Highly Selective and Stable Carbon Dioxide Uptake in Polyindole-Derived Microporous Carbon Materials

摘要

Adsorption with solid sorbents is considered to be one of the most promising methods for the capture of carbon dioxide (CO_2) from power plant flue gases. in this study, microporous carbon materials used for CO_2 capture were synthesized by the chemical activation of polyindole nanofibers (PIF) at temperatures from 500 to 800 ℃ using KOH, which resulted in nitrogen (N)-doped carbon materials. The N-doped carbon materials were found to be microporous with an optimal adsorption pore size for CO_2 of 0.6 nm and a maximum (Brunauer-Emmett-Teller) BET surface area of 1185 m~2 g~(-1). The PIF activated at 600 ℃ (PIF6) has a surface area of 527 m~2 g~(-1) and a maximum CO_2 storage capacity of 3.2 mmol g~(-1) at 25 ℃ and 1 bar. This high CO_2 uptake is attributed to its highly microporous character and optimum N wntent. Additionally, PIF6 material displays a high CO_2 uptake at low pressure (1.81 mmol g~(-1) at 0.2 bar and 25 ℃), which is the best low pressure CO_2 uptake reported for carbon-based materials. The adsorption capacity of this material remained remarkably stable even after 10 cycles. The isosteric heat of adsorption was calculated to be in the range of 42.7-24.1 kI mol~(-1). Besides the excellent CO_2 uptake and stability, PiF6 also exhibits high selectivity values for CO_2 over N_2, CH_4, and H-2 of 58.9, 12.3, and 101.1 at 25 ℃, respectively, and these values are significantly higher than reported values.