CO₂ Uptake Behavior of Supported Tetraethylenepentamine Sorbents

Supported tetraethylenepentamine (TEPA) sorbents have been proposed as an attractive alternative for postcombustion carbon capture. To promote the application of these sorbents, in this work, a systematic investigation of CO₂ absorption behavior on five TEPA-immobilized sorbents was conducted, in which the effects of TEPA loading, supports, and temperatures on both CO₂ absorption working capacity and kinetics were studied. Poly(methyl methacrylate) (PMMA)-TEPA is the best among the studied sorbents. The optimal temperature for PMMA-TEPA was 25 deg lower compared to other sorbents studied in this work, and the maximum CO₂ capacity was 0.17 g/g-sorbent. This is the highest value reported to date for PMMA-TEPA sorbents, and one of the high values that have been reported for TEPA-immobilized sorbents. In addition, the working capacity of PMMA-TEPA after six cycles of regeneration was 0.16 g/g-sorbent (i.e., with only 6% decrease). Therefore, PMMA is promising to be used as supporting material for TEPA in CO₂ capture. The kinetics analysis with both the Avrami's fractional-order kinetic model and the mass-transfer model on the basis of nonequilibrium thermodynamics was further conducted and discussed. Besides, it was also found that the CO₂ absorption kinetics and capacity were affected by both the pore structure and the surface chemistry of the support.