An activated carbon was successfully modified through Polyethylenimine (PEI) impregnation. Virgin and PEI-impregnated samples were tested for CO2 capture under post-combustion conditions (53 °C, 15 % CO2/85 % N2) by using a thermogravimetric analyser (TGA). The influence of different factors (e.g. PEI loading, type of solvent and stirring time) onto the CO2 sorption capacity of the modified carbons was assessed. In particular, compared to the conventional procedure [1], a longer agitation of the mixture PEI solution/carbon entailed attaining higher uptakes, likely due to a better dispersion of the polymer onto the support’s pores. Moreover, using water as solvent rather than methanol allowed achieving better performances, with the additional advantage of carrying out a more eco-friendly route. Despite a moderate pore blockage exhibited by all the modified samples, after the chemical treatment the virgin carbon’s CO2 capacity increased more than three folds. This outstanding enhancement was attributed to the N-based functionalities incorporated onto pristine carbon’s surface after the PEI impregnation. These were detected by XPS analyses, which confirmed the effectiveness of the surface modification. This result is corroborated by the increased N content measured for PEI-modified samples by elemental analysis (CHNS). Basic groups ensured a higher selectivity of the sorbents toward carbon dioxide molecule. Furthermore, PEI-impregnated carbon showed larger uptakes and faster kinetics than those attained by Z13X included for comparison purposes. Overall, it was demonstrated that the improved PEI impregnation was an effective route to obtain selective CO2 sorbents starting from activated carbons. PEI-loaded sorbents are a promising alternative to liquid amines for post-combustion capture of CO2.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)