Nitrogen-enriched and hierarchically porous carbon macro-spheres – ideal for large-scale CO<inf>2</inf> capture

Abstract

A facile and efficient "spheridization" method is developed to produce nitrogen-enriched hierarchically porous carbon spheres of millimeters in diameter, with intricate micro-, meso- and macro-structural features. Such spheres not only show exceptional working capacity for CO2sorption, but also satisfy practical requirements for dynamic flow in post-combustion CO2capture. Those were achieved using co-polymerized acrylonitrile and acrylamide as the N-enriched carbon precursor, a solvent-exchange process to create hierarchically porous macro-sphere preforms, oxidization to induce cyclization of the polymer chains, and carbonization with concurrent chemical activation by KOH. The resulting carbon spheres show a relatively high CO2uptake of 16.7 wt% under 1 bar of CO2and, particularly, an exceptional uptake of 9.3 wt% under a CO2partial pressure of 0.15 bar at 25 °C. Subsequent structural and chemical analyses suggest that the outstanding properties are due to highly developed microporous structures and the relatively high pyridinic nitrogen content inherited from the co-polymer precursor, incorporated within the hierarchical porous structures. © 2014 the Partner Organisations.