Multiple-amine functionalized γ–Al2O3 for post-combustion CO2 capture: Performance, mechanism, and kinetics

High-efficiency and cost-effective adsorbents are crucial to dry capture of carbon dioxide (CO 2 ). The polyethyleneimine (PEI) was co-impregnated with tetraethylenepentamine (TEPA) on γ-alumina (Al 2 O 3 ) to synthesize the adsorbent and enhance the capture process. The influence of amine loading and operating parameters on CO 2 adsorption was investigated, and the process parameters were modeled. The results depict that the optimal loading is 50 % when functionalized either PEI or TEPA individually, which is 3.7 and 4.6 times higher than γ–Al 2 O 3 . The CO 2 capacity of γ–Al 2 O 3 functionalized with multiple amines (30 %PEI+20 %TEPA) is 2.65 mmol/g, due to the synergies of the two amines to increase the chance of CO 2 binding to the sites. Regeneration performance illustrates that the adsorbent remains at 90.2 % of the initial capacity after seven tests. The maximal capacity of 2.70 mmol/g occurs at 70 °C. Modeling results indicate the kinetics can be evaluated by the Avrami model (R 2  > 0.990) with the activation energy of 5.65 kJ/mol. The process is controlled by physical–chemical adsorption, influenced by intraparticle diffusion, as described by the deactivation model. Finally, a comparison and assessment were conducted for their techno-economic performances, and the pathway to applications was also proposed in engineering practice.