Chemical Engineering Journal, Vol.286, 98-105, 2016
Role of micropores and nitrogen-containing groups in CO2 adsorption on indole-3-butyric acid potassium derived carbons
Nitrogen-rich carbons for CO2 capture have received much attention in recent years, but the role of N-containing groups in CO2 adsorption has not been clearly elucidated. In this study, indole-3-butyric acid potassium (IBAP) as a new precursor was used to prepare the nitrogen-rich carbons via one-step carbonization. The IBAP-derived carbon prepared at 700 degrees C exhibited high CO2 adsorption of 1.48 mmol/g at 0.15 bar and 4.53 mmol/g at 1 bar and 25 degrees C, among the highly efficient activated carbons for CO2 adsorption. The high CO2 adsorption was attributed to not only the high volume of effective micropores, but also the effective N-containing groups on the IBAP-derived carbons. When carbonization temperatures increased from 500 degrees C to 900 degrees C, the nitrogen contents in the IBAP-derived carbons decreased from 6.35% to 0.70%. X-ray photoelectron spectroscopy (XPS) analysis confirmed that the pyrrolic-N in IBAP was converted into pyridinic-N, quaternary nitrogen and pyridinic-N-oxide in the carbonization process, and their contents first increased and then decreased with increasing carbonization temperatures. Only the pyrrolic-N was proved to be effective for CO2 adsorption on the IBAP-derived carbons, and its contribution to CO2 adsorption was pronounced for the carbons prepared at low temperatures. For the well-developed porous carbons, the effective micropores were mainly responsible for CO2 adsorption via micropore filling. (C) 2015 Elsevier B.V. All rights reserved.