CO2 Adsorption of Nitrogen-Doped Carbons Prepared from Nitric Acid Preoxidized Petroleum Coke
2017
Yang, Jie | Yue, Limin | Lin, Binbin | Wang, Linlin | Zhao, Yongle | Lin, Ying | Chang, Kaijiao | DaCosta, Herbert | Hu, Xin
Petroleum coke was pretreated by HNO₃ before urea modification and KOH activation to synthesize N-doped porous carbons. The as-synthesized samples were carefully characterized by various techniques. This series of samples demonstrate high CO₂ uptake at 1 bar up to 4.13 mmol/g at 25 °C and 6.24 mmol/g at 0 °C, respectively. In addition, these sorbents possess high CO₂/N₂ selectivity, stable reusability, moderate heat of CO₂ adsorption, and high dynamic CO₂ capture capacity under simulated flue gas conditions. Further comparison shows that sorbents synthesized by HNO₃ pretreatment possess higher nitrogen content and narrow microporosity than the control sample without HNO₃ pretreatment but a lower CO₂ uptake. Additional investigations show that in addition to nitrogen content and narrow micropores, the size of narrow micropores, the narrow micropore size distributions, surface acidity, and the content of specific N and O species on the surface of the N-doped porous carbons also play major roles in determining the CO₂ capture capacity under ambient condition. This work is intended to provide useful information and to inspire ways to develop new carbonaceous sorbents for removing CO₂ from combustion flue gas.
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