High-performance CO2 sorbents from algae

Highly porous N-doped carbon materials with apparent surface areas in the 1300 2400 m g range and pore volumes up to 1.2 cm g have been synthesized from hydrothermal carbons obtained from mixtures of algae and glucose. The porosity of these materials is made up of uniform micropores, most of them having sizes < 1 nm. Moreover, they have N contents in the 1.1 4.7 wt% range, this heteroatom being mainly as pyridone-type structures. These microporous carbons present unprecedented large CO2 capture capacities, up to 7.4 mmol g (1 bar, 0 oC). The importance of the pore size on the CO2 capture capacity of microporous carbon materials is clearly demonstrated. Indeed, a good correlation between the CO2 capture capacity at subatmospheric pressure and the volume of narrow micropores is observed. The results suggest that pyridinic-N, pyridonic/pyrrolic-N and quaternary-N do not contribute significantly to the CO2 adsorption capacity, owing probably to their low basicity in comparison with amines. These findings point out a key for the design of highperformance CO2 capture sorbents.