Resorcinol–formaldehyde resin-based porous carbon spheres with high CO2 capture capacities

Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol–formaldehyde resin spheres, and are investigated as CO2 adsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation" effect produced by the mono-dispersed potassium ions as a form of –OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high CO2 capture capacity of 4.83 mmol/g and good CO2/N2 selectivity of ∼17–45. We believe that the presence of a well-developed ultra-microporosity is responsible for excellent CO2 sorption performance at room temperature and ambient pressure.