Adsorption of CO2 by Petroleum Coke Nitrogen-Doped Porous Carbons Synthesized by Combining Ammoxidation with KOH Activation
2016
Yang, Mingli | Guo, Liping | Hu, Gengshen | Hu, Xin | Chen, Jie | Shen, Siwei | Dai, Wei | Fan, Maohong
The goal of our research is developing an efficient and cost-effective carbonaceous CO₂ sorbent. Using petroleum coke as the precursor, porous nitrogen-doped carbons were prepared by combining ammoxidation with KOH activation. The as-synthesized samples possess highly developed microporosities and large nitrogen loadings. High CO₂ adsorption capacities of 3.76–4.57 mmol/g at 25 °C and 5.80–6.62 mmol/g at 0 °C under atmospheric pressure were achieved. Specifically, the sample prepared under mild temperature (650 °C) and low KOH/precursor ratio (KOH/precursor = 2) shows a CO₂ uptake of 4.57 mmol/g at 25 °C, among the highest achieved for nitrogen-doped porous carbons. This high CO₂ capture capacity can be attributed to the synergistic effect of nitrogen doping and high narrow microporosity of the sorbent. However, experimental evidence suggests that nitrogen doping contributes less than narrow microporosity. Additionally, the CO₂/N₂ selectivity and CO₂ heats of adsorption of the sorbent are as high as 22 and 37 kJ/mol, respectively. The sorbent also shows high cyclic stability, fast kinetics, and superior dynamic CO₂ capture capacity under simulated flue gas conditions, thereby demonstrating that it is an excellent candidate for CO₂ capture.
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