Enhancing Sorption Performance of Solid Amine Sorbents for CO2 Capture by Additives

In order to improve the CO2 sorption performance of solid amine sorbent, the additives has been introduced into polyethylenimine (PEI) for reducing the diffusion resistance for CO2 molecular. Several additives have been added into the PEI in the sorbent to examine their effects on the sorption capacity and the sorption rate. The sorption performance of the sorbents with different additive in PEI was evaluated by using TGA, and the results show that only some additives can significant increase the sorption capacity, but not all of them. In order to understand how the additives improved the sorption performance, the viscosity of PEI with and without the additives was measured in the presence and absence of CO2. It was found that the decrease in viscosity after adding the additives may be one of the reasons for facilitating the diffusion of the sorbed CO2 molecules from the surface of PEI into the bulk of PEI, probably due to weakening the interaction of the CO2 molecule with the amine group. The additives may also provide some channels for CO2 moving into deeper PEI films, and thus increase the total accessible sites and improve the efficiency of amine. And this may be another reason for additives enhance sorption performance. (C) 2013 The Authors. Published by Elsevier Ltd.