Separating trace propyne from propylene is of great importance in the petrochemical industry but difficult because of very close molecular sizes and physicochemical properties, which promotes the development of high-performance porous materials with great stability in practical adsorptive separation; however, a limited number of efficient adsorbents have been reported. Here, a class of robust functionalized ionic ultramicroporous polymers (IUPs) with different branched structures that feature high-density preferential anionic binding sites and outstanding thermal and water stability is systematically studied for the separation of propyne and propylene for the first time. The functionalized pore environment of IUPs achieves the highest selectivity of propyne and propylene (126.5) for the 1/99 (v/v) mixture among porous organic polymers, as well as excellent and recyclable dynamic separation performance. Modeling studies reveal that strong basic sites of IUPs with abundant ultramicroporosity facilitate the efficient removal of propyne from propylene. This study provides important clues for the design of robust functionalized adsorbents and thus expands the currently limited dictionary of adsorbents for the separation of important gas mixtures.
Keywords: adsorption; anion; cross-linking strategy; ionic ultramicroporous polymers; propylene; propyne; separation.