Preparation of biomass-derived porous carbons by a facile method and application to CO2 adsorption

Abstract

In this work, a facile KOH activation was explored to prepare porous carbonaceous CO2 adsorbents using water chestnut shell as the raw material. This strategy integrates the carbonization and activation process together, which can avoid tedious multiple-step synthesis. The resultant adsorbents possess highly developed porous structures, which leads to good CO2 uptake under 1 bar, up to 3.61 and 5.23 mmol/g at 1 bar, 25 °C and 0 °C, respectively. Additional investigation was conducted to point out the main factors that determine the CO2 uptake of as-synthesized adsorbents. It is found that in addition to the volume of narrow micropores, pore size and pore size distribution of the sorbents play indispensable roles in their CO2 adsorption capacities. Thus, carbonaceous sorbents with high CO2 uptake should have the features of high amount of narrow micropores, together with small and narrow-distributed pore size. Aside from large CO2 uptake, these water chestnut shell-based carbons also hold stable recyclability, good CO2/N2 selectivity, suitable heat of adsorption, fast adsorption kinetics, and fair dynamic adsorption capacity. This study hopes to provide useful information that might profit the CO2 capture by biomass-derived carbons in realistic application.