Adsorption may be a potentially attractive alternative to capturing CO 2 from stationary sources in the context of Carbon Capture and Sequestration (CCS) technologies. Activated carbon and zeolites are state-of-art adsorbents which may be used for CO 2 adsorption, however physisorption alone tends to be insignificant at high temperatures. In the present work, commercial adsorbents have been impregnated with monoethanolamine (MEA) and triethanolamine (TEA) in order to investigate the effect of the modified surface chemistry on CO 2 adsorption, especially above room temperature. Adsorption isotherms for CO 2 , N 2 and CH 4 were measured in a gravimetrically system in the pressure range of UHV to 10 bar, at 298 and 348 K for activated carbon and zeolite 13X supports. The adsorbed concentration of CO 2 was significantly higher than those of CH 4 and N 2 for both adsorbents in the whole pressure range studied, zeolite 13X showing a remarkable affinity for CO 2 at very low pressures. However, at 348 K, the adsorbed concentration of CO 2 decreases significantly. The supports impregnated with concentrated amine solutions and dried in air suffered a detrimental effect on the textural properties, although CO 2 uptake became much less susceptible to temperature increase. Impregnations carried out with dilute solution followed by drying in inert atmosphere yielded materials with very similar textural characteristics as compared to the parent support. CO 2 isotherms in such materials showed a significant change with similar capacities at 348 K as compared to the original support at 298 K in the case of activated carbons. The impregnated zeolite showed a decrease in adsorbed phase concentration in low pressures for a given temperature, but the adsorbed amount also seemed to be less affected by temperature. These results are promising and indicate that CO 2 adsorption may be enhanced despite high process temperatures (e.g. 348 K), if convenient impregnation and drying methods are applied.

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Adsorption on amine-grafted materials may be a potentially attractive alternative to capture CO 2 from power plants. Activated carbon (AC) has been proposed as a potential adsorbent due to its natural affinity for CO 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 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 2 at 298 and 348 K, except for adsorption on ACN10 at 348 K, which suggests the occurrence of chemisorption.