CO2 Capture Performance and Oxidative Degradation of Tetraethylenepentamine-Containing Adsorbents: Insights into the Contribution of Each Component

Amine-functionalized materials have been widely investigated as promising candidates for CO2 capture. Tetraethylenepentamine (TEPA) is a commercial polyamine commonly used as a prototypical amine to develop effective adsorbents for post-combustion CO2 capture. In previous studies, TEPA has been explicitly or implicitly treated as a pure compound of a linear molecule bearing five nitrogen atoms linked by four ethylene units. However, TEPA is a mixture of four main ethyleneamine compounds, including a linear, a branched, and two cyclic structural products, with similar boiling points. The four main components of TEPA were separated and purified in this work. The CO2 adsorption performance and stability of the purified TEPA components were then investigated, clarifying the influence of the structure of the TEPA components on the adsorption performance and stability of amine solid sorbents. The CO2 adsorption performance and oxidative stability of the sorbents were found to be dependent on the structure of the TEPA components. Among the isolated TEPA components, polyamines with piperazine rings exhibited a higher amine efficiency, regeneration ability, and O2 resistance. The evidence from infrared gas chromatography, and nuclear magnetic resonance data suggests that the deactivation of TEPA components can be caused by chain cleavage, branching, and/or cross-linking, leading to the formation of new species. The results of this work could open a new approach for the further development of novel effective and stable amine solid sorbents for CO2 capture.