C 2 H 2 and discuss how their distinct electronic structure led to different adsorption behavior within MOFs.We then summarize recent advances in MOFs designed for inverse C 2 H 2 /CO 2 separation, highlighting four key strategies: enhanced CO 2 recognition ability, suppressed C 2 H 2 binding sites, exploited framework flexibility, and regulated thermodynamic and kinetic factors. Finally, we offer our perspectives on the remaining challenges and future direction in this field, considering chemistry, materials science, and practical implementation.