Porous carbonaceous materials from hydrothermal carbonization and KOH activation of corn stover for highly efficient CO2 capture

Sustainable biomass-derived carbon materials were produced by hydrothermal carbonization of corn stover that was followed by chemical activation with KOH. The prepared carbon materials were used for CO2 adsorption and had a CO2 uptake of 7.14 mmol/g at a pressure of 1 bar and at 0°C that was much higher than CO2 uptake by activated carbon that was prepared from direct activation of corn stover (2.78 mmol/g). The porous corn stover-derived carbonaceous material had high surface area (2442 m2/g) and large pore volume (1.55 cm3/g). Product yields obtained by the activation of hydrothermally carbonized corn stover were significantly higher than those obtained by the direct activation of corn stover (36–75 vs. 8%). The prepared corn stover-derived porous carbon had a high CO2/N2 selectivity of 15.5 and exhibited constant CO2 uptake for five successive reuse cycles. The hydrothermal carbonization step plays an important role for producing porous carbons from biomass that have high and specific adsorption properties.