Enhanced N-doped Porous Carbon Derived from KOH-Activated Waste Wool: A Promising Material for Selective Adsorption of CO(2)/CH(4) and CH(4)/N(2)

Separation of impurities (CO(2) and N(2)) from CH(4) is an important issue for natural gas alternatives (such as coalbed gas, biogas, and landfill gas) upgrading. It is notably challenging to synthesize high N-doped porous carbon with an appropriate porous structure. In this work, high N content (14.48 wt %) porous carbon with micropore size of 0.52 and 1.2 nm and specific surface area of 862 m(2) g(−1) has been synthesized from potassium hydroxide (KOH) activated waste wool upon the urea modification. Pure component adsorption isotherms of CO(2), CH(4), and N(2) are systematically measured on this enhanced N-doped porous carbon at 0 and 25 °C, up to 1 bar, to evaluate the gases adsorption capability, and correlated with the Langmuir model. These data are used to estimate the separation selectivities for binary mixtures of CO(2)/CH(4) and CH(4)/N(2) at different mixing ratios according to the ideal adsorbed solution theory (IAST) model. At an ambient condition of 25 °C and 1 bar, the predicted selectivities for equimolar CO(2)/CH(4) and CH(4)/N(2) are 3.19 and 7.62, respectively, and the adsorption capacities for CO(2), CH(4), and N(2) are 2.91, 1.01, and 0.13 mmol g(−1), respectively. This report introduces a simple pathway to obtain enhanced N-doped porous carbon with large adsorption capacities for gas separation of CO(2)/CH(4) and CH(4)/N(2).