Sulfate-Pillared Adsorbent for Efficient Acetylene Separation from Carbon Dioxide and Ethylene

The effective separation of acetylene (C₂H₂) from carbon dioxide (CO₂) and ethylene (C₂H₄) presents considerable challenges in the petrochemical industry. In this work, we report a novel sulfate-pillared (SO₄ ^2-) ultra-microporous material, denoted as SOFOUR-DPDS-Ni (SOFOUR = SO₄ ^2-, 4-DPDS = 4,4'-dipyridyldisulfide), for efficient C₂H₂ capture from both CO₂ and C₂H₄. The sulfate pillars play a crucial role in inducing robust negative electrostatic potentials within the intralayer cavities and interlayer channels, thereby facilitating the selective recognition of C₂H₂. As a result, SOFOUR-DPDS-Ni demonstrates a remarkable C₂H₂ adsorption capacity of 1.60 mmol g^-1 at 0.01 bar, an exceptional selectivity of 174 for the 50/50 C₂H₂/CO₂ mixture, and a high selectivity of 65 for the 1/99 C₂H₂/C₂H₄ mixture. These impressive metrics position SOFOUR-DPDS-Ni as a promising adsorbent for benchmark C₂H₂ separations. Dynamic breakthrough experiments validate its outstanding performance in separating C₂H₂ from both the CO₂ and C₂H₄ mixtures. Computational simulations reveal the strong interactions between C₂H₂ and sulfate pillars, shedding light on the underlying mechanisms driving the adsorption process.