Comparative Study of CO₂ Capture by Carbon Nanotubes, Activated Carbons, and Zeolites

Carbon nanotubes (CNTs), granular activated carbon (GAC), and zeolites were modified by 3-aminopropyl-triethoxysilane (APTS) and were selected as adsorbents to study their physicochemical properties and adsorption behaviors of CO 2 from gas streams. The surface nature of these adsorbents was changed after the modification, which make them adsorb more CO 2 gases. Under the same conditions, the modified CNTs possess the greatest adsorption capacity of CO 2, followed by the modified zeolites and then the modified GAC. The mechanism of CO 2 adsorption on these adsorbents appears mainly attributable to physical force, which makes regeneration of spent adsorbents at a relatively low temperature become feasible. The APTS-modified CNTs show good performance of CO 2 adsorption as compared to many types of modified carbon and silica adsorbents reported in the literature. This suggests that the APTS-modified CNTs are efficient CO 2 adsorbents and that they possess potential applications for CO 2 capture from gas streams.