Plasma-mediated F-doped activated carbon embedded with N and S atoms for the effective removal of CO2 gas

Abstract

In this work, we suggest NF₃ plasma-treated vacuum residue oil(VR)-based activated carbon(AC) as a highly effective CO₂ adsorbent. The VR was pyrolyzed and activated under various conditions to determine the optimal activation conditions. The VR800AC, which have highest specific surface area of 1792.2 m²/g was selected as optimal sample and then, the VR800AC was treated with NF₃ plasma. Effects of NF₃ plasma treatment on the porosity and functionality of the VR-based AC were evaluated. Surface etching from plasma discharge induced micropores in the AC and enlarged the specific surface area. Moreover, fluorine functional groups were introduced after NF₃ plasma treatment. Synergistic effect of the N and S groups embedded in VR, F-groups derived from NF₃ plasma treatment, and micropores generated from plasma etching enhanced the CO₂ adsorption capacity of the NF₃ plasma-treated AC. After 60 s of NF₃ plasma treatment, the plasma-treated AC showed 14.5 % increased specific surface area, 13 % of surface fluorine groups, and revealed to have a CO₂ adsorption capacity of 4.55 mmol/g at 298 K and 1 bar, which is superior to that of the other heteroatom-doped ACs. Moreover, the NF₃ plasma-treated VR-based AC has excellent CO₂/N₂ adsorption selectivity and high CO₂ adsorption cyclability.