Base-type nitrogen doping in zeolite-templated carbon for enhancement of carbon dioxide sorption

Nitrogen-doped microporous carbons were synthesized via pyrolytic carbonization of pyrrole in a FAU zeolite template, using a carbonization temperature of either 600 or 700 °C. The carbon products, which were freed by dissolution of the template, all possessed a zeolite-like ordered pore arrangement with a high specific surface area of 2300–2500 m2 g−1 and a sharp distribution of pore diameters centered at 0.9 nm. The N content was similarly 5 wt%, but X-ray photoelectron spectroscopy analysis indicated that the 600 °C-pyrolized carbon had a relatively higher content of base-type N atoms (i.e., pyridinic and pyrrolic) than non-basic N (graphenic and oxidic), compared to the case at 700 °C. The 600 °C-pyrolized carbon exhibited an outstandingly high CO2 uptake. A breakthrough test with a CO2-H2O-N2 mixture at 1 bar indicated that the 600 °C-pyrolized carbon could capture CO2 effectively under humid conditions. This result suggests that it is important for CO2 capture, to achieve a high N content when doping with pyridinic or pyrrolic N as the major species. The high adsorption performance of zeolite-template carbon was attributable to the higher content of pyridinic N and pyrrolic N over graphitic N in the carbon, which provided basicity resulting in a strong chemisorption interaction with CO2.