Effect of pore size on carbon dioxide sorption by carbide derived carbon

Abstract

CO 2 sorption at atmospheric and sub-atmospheric pressures is a key step towards carbon capture and sequestration (CCS) and materials capable of fast and efficient CO 2 uptake are currently being studied extensively. Carbide-derived carbons (CDCs) show a very high sorption capacity for CO 2 of up to 7.1 mol/kg at 0 °C and ambient pressure. This value is significantly higher than other carbon materials. Systematic experimental investigation of a large number of different CDCs derived from nano- and micrometer sized precursors with and without activation show a linear correlation between the CO 2 uptake at a certain pressure and the pore volume. However, CO 2 sorption is not limited by the total pore volume but only by pores smaller than a certain diameter. At 1 bar, pores smaller than 0.8 nm contribute the most to the CO 2 uptake and at 0.1 bar pores smaller or equal to 0.5 nm are preferred. With lower total pressure, smaller pores contribute more to the measured amount of adsorbed CO 2. The prediction of the CO 2 uptake based on the pore volume for pores of a certain diameter is much more accurate than predictions based on the mean pore size or the specific surface area. This study provides guidelines for the design of materials with an improved ability to remove carbon dioxide from the environment at atmospheric and lower pressures. © 2011 The Royal Society of Chemistry.