Selective separation of acetylene from ethylene with branched ionic ultramicroporous polymer

Abstract Capturing acetylene (C2H2) from ethylene (C2H4) is an important but tough task, due to their similar physicochemical properties and close kinetic diameters. Physisorption is an efficient and energy-saving separation technology, but the combination of long-term stability and desired pore environment for efficient separation performance of porous materials still faces challenges at industrially relevant conditions. Here, a new ionic ultramicroporous polymer (IUP) has been successfully constructed based on a branched ionic monomer featuring a large and flexible triphenylmethane-based skeleton. The IUP possesses narrowly distributed ultramicroporosity and high-density inorganic anions along with impressive tolerance against various solvents and pH environments, and excellent amphiphilicity. The excellent C2H2/C2H4 selectivity (18.8-65.8) and moderate C2H2 capacity (28.5 cm3 g-1) have been achieved by such well-designed architecture. Efficient and recyclable dynamic separation performance make IUPs promising candidates in the field of advanced separation. This work will provide important guidance on the development of IUPs, and facilitate designing adsorbent materials for high-performance separation of industrially important hydrocarbons.