Acetylated narrow micropores carbon for CO2 and CH4 adsorption

In this study, a series of microporous carbon bead adsorbents were prepared via the hydrothermal activation of acetyl-rich cellulose acetate with potassium hydroxide at elevated temperatures. The adsorbents were characterized through the use of a range of analytical techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR), X-ray diffraction (XRD), HCS thermodynamic software, and Raman spectroscopy (Raman). The results showed that the surface pores of carbon microspheres were uniformly distributed with homogeneous narrow microporous structure (0.50–1.14 nm) when the acetyl group content was 54.5%, and the narrow micropores pore volume of the adsorbent increased with the increase of the acetyl group content, so that the CAC-54.5–700 had the highest V_{0.50–1.14 nm} (0.47 m³/g), which provided an excellent adsorption site for the adsorption of CH₄ and CO₂, and at the same time The acetyl group provides more oxygen-containing functional groups (C–O), which improves the adsorption capacity and regeneration ability of the adsorbent. The carbon material CAC-54.5–700 showed excellent selectivity for CO₂ and CH₄ adsorption up to 6.05 mmol/g and 3.18 mmol/g, as well as for CH₄/N₂ (21.6), and the adsorption process conformed to the Freundlich model. After several adsorption–desorption cycles, the adsorption penetration time of CH₄ was stabilized at 804 s/g, and the dynamic adsorption amount of CO₂ was stabilized at 1.6 mmol/g, indicating that the prepared acetylated porous carbon has good potentials for application in CH₄ and CO₂ enrichment.