Two-step preparation of asphalt-based porous carbon adsorbent with superior C₂H₆/CH₄ selectivity for ethane recovery from natural gas

Efficient recovery of ethane (C₂H₆) from natural gas is of industrial importance, yet it poses considerable challenges. Herein, we report the two-step green preparation of asphalt-based carbon adsorbent Asphalt-based Carbon adsorbents (AsCs) with exceptional C₂H₆/CH₄ selectivity and high capacity, where the KOH usage can be significantly reduced by 75% than conventional chemical activation processes. More importantly, the resulting AsC-0.75-900 exhibits exceptional C₂H₆/CH₄ separation performance with the ideal adsorbed solution theory (IAST) selectivity of 30.74 and C₂H₆ capacity of 4.53 mmol/g at 298 K and 100 kPa. Notably, even at the low pressure of 10 kPa, its C₂H₆ uptake remains high at 2.25 mmol/g, comparable to many advanced metal-organic frameworks (MOFs). Molecular simulation was used to elucidate the adsorption mechanism. Fixed-bed experiments further demonstrate dynamic separation performance, achieving complete separation of a C₂H₆/CH₄ binary mixture (10:90, v/v) at ambient condition. In addition to superior separation performance, AsC-0.75-900 offers inherent structural stability and cost-effectiveness, positioning it a highly promising candidate for C₂H₆ recovery from natural gas.