N-rich porous carbon with high CO2 capture capacity derived from polyamine-incorporated metal–organic framework materials

Abstract

N-doped porous carbon has a wide range of applications in many fields, such as gas adsorption and super-capacitor, which has stimulated active research for developing efficient strategies to fabricate N-rich porous carbon. In the present study, a series of N-rich porous carbons are derived from polyamine-incorporated metal–organic framework materials (MOFs). Results show that the N content of as-prepared porous carbon is greatly increased by loading polyethyleneimine (PEI) into ZIF-70 frameworks because the loaded PEI can adsorb onto the pore walls of the ZIF-70 and simultaneously supply carbon and N sources during the carbonization process. As a result, the surface area of the as-prepared sample is also increased. In addition, the N content of the porous carbon can be tuned by PEI loadings and carbonization temperature. The as-prepared N-rich porous carbons exhibit greatly enhanced CO₂-selective adsorption capacity compared to ZIF-70 and porous carbon derived from ZIF-70. Here the CO₂ capture capacity of the as-prepared N-rich porous increases with increasing N content due to considerable interaction affinity between doped N and CO₂ molecules. Thus, the as-prepared porous carbon with N content of 11.08 wt% displays high CO₂ uptake of 4.86 mmol g⁻¹ at 0 °C and 1 bar, albeit it has a moderate surface area of 652 m² g⁻¹. Moreover, the N-rich porous carbon clearly shows an excellent separation performance for CO₂-over-N₂ and CO₂-over-CH₄. Overall, polyamine-incorporated MOFs are an efficient strategy for controllable fabrication of N-rich porous carbon. The resulting products display a high CO₂-selective capture performance. It should be noted that, to achieve the optimal CO₂ capture ability, a comprehensive optimization of the polyamine-MOFs-derived porous carbon should be performed.