The N-doped activated carbon derived from sugarcane bagasse for CO2 adsorption

In this study, a highly selective CO2 adsorbent from sugarcane bagasse (waste biomass) was prepared, and the enrichment of nitrogen in the adsorbent was achieved via urea-KOH method. Moreover, the influence of preparing parameters such as urea addition, KOH/carbon ratio and activation temperature on the pore textural properties and CO2 uptake capacity of adsorbents were investigated. Brunauer Emmet Teller (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier Transform Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the adsorbents. The results indicated that whereas the temperature and pressure of 25 degrees C and 1 bar, the adsorbent had the highest CO2 uptake of 4.8 mmol/g. The preparation condition of the adsorbent was at 600 degrees C with 15 wt % urea additions and KOH/carbon ratio of 2.0. It was also found that there were pyridinic-N (N-6), pyrrolic-/pyridonic-N (N-5), quaternary-N (N-Q) and pyridine-N-oxide (N-X) functional groups at the surface. At the same time, the SB-AC had uniform micropores (similar to 0.55 nm). Hence, the adsorbent had an excellent CO2/N-2 selectivity. The CO2 uptake of the adsorbent was almost identical during the five runs of CO2 adsorption/desorption measurements, indicating good stability and regenerability CO2 adsorption. The narrow micro-pore volume (pore width <= 1 nm) fraction and N content in SB-ACs were 80-89% and 0.6-3.34 wt%, respectively. The results led to the conclusion that the narrow micropores and N content in the adsorbent were considered as the important roles for CO2 adsorption.