Adsorption of Low-Concentration Carbon Dioxide on Amine-Modified Carbon Nanotubes at Ambient Temperature

A solid amine adsorbent for CO 2 was developed by carbon nanotubes (CNTs) impregnated with tetraethylenepentamine (TEPA). The adsorption behavior toward CO 2 (2.0 vol %) was investigated in a fixed-bed column. After modification, the adsorption capacity of CNTs–TEPA reached 2.97 mmol g –1 at 298 K. Rising temperatures from 283 to 313 K enhanced the CO 2 adsorption capacity. The maximum adsorption capacity was approximately 3.56 mmol g –1 at 313 K. The adsorption capacity was also influenced by moisture and reached as high as 3.87 mmol g –1 (2.0% H 2 O). In comparison to many other types of modified carbon or silica adsorbents in the literature, CNTs–TEPA had a higher adsorption capacity at the same temperature. The adsorption capacity for CO 2 remained almost the same after cyclic regeneration experiments. A deactivation model, capable of describing the uptake of CO 2, was applied under various conditions. In all cases, the experimental data agreed with the predicted breakthrough model.