Imidazole-based hyper-cross-linked polymers derived porous carbons for CO2 capture

N-doped porous carbons (NPCs) are promising adsorbents for CO2 capture and sequestration. Herein a series of NPCs was easily prepared from imidazole-based hyper-cross-linked polymers (HCPs) by KOH chemical activation, and the nitrogen (N) content and porosity of the NPCs were carefully tuned by using pre-designed HCPs prepared from N-vinylimidazole (VIM) with the different feeding amount in the polymerization. The results indicate that the NPCs have a controllable N content (0.44-2.81 wt%) and porosity (BET surface area: 1248-2059 m(2)/g, pore volume: 0.80-1.12 cm(3)/g). These NPCs have a high CO2 uptake (180-258 mg/g at 273 K and 1.0 bar, 41-73 mg/g at 273 K and 0.15 bar) at a low pressure. In particular, the N content plays negligible role as compared to the porosity, and the CO2 uptake is linearly dependent on the pore volume for narrow micropores (V-d, d < 1.2 nm) and the ratio of V-d (d < 1.4 nm) in relation to the total pore volume (V-total). These NPCs own low isosteric heat of adsorption (20.0-29.9 kJ/mol), excellent recycling performance, and acceptable CO2/N-2 selectivity (Henry's law: 10.5-12.9). Our study provides promising porous carbons for CO2 capture and offers outstanding strategy for design and synthesis of the porous materials.