On the limits of CO2 capture capacity of carbons

This study shows that standard techniques used for carbons characterization, such as physical adsorption of CO2 at 273 K and N-2 at 77K, can be used to assess, with a good accuracy, the maximum capacity of carbons to capture CO2 under post- and pre-combustion conditions. The analysis of the corresponding adsorption isotherms, within the general theoretical framework of Dubinin's theory, leads to the values of the micropore volume, W-o, and the characteristic energy, E-o, of the carbons, which provide direct information on the equilibrium CO2 uptake of the carbons at different pressures and temperatures. Although in special cases slightly higher values can be obtained, an overall assessment of the textural parameters for a large variety of activated carbons, indicates that a CO2 uptake upper-bound around 10-11 wt% seems to be realistic for standard activated carbons under post-combustion conditions. In the case of pre-combustion conditions, this limit would not exceed 60-70 wt%. (C) 2010 Elsevier B.V. All rights reserved.