Activation Effect of Fullerene C60 on the Carbon Dioxide Absorption Performance of Amine-Rich Polypropylenimine Dendrimers

Abstract

Converting amine-rich compounds into highly effective carbon dioxide (CO2 ) sorbents requires a better understanding and control of their properties. The reaction of fullerene C60 with polyethyleneimine converts the polymer into a high-performance CO2 sorbent. In this study, experimental evidence is reported for the activation effect of C60 on the amine moieties of the polymer. To do so, polypropylenimine (PPI) dendrimers that allowed for a systematic comparison of molecular composition and CO2 absorption were used. The addition of C60 to PPI to form PPI-C60 results in a reduction of the energy barrier of CO2 absorption, but also in a parallel decrease in the frequency of successful collisions between CO2 and PPI-C60 due to a possible disruption of the hydrogen-bonding network of amino groups and bound water in PPI. This finding supports the existence of a non-affinity "repulsive" effect between hydrophobic C60 and hydrophilic amines that forces them to be actively exposed to CO2.

Keywords: absorption; carbon dioxide capture; dendrimers; fullerenes; kinetics.