Enhanced N-doped Porous Carbon Derived from KOH-Activated Waste Wool: A Promising Material for Selective Adsorption of CO2/CH4 and CH4/N2

Separation of impurities (CO2 and N-2) from CH4 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 CO2, CH4, and N-2 are systematically measured on this enhanced N-doped porous carbon at 0 and 25 degrees 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 CO2/CH4 and CH4/N-2 at different mixing ratios according to the ideal adsorbed solution theory (IAST) model. At an ambient condition of 25 degrees C and 1 bar, the predicted selectivities for equimolar CO2/CH4 and CH4/N-2 are 3.19 and 7.62, respectively, and the adsorption capacities for CO2, CH4, 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 CO2/CH4 and CH4/N-2.