Abstract
The efficient separation of light gaseous hydrocarbons, particularly the extraction of propane (C(3)H(8)) from natural gas, is critical for optimizing petroleum refining processes and reducing energy consumption. In this study, we demonstrate the synthesis of cost-effective porous carbon adsorbents derived from waste distiller's grains using an alkali-ion activation approach. By tuning the activating agent-to-precursor ratio, we systematically controlled the pore structure of the resulting materials, leading to a proportional increase in the specific surface area with higher activating agent concentrations. The optimized adsorbent, designated AC-3-800, exhibited exceptional performance at 273 K and 1 bar, achieving adsorption capacities of 14.87 mmol g(-1) for C(3)H(8) and 9.55 mmol g(-1) for ethane (C(2)H(6)). Ideal adsorbed solution theory (IAST) calculations further validated its high selectivity, with predicted values of 79.6 for C(3)H(8)/CH(4) and 14.9 for C(2)H(6)/CH(4) separations. Breakthrough experiments confirmed the practical viability of AC-3-800, demonstrating complete separation of a 15/85 C(3)H(8)/CH(4) mixture at 298 K and excellent cyclic stability over multiple adsorption/desorption cycles. These findings highlight AC-3-800 as a scalable and sustainable adsorbent for light hydrocarbon separations, offering a compelling balance of low cost, high adsorption capacity, and superior C(3)H(8)/CH(4) selectivity. Its performance positions it as a promising candidate for industrial-scale natural gas upgrading and petrochemical applications.