Efficient CO2 adsorption on porous carbon with nitrogen functionalities based on polybenzoxazine: High-pressure adsorption characteristics

Abstract

Ordered-interconnected porous carbon with nitrogen functionalities is a potential adsorbent for CO2 capture since it could adsorb CO2 gas through both physical and chemical mechanisms. Herein, we reported the preparation of ordered-interconnected porous carbons having nitrogen functionalities based on polybenzoxazine using a silica templating method. The CO2 adsorption measurement was performed at 30 °C and the pressure was varied from 1 to 40 bar. The results showed that the specific surface area (SSA) and pore volume showed a correlation trend indicating the increase with increasing silica templates up to 40 % and the carbon samples contained nitrogen functionalities on the surface (pyrrolic and pyridonic nitrogen, pyridinic nitrogen, and oxidized nitrogen). After CO2 activation, the nitrogen functionalities are still present on the surface of the porous carbon and the sample based on 40 wt% of silica (AC40%Si-800) exhibited the greatest SSA (1,391 m2/g) with extremely large pore volume (3.77 cm3/g). This led to the largest amount of CO2 uptake (25.07 mmol/g at 40 bar) recorded to date. For the first time, the computational study revealed that only pyridinic nitrogen (N-6) is capable of chemically adsorbing CO2 molecules via Lewis acid-base interaction, which synergistically enhanced the adsorption capability.