Efficient micropore sizes for carbon dioxide physisorption of pine cone-based carbonaceous materials at different temperatures

Abstract

Biomass-based activated carbons (ACs) are widely used as CO2 capturing materials. Most plant-based biomass contains a phytolith component that mainly comprises silica, which is an obstacle for developing the porosity of ACs. The silica elimination process (SE) has rarely been studied for developing the porosity of ACs. Here, we prepared pre-carbonized pine cones (CPC) as a starting material to investigate optimizing the micropores of ACs according to the preparation sequence. One was prepared by chemical activation (CA) and the subsequent SE (CPC-CA-SE/ACs) and the other was carried out the SE before CA (CPC-SE-CA/ACs). It was found significant differences on the pore development between two samples, the former showed a specific surface area of 1787 m2 g−1 and the microporosity of ∼92 % while the latter were 2047 m2 g−1 and ∼74 %, respectively. The highest CO2 adsorption capacities were exhibited in CPC-CA-SE/ACs of 6.57 mmol g−1 at 273 K and 1 bar, resulting from the effective pore size (< 1.1 nm). Furthermore, the highest CO2 capture performance of 0.75 mmol g−1 in the typical flue gas condition (15 % CO2/85 % N2) and superior regeneration properties during 10 adsorption–desorption cycles at 313 K were achieved in CPC-CA-SE/ACs. From the results, we found that the preparation sequence had a strong effect on the textural properties of the resultant of biomass-based ACs and their CO2 capture performance.