The effect of pore structure on the CO2 adsorption efficiency of polyamine impregnated porous carbons

The effect of polyamine impregnation on the CO2 adsorption properties of two different porous carbons, one microporous and one mesoporous, was studied systematically. The pore filling during impregnation with polyamines was shown to result in a fraction of the unfilled micropore volume being blocked for gas adsorption. Thermal gravimetric analysis was used to compare the CO2 capacity at 0.1 bar with respect to the carbon support type, the amount of amine loading, and the type of amine. A 12 fold increase in the CO2 capacity was observed when the impregnated activated carbon was compared to the raw starting material. A heat of adsorption for amine impregnated support of ~90 kJ mol-1 was found, clearly indicating a chemisorption mechanism. The mesoporous material provided a more efficient support for the amine to interact with the CO2. The interaction between low molecular weight amines and CO2 showed a more efficient utilization of the basic groups in comparison to high molecular weight species.