A new nanoporous nitrogen-doped highly-efficient carbonaceous CO2 sorbent synthesized with inexpensive urea and petroleum coke

The objective of this research is to develop a cost-effective carbonaceous CO2 sorbent. Highly nanoporous N-doped carbons were synthesized by KOH activation of urea-modified petroleum coke. The resulting carbons show highly developed porosity and different amounts of nitrogen, depending on preparation conditions. This series of carbons exhibits high CO2 adsorption capacities ranging from 3.69 to 4.40 mmol/g and 5.69 to 6.75 mmol/g at 25 °C and 0 °C under atmospheric pressure, respectively. Specifically, the sample UC-650-2 prepared at 650 °C with KOH/precursor ratio of 2 shows the highest CO2 uptake of 4.40 mmol/g at 25 °C, which is among the best of the known nitrogen-doped porous carbons. This high CO2 capture capacity is due to the synergy of the sorbent's high microporosity and nitrogen content. In addition, the CO2/N2 selectivity of the sorbent is 17, higher than that of many reported CO2 sorbents. The multi advantages of the sorbent including its easy synthesis, low cost, high CO2 uptake capacity and selectivity as well as regenerability demonstrates that the nanoporous nitrogen-doped carbon is promising for CO2 capture.