Hierarchical porous carbon beads for selective CO2 capture

Excessive CO2 emissions from increased energy consumption are causing an environmental disaster that threatens humanity. Herein, we report the development of hierarchical porous carbon beads with interconnected micro- and mesopores for selective CO2 capture. Hierarchical porous carbon beads were prepared by the carbonization of potassium-exchanged phenol formaldehyde resin (PFR) beads obtained from exchange of K+ to the PFR OH groups. Interestingly, the carbonized K2CO3-treated PFR (CPFRs) exhibited notably high surface areas and total pore volumes with interconnected micro- and mesopores. Based on their high porosities and nitrogen contents, the K2CO3-treated CPFR beads adsorbed 7.80 wt% CO2 at 0.15 bar and 298 K, which is an adsorption result that is much higher than those (4.41 wt% and 5.33 wt%) of pristine and KOH-treated CPFR beads, respectively. More importantly, the ideal CO2/N-2 selectivity (52.6) of K2CO3-treated CPFR beads, as determined by Henry's constant at room temperature, is superior to those (24.2 and 28.6) of pristine and KOH-treated CPFR beads, respectively. Breakthrough experiments with 15 % CO2 in N-2, which has a similar partial pressure to the CO2 partial pressure in flue gases from coal power plants, revealed that K2CO3-treated CPFR beads selectively adsorb 5.5 wt% of CO2 over N-2. This selective CO2 capacity is superior to those reported in other porous carbon materials. Therefore, to reduce CO2 emissions, hierarchical porous carbon beads with inter-connected micro- and mesopores can play an important role in CO2 capture and separation.