Asphalt-derived high surface area activated porous carbons for carbon dioxide capture

Research activity toward the development of new sorbents for carbon dioxide (CO₂) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO₂ uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO₂ uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (>600°C) yields porous carbon materials (A-PC) with high surface areas of up to 2780 m² g^-1 and high CO₂ uptake performance of 21 mmol g^-1 or 93 wt % at 30 bar and 25°C. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in the Brunauer-Emmett-Teller (BET) surface areas up to 2860 m² g^-1 for A-NPC and CO₂ uptake to 26 mmol g^-1 or 114 wt % at 30 bar and 25°C for A-rNPC. This is the highest reported CO₂ uptake among the family of the activated porous carbonaceous materials. Thus, the porous carbon materials from asphalt have excellent properties for reversibly capturing CO₂ at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO₂. Through a pressure swing sorption process, when the asphalt-derived material is returned to 1 bar, the CO₂ is released, thereby rendering a reversible capture medium that is highly efficient yet very inexpensive.