Heteroatom self-doped activated biocarbons from fir bark and their excellent performance for carbon dioxide adsorption

A series of cost-effective heteroatom-doped porous carbons has been developed from the agricultural by-products of fir bark by a two-step carbonization and activation process. The morphology, chemical characterization and texture properties were investigated by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), elemental analysis (EA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and N2 adsorption-desorption at 77 K. The results show that fir bark is a suitable precursor for preparing heteroatom-doped activated carbon, corresponding to hetero-oxygen (2.05–7.35 wt. %) and nitrogen (0.8-1.5 wt. %) doping. The lab-made AC materials derived from fir bark, with a surface area of 1377 m2/g, showed a very excellent sorption performance for CO2 up to 7 mmol/g and 5.2 mmol/g at 273 K and 298 K up to 1 bar, which was significantly higher than the commercial carbon materials and were among the highest compared with other biomass based ACs. The high CO2 uptakes, moderate heat of adsorption (Qst), good selectivity show that the high performance activated carbons for CO2 capturing at low pressure can be prepared by KOH activation of fir bark.