Adsorption of CO sub(2) on Amine-Grafted Activated Carbon

Adsorption on amine-grafted materials may be a potentially attractive alternative to capture CO sub(2) from power plants. Activated carbon (AC) has been proposed as a potential adsorbent due to its natural affinity for CO sub(2) and the possibility of tailoring its textural properties and surface chemistry to enhance capacity and selectivity. An AC commercial sample was functionalized with monoethanolamine to obtain nitrogen-enriched AC with two different loadings (ACN10 and ACN20). Characterization of the sample was carried out by nitrogen adsorption-desorption isotherms at 77 K, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and adsorption microcalorimetry. The CO sub(2) equilibrium adsorption experiments were carried out in a volumetric system within the pressure range from vacuum to 13 bar, at 298 and 348 K. Impregnated AC showed different chemical and textural characteristics with a significant reduction in the surface area, depending on the amine loading. A high adsorption capacity at room temperature (298 K) and high pressure was observed for the pristine AC as compared with the modified samples. The reduction in surface area affected the adsorption capacity of CO sub(2) at 298 and 348 K, except for adsorption on ACN10 at 348 K, which suggests the occurrence of chemisorption.