Waste-to-Resource Transformation: Porous Carbon Materials Derived from Distiller’s Grains for Efficient Adsorption of Light Gaseous Hydrocarbons

The efficient separation of light gaseous hydrocarbons, particularly the extraction of propane (C3H8) 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 C3H8 and 9.55 mmol g–1 for ethane (C2H6). Ideal adsorbed solution theory (IAST) calculations further validated its high selectivity, with predicted values of 79.6 for C3H8/CH4 and 14.9 for C2H6/CH4 separations. Breakthrough experiments confirmed the practical viability of AC-3-800, demonstrating complete separation of a 15/85 C3H8/CH4 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 C3H8/CH4 selectivity. Its performance positions it as a promising candidate for industrial-scale natural gas upgrading and petrochemical applications.