Effects of Microporosity and Surface Chemistry on Separation Performances of N-Containing Pitch-Based Activated Carbons for CO2/N2 Binary Mixture

In this study, N-containing pitch-based activated carbons (NPCs) were prepared using petroleum pitch with a low softening point and melamine with a high nitrogen content. The major advantage of the preparation method is that it enables variations in chemical structures and textural properties by steam activation at high temperatures. The adequate micropore structures, appropriate chemical modifications, and high adsorption enthalpies of NPCs are favorable for CO 2 adsorption onto carbon surfaces. Furthermore, the structure generates a considerable gas/N-containing carbon interfacial area, and provides selective access to CO 2 molecules over N 2 molecules by offering an increased number of active sites on the carbon surfaces. The highest CO 2 /N 2 selectivity, i.e., 47.5, and CO 2 adsorption capacity for a CO 2 /N 2 (0.15:0.85) binary gas mixture, i.e., 5.30 wt%, were attained at 298 K. The NPCs also gave reversible and durable CO 2 -capturing performances. All the results suggest that NPCs are promising CO 2 sorbents, which can meet the challenges of current CO 2 capture and separation techniques.